Merge branch 'master' into wm-drag-drop-rewritewm-drag-drop-rewrite

14 files changed, 2953 insertions, 1688 deletions

diff --git a/source/blender/blenloader/intern/readblenentry.c b/source/blender/blenloader/intern/readblenentry.c
index adf7db0267e..1309b3e3c33 100644
--- a/source/blender/blenloader/intern/readblenentry.c
+++ b/source/blender/blenloader/intern/readblenentry.c
@@ -428,41 +428,6 @@ BlendFileData *BLO_read_from_memfile(Main *oldmain,
      * but oldmain itself shall *never* be 'transferred' to new mainlist! */
     BLI_assert(old_mainlist.first == oldmain);
 
-    if (bfd && old_mainlist.first != old_mainlist.last) {
-      /* Even though directly used libs have been already moved to new main,
-       * indirect ones have not.
-       * This is a bit annoying, but we have no choice but to keep them all for now -
-       * means some now unused data may remain in memory, but think we'll have to live with it. */
-      Main *libmain, *libmain_next;
-      Main *newmain = bfd->main;
-      ListBase new_mainlist = {newmain, newmain};
-
-      for (libmain = oldmain->next; libmain; libmain = libmain_next) {
-        libmain_next = libmain->next;
-        /* Note that LIB_INDIRECT does not work with libraries themselves, so we use non-NULL
-         * parent to detect indirect-linked ones. */
-        if (libmain->curlib && (libmain->curlib->parent != NULL)) {
-          BLI_remlink(&old_mainlist, libmain);
-          BLI_addtail(&new_mainlist, libmain);
-        }
-        else {
-#ifdef PRINT_DEBUG
-          printf("Dropped Main for lib: %s\n", libmain->curlib->id.name);
-#endif
-        }
-      }
-      /* In any case, we need to move all lib data-blocks themselves - those are
-       * 'first level data', getting rid of them would imply updating spaces & co
-       * to prevent invalid pointers access. */
-      BLI_movelisttolist(&newmain->libraries, &oldmain->libraries);
-
-      blo_join_main(&new_mainlist);
-    }
-
-#if 0
-    printf("Remaining mains/libs in oldmain: %d\n", BLI_listbase_count(&fd->old_mainlist) - 1);
-#endif
-
     /* That way, libs (aka mains) we did not reuse in new undone/redone state
      * will be cleared together with oldmain... */
     blo_join_main(&old_mainlist);
diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index 61179f65ad2..6a51102a969 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -86,6 +86,7 @@
 #include "DNA_sdna_types.h"
 #include "DNA_sequence_types.h"
 #include "DNA_shader_fx_types.h"
+#include "DNA_simulation_types.h"
 #include "DNA_sound_types.h"
 #include "DNA_space_types.h"
 #include "DNA_speaker_types.h"
@@ -109,7 +110,7 @@
 #include "BLT_translation.h"
 
 #include "BKE_action.h"
-#include "BKE_animsys.h"
+#include "BKE_anim_data.h"
 #include "BKE_armature.h"
 #include "BKE_brush.h"
 #include "BKE_collection.h"
@@ -117,7 +118,7 @@
 #include "BKE_constraint.h"
 #include "BKE_curve.h"
 #include "BKE_effect.h"
-#include "BKE_fcurve.h"
+#include "BKE_fcurve_driver.h"
 #include "BKE_fluid.h"
 #include "BKE_global.h"  // for G
 #include "BKE_gpencil_modifier.h"
@@ -146,6 +147,7 @@
 #include "BKE_screen.h"
 #include "BKE_sequencer.h"
 #include "BKE_shader_fx.h"
+#include "BKE_simulation.h"
 #include "BKE_sound.h"
 #include "BKE_volume.h"
 #include "BKE_workspace.h"
@@ -158,6 +160,7 @@
 
 #include "BLO_blend_defs.h"
 #include "BLO_blend_validate.h"
+#include "BLO_read_write.h"
 #include "BLO_readfile.h"
 #include "BLO_undofile.h"
 
@@ -470,8 +473,9 @@ static void *oldnewmap_liblookup(OldNewMap *onm, const void *addr, const void *l
   return NULL;
 }
 
-static void oldnewmap_free_unused(OldNewMap *onm)
+static void oldnewmap_clear(OldNewMap *onm)
 {
+  /* Free unused data. */
   for (int i = 0; i < onm->nentries; i++) {
     OldNew *entry = &onm->entries[i];
     if (entry->nr == 0) {
@@ -479,10 +483,7 @@ static void oldnewmap_free_unused(OldNewMap *onm)
       entry->newp = NULL;
     }
   }
-}
 
-static void oldnewmap_clear(OldNewMap *onm)
-{
   onm->capacity_exp = DEFAULT_SIZE_EXP;
   oldnewmap_clear_map(onm);
   onm->nentries = 0;
@@ -664,7 +665,7 @@ static Main *blo_find_main(FileData *fd, const char *filepath, const char *relab
   char name1[FILE_MAX];
 
   BLI_strncpy(name1, filepath, sizeof(name1));
-  BLI_cleanup_path(relabase, name1);
+  BLI_path_normalize(relabase, name1);
 
   //  printf("blo_find_main: relabase  %s\n", relabase);
   //  printf("blo_find_main: original in  %s\n", filepath);
@@ -691,7 +692,7 @@ static Main *blo_find_main(FileData *fd, const char *filepath, const char *relab
   /* Important, consistency with main ID reading code from read_libblock(). */
   lib->id.us = ID_FAKE_USERS(lib);
 
-  /* Matches lib_link_library(). */
+  /* Matches direct_link_library(). */
   id_us_ensure_real(&lib->id);
 
   BLI_strncpy(lib->name, filepath, sizeof(lib->name));
@@ -713,6 +714,20 @@ static Main *blo_find_main(FileData *fd, const char *filepath, const char *relab
 /** \name File Parsing
  * \{ */
 
+typedef struct BlendDataReader {
+  FileData *fd;
+} BlendDataReader;
+
+typedef struct BlendLibReader {
+  FileData *fd;
+  Main *main;
+} BlendLibReader;
+
+typedef struct BlendExpander {
+  FileData *fd;
+  Main *main;
+} BlendExpander;
+
 static void switch_endian_bh4(BHead4 *bhead)
 {
   /* the ID_.. codes */
@@ -1680,7 +1695,7 @@ bool BLO_library_path_explode(const char *path, char *r_dir, char **r_group, cha
 
   strcpy(r_dir, path);
 
-  while ((slash = (char *)BLI_last_slash(r_dir))) {
+  while ((slash = (char *)BLI_path_slash_rfind(r_dir))) {
     char tc = *slash;
     *slash = '\0';
     if (BLO_has_bfile_extension(r_dir) && BLI_is_file(r_dir)) {
@@ -2376,9 +2391,6 @@ static void *read_struct(FileData *fd, BHead *bh, const char *blockname)
       }
     }
 
-    if (!BHEADN_FROM_BHEAD(bh)->is_memchunk_identical) {
-      fd->are_memchunks_identical = false;
-    }
 #ifdef USE_BHEAD_READ_ON_DEMAND
     if (bh_orig != bh) {
       MEM_freeN(BHEADN_FROM_BHEAD(bh));
@@ -2389,6 +2401,15 @@ static void *read_struct(FileData *fd, BHead *bh, const char *blockname)
   return temp;
 }
 
+/* Like read_struct, but gets a pointer without allocating. Only works for
+ * undo since DNA must match. */
+static const void *peek_struct_undo(FileData *fd, BHead *bhead)
+{
+  BLI_assert(fd->memfile != NULL);
+  UNUSED_VARS_NDEBUG(fd);
+  return (bhead->len) ? (const void *)(bhead + 1) : NULL;
+}
+
 typedef void (*link_list_cb)(FileData *fd, void *data);
 
 static void link_list_ex(FileData *fd, ListBase *lb, link_list_cb callback) /* only direct data */
@@ -2670,7 +2691,7 @@ static void IDP_LibLinkProperty(IDProperty *prop, FileData *fd)
     }
     case IDP_GROUP: /* PointerProperty */
     {
-      for (IDProperty *loop = prop->data.group.first; loop; loop = loop->next) {
+      LISTBASE_FOREACH (IDProperty *, loop, &prop->data.group) {
         IDP_LibLinkProperty(loop, fd);
       }
       break;
@@ -2715,7 +2736,7 @@ static void lib_link_id(FileData *fd, Main *bmain, ID *id);
 static void lib_link_nodetree(FileData *fd, Main *bmain, bNodeTree *ntree);
 static void lib_link_collection(FileData *fd, Main *bmain, Collection *collection);
 
-static void lib_link_id_private_id(FileData *fd, Main *bmain, ID *id)
+static void lib_link_id_embedded_id(FileData *fd, Main *bmain, ID *id)
 {
   /* Handle 'private IDs'. */
   bNodeTree *nodetree = ntreeFromID(id);
@@ -2749,7 +2770,7 @@ static void lib_link_id(FileData *fd, Main *bmain, ID *id)
     id->override_library->storage = newlibadr(fd, id->lib, id->override_library->storage);
   }
 
-  lib_link_id_private_id(fd, bmain, id);
+  lib_link_id_embedded_id(fd, bmain, id);
 }
 
 static void direct_link_id_override_property_operation_cb(FileData *fd, void *data)
@@ -2758,6 +2779,8 @@ static void direct_link_id_override_property_operation_cb(FileData *fd, void *da
 
   opop->subitem_reference_name = newdataadr(fd, opop->subitem_reference_name);
   opop->subitem_local_name = newdataadr(fd, opop->subitem_local_name);
+
+  opop->tag = 0; /* Runtime only. */
 }
 
 static void direct_link_id_override_property_cb(FileData *fd, void *data)
@@ -2765,20 +2788,28 @@ static void direct_link_id_override_property_cb(FileData *fd, void *data)
   IDOverrideLibraryProperty *op = data;
 
   op->rna_path = newdataadr(fd, op->rna_path);
+
+  op->tag = 0; /* Runtime only. */
+
   link_list_ex(fd, &op->operations, direct_link_id_override_property_operation_cb);
 }
 
-static void direct_link_id(FileData *fd, ID *id, ID *id_old);
+static void direct_link_id_common(
+    FileData *fd, Library *current_library, ID *id, ID *id_old, const int tag);
 static void direct_link_nodetree(FileData *fd, bNodeTree *ntree);
 static void direct_link_collection(FileData *fd, Collection *collection);
 
-static void direct_link_id_private_id(FileData *fd, ID *id, ID *id_old)
+static void direct_link_id_embedded_id(FileData *fd, Library *current_library, ID *id, ID *id_old)
 {
   /* Handle 'private IDs'. */
   bNodeTree **nodetree = BKE_ntree_ptr_from_id(id);
   if (nodetree != NULL && *nodetree != NULL) {
     *nodetree = newdataadr(fd, *nodetree);
-    direct_link_id(fd, (ID *)*nodetree, id_old != NULL ? (ID *)ntreeFromID(id_old) : NULL);
+    direct_link_id_common(fd,
+                          current_library,
+                          (ID *)*nodetree,
+                          id_old != NULL ? (ID *)ntreeFromID(id_old) : NULL,
+                          0);
     direct_link_nodetree(fd, *nodetree);
   }
 
@@ -2786,28 +2817,106 @@ static void direct_link_id_private_id(FileData *fd, ID *id, ID *id_old)
     Scene *scene = (Scene *)id;
     if (scene->master_collection != NULL) {
       scene->master_collection = newdataadr(fd, scene->master_collection);
-      direct_link_id(fd,
-                     &scene->master_collection->id,
-                     id_old != NULL ? &((Scene *)id_old)->master_collection->id : NULL);
+      direct_link_id_common(fd,
+                            current_library,
+                            &scene->master_collection->id,
+                            id_old != NULL ? &((Scene *)id_old)->master_collection->id : NULL,
+                            0);
       direct_link_collection(fd, scene->master_collection);
     }
   }
 }
 
-static void direct_link_id(FileData *fd, ID *id, ID *id_old)
+static int direct_link_id_restore_recalc_exceptions(const ID *id_current)
+{
+  /* Exception for armature objects, where the pose has direct points to the
+   * armature databolock. */
+  if (GS(id_current->name) == ID_OB && ((Object *)id_current)->pose) {
+    return ID_RECALC_GEOMETRY;
+  }
+
+  return 0;
+}
+
+static int direct_link_id_restore_recalc(const FileData *fd,
+                                         const ID *id_target,
+                                         const ID *id_current,
+                                         const bool is_identical)
+{
+  /* These are the evaluations that had not been performed yet at the time the
+   * target undo state was written. These need to be done again, since they may
+   * flush back changes to the original datablock. */
+  int recalc = id_target->recalc;
+
+  if (id_current == NULL) {
+    /* ID does not currently exist in the database, so also will not exist in
+     * the dependency graphs. That means it will be newly created and as a
+     * result also fully re-evaluated regardless of the recalc flag set here. */
+    recalc |= ID_RECALC_ALL;
+  }
+  else {
+    /* If the contents datablock changed, the depsgraph needs to copy the
+     * datablock again to ensure it matches the original datablock. */
+    if (!is_identical) {
+      recalc |= ID_RECALC_COPY_ON_WRITE;
+    }
+
+    /* Special exceptions. */
+    recalc |= direct_link_id_restore_recalc_exceptions(id_current);
+
+    /* Evaluations for the current state that have not been performed yet
+     * by the time we are performing this undo step. */
+    recalc |= id_current->recalc;
+
+    /* Tags that were set between the target state and the current state,
+     * that we need to perform again. */
+    if (fd->undo_direction < 0) {
+      /* Undo: tags from target to the current state. */
+      recalc |= id_current->recalc_up_to_undo_push;
+    }
+    else {
+      /* Redo: tags from current to the target state. */
+      recalc |= id_target->recalc_up_to_undo_push;
+    }
+  }
+
+  return recalc;
+}
+
+static void direct_link_id_common(
+    FileData *fd, Library *current_library, ID *id, ID *id_old, const int tag)
 {
+  if (fd->memfile == NULL) {
+    /* When actually reading a file , we do want to reset/re-generate session uuids.
+     * In undo case, we want to re-use existing ones. */
+    id->session_uuid = MAIN_ID_SESSION_UUID_UNSET;
+  }
+
+  BKE_lib_libblock_session_uuid_ensure(id);
+
+  id->lib = current_library;
+  id->us = ID_FAKE_USERS(id);
+  id->icon_id = 0;
+  id->newid = NULL; /* Needed because .blend may have been saved with crap value here... */
+  id->orig_id = NULL;
+  id->py_instance = NULL;
+
+  /* Initialize with provided tag. */
+  id->tag = tag;
+
+  if (tag & LIB_TAG_ID_LINK_PLACEHOLDER) {
+    /* For placeholder we only need to set the tag and properly initialize generic ID fields above,
+     * no further data to read. */
+    return;
+  }
+
   /*link direct data of ID properties*/
   if (id->properties) {
     id->properties = newdataadr(fd, id->properties);
     /* this case means the data was written incorrectly, it should not happen */
     IDP_DirectLinkGroup_OrFree(&id->properties, (fd->flags & FD_FLAGS_SWITCH_ENDIAN), fd);
   }
-  id->py_instance = NULL;
 
-  /* That way data-lock reading not going through main read_libblock()
-   * function are still in a clear tag state.
-   * (glowering at certain nodetree fake data-lock here...). */
-  id->tag = 0;
   id->flag &= ~LIB_INDIRECT_WEAK_LINK;
 
   /* NOTE: It is important to not clear the recalc flags for undo/redo.
@@ -2820,32 +2929,11 @@ static void direct_link_id(FileData *fd, ID *id, ID *id_old)
    * the version the file has been saved with. */
   if (fd->memfile == NULL) {
     id->recalc = 0;
-    id->recalc_undo_accumulated = 0;
+    id->recalc_after_undo_push = 0;
   }
   else if ((fd->skip_flags & BLO_READ_SKIP_UNDO_OLD_MAIN) == 0) {
-    if (fd->undo_direction < 0) {
-      /* We are coming from the future (i.e. do an actual undo, and not a redo), and we found an
-       * old (aka existing) ID: we use its 'accumulated recalc flags since last memfile undo step
-       * saving' as recalc flags of our newly read ID. */
-      if (id_old != NULL) {
-        id->recalc = id_old->recalc_undo_accumulated;
-      }
-    }
-    else {
-      /* We are coming from the past (i.e. do a redo), we use saved 'accumulated
-       * recalc flags since last memfile undo step saving' as recalc flags of our newly read ID. */
-      id->recalc = id->recalc_undo_accumulated;
-    }
-    /* In any case, we need to flush the depsgraph's CoWs, as even if the ID address itself did not
-     * change, internal data most likely have. */
-    id->recalc |= ID_RECALC_COPY_ON_WRITE;
-
-    /* We need to 'accumulate' the accumulated recalc flags of all undo steps until we actually
-     * perform a depsgraph update, otherwise we'd only ever use the flags from one of the steps,
-     * and never get proper flags matching all others. */
-    if (id_old != NULL) {
-      id->recalc_undo_accumulated |= id_old->recalc_undo_accumulated;
-    }
+    id->recalc = direct_link_id_restore_recalc(fd, id, id_old, false);
+    id->recalc_after_undo_push = 0;
   }
 
   /* Link direct data of overrides. */
@@ -2861,7 +2949,7 @@ static void direct_link_id(FileData *fd, ID *id, ID *id_old)
   }
 
   /* Handle 'private IDs'. */
-  direct_link_id_private_id(fd, id, id_old);
+  direct_link_id_embedded_id(fd, current_library, id, id_old);
 }
 
 /** \} */
@@ -2955,6 +3043,19 @@ static void direct_link_brush(FileData *fd, Brush *brush)
                                                          brush->gpencil_settings->curve_strength);
     brush->gpencil_settings->curve_jitter = newdataadr(fd, brush->gpencil_settings->curve_jitter);
 
+    brush->gpencil_settings->curve_rand_pressure = newdataadr(
+        fd, brush->gpencil_settings->curve_rand_pressure);
+    brush->gpencil_settings->curve_rand_strength = newdataadr(
+        fd, brush->gpencil_settings->curve_rand_strength);
+    brush->gpencil_settings->curve_rand_uv = newdataadr(fd,
+                                                        brush->gpencil_settings->curve_rand_uv);
+    brush->gpencil_settings->curve_rand_hue = newdataadr(fd,
+                                                         brush->gpencil_settings->curve_rand_hue);
+    brush->gpencil_settings->curve_rand_saturation = newdataadr(
+        fd, brush->gpencil_settings->curve_rand_saturation);
+    brush->gpencil_settings->curve_rand_value = newdataadr(
+        fd, brush->gpencil_settings->curve_rand_value);
+
     if (brush->gpencil_settings->curve_sensitivity) {
       direct_link_curvemapping(fd, brush->gpencil_settings->curve_sensitivity);
     }
@@ -2966,6 +3067,30 @@ static void direct_link_brush(FileData *fd, Brush *brush)
     if (brush->gpencil_settings->curve_jitter) {
       direct_link_curvemapping(fd, brush->gpencil_settings->curve_jitter);
     }
+
+    if (brush->gpencil_settings->curve_rand_pressure) {
+      direct_link_curvemapping(fd, brush->gpencil_settings->curve_rand_pressure);
+    }
+
+    if (brush->gpencil_settings->curve_rand_strength) {
+      direct_link_curvemapping(fd, brush->gpencil_settings->curve_rand_strength);
+    }
+
+    if (brush->gpencil_settings->curve_rand_uv) {
+      direct_link_curvemapping(fd, brush->gpencil_settings->curve_rand_uv);
+    }
+
+    if (brush->gpencil_settings->curve_rand_hue) {
+      direct_link_curvemapping(fd, brush->gpencil_settings->curve_rand_hue);
+    }
+
+    if (brush->gpencil_settings->curve_rand_saturation) {
+      direct_link_curvemapping(fd, brush->gpencil_settings->curve_rand_saturation);
+    }
+
+    if (brush->gpencil_settings->curve_rand_value) {
+      direct_link_curvemapping(fd, brush->gpencil_settings->curve_rand_value);
+    }
   }
 
   brush->preview = NULL;
@@ -3030,7 +3155,7 @@ static PackedFile *direct_link_packedfile(FileData *fd, PackedFile *oldpf)
 // XXX deprecated - old animation system
 static void lib_link_ipo(FileData *fd, Main *UNUSED(bmain), Ipo *ipo)
 {
-  for (IpoCurve *icu = ipo->curve.first; icu; icu = icu->next) {
+  LISTBASE_FOREACH (IpoCurve *, icu, &ipo->curve) {
     if (icu->driver) {
       icu->driver->ob = newlibadr(fd, ipo->id.lib, icu->driver->ob);
     }
@@ -3251,7 +3376,7 @@ static void direct_link_fcurves(FileData *fd, ListBase *list)
 static void lib_link_action(FileData *fd, Main *UNUSED(bmain), bAction *act)
 {
   // XXX deprecated - old animation system <<<
-  for (bActionChannel *chan = act->chanbase.first; chan; chan = chan->next) {
+  LISTBASE_FOREACH (bActionChannel *, chan, &act->chanbase) {
     chan->ipo = newlibadr(fd, act->id.lib, chan->ipo);
     lib_link_constraint_channels(fd, &act->id, &chan->constraintChannels);
   }
@@ -3259,7 +3384,7 @@ static void lib_link_action(FileData *fd, Main *UNUSED(bmain), bAction *act)
 
   lib_link_fcurves(fd, &act->id, &act->curves);
 
-  for (TimeMarker *marker = act->markers.first; marker; marker = marker->next) {
+  LISTBASE_FOREACH (TimeMarker *, marker, &act->markers) {
     if (marker->camera) {
       marker->camera = newlibadr(fd, act->id.lib, marker->camera);
     }
@@ -3305,11 +3430,6 @@ static void lib_link_nladata_strips(FileData *fd, ID *id, ListBase *list)
 
     /* reassign the counted-reference to action */
     strip->act = newlibadr(fd, id->lib, strip->act);
-
-    /* fix action id-root (i.e. if it comes from a pre 2.57 .blend file) */
-    if ((strip->act) && (strip->act->idroot == 0)) {
-      strip->act->idroot = GS(id->name);
-    }
   }
 }
 
@@ -3404,14 +3524,6 @@ static void lib_link_animdata(FileData *fd, ID *id, AnimData *adt)
   adt->action = newlibadr(fd, id->lib, adt->action);
   adt->tmpact = newlibadr(fd, id->lib, adt->tmpact);
 
-  /* fix action id-roots (i.e. if they come from a pre 2.57 .blend file) */
-  if ((adt->action) && (adt->action->idroot == 0)) {
-    adt->action->idroot = GS(id->name);
-  }
-  if ((adt->tmpact) && (adt->tmpact->idroot == 0)) {
-    adt->tmpact->idroot = GS(id->name);
-  }
-
   /* link drivers */
   lib_link_fcurves(fd, id, &adt->drivers);
 
@@ -3482,15 +3594,11 @@ static void direct_link_cachefile(FileData *fd, CacheFile *cache_file)
 
 static void lib_link_workspaces(FileData *fd, Main *bmain, WorkSpace *workspace)
 {
-  ListBase *layouts = BKE_workspace_layouts_get(workspace);
   ID *id = (ID *)workspace;
 
-  id_us_ensure_real(id);
-
-  for (WorkSpaceLayout *layout = layouts->first, *layout_next; layout; layout = layout_next) {
+  LISTBASE_FOREACH_MUTABLE (WorkSpaceLayout *, layout, &workspace->layouts) {
     layout->screen = newlibadr(fd, id->lib, layout->screen);
 
-    layout_next = layout->next;
     if (layout->screen) {
       if (ID_IS_LINKED(id)) {
         layout->screen->winid = 0;
@@ -3510,39 +3618,34 @@ static void lib_link_workspaces(FileData *fd, Main *bmain, WorkSpace *workspace)
 
 static void direct_link_workspace(FileData *fd, WorkSpace *workspace, const Main *main)
 {
-  link_list(fd, BKE_workspace_layouts_get(workspace));
+  link_list(fd, &workspace->layouts);
   link_list(fd, &workspace->hook_layout_relations);
   link_list(fd, &workspace->owner_ids);
   link_list(fd, &workspace->tools);
 
-  for (WorkSpaceDataRelation *relation = workspace->hook_layout_relations.first; relation;
-       relation = relation->next) {
-
+  LISTBASE_FOREACH (WorkSpaceDataRelation *, relation, &workspace->hook_layout_relations) {
     /* data from window - need to access through global oldnew-map */
     relation->parent = newglobadr(fd, relation->parent);
-
     relation->value = newdataadr(fd, relation->value);
   }
 
   /* Same issue/fix as in direct_link_workspace_link_scene_data: Can't read workspace data
    * when reading windows, so have to update windows after/when reading workspaces. */
   for (wmWindowManager *wm = main->wm.first; wm; wm = wm->id.next) {
-    for (wmWindow *win = wm->windows.first; win; win = win->next) {
-      WorkSpaceLayout *act_layout = newdataadr(
-          fd, BKE_workspace_active_layout_get(win->workspace_hook));
-      if (act_layout) {
-        BKE_workspace_active_layout_set(win->workspace_hook, act_layout);
-      }
+    LISTBASE_FOREACH (wmWindow *, win, &wm->windows) {
+      win->workspace_hook->act_layout = newdataadr(fd, win->workspace_hook->act_layout);
     }
   }
 
-  for (bToolRef *tref = workspace->tools.first; tref; tref = tref->next) {
+  LISTBASE_FOREACH (bToolRef *, tref, &workspace->tools) {
     tref->runtime = NULL;
     tref->properties = newdataadr(fd, tref->properties);
     IDP_DirectLinkGroup_OrFree(&tref->properties, (fd->flags & FD_FLAGS_SWITCH_ENDIAN), fd);
   }
 
   workspace->status_text = NULL;
+
+  id_us_ensure_real(&workspace->id);
 }
 
 static void lib_link_workspace_instance_hook(FileData *fd, WorkSpaceInstanceHook *hook, ID *id)
@@ -3557,6 +3660,45 @@ static void lib_link_workspace_instance_hook(FileData *fd, WorkSpaceInstanceHook
 /** \name Read ID: Node Tree
  * \{ */
 
+static void lib_link_node_socket(FileData *fd, Library *lib, bNodeSocket *sock)
+{
+  IDP_LibLinkProperty(sock->prop, fd);
+
+  switch ((eNodeSocketDatatype)sock->type) {
+    case SOCK_OBJECT: {
+      bNodeSocketValueObject *default_value = sock->default_value;
+      default_value->value = newlibadr(fd, lib, default_value->value);
+      break;
+    }
+    case SOCK_IMAGE: {
+      bNodeSocketValueImage *default_value = sock->default_value;
+      default_value->value = newlibadr(fd, lib, default_value->value);
+      break;
+    }
+    case SOCK_FLOAT:
+    case SOCK_VECTOR:
+    case SOCK_RGBA:
+    case SOCK_BOOLEAN:
+    case SOCK_INT:
+    case SOCK_STRING:
+    case __SOCK_MESH:
+    case SOCK_CUSTOM:
+    case SOCK_SHADER:
+    case SOCK_EMITTERS:
+    case SOCK_EVENTS:
+    case SOCK_FORCES:
+    case SOCK_CONTROL_FLOW:
+      break;
+  }
+}
+
+static void lib_link_node_sockets(FileData *fd, Library *lib, ListBase *sockets)
+{
+  LISTBASE_FOREACH (bNodeSocket *, sock, sockets) {
+    lib_link_node_socket(fd, lib, sock);
+  }
+}
+
 /* Single node tree (also used for material/scene trees), ntree is not NULL */
 static void lib_link_ntree(FileData *fd, Library *lib, bNodeTree *ntree)
 {
@@ -3564,27 +3706,19 @@ static void lib_link_ntree(FileData *fd, Library *lib, bNodeTree *ntree)
 
   ntree->gpd = newlibadr(fd, lib, ntree->gpd);
 
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     /* Link ID Properties -- and copy this comment EXACTLY for easy finding
      * of library blocks that implement this.*/
     IDP_LibLinkProperty(node->prop, fd);
 
     node->id = newlibadr(fd, lib, node->id);
 
-    for (bNodeSocket *sock = node->inputs.first; sock; sock = sock->next) {
-      IDP_LibLinkProperty(sock->prop, fd);
-    }
-    for (bNodeSocket *sock = node->outputs.first; sock; sock = sock->next) {
-      IDP_LibLinkProperty(sock->prop, fd);
-    }
+    lib_link_node_sockets(fd, lib, &node->inputs);
+    lib_link_node_sockets(fd, lib, &node->outputs);
   }
 
-  for (bNodeSocket *sock = ntree->inputs.first; sock; sock = sock->next) {
-    IDP_LibLinkProperty(sock->prop, fd);
-  }
-  for (bNodeSocket *sock = ntree->outputs.first; sock; sock = sock->next) {
-    IDP_LibLinkProperty(sock->prop, fd);
-  }
+  lib_link_node_sockets(fd, lib, &ntree->inputs);
+  lib_link_node_sockets(fd, lib, &ntree->outputs);
 
   /* Set node->typeinfo pointers. This is done in lib linking, after the
    * first versioning that can change types still without functions that
@@ -3595,7 +3729,7 @@ static void lib_link_ntree(FileData *fd, Library *lib, bNodeTree *ntree)
   /* For nodes with static socket layout, add/remove sockets as needed
    * to match the static layout. */
   if (fd->memfile == NULL) {
-    for (bNode *node = ntree->nodes.first; node; node = node->next) {
+    LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
       node_verify_socket_templates(ntree, node);
     }
   }
@@ -3757,23 +3891,23 @@ static void direct_link_nodetree(FileData *fd, bNodeTree *ntree)
   }
 
 #if 0
-	if (ntree->previews) {
-		bNodeInstanceHash* new_previews = BKE_node_instance_hash_new("node previews");
-		bNodeInstanceHashIterator iter;
-
-		NODE_INSTANCE_HASH_ITER(iter, ntree->previews) {
-			bNodePreview* preview = BKE_node_instance_hash_iterator_get_value(&iter);
-			if (preview) {
-				bNodePreview* new_preview = newimaadr(fd, preview);
-				if (new_preview) {
-					bNodeInstanceKey key = BKE_node_instance_hash_iterator_get_key(&iter);
-					BKE_node_instance_hash_insert(new_previews, key, new_preview);
-				}
-			}
-		}
-		BKE_node_instance_hash_free(ntree->previews, NULL);
-		ntree->previews = new_previews;
-	}
+  if (ntree->previews) {
+    bNodeInstanceHash* new_previews = BKE_node_instance_hash_new("node previews");
+    bNodeInstanceHashIterator iter;
+
+    NODE_INSTANCE_HASH_ITER(iter, ntree->previews) {
+      bNodePreview* preview = BKE_node_instance_hash_iterator_get_value(&iter);
+      if (preview) {
+        bNodePreview* new_preview = newimaadr(fd, preview);
+        if (new_preview) {
+          bNodeInstanceKey key = BKE_node_instance_hash_iterator_get_key(&iter);
+          BKE_node_instance_hash_insert(new_previews, key, new_preview);
+        }
+      }
+    }
+    BKE_node_instance_hash_free(ntree->previews, NULL);
+    ntree->previews = new_previews;
+  }
 #else
   /* XXX TODO */
   ntree->previews = NULL;
@@ -3796,20 +3930,11 @@ typedef struct tConstraintLinkData {
 /* callback function used to relink constraint ID-links */
 static void lib_link_constraint_cb(bConstraint *UNUSED(con),
                                    ID **idpoin,
-                                   bool is_reference,
+                                   bool UNUSED(is_reference),
                                    void *userdata)
 {
   tConstraintLinkData *cld = (tConstraintLinkData *)userdata;
-
-  /* for reference types, we need to increment the user-counts on load... */
-  if (is_reference) {
-    /* reference type - with usercount */
-    *idpoin = newlibadr(cld->fd, cld->id->lib, *idpoin);
-  }
-  else {
-    /* target type - no usercount needed */
-    *idpoin = newlibadr(cld->fd, cld->id->lib, *idpoin);
-  }
+  *idpoin = newlibadr(cld->fd, cld->id->lib, *idpoin);
 }
 
 static void lib_link_constraints(FileData *fd, ID *id, ListBase *conlist)
@@ -3929,7 +4054,7 @@ static void lib_link_pose(FileData *fd, Main *bmain, Object *ob, bPose *pose)
     }
   }
 
-  for (bPoseChannel *pchan = pose->chanbase.first; pchan; pchan = pchan->next) {
+  LISTBASE_FOREACH (bPoseChannel *, pchan, &pose->chanbase) {
     lib_link_constraints(fd, (ID *)ob, &pchan->constraints);
 
     pchan->bone = BKE_armature_find_bone_name(arm, pchan->name);
@@ -3958,14 +4083,14 @@ static void lib_link_bones(FileData *fd, Bone *bone)
 {
   IDP_LibLinkProperty(bone->prop, fd);
 
-  for (Bone *curbone = bone->childbase.first; curbone; curbone = curbone->next) {
+  LISTBASE_FOREACH (Bone *, curbone, &bone->childbase) {
     lib_link_bones(fd, curbone);
   }
 }
 
 static void lib_link_armature(FileData *fd, Main *UNUSED(bmain), bArmature *arm)
 {
-  for (Bone *curbone = arm->bonebase.first; curbone; curbone = curbone->next) {
+  LISTBASE_FOREACH (Bone *, curbone, &arm->bonebase) {
     lib_link_bones(fd, curbone);
   }
 }
@@ -4026,7 +4151,7 @@ static void lib_link_camera(FileData *fd, Main *UNUSED(bmain), Camera *ca)
   ca->dof_ob = newlibadr(fd, ca->id.lib, ca->dof_ob); /* deprecated, for versioning */
   ca->dof.focus_object = newlibadr(fd, ca->id.lib, ca->dof.focus_object);
 
-  for (CameraBGImage *bgpic = ca->bg_images.first; bgpic; bgpic = bgpic->next) {
+  LISTBASE_FOREACH (CameraBGImage *, bgpic, &ca->bg_images) {
     bgpic->ima = newlibadr(fd, ca->id.lib, bgpic->ima);
     bgpic->clip = newlibadr(fd, ca->id.lib, bgpic->clip);
   }
@@ -4039,7 +4164,7 @@ static void direct_link_camera(FileData *fd, Camera *ca)
 
   link_list(fd, &ca->bg_images);
 
-  for (CameraBGImage *bgpic = ca->bg_images.first; bgpic; bgpic = bgpic->next) {
+  LISTBASE_FOREACH (CameraBGImage *, bgpic, &ca->bg_images) {
     bgpic->iuser.ok = 1;
     bgpic->iuser.scene = NULL;
   }
@@ -4232,10 +4357,10 @@ static void direct_link_text(FileData *fd, Text *text)
   text->compiled = NULL;
 
 #if 0
-	if (text->flags & TXT_ISEXT) {
-		BKE_text_reload(text);
-	}
-	/* else { */
+  if (text->flags & TXT_ISEXT) {
+    BKE_text_reload(text);
+  }
+  /* else { */
 #endif
 
   link_list(fd, &text->lines);
@@ -4614,7 +4739,7 @@ static void lib_link_particlesettings(FileData *fd, Main *UNUSED(bmain), Particl
   }
 
   if (part->instance_weights.first && part->instance_collection) {
-    for (ParticleDupliWeight *dw = part->instance_weights.first; dw; dw = dw->next) {
+    LISTBASE_FOREACH (ParticleDupliWeight *, dw, &part->instance_weights) {
       dw->ob = newlibadr(fd, part->id.lib, dw->ob);
     }
   }
@@ -4745,7 +4870,7 @@ static void lib_link_particlesystems(FileData *fd, Object *ob, ID *id, ListBase
       /* particle modifier must be removed before particle system */
       ParticleSystemModifierData *psmd = psys_get_modifier(ob, psys);
       BLI_remlink(&ob->modifiers, psmd);
-      modifier_free((ModifierData *)psmd);
+      BKE_modifier_free((ModifierData *)psmd);
 
       BLI_remlink(particles, psys);
       MEM_freeN(psys);
@@ -5114,7 +5239,7 @@ static void lib_link_modifiers_common(void *userData, Object *ob, ID **idpoin, i
 
 static void lib_link_modifiers(FileData *fd, Object *ob)
 {
-  modifiers_foreachIDLink(ob, lib_link_modifiers_common, fd);
+  BKE_modifiers_foreach_ID_link(ob, lib_link_modifiers_common, fd);
 
   /* If linking from a library, clear 'local' library override flag. */
   if (ob->id.lib != NULL) {
@@ -5126,7 +5251,7 @@ static void lib_link_modifiers(FileData *fd, Object *ob)
 
 static void lib_link_gpencil_modifiers(FileData *fd, Object *ob)
 {
-  BKE_gpencil_modifiers_foreachIDLink(ob, lib_link_modifiers_common, fd);
+  BKE_gpencil_modifiers_foreach_ID_link(ob, lib_link_modifiers_common, fd);
 
   /* If linking from a library, clear 'local' library override flag. */
   if (ob->id.lib != NULL) {
@@ -5139,7 +5264,7 @@ static void lib_link_gpencil_modifiers(FileData *fd, Object *ob)
 
 static void lib_link_shaderfxs(FileData *fd, Object *ob)
 {
-  BKE_shaderfx_foreachIDLink(ob, lib_link_modifiers_common, fd);
+  BKE_shaderfx_foreach_ID_link(ob, lib_link_modifiers_common, fd);
 
   /* If linking from a library, clear 'local' library override flag. */
   if (ob->id.lib != NULL) {
@@ -5223,7 +5348,7 @@ static void lib_link_object(FileData *fd, Main *bmain, Object *ob)
        * some leaked memory rather then crashing immediately
        * while bad this _is_ an exceptional case - campbell */
 #if 0
-			BKE_pose_free(ob->pose);
+      BKE_pose_free(ob->pose);
 #else
       MEM_freeN(ob->pose);
 #endif
@@ -5259,14 +5384,14 @@ static void lib_link_object(FileData *fd, Main *bmain, Object *ob)
   lib_link_nlastrips(fd, &ob->id, &ob->nlastrips);
   // >>> XXX deprecated - old animation system
 
-  for (PartEff *paf = ob->effect.first; paf; paf = paf->next) {
+  LISTBASE_FOREACH (PartEff *, paf, &ob->effect) {
     if (paf->type == EFF_PARTICLE) {
       paf->group = newlibadr(fd, ob->id.lib, paf->group);
     }
   }
 
   {
-    FluidsimModifierData *fluidmd = (FluidsimModifierData *)modifiers_findByType(
+    FluidsimModifierData *fluidmd = (FluidsimModifierData *)BKE_modifiers_findby_type(
         ob, eModifierType_Fluidsim);
 
     if (fluidmd && fluidmd->fss) {
@@ -5276,12 +5401,19 @@ static void lib_link_object(FileData *fd, Main *bmain, Object *ob)
   }
 
   {
-    FluidModifierData *mmd = (FluidModifierData *)modifiers_findByType(ob, eModifierType_Fluid);
+    FluidModifierData *mmd = (FluidModifierData *)BKE_modifiers_findby_type(ob,
+                                                                            eModifierType_Fluid);
 
     if (mmd && (mmd->type == MOD_FLUID_TYPE_DOMAIN) && mmd->domain) {
       /* Flag for refreshing the simulation after loading */
       mmd->domain->flags |= FLUID_DOMAIN_FILE_LOAD;
     }
+    else if (mmd && (mmd->type == MOD_FLUID_TYPE_FLOW) && mmd->flow) {
+      mmd->flow->flags &= ~FLUID_FLOW_NEEDS_UPDATE;
+    }
+    else if (mmd && (mmd->type == MOD_FLUID_TYPE_EFFEC) && mmd->effector) {
+      mmd->effector->flags &= ~FLUID_EFFECTOR_NEEDS_UPDATE;
+    }
   }
 
   /* texture field */
@@ -5412,7 +5544,7 @@ static ModifierData *modifier_replace_with_fluid(FileData *fd,
                                                  ListBase *modifiers,
                                                  ModifierData *old_modifier_data)
 {
-  ModifierData *new_modifier_data = modifier_new(eModifierType_Fluid);
+  ModifierData *new_modifier_data = BKE_modifier_new(eModifierType_Fluid);
   FluidModifierData *fluid_modifier_data = (FluidModifierData *)new_modifier_data;
 
   if (old_modifier_data->type == eModifierType_Fluidsim) {
@@ -5535,7 +5667,7 @@ static void direct_link_modifiers(FileData *fd, ListBase *lb, Object *ob)
       is_allocated = true;
     }
     /* if modifiers disappear, or for upward compatibility */
-    if (NULL == modifierType_getInfo(md->type)) {
+    if (NULL == BKE_modifier_get_info(md->type)) {
       md->type = eModifierType_None;
     }
 
@@ -5693,15 +5825,15 @@ static void direct_link_modifiers(FileData *fd, ListBase *lb, Object *ob)
     else if (md->type == eModifierType_Collision) {
       CollisionModifierData *collmd = (CollisionModifierData *)md;
 #if 0
-			// TODO: CollisionModifier should use pointcache
-			// + have proper reset events before enabling this
-			collmd->x = newdataadr(fd, collmd->x);
-			collmd->xnew = newdataadr(fd, collmd->xnew);
-			collmd->mfaces = newdataadr(fd, collmd->mfaces);
-
-			collmd->current_x = MEM_calloc_arrayN(collmd->numverts, sizeof(MVert), "current_x");
-			collmd->current_xnew = MEM_calloc_arrayN(collmd->numverts, sizeof(MVert), "current_xnew");
-			collmd->current_v = MEM_calloc_arrayN(collmd->numverts, sizeof(MVert), "current_v");
+      // TODO: CollisionModifier should use pointcache
+      // + have proper reset events before enabling this
+      collmd->x = newdataadr(fd, collmd->x);
+      collmd->xnew = newdataadr(fd, collmd->xnew);
+      collmd->mfaces = newdataadr(fd, collmd->mfaces);
+
+      collmd->current_x = MEM_calloc_arrayN(collmd->numverts, sizeof(MVert), "current_x");
+      collmd->current_xnew = MEM_calloc_arrayN(collmd->numverts, sizeof(MVert), "current_xnew");
+      collmd->current_v = MEM_calloc_arrayN(collmd->numverts, sizeof(MVert), "current_v");
 #endif
 
       collmd->x = NULL;
@@ -5889,7 +6021,7 @@ static void direct_link_gpencil_modifiers(FileData *fd, ListBase *lb)
     md->error = NULL;
 
     /* if modifiers disappear, or for upward compatibility */
-    if (NULL == BKE_gpencil_modifierType_getInfo(md->type)) {
+    if (NULL == BKE_gpencil_modifier_get_info(md->type)) {
       md->type = eModifierType_None;
     }
 
@@ -5970,7 +6102,7 @@ static void direct_link_shaderfxs(FileData *fd, ListBase *lb)
     fx->error = NULL;
 
     /* if shader disappear, or for upward compatibility */
-    if (NULL == BKE_shaderfxType_getInfo(fx->type)) {
+    if (NULL == BKE_shaderfx_get_info(fx->type)) {
       fx->type = eShaderFxType_None;
     }
   }
@@ -6033,7 +6165,7 @@ static void direct_link_object(FileData *fd, Object *ob)
     if (paf->type == EFF_WAVE) {
       WaveEff *wav = (WaveEff *)paf;
       PartEff *next = paf->next;
-      WaveModifierData *wmd = (WaveModifierData *)modifier_new(eModifierType_Wave);
+      WaveModifierData *wmd = (WaveModifierData *)BKE_modifier_new(eModifierType_Wave);
 
       wmd->damp = wav->damp;
       wmd->flag = wav->flag;
@@ -6057,7 +6189,7 @@ static void direct_link_object(FileData *fd, Object *ob)
     if (paf->type == EFF_BUILD) {
       BuildEff *baf = (BuildEff *)paf;
       PartEff *next = paf->next;
-      BuildModifierData *bmd = (BuildModifierData *)modifier_new(eModifierType_Build);
+      BuildModifierData *bmd = (BuildModifierData *)BKE_modifier_new(eModifierType_Build);
 
       bmd->start = baf->sfra;
       bmd->length = baf->len;
@@ -6134,7 +6266,7 @@ static void direct_link_object(FileData *fd, Object *ob)
   link_list(fd, &ob->hooks);
   while (ob->hooks.first) {
     ObHook *hook = ob->hooks.first;
-    HookModifierData *hmd = (HookModifierData *)modifier_new(eModifierType_Hook);
+    HookModifierData *hmd = (HookModifierData *)BKE_modifier_new(eModifierType_Hook);
 
     hook->indexar = newdataadr(fd, hook->indexar);
     if (fd->flags & FD_FLAGS_SWITCH_ENDIAN) {
@@ -6156,7 +6288,7 @@ static void direct_link_object(FileData *fd, Object *ob)
     BLI_addhead(&ob->modifiers, hmd);
     BLI_remlink(&ob->hooks, hook);
 
-    modifier_unique_name(&ob->modifiers, (ModifierData *)hmd);
+    BKE_modifier_unique_name(&ob->modifiers, (ModifierData *)hmd);
 
     MEM_freeN(hook);
   }
@@ -6204,7 +6336,7 @@ static void direct_link_view_settings(FileData *fd, ColorManagedViewSettings *vi
 static void direct_link_layer_collections(FileData *fd, ListBase *lb, bool master)
 {
   link_list(fd, lb);
-  for (LayerCollection *lc = lb->first; lc; lc = lc->next) {
+  LISTBASE_FOREACH (LayerCollection *, lc, lb) {
 #ifdef USE_COLLECTION_COMPAT_28
     lc->scene_collection = newdataadr(fd, lc->scene_collection);
 #endif
@@ -6257,12 +6389,11 @@ static void lib_link_layer_collection(FileData *fd,
 
 static void lib_link_view_layer(FileData *fd, Library *lib, ViewLayer *view_layer)
 {
-  for (FreestyleModuleConfig *fmc = view_layer->freestyle_config.modules.first; fmc;
-       fmc = fmc->next) {
+  LISTBASE_FOREACH (FreestyleModuleConfig *, fmc, &view_layer->freestyle_config.modules) {
     fmc->script = newlibadr(fd, lib, fmc->script);
   }
 
-  for (FreestyleLineSet *fls = view_layer->freestyle_config.linesets.first; fls; fls = fls->next) {
+  LISTBASE_FOREACH (FreestyleLineSet *, fls, &view_layer->freestyle_config.linesets) {
     fls->linestyle = newlibadr(fd, lib, fls->linestyle);
     fls->group = newlibadr(fd, lib, fls->group);
   }
@@ -6305,19 +6436,19 @@ static void direct_link_scene_collection(FileData *fd, SceneCollection *sc)
   link_list(fd, &sc->objects);
   link_list(fd, &sc->scene_collections);
 
-  for (SceneCollection *nsc = sc->scene_collections.first; nsc; nsc = nsc->next) {
+  LISTBASE_FOREACH (SceneCollection *, nsc, &sc->scene_collections) {
     direct_link_scene_collection(fd, nsc);
   }
 }
 
 static void lib_link_scene_collection(FileData *fd, Library *lib, SceneCollection *sc)
 {
-  for (LinkData *link = sc->objects.first; link; link = link->next) {
+  LISTBASE_FOREACH (LinkData *, link, &sc->objects) {
     link->data = newlibadr(fd, lib, link->data);
     BLI_assert(link->data);
   }
 
-  for (SceneCollection *nsc = sc->scene_collections.first; nsc; nsc = nsc->next) {
+  LISTBASE_FOREACH (SceneCollection *, nsc, &sc->scene_collections) {
     lib_link_scene_collection(fd, lib, nsc);
   }
 }
@@ -6625,7 +6756,7 @@ static void lib_link_scene(FileData *fd, Main *UNUSED(bmain), Scene *sce)
   }
   SEQ_END;
 
-  for (TimeMarker *marker = sce->markers.first; marker; marker = marker->next) {
+  LISTBASE_FOREACH (TimeMarker *, marker, &sce->markers) {
     if (marker->camera) {
       marker->camera = newlibadr(fd, sce->id.lib, marker->camera);
     }
@@ -6649,12 +6780,12 @@ static void lib_link_scene(FileData *fd, Main *UNUSED(bmain), Scene *sce)
     composite_patch(sce->nodetree, sce);
   }
 
-  for (SceneRenderLayer *srl = sce->r.layers.first; srl; srl = srl->next) {
+  LISTBASE_FOREACH (SceneRenderLayer *, srl, &sce->r.layers) {
     srl->mat_override = newlibadr(fd, sce->id.lib, srl->mat_override);
-    for (FreestyleModuleConfig *fmc = srl->freestyleConfig.modules.first; fmc; fmc = fmc->next) {
+    LISTBASE_FOREACH (FreestyleModuleConfig *, fmc, &srl->freestyleConfig.modules) {
       fmc->script = newlibadr(fd, sce->id.lib, fmc->script);
     }
-    for (FreestyleLineSet *fls = srl->freestyleConfig.linesets.first; fls; fls = fls->next) {
+    LISTBASE_FOREACH (FreestyleLineSet *, fls, &srl->freestyleConfig.linesets) {
       fls->linestyle = newlibadr(fd, sce->id.lib, fls->linestyle);
       fls->group = newlibadr(fd, sce->id.lib, fls->group);
     }
@@ -6668,7 +6799,7 @@ static void lib_link_scene(FileData *fd, Main *UNUSED(bmain), Scene *sce)
   }
 #endif
 
-  for (ViewLayer *view_layer = sce->view_layers.first; view_layer; view_layer = view_layer->next) {
+  LISTBASE_FOREACH (ViewLayer *, view_layer, &sce->view_layers) {
     lib_link_view_layer(fd, sce->id.lib, view_layer);
   }
 
@@ -6825,7 +6956,6 @@ static void direct_link_scene(FileData *fd, Scene *sce)
 
     direct_link_paint(fd, sce, &sce->toolsettings->imapaint.paint);
 
-    sce->toolsettings->imapaint.paintcursor = NULL;
     sce->toolsettings->particle.paintcursor = NULL;
     sce->toolsettings->particle.scene = NULL;
     sce->toolsettings->particle.object = NULL;
@@ -7199,11 +7329,11 @@ static void direct_link_panel_list(FileData *fd, ListBase *lb)
 {
   link_list(fd, lb);
 
-  for (Panel *pa = lb->first; pa; pa = pa->next) {
-    pa->runtime_flag = 0;
-    pa->activedata = NULL;
-    pa->type = NULL;
-    direct_link_panel_list(fd, &pa->children);
+  LISTBASE_FOREACH (Panel *, panel, lb) {
+    panel->runtime_flag = 0;
+    panel->activedata = NULL;
+    panel->type = NULL;
+    direct_link_panel_list(fd, &panel->children);
   }
 }
 
@@ -7408,10 +7538,10 @@ static void direct_link_area(FileData *fd, ScrArea *area)
        * so sacrifice a few old files for now to avoid crashes with new files!
        * committed: r28002 */
 #if 0
-			sima->gpd = newdataadr(fd, sima->gpd);
-			if (sima->gpd) {
-				direct_link_gpencil(fd, sima->gpd);
-			}
+      sima->gpd = newdataadr(fd, sima->gpd);
+      if (sima->gpd) {
+        direct_link_gpencil(fd, sima->gpd);
+      }
 #endif
     }
     else if (sl->spacetype == SPACE_NODE) {
@@ -7442,10 +7572,10 @@ static void direct_link_area(FileData *fd, ScrArea *area)
        * simple return NULL here (sergey)
        */
 #if 0
-			if (sseq->gpd) {
-				sseq->gpd = newdataadr(fd, sseq->gpd);
-				direct_link_gpencil(fd, sseq->gpd);
-			}
+      if (sseq->gpd) {
+        sseq->gpd = newdataadr(fd, sseq->gpd);
+        direct_link_gpencil(fd, sseq->gpd);
+      }
 #endif
       sseq->scopes.reference_ibuf = NULL;
       sseq->scopes.zebra_ibuf = NULL;
@@ -7524,7 +7654,7 @@ static void lib_link_area(FileData *fd, ID *parent_id, ScrArea *area)
 
   memset(&area->runtime, 0x0, sizeof(area->runtime));
 
-  for (SpaceLink *sl = area->spacedata.first; sl; sl = sl->next) {
+  LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
     switch (sl->spacetype) {
       case SPACE_VIEW3D: {
         View3D *v3d = (View3D *)sl;
@@ -7701,12 +7831,12 @@ static bool direct_link_area_map(FileData *fd, ScrAreaMap *area_map)
   link_list(fd, &area_map->vertbase);
   link_list(fd, &area_map->edgebase);
   link_list(fd, &area_map->areabase);
-  for (ScrArea *area = area_map->areabase.first; area; area = area->next) {
+  LISTBASE_FOREACH (ScrArea *, area, &area_map->areabase) {
     direct_link_area(fd, area);
   }
 
   /* edges */
-  for (ScrEdge *se = area_map->edgebase.first; se; se = se->next) {
+  LISTBASE_FOREACH (ScrEdge *, se, &area_map->edgebase) {
     se->v1 = newdataadr(fd, se->v1);
     se->v2 = newdataadr(fd, se->v2);
     BKE_screen_sort_scrvert(&se->v1, &se->v2);
@@ -7823,7 +7953,7 @@ static void direct_link_windowmanager(FileData *fd, wmWindowManager *wm)
 
 static void lib_link_windowmanager(FileData *fd, Main *UNUSED(bmain), wmWindowManager *wm)
 {
-  for (wmWindow *win = wm->windows.first; win; win = win->next) {
+  LISTBASE_FOREACH (wmWindow *, win, &wm->windows) {
     if (win->workspace_hook) { /* NULL for old files */
       lib_link_workspace_instance_hook(fd, win->workspace_hook, &wm->id);
     }
@@ -7831,7 +7961,7 @@ static void lib_link_windowmanager(FileData *fd, Main *UNUSED(bmain), wmWindowMa
     /* deprecated, but needed for versioning (will be NULL'ed then) */
     win->screen = newlibadr(fd, NULL, win->screen);
 
-    for (ScrArea *area = win->global_areas.areabase.first; area; area = area->next) {
+    LISTBASE_FOREACH (ScrArea *, area, &win->global_areas.areabase) {
       lib_link_area(fd, &wm->id, area);
     }
 
@@ -7847,17 +7977,17 @@ static void lib_link_windowmanager(FileData *fd, Main *UNUSED(bmain), wmWindowMa
 
 /* note: file read without screens option G_FILE_NO_UI;
  * check lib pointers in call below */
-static void lib_link_screen(FileData *fd, Main *UNUSED(bmain), bScreen *sc)
+static void lib_link_screen(FileData *fd, Main *UNUSED(bmain), bScreen *screen)
 {
   /* deprecated, but needed for versioning (will be NULL'ed then) */
-  sc->scene = newlibadr(fd, sc->id.lib, sc->scene);
+  screen->scene = newlibadr(fd, screen->id.lib, screen->scene);
 
-  sc->animtimer = NULL; /* saved in rare cases */
-  sc->tool_tip = NULL;
-  sc->scrubbing = false;
+  screen->animtimer = NULL; /* saved in rare cases */
+  screen->tool_tip = NULL;
+  screen->scrubbing = false;
 
-  for (ScrArea *area = sc->areabase.first; area; area = area->next) {
-    lib_link_area(fd, &sc->id, area);
+  LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+    lib_link_area(fd, &screen->id, area);
   }
 }
 
@@ -8010,8 +8140,8 @@ static void lib_link_window_scene_data_restore(wmWindow *win, Scene *scene, View
 {
   bScreen *screen = BKE_workspace_active_screen_get(win->workspace_hook);
 
-  for (ScrArea *area = screen->areabase.first; area; area = area->next) {
-    for (SpaceLink *sl = area->spacedata.first; sl; sl = sl->next) {
+  LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+    LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
       if (sl->spacetype == SPACE_VIEW3D) {
         View3D *v3d = (View3D *)sl;
 
@@ -8039,7 +8169,7 @@ static void lib_link_window_scene_data_restore(wmWindow *win, Scene *scene, View
             /* Regionbase storage is different depending if the space is active. */
             ListBase *regionbase = (sl == area->spacedata.first) ? &area->regionbase :
                                                                    &sl->regionbase;
-            for (ARegion *region = regionbase->first; region; region = region->next) {
+            LISTBASE_FOREACH (ARegion *, region, regionbase) {
               if (region->regiontype == RGN_TYPE_WINDOW) {
                 RegionView3D *rv3d = region->regiondata;
                 if (rv3d->localvd) {
@@ -8063,26 +8193,13 @@ static void lib_link_workspace_layout_restore(struct IDNameLib_Map *id_map,
 
   /* avoid conflicts with 2.8x branch */
   {
-    for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-      for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+    LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+      LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
         if (sl->spacetype == SPACE_VIEW3D) {
           View3D *v3d = (View3D *)sl;
-          ARegion *region;
 
           v3d->camera = restore_pointer_by_name(id_map, (ID *)v3d->camera, USER_REAL);
           v3d->ob_center = restore_pointer_by_name(id_map, (ID *)v3d->ob_center, USER_REAL);
-
-          /* Free render engines for now. */
-          ListBase *regionbase = (sl == sa->spacedata.first) ? &sa->regionbase : &sl->regionbase;
-          for (region = regionbase->first; region; region = region->next) {
-            if (region->regiontype == RGN_TYPE_WINDOW) {
-              RegionView3D *rv3d = region->regiondata;
-              if (rv3d && rv3d->render_engine) {
-                RE_engine_free(rv3d->render_engine);
-                rv3d->render_engine = NULL;
-              }
-            }
-          }
         }
         else if (sl->spacetype == SPACE_GRAPH) {
           SpaceGraph *sipo = (SpaceGraph *)sl;
@@ -8145,11 +8262,11 @@ static void lib_link_workspace_layout_restore(struct IDNameLib_Map *id_map,
           sima->iuser.scene = NULL;
 
 #if 0
-					/* Those are allocated and freed by space code, no need to handle them here. */
-					MEM_SAFE_FREE(sima->scopes.waveform_1);
-					MEM_SAFE_FREE(sima->scopes.waveform_2);
-					MEM_SAFE_FREE(sima->scopes.waveform_3);
-					MEM_SAFE_FREE(sima->scopes.vecscope);
+          /* Those are allocated and freed by space code, no need to handle them here. */
+          MEM_SAFE_FREE(sima->scopes.waveform_1);
+          MEM_SAFE_FREE(sima->scopes.waveform_2);
+          MEM_SAFE_FREE(sima->scopes.waveform_3);
+          MEM_SAFE_FREE(sima->scopes.vecscope);
 #endif
           sima->scopes.ok = 0;
 
@@ -8194,7 +8311,7 @@ static void lib_link_workspace_layout_restore(struct IDNameLib_Map *id_map,
 
           scpt->script = restore_pointer_by_name(id_map, (ID *)scpt->script, USER_REAL);
 
-          /*sc->script = NULL; - 2.45 set to null, better re-run the script */
+          /*screen->script = NULL; - 2.45 set to null, better re-run the script */
           if (scpt->script) {
             SCRIPT_SET_NULL(scpt->script);
           }
@@ -8300,14 +8417,12 @@ void blo_lib_link_restore(Main *oldmain,
 
   for (WorkSpace *workspace = newmain->workspaces.first; workspace;
        workspace = workspace->id.next) {
-    ListBase *layouts = BKE_workspace_layouts_get(workspace);
-
-    for (WorkSpaceLayout *layout = layouts->first; layout; layout = layout->next) {
+    LISTBASE_FOREACH (WorkSpaceLayout *, layout, &workspace->layouts) {
       lib_link_workspace_layout_restore(id_map, newmain, layout);
     }
   }
 
-  for (wmWindow *win = curwm->windows.first; win; win = win->next) {
+  LISTBASE_FOREACH (wmWindow *, win, &curwm->windows) {
     WorkSpace *workspace = BKE_workspace_active_get(win->workspace_hook);
     ID *workspace_id = (ID *)workspace;
     Scene *oldscene = win->scene;
@@ -8377,22 +8492,22 @@ void blo_do_versions_view3d_split_250(View3D *v3d, ListBase *regions)
   }
 }
 
-static bool direct_link_screen(FileData *fd, bScreen *sc)
+static bool direct_link_screen(FileData *fd, bScreen *screen)
 {
-  bool wrong_id = false;
+  bool success = true;
 
-  sc->regionbase.first = sc->regionbase.last = NULL;
-  sc->context = NULL;
-  sc->active_region = NULL;
+  screen->regionbase.first = screen->regionbase.last = NULL;
+  screen->context = NULL;
+  screen->active_region = NULL;
 
-  sc->preview = direct_link_preview_image(fd, sc->preview);
+  screen->preview = direct_link_preview_image(fd, screen->preview);
 
-  if (!direct_link_area_map(fd, AREAMAP_FROM_SCREEN(sc))) {
-    printf("Error reading Screen %s... removing it.\n", sc->id.name + 2);
-    wrong_id = true;
+  if (!direct_link_area_map(fd, AREAMAP_FROM_SCREEN(screen))) {
+    printf("Error reading Screen %s... removing it.\n", screen->id.name + 2);
+    success = false;
   }
 
-  return wrong_id;
+  return success;
 }
 
 /** \} */
@@ -8437,7 +8552,7 @@ static void direct_link_library(FileData *fd, Library *lib, Main *main)
 
   /* make sure we have full path in lib->filepath */
   BLI_strncpy(lib->filepath, lib->name, sizeof(lib->name));
-  BLI_cleanup_path(fd->relabase, lib->filepath);
+  BLI_path_normalize(fd->relabase, lib->filepath);
 
   //  printf("direct_link_library: name %s\n", lib->name);
   //  printf("direct_link_library: filepath %s\n", lib->filepath);
@@ -8450,11 +8565,12 @@ static void direct_link_library(FileData *fd, Library *lib, Main *main)
   newmain->curlib = lib;
 
   lib->parent = NULL;
+
+  id_us_ensure_real(&lib->id);
 }
 
-static void lib_link_library(FileData *UNUSED(fd), Main *UNUSED(bmain), Library *lib)
+static void lib_link_library(FileData *UNUSED(fd), Main *UNUSED(bmain), Library *UNUSED(lib))
 {
-  id_us_ensure_real(&lib->id);
 }
 
 /* Always call this once you have loaded new library data to set the relative paths correctly
@@ -8522,8 +8638,8 @@ static void direct_link_speaker(FileData *fd, Speaker *spk)
   direct_link_animdata(fd, spk->adt);
 
 #if 0
-	spk->sound = newdataadr(fd, spk->sound);
-	direct_link_sound(fd, spk->sound);
+  spk->sound = newdataadr(fd, spk->sound);
+  direct_link_sound(fd, spk->sound);
 #endif
 }
 
@@ -8685,7 +8801,7 @@ static void lib_link_movieclip(FileData *fd, Main *UNUSED(bmain), MovieClip *cli
   lib_link_movieTracks(fd, clip, &tracking->tracks);
   lib_link_moviePlaneTracks(fd, clip, &tracking->plane_tracks);
 
-  for (MovieTrackingObject *object = tracking->objects.first; object; object = object->next) {
+  LISTBASE_FOREACH (MovieTrackingObject *, object, &tracking->objects) {
     lib_link_movieTracks(fd, clip, &object->tracks);
     lib_link_moviePlaneTracks(fd, clip, &object->plane_tracks);
   }
@@ -8762,7 +8878,7 @@ static void lib_link_mask_parent(FileData *fd, Mask *mask, MaskParent *parent)
 
 static void lib_link_mask(FileData *fd, Main *UNUSED(bmain), Mask *mask)
 {
-  for (MaskLayer *masklay = mask->masklayers.first; masklay; masklay = masklay->next) {
+  LISTBASE_FOREACH (MaskLayer *, masklay, &mask->masklayers) {
     MaskSpline *spline;
 
     spline = masklay->splines.first;
@@ -9107,6 +9223,24 @@ static void direct_link_volume(FileData *fd, Volume *volume)
 /** \} */
 
 /* -------------------------------------------------------------------- */
+/** \name Read ID: Simulation
+ * \{ */
+
+static void lib_link_simulation(FileData *UNUSED(fd),
+                                Main *UNUSED(main),
+                                Simulation *UNUSED(simulation))
+{
+}
+
+static void direct_link_simulation(FileData *fd, Simulation *simulation)
+{
+  simulation->adt = newdataadr(fd, simulation->adt);
+  direct_link_animdata(fd, simulation->adt);
+}
+
+/** \} */
+
+/* -------------------------------------------------------------------- */
 /** \name Read Library Data Block
  * \{ */
 
@@ -9224,328 +9358,33 @@ static const char *dataname(short id_code)
       return "Data from PT";
     case ID_VO:
       return "Data from VO";
+    case ID_SIM:
+      return "Data from SIM";
   }
   return "Data from Lib Block";
 }
 
-static BHead *read_data_into_oldnewmap(FileData *fd, BHead *bhead, const char *allocname)
+static bool direct_link_id(FileData *fd, Main *main, const int tag, ID *id, ID *id_old)
 {
-  bhead = blo_bhead_next(fd, bhead);
-
-  while (bhead && bhead->code == DATA) {
-    void *data;
-#if 0
-		/* XXX DUMB DEBUGGING OPTION TO GIVE NAMES for guarded malloc errors */
-		short* sp = fd->filesdna->structs[bhead->SDNAnr];
-		char* tmp = malloc(100);
-		allocname = fd->filesdna->types[sp[0]];
-		strcpy(tmp, allocname);
-		data = read_struct(fd, bhead, tmp);
-#else
-    data = read_struct(fd, bhead, allocname);
-#endif
-
-    if (data) {
-      oldnewmap_insert(fd->datamap, bhead->old, data, 0);
-    }
+  /* Read part of datablock that is common between real and embedded datablocks. */
+  direct_link_id_common(fd, main->curlib, id, id_old, tag);
 
-    bhead = blo_bhead_next(fd, bhead);
+  if (tag & LIB_TAG_ID_LINK_PLACEHOLDER) {
+    /* For placeholder we only need to set the tag, no further data to read. */
+    id->tag = tag;
+    return true;
   }
 
-  return bhead;
-}
-
-static BHead *read_libblock(FileData *fd,
-                            Main *main,
-                            BHead *bhead,
-                            const int tag,
-                            const bool placeholder_set_indirect_extern,
-                            ID **r_id)
-{
-  /* this routine reads a libblock and its direct data. Use link functions to connect it all
-   */
-  ID *id;
-  ListBase *lb;
-  const char *allocname;
-
-  /* XXX Very weakly handled currently, see comment at the end of this function before trying to
+  /* XXX Very weakly handled currently, see comment in read_libblock() before trying to
    * use it for anything new. */
-  bool wrong_id = false;
-
-  /* In undo case, most libs and linked data should be kept as is from previous state
-   * (see BLO_read_from_memfile).
-   * However, some needed by the snapshot being read may have been removed in previous one,
-   * and would go missing.
-   * This leads e.g. to disappearing objects in some undo/redo case, see T34446.
-   * That means we have to carefully check whether current lib or
-   * libdata already exits in old main, if it does we merely copy it over into new main area,
-   * otherwise we have to do a full read of that bhead... */
-  if (fd->memfile && ELEM(bhead->code, ID_LI, ID_LINK_PLACEHOLDER)) {
-    const char *idname = blo_bhead_id_name(fd, bhead);
-
-    DEBUG_PRINTF("Checking %s...\n", idname);
-
-    if (bhead->code == ID_LI) {
-      Main *libmain = fd->old_mainlist->first;
-      /* Skip oldmain itself... */
-      for (libmain = libmain->next; libmain; libmain = libmain->next) {
-        DEBUG_PRINTF("... against %s: ", libmain->curlib ? libmain->curlib->id.name : "<NULL>");
-        if (libmain->curlib && STREQ(idname, libmain->curlib->id.name)) {
-          Main *oldmain = fd->old_mainlist->first;
-          DEBUG_PRINTF("FOUND!\n");
-          /* In case of a library, we need to re-add its main to fd->mainlist,
-           * because if we have later a missing ID_LINK_PLACEHOLDER,
-           * we need to get the correct lib it is linked to!
-           * Order is crucial, we cannot bulk-add it in BLO_read_from_memfile()
-           * like it used to be. */
-          BLI_remlink(fd->old_mainlist, libmain);
-          BLI_remlink_safe(&oldmain->libraries, libmain->curlib);
-          BLI_addtail(fd->mainlist, libmain);
-          BLI_addtail(&main->libraries, libmain->curlib);
-
-          if (r_id) {
-            *r_id = NULL; /* Just in case... */
-          }
-          return blo_bhead_next(fd, bhead);
-        }
-        DEBUG_PRINTF("nothing...\n");
-      }
-    }
-    else {
-      DEBUG_PRINTF("... in %s (%s): ",
-                   main->curlib ? main->curlib->id.name : "<NULL>",
-                   main->curlib ? main->curlib->name : "<NULL>");
-      if ((id = BKE_libblock_find_name(main, GS(idname), idname + 2))) {
-        DEBUG_PRINTF("FOUND!\n");
-        /* Even though we found our linked ID,
-         * there is no guarantee its address is still the same. */
-        if (id != bhead->old) {
-          oldnewmap_insert(fd->libmap, bhead->old, id, GS(id->name));
-        }
-
-        /* No need to do anything else for ID_LINK_PLACEHOLDER,
-         * it's assumed already present in its lib's main. */
-        if (r_id) {
-          *r_id = NULL; /* Just in case... */
-        }
-        return blo_bhead_next(fd, bhead);
-      }
-      DEBUG_PRINTF("nothing...\n");
-    }
-  }
-
-  /* read libblock */
-  fd->are_memchunks_identical = true;
-  id = read_struct(fd, bhead, "lib block");
-  const short idcode = id != NULL ? GS(id->name) : 0;
-
-  BHead *id_bhead = bhead;
-  /* Used when undoing from memfile, we swap changed IDs into their old addresses when found. */
-  ID *id_old = NULL;
-  bool do_id_swap = false;
-
-  if (id != NULL) {
-    const bool do_partial_undo = (fd->skip_flags & BLO_READ_SKIP_UNDO_OLD_MAIN) == 0;
-
-    if (id_bhead->code != ID_LINK_PLACEHOLDER) {
-      /* need a name for the mallocN, just for debugging and sane prints on leaks */
-      allocname = dataname(idcode);
-
-      /* read all data into fd->datamap */
-      /* TODO: instead of building oldnewmap here we could just quickly check the bheads... could
-       * save some more ticks. Probably not worth it though, bottleneck is full depsgraph rebuild
-       * and evaluate, not actual file reading. */
-      bhead = read_data_into_oldnewmap(fd, id_bhead, allocname);
-
-      DEBUG_PRINTF(
-          "%s: ID %s is unchanged: %d\n", __func__, id->name, fd->are_memchunks_identical);
-
-      if (fd->memfile != NULL) {
-        BLI_assert(fd->old_idmap != NULL || !do_partial_undo);
-        /* This code should only ever be reached for local data-blocks. */
-        BLI_assert(main->curlib == NULL);
-
-        /* Find the 'current' existing ID we want to reuse instead of the one we would read from
-         * the undo memfile. */
-        DEBUG_PRINTF("\t Looking for ID %s with uuid %u instead of newly read one\n",
-                     id->name,
-                     id->session_uuid);
-        id_old = do_partial_undo ? BKE_main_idmap_lookup_uuid(fd->old_idmap, id->session_uuid) :
-                                   NULL;
-        bool can_finalize_and_return = false;
-
-        if (ELEM(idcode, ID_WM, ID_SCR, ID_WS)) {
-          /* Read WindowManager, Screen and WorkSpace IDs are never actually used during undo (see
-           * `setup_app_data()` in `blendfile.c`).
-           * So we can just abort here, just ensuring libmapping is set accordingly. */
-          can_finalize_and_return = true;
-        }
-        else if (id_old != NULL && fd->are_memchunks_identical) {
-          /* Do not add LIB_TAG_NEW here, this should not be needed/used in undo case anyway (as
-           * this is only for do_version-like code), but for sake of consistency, and also because
-           * it will tell us which ID is re-used from old Main, and which one is actually new. */
-          id_old->tag = tag | LIB_TAG_NEED_LINK | LIB_TAG_UNDO_OLD_ID_REUSED;
-          id_old->lib = main->curlib;
-          id_old->us = ID_FAKE_USERS(id_old);
-          /* Do not reset id->icon_id here, memory allocated for it remains valid. */
-          /* Needed because .blend may have been saved with crap value here... */
-          id_old->newid = NULL;
-          id_old->orig_id = NULL;
-
-          /* About recalc: since that ID did not change at all, we know that its recalc fields also
-           * remained unchanged, so no need to handle neither recalc nor recalc_undo_future here.
-           */
-
-          Main *old_bmain = fd->old_mainlist->first;
-          ListBase *old_lb = which_libbase(old_bmain, idcode);
-          ListBase *new_lb = which_libbase(main, idcode);
-          BLI_remlink(old_lb, id_old);
-          BLI_addtail(new_lb, id_old);
-
-          can_finalize_and_return = true;
-        }
-
-        if (can_finalize_and_return) {
-          DEBUG_PRINTF("Re-using existing ID %s instead of newly read one\n", id_old->name);
-          oldnewmap_insert(fd->libmap, id_bhead->old, id_old, id_bhead->code);
-          oldnewmap_insert(fd->libmap, id_old, id_old, id_bhead->code);
-
-          if (r_id) {
-            *r_id = id_old;
-          }
-
-          if (do_partial_undo) {
-            /* Even though we re-use the old ID as-is, it does not mean that we are 100% safe from
-             * needing some depsgraph updates for it (it could depend on another ID which address
-             * did
-             * not change, but which actual content might have been re-read from the memfile). */
-            if (fd->undo_direction < 0) {
-              /* We are coming from the future (i.e. do an actual undo, and not a redo), we use our
-               * old reused ID's 'accumulated recalc flags since last memfile undo step saving' as
-               * recalc flags. */
-              id_old->recalc = id_old->recalc_undo_accumulated;
-            }
-            else {
-              /* We are coming from the past (i.e. do a redo), we use the saved 'accumulated recalc
-               * flags since last memfile undo step saving' from the newly read ID as recalc flags.
-               */
-              id_old->recalc = id->recalc_undo_accumulated;
-            }
-            /* There is no need to flush the depsgraph's CoWs here, since that ID's data itself did
-             * not change. */
-
-            /* We need to 'accumulate' the accumulated recalc flags of all undo steps until we
-             * actually perform a depsgraph update, otherwise we'd only ever use the flags from one
-             * of the steps, and never get proper flags matching all others. */
-            id_old->recalc_undo_accumulated |= id->recalc_undo_accumulated;
-          }
-
-          MEM_freeN(id);
-          oldnewmap_free_unused(fd->datamap);
-          oldnewmap_clear(fd->datamap);
-
-          return bhead;
-        }
-      }
-    }
-
-    /* do after read_struct, for dna reconstruct */
-    lb = which_libbase(main, idcode);
-    if (lb) {
-      /* Some re-used old IDs might also use newly read ones, so we have to check for old memory
-       * addresses for those as well. */
-      if (fd->memfile != NULL && do_partial_undo && id->lib == NULL) {
-        BLI_assert(fd->old_idmap != NULL);
-        DEBUG_PRINTF("\t Looking for ID %s with uuid %u instead of newly read one\n",
-                     id->name,
-                     id->session_uuid);
-        id_old = BKE_main_idmap_lookup_uuid(fd->old_idmap, id->session_uuid);
-        if (id_old != NULL) {
-          BLI_assert(MEM_allocN_len(id) == MEM_allocN_len(id_old));
-          /* UI IDs are always re-used from old bmain at higher-level calling code, so never swap
-           * those. Besides maybe custom properties, no other ID should have pointers to those
-           * anyway...
-           * And linked IDs are handled separately as well. */
-          do_id_swap = !ELEM(idcode, ID_WM, ID_SCR, ID_WS) &&
-                       !(id_bhead->code == ID_LINK_PLACEHOLDER);
-        }
-      }
-
-      /* At this point, we know we are going to keep that newly read & allocated ID, so we need to
-       * reallocate it to ensure we actually get a unique memory address for it. */
-      if (!do_id_swap) {
-        DEBUG_PRINTF("using newly-read ID %s to a new mem address\n", id->name);
-      }
-      else {
-        DEBUG_PRINTF("using newly-read ID %s to its old, already existing address\n", id->name);
-      }
-
-      /* for ID_LINK_PLACEHOLDER check */
-      ID *id_target = do_id_swap ? id_old : id;
-      oldnewmap_insert(fd->libmap, id_bhead->old, id_target, id_bhead->code);
-      oldnewmap_insert(fd->libmap, id_old, id_target, id_bhead->code);
-
-      BLI_addtail(lb, id);
-
-      if (fd->memfile == NULL) {
-        /* When actually reading a file , we do want to reset/re-generate session uuids.
-         * In unod case, we want to re-use existing ones. */
-        id->session_uuid = MAIN_ID_SESSION_UUID_UNSET;
-      }
-
-      BKE_lib_libblock_session_uuid_ensure(id);
-    }
-    else {
-      /* unknown ID type */
-      printf("%s: unknown id code '%c%c'\n", __func__, (idcode & 0xff), (idcode >> 8));
-      MEM_freeN(id);
-      id = NULL;
-    }
-  }
-
-  if (r_id) {
-    *r_id = do_id_swap ? id_old : id;
-  }
-  if (!id) {
-    return blo_bhead_next(fd, id_bhead);
-  }
-
-  id->lib = main->curlib;
-  id->us = ID_FAKE_USERS(id);
-  id->icon_id = 0;
-  id->newid = NULL; /* Needed because .blend may have been saved with crap value here... */
-  id->orig_id = NULL;
-
-  /* this case cannot be direct_linked: it's just the ID part */
-  if (id_bhead->code == ID_LINK_PLACEHOLDER) {
-    /* That way, we know which data-lock needs do_versions (required currently for linking). */
-    id->tag = tag | LIB_TAG_ID_LINK_PLACEHOLDER | LIB_TAG_NEED_LINK | LIB_TAG_NEW;
-
-    if (placeholder_set_indirect_extern) {
-      if (id->flag & LIB_INDIRECT_WEAK_LINK) {
-        id->tag |= LIB_TAG_INDIRECT;
-      }
-      else {
-        id->tag |= LIB_TAG_EXTERN;
-      }
-    }
-
-    return blo_bhead_next(fd, id_bhead);
-  }
-
-  /* init pointers direct data */
-  direct_link_id(fd, id, id_old);
-
-  /* That way, we know which data-lock needs do_versions (required currently for linking). */
-  /* Note: doing this after direct_link_id(), which resets that field. */
-  id->tag = tag | LIB_TAG_NEED_LINK | LIB_TAG_NEW;
+  bool success = true;
 
-  switch (idcode) {
+  switch (GS(id->name)) {
     case ID_WM:
       direct_link_windowmanager(fd, (wmWindowManager *)id);
       break;
     case ID_SCR:
-      wrong_id = direct_link_screen(fd, (bScreen *)id);
+      success = direct_link_screen(fd, (bScreen *)id);
       break;
     case ID_SCE:
       direct_link_scene(fd, (Scene *)id);
@@ -9658,12 +9497,372 @@ static BHead *read_libblock(FileData *fd,
     case ID_VO:
       direct_link_volume(fd, (Volume *)id);
       break;
+    case ID_SIM:
+      direct_link_simulation(fd, (Simulation *)id);
+      break;
   }
 
-  oldnewmap_free_unused(fd->datamap);
+  return success;
+}
+
+/* Read all data associated with a datablock into datamap. */
+static BHead *read_data_into_datamap(FileData *fd, BHead *bhead, const char *allocname)
+{
+  bhead = blo_bhead_next(fd, bhead);
+
+  while (bhead && bhead->code == DATA) {
+    void *data;
+#if 0
+    /* XXX DUMB DEBUGGING OPTION TO GIVE NAMES for guarded malloc errors */
+    short* sp = fd->filesdna->structs[bhead->SDNAnr];
+    char* tmp = malloc(100);
+    allocname = fd->filesdna->types[sp[0]];
+    strcpy(tmp, allocname);
+    data = read_struct(fd, bhead, tmp);
+#else
+    data = read_struct(fd, bhead, allocname);
+#endif
+
+    if (data) {
+      oldnewmap_insert(fd->datamap, bhead->old, data, 0);
+    }
+
+    bhead = blo_bhead_next(fd, bhead);
+  }
+
+  return bhead;
+}
+
+/* Verify if the datablock and all associated data is identical. */
+static bool read_libblock_is_identical(FileData *fd, BHead *bhead)
+{
+  /* Test ID itself. */
+  if (bhead->len && !BHEADN_FROM_BHEAD(bhead)->is_memchunk_identical) {
+    return false;
+  }
+
+  /* Test any other data that is part of ID (logic must match read_data_into_datamap). */
+  bhead = blo_bhead_next(fd, bhead);
+
+  while (bhead && bhead->code == DATA) {
+    if (bhead->len && !BHEADN_FROM_BHEAD(bhead)->is_memchunk_identical) {
+      return false;
+    }
+
+    bhead = blo_bhead_next(fd, bhead);
+  }
+
+  return true;
+}
+
+/* For undo, restore matching library datablock from the old main. */
+static bool read_libblock_undo_restore_library(FileData *fd, Main *main, const ID *id)
+{
+  /* In undo case, most libs and linked data should be kept as is from previous state
+   * (see BLO_read_from_memfile).
+   * However, some needed by the snapshot being read may have been removed in previous one,
+   * and would go missing.
+   * This leads e.g. to disappearing objects in some undo/redo case, see T34446.
+   * That means we have to carefully check whether current lib or
+   * libdata already exits in old main, if it does we merely copy it over into new main area,
+   * otherwise we have to do a full read of that bhead... */
+  DEBUG_PRINTF("UNDO: restore library %s\n", id->name);
+
+  Main *libmain = fd->old_mainlist->first;
+  /* Skip oldmain itself... */
+  for (libmain = libmain->next; libmain; libmain = libmain->next) {
+    DEBUG_PRINTF("  compare with %s -> ", libmain->curlib ? libmain->curlib->id.name : "<NULL>");
+    if (libmain->curlib && STREQ(id->name, libmain->curlib->id.name)) {
+      Main *oldmain = fd->old_mainlist->first;
+      DEBUG_PRINTF("match!\n");
+      /* In case of a library, we need to re-add its main to fd->mainlist,
+       * because if we have later a missing ID_LINK_PLACEHOLDER,
+       * we need to get the correct lib it is linked to!
+       * Order is crucial, we cannot bulk-add it in BLO_read_from_memfile()
+       * like it used to be. */
+      BLI_remlink(fd->old_mainlist, libmain);
+      BLI_remlink_safe(&oldmain->libraries, libmain->curlib);
+      BLI_addtail(fd->mainlist, libmain);
+      BLI_addtail(&main->libraries, libmain->curlib);
+      return true;
+    }
+    DEBUG_PRINTF("no match\n");
+  }
+
+  return false;
+}
+
+/* For undo, restore existing linked datablock from the old main. */
+static bool read_libblock_undo_restore_linked(FileData *fd, Main *main, const ID *id, BHead *bhead)
+{
+  DEBUG_PRINTF("UNDO: restore linked datablock %s\n", id->name);
+  DEBUG_PRINTF("  from %s (%s): ",
+               main->curlib ? main->curlib->id.name : "<NULL>",
+               main->curlib ? main->curlib->name : "<NULL>");
+
+  ID *id_old = BKE_libblock_find_name(main, GS(id->name), id->name + 2);
+  if (id_old != NULL) {
+    DEBUG_PRINTF("  found!\n");
+    /* Even though we found our linked ID, there is no guarantee its address
+     * is still the same. */
+    if (id_old != bhead->old) {
+      oldnewmap_insert(fd->libmap, bhead->old, id_old, GS(id_old->name));
+    }
+
+    /* No need to do anything else for ID_LINK_PLACEHOLDER, it's assumed
+     * already present in its lib's main. */
+    return true;
+  }
+
+  DEBUG_PRINTF("  not found\n");
+  return false;
+}
+
+/* For undo, restore unchanged datablock from old main. */
+static void read_libblock_undo_restore_identical(
+    FileData *fd, Main *main, const ID *UNUSED(id), ID *id_old, const int tag)
+{
+  BLI_assert((fd->skip_flags & BLO_READ_SKIP_UNDO_OLD_MAIN) == 0);
+  BLI_assert(id_old != NULL);
+
+  /* Some tags need to be preserved here. */
+  id_old->tag = tag | (id_old->tag & LIB_TAG_EXTRAUSER);
+  id_old->lib = main->curlib;
+  id_old->us = ID_FAKE_USERS(id_old);
+  /* Do not reset id->icon_id here, memory allocated for it remains valid. */
+  /* Needed because .blend may have been saved with crap value here... */
+  id_old->newid = NULL;
+  id_old->orig_id = NULL;
+
+  const short idcode = GS(id_old->name);
+  Main *old_bmain = fd->old_mainlist->first;
+  ListBase *old_lb = which_libbase(old_bmain, idcode);
+  ListBase *new_lb = which_libbase(main, idcode);
+  BLI_remlink(old_lb, id_old);
+  BLI_addtail(new_lb, id_old);
+
+  /* Recalc flags, mostly these just remain as they are. */
+  id_old->recalc |= direct_link_id_restore_recalc_exceptions(id_old);
+  id_old->recalc_after_undo_push = 0;
+
+  /* As usual, proxies require some special love...
+   * In `blo_clear_proxy_pointers_from_lib()` we clear all `proxy_from` pointers to local IDs, for
+   * undo. This is required since we do not re-read linked data in that case, so we also do not
+   * re-'lib_link' their pointers.
+   * Those `proxy_from` pointers are then re-defined properly when lib_linking the newly read local
+   * object. However, in case of re-used data 'as-is', we never lib_link it again, so we have to
+   * fix those backward pointers here. */
+  if (GS(id_old->name) == ID_OB) {
+    Object *ob = (Object *)id_old;
+    if (ob->proxy != NULL) {
+      ob->proxy->proxy_from = ob;
+    }
+  }
+}
+
+/* For undo, store changed datablock at old address. */
+static void read_libblock_undo_restore_at_old_address(FileData *fd, Main *main, ID *id, ID *id_old)
+{
+  /* During memfile undo, if an ID changed and we cannot directly re-use existing one from old
+   * bmain, we do a full read of the new id from the memfile, and then fully swap its content
+   * with the old id. This allows us to keep the same pointer even for modified data, which
+   * helps reducing further detected changes by the depsgraph (since unchanged IDs remain fully
+   * unchanged, even if they are using/pointing to a changed one). */
+  BLI_assert((fd->skip_flags & BLO_READ_SKIP_UNDO_OLD_MAIN) == 0);
+  BLI_assert(id_old != NULL);
+
+  const short idcode = GS(id->name);
+
+  /* XXX 3DCursor (witch is UI data and as such should not be affected by undo) is stored in
+   * Scene... So this requires some special handling, previously done in `blo_lib_link_restore()`,
+   * but this cannot work anymore when we overwrite existing memory... */
+  if (idcode == ID_SCE) {
+    Scene *scene_old = (Scene *)id_old;
+    Scene *scene = (Scene *)id;
+    SWAP(View3DCursor, scene_old->cursor, scene->cursor);
+  }
+
+  Main *old_bmain = fd->old_mainlist->first;
+  ListBase *old_lb = which_libbase(old_bmain, idcode);
+  ListBase *new_lb = which_libbase(main, idcode);
+  BLI_remlink(old_lb, id_old);
+  BLI_remlink(new_lb, id);
+
+  /* We do not need any remapping from this call here, since no ID pointer is valid in the data
+   * currently (they are all pointing to old addresses, and need to go through `lib_link`
+   * process). So we can pass NULL for the Main pointer parameter. */
+  BKE_lib_id_swap_full(NULL, id, id_old);
+
+  BLI_addtail(new_lb, id_old);
+  BLI_addtail(old_lb, id);
+}
+
+static bool read_libblock_undo_restore(
+    FileData *fd, Main *main, BHead *bhead, const int tag, ID **r_id_old)
+{
+  /* Get pointer to memory of new ID that we will be reading. */
+  const ID *id = peek_struct_undo(fd, bhead);
+  const short idcode = GS(id->name);
+
+  if (bhead->code == ID_LI) {
+    /* Restore library datablock. */
+    if (read_libblock_undo_restore_library(fd, main, id)) {
+      return true;
+    }
+  }
+  else if (bhead->code == ID_LINK_PLACEHOLDER) {
+    /* Restore linked datablock. */
+    if (read_libblock_undo_restore_linked(fd, main, id, bhead)) {
+      return true;
+    }
+  }
+  else if (ELEM(idcode, ID_WM, ID_SCR, ID_WS)) {
+    /* Skip reading any UI datablocks, existing ones are kept. We don't
+     * support pointers from other datablocks to UI datablocks so those
+     * we also don't put UI datablocks in fd->libmap. */
+    return true;
+  }
+
+  /* Restore local datablocks. */
+  DEBUG_PRINTF("UNDO: read %s (uuid %u) -> ", id->name, id->session_uuid);
+
+  ID *id_old = NULL;
+  const bool do_partial_undo = (fd->skip_flags & BLO_READ_SKIP_UNDO_OLD_MAIN) == 0;
+  if (do_partial_undo && (bhead->code != ID_LINK_PLACEHOLDER)) {
+    /* This code should only ever be reached for local data-blocks. */
+    BLI_assert(main->curlib == NULL);
+
+    /* Find the 'current' existing ID we want to reuse instead of the one we
+     * would read from the undo memfile. */
+    BLI_assert(fd->old_idmap != NULL);
+    id_old = BKE_main_idmap_lookup_uuid(fd->old_idmap, id->session_uuid);
+  }
+
+  if (id_old != NULL && read_libblock_is_identical(fd, bhead)) {
+    /* Local datablock was unchanged, restore from the old main. */
+    DEBUG_PRINTF("keep identical datablock\n");
+
+    /* Do not add LIB_TAG_NEW here, this should not be needed/used in undo case anyway (as
+     * this is only for do_version-like code), but for sake of consistency, and also because
+     * it will tell us which ID is re-used from old Main, and which one is actually new. */
+    /* Also do not add LIB_TAG_NEED_LINK, those IDs will never be re-liblinked, hence that tag will
+     * never be cleared, leading to critical issue in link/append code. */
+    const int id_tag = tag | LIB_TAG_UNDO_OLD_ID_REUSED;
+    read_libblock_undo_restore_identical(fd, main, id, id_old, id_tag);
+
+    /* Insert into library map for lookup by newly read datablocks (with pointer value bhead->old).
+     * Note that existing datablocks in memory (which pointer value would be id_old) are not
+     * remapped anymore, so no need to store this info here. */
+    oldnewmap_insert(fd->libmap, bhead->old, id_old, bhead->code);
+
+    *r_id_old = id_old;
+    return true;
+  }
+  else if (id_old != NULL) {
+    /* Local datablock was changed. Restore at the address of the old datablock. */
+    DEBUG_PRINTF("read to old existing address\n");
+    *r_id_old = id_old;
+    return false;
+  }
+  else {
+    /* Local datablock does not exist in the undo step, so read from scratch. */
+    DEBUG_PRINTF("read at new address\n");
+    return false;
+  }
+}
+
+/* This routine reads a datablock and its direct data, and advances bhead to
+ * the next datablock. For library linked datablocks, only a placeholder will
+ * be generated, to be replaced in read_library_linked_ids.
+ *
+ * When reading for undo, libraries, linked datablocks and unchanged datablocks
+ * will be restored from the old database. Only new or changed datablocks will
+ * actually be read. */
+static BHead *read_libblock(FileData *fd,
+                            Main *main,
+                            BHead *bhead,
+                            const int tag,
+                            const bool placeholder_set_indirect_extern,
+                            ID **r_id)
+{
+  /* First attempt to restore existing datablocks for undo.
+   * When datablocks are changed but still exist, we restore them at the old
+   * address and inherit recalc flags for the dependency graph. */
+  ID *id_old = NULL;
+  if (fd->memfile != NULL) {
+    if (read_libblock_undo_restore(fd, main, bhead, tag, &id_old)) {
+      if (r_id) {
+        *r_id = id_old;
+      }
+      return blo_bhead_next(fd, bhead);
+    }
+  }
+
+  /* Read libblock struct. */
+  ID *id = read_struct(fd, bhead, "lib block");
+  if (id == NULL) {
+    if (r_id) {
+      *r_id = NULL;
+    }
+    return blo_bhead_next(fd, bhead);
+  }
+
+  /* Determine ID type and add to main database list. */
+  const short idcode = GS(id->name);
+  ListBase *lb = which_libbase(main, idcode);
+  if (lb == NULL) {
+    /* Unknown ID type. */
+    printf("%s: unknown id code '%c%c'\n", __func__, (idcode & 0xff), (idcode >> 8));
+    MEM_freeN(id);
+    if (r_id) {
+      *r_id = NULL;
+    }
+    return blo_bhead_next(fd, bhead);
+  }
+
+  /* NOTE: id must be added to the list before direct_link_id(), since
+   * direct_link_library() may remove it from there in case of duplicates. */
+  BLI_addtail(lb, id);
+
+  /* Insert into library map for lookup by newly read datablocks (with pointer value bhead->old).
+   * Note that existing datablocks in memory (which pointer value would be id_old) are not remapped
+   * remapped anymore, so no need to store this info here. */
+  ID *id_target = id_old ? id_old : id;
+  oldnewmap_insert(fd->libmap, bhead->old, id_target, bhead->code);
+
+  if (r_id) {
+    *r_id = id_target;
+  }
+
+  /* Set tag for new datablock to indicate lib linking and versioning needs
+   * to be done still. */
+  int id_tag = tag | LIB_TAG_NEED_LINK | LIB_TAG_NEW;
+
+  if (bhead->code == ID_LINK_PLACEHOLDER) {
+    /* Read placeholder for linked datablock. */
+    id_tag |= LIB_TAG_ID_LINK_PLACEHOLDER;
+
+    if (placeholder_set_indirect_extern) {
+      if (id->flag & LIB_INDIRECT_WEAK_LINK) {
+        id_tag |= LIB_TAG_INDIRECT;
+      }
+      else {
+        id_tag |= LIB_TAG_EXTERN;
+      }
+    }
+
+    direct_link_id(fd, main, id_tag, id, id_old);
+    return blo_bhead_next(fd, bhead);
+  }
+
+  /* Read datablock contents.
+   * Use convenient malloc name for debugging and better memory link prints. */
+  const char *allocname = dataname(idcode);
+  bhead = read_data_into_datamap(fd, bhead, allocname);
+  const bool success = direct_link_id(fd, main, id_tag, id, id_old);
   oldnewmap_clear(fd->datamap);
 
-  if (wrong_id) {
+  if (!success) {
     /* XXX This is probably working OK currently given the very limited scope of that flag.
      * However, it is absolutely **not** handled correctly: it is freeing an ID pointer that has
      * been added to the fd->libmap mapping, which in theory could lead to nice crashes...
@@ -9673,39 +9872,12 @@ static BHead *read_libblock(FileData *fd,
       *r_id = NULL;
     }
   }
-  else if (do_id_swap) {
-    /* During memfile undo, if an ID changed and we cannot directly re-use existing one from old
-     * bmain, we do a full read of the new id from the memfile, and then fully swap its content
-     * with the old id. This allows us to keep the same pointer even for modified data, which helps
-     * reducing further detected changes by the depsgraph (since unchanged IDs remain fully
-     * unchanged, even if they are using/pointing to a changed one). */
-
-    BLI_assert((fd->skip_flags & BLO_READ_SKIP_UNDO_OLD_MAIN) == 0);
-
-    Main *old_bmain = fd->old_mainlist->first;
-    BLI_assert(id_old != NULL);
-
-    ListBase *old_lb = which_libbase(old_bmain, idcode);
-    ListBase *new_lb = which_libbase(main, idcode);
-    BLI_remlink(old_lb, id_old);
-    BLI_remlink(new_lb, id);
-
-    /* We do not need any remapping from this call here, since no ID pointer is valid in the data
-     * currently (they are all pointing to old addresses, and need to go through `lib_link`
-     * process). So we can pass NULL for the Main pointer parameter. */
-    BKE_lib_id_swap_full(NULL, id, id_old);
-
-    BLI_addtail(new_lb, id_old);
-    BLI_addtail(old_lb, id);
-  }
-  else if (fd->memfile != NULL) {
-    DEBUG_PRINTF("We had to fully re-recreate ID %s (old addr: %p, new addr: %p)...\n",
-                 id->name,
-                 id_old,
-                 id);
+  else if (id_old) {
+    /* For undo, store contents read into id at id_old. */
+    read_libblock_undo_restore_at_old_address(fd, main, id, id_old);
   }
 
-  return (bhead);
+  return bhead;
 }
 
 /** \} */
@@ -9823,6 +9995,9 @@ static void do_versions(FileData *fd, Library *lib, Main *main)
 {
   /* WATCH IT!!!: pointers from libdata have not been converted */
 
+  /* Don't allow versioning to create new data-blocks. */
+  main->is_locked_for_linking = true;
+
   if (G.debug & G_DEBUG) {
     char build_commit_datetime[32];
     time_t temp_time = main->build_commit_timestamp;
@@ -9847,12 +10022,15 @@ static void do_versions(FileData *fd, Library *lib, Main *main)
   blo_do_versions_260(fd, lib, main);
   blo_do_versions_270(fd, lib, main);
   blo_do_versions_280(fd, lib, main);
+  blo_do_versions_290(fd, lib, main);
   blo_do_versions_cycles(fd, lib, main);
 
   /* WATCH IT!!!: pointers from libdata have not been converted yet here! */
   /* WATCH IT 2!: Userdef struct init see do_versions_userdef() above! */
 
   /* don't forget to set version number in BKE_blender_version.h! */
+
+  main->is_locked_for_linking = false;
 }
 
 static void do_versions_after_linking(Main *main, ReportList *reports)
@@ -9860,11 +10038,17 @@ static void do_versions_after_linking(Main *main, ReportList *reports)
   //  printf("%s for %s (%s), %d.%d\n", __func__, main->curlib ? main->curlib->name : main->name,
   //         main->curlib ? "LIB" : "MAIN", main->versionfile, main->subversionfile);
 
+  /* Don't allow versioning to create new data-blocks. */
+  main->is_locked_for_linking = true;
+
   do_versions_after_linking_250(main);
   do_versions_after_linking_260(main);
   do_versions_after_linking_270(main);
   do_versions_after_linking_280(main, reports);
+  do_versions_after_linking_290(main, reports);
   do_versions_after_linking_cycles(main);
+
+  main->is_locked_for_linking = false;
 }
 
 /** \} */
@@ -10019,6 +10203,9 @@ static void lib_link_all(FileData *fd, Main *bmain)
       case ID_AC:
         lib_link_action(fd, bmain, (bAction *)id);
         break;
+      case ID_SIM:
+        lib_link_simulation(fd, bmain, (Simulation *)id);
+        break;
       case ID_IP:
         /* XXX deprecated... still needs to be maintained for version patches still. */
         lib_link_ipo(fd, bmain, (Ipo *)id);
@@ -10051,6 +10238,15 @@ static void lib_link_all(FileData *fd, Main *bmain)
      * 'permanently' in our data structures... */
     BKE_main_collections_parent_relations_rebuild(bmain);
   }
+
+#ifndef NDEBUG
+  /* Double check we do not have any 'need link' tag remaining, this should never be the case once
+   * this function has run. */
+  FOREACH_MAIN_ID_BEGIN (bmain, id) {
+    BLI_assert((id->tag & LIB_TAG_NEED_LINK) == 0);
+  }
+  FOREACH_MAIN_ID_END;
+#endif
 }
 
 /** \} */
@@ -10082,7 +10278,7 @@ static BHead *read_userdef(BlendFileData *bfd, FileData *fd, BHead *bhead)
   user->subversionfile = bfd->main->subversionfile;
 
   /* read all data into fd->datamap */
-  bhead = read_data_into_oldnewmap(fd, bhead, "user def");
+  bhead = read_data_into_datamap(fd, bhead, "user def");
 
   link_list(fd, &user->themes);
   link_list(fd, &user->user_keymaps);
@@ -10116,14 +10312,14 @@ static BHead *read_userdef(BlendFileData *bfd, FileData *fd, BHead *bhead)
     }
   }
 
-  for (wmKeyConfigPref *kpt = user->user_keyconfig_prefs.first; kpt; kpt = kpt->next) {
+  LISTBASE_FOREACH (wmKeyConfigPref *, kpt, &user->user_keyconfig_prefs) {
     kpt->prop = newdataadr(fd, kpt->prop);
     IDP_DirectLinkGroup_OrFree(&kpt->prop, (fd->flags & FD_FLAGS_SWITCH_ENDIAN), fd);
   }
 
-  for (bUserMenu *um = user->user_menus.first; um; um = um->next) {
+  LISTBASE_FOREACH (bUserMenu *, um, &user->user_menus) {
     link_list(fd, &um->items);
-    for (bUserMenuItem *umi = um->items.first; umi; umi = umi->next) {
+    LISTBASE_FOREACH (bUserMenuItem *, umi, &um->items) {
       if (umi->type == USER_MENU_TYPE_OPERATOR) {
         bUserMenuItem_Op *umi_op = (bUserMenuItem_Op *)umi;
         umi_op->prop = newdataadr(fd, umi_op->prop);
@@ -10150,7 +10346,6 @@ static BHead *read_userdef(BlendFileData *bfd, FileData *fd, BHead *bhead)
   user->edit_studio_light = 0;
 
   /* free fd->datamap again */
-  oldnewmap_free_unused(fd->datamap);
   oldnewmap_clear(fd->datamap);
 
   return bhead;
@@ -10168,6 +10363,10 @@ BlendFileData *blo_read_file_internal(FileData *fd, const char *filepath)
   BlendFileData *bfd;
   ListBase mainlist = {NULL, NULL};
 
+  if (fd->memfile != NULL) {
+    DEBUG_PRINTF("\nUNDO: read step\n");
+  }
+
   bfd = MEM_callocN(sizeof(BlendFileData), "blendfiledata");
 
   bfd->main = BKE_main_new();
@@ -10285,7 +10484,7 @@ BlendFileData *blo_read_file_internal(FileData *fd, const char *filepath)
 
       /* Yep, second splitting... but this is a very cheap operation, so no big deal. */
       blo_split_main(&mainlist, bfd->main);
-      for (Main *mainvar = mainlist.first; mainvar; mainvar = mainvar->next) {
+      LISTBASE_FOREACH (Main *, mainvar, &mainlist) {
         BLI_assert(mainvar->versionfile != 0);
         do_versions_after_linking(mainvar, fd->reports);
       }
@@ -10394,7 +10593,7 @@ static BHead *find_previous_lib(FileData *fd, BHead *bhead)
 static BHead *find_bhead(FileData *fd, void *old)
 {
 #if 0
-	BHead* bhead;
+  BHead* bhead;
 #endif
   struct BHeadSort *bhs, bhs_s;
 
@@ -10414,11 +10613,11 @@ static BHead *find_bhead(FileData *fd, void *old)
   }
 
 #if 0
-	for (bhead = blo_bhead_first(fd); bhead; bhead = blo_bhead_next(fd, bhead)) {
-		if (bhead->old == old) {
-			return bhead;
-		}
-	}
+  for (bhead = blo_bhead_first(fd); bhead; bhead = blo_bhead_next(fd, bhead)) {
+    if (bhead->old == old) {
+      return bhead;
+    }
+  }
 #endif
 
   return NULL;
@@ -10549,9 +10748,9 @@ static void expand_doit_library(void *fdhandle, Main *mainvar, void *old)
 
       /* Commented because this can print way too much. */
 #if 0
-			if (G.debug & G_DEBUG) {
-				printf("expand_doit: already linked: %s lib: %s\n", id->name, lib->name);
-			}
+      if (G.debug & G_DEBUG) {
+        printf("expand_doit: already linked: %s lib: %s\n", id->name, lib->name);
+      }
 #endif
     }
 
@@ -10703,7 +10902,7 @@ static void expand_idprops(FileData *fd, Main *mainvar, IDProperty *prop)
       break;
     }
     case IDP_GROUP:
-      for (IDProperty *loop = prop->data.group.first; loop; loop = loop->next) {
+      LISTBASE_FOREACH (IDProperty *, loop, &prop->data.group) {
         expand_idprops(fd, mainvar, loop);
       }
       break;
@@ -10714,7 +10913,7 @@ static void expand_id(FileData *fd, Main *mainvar, ID *id);
 static void expand_nodetree(FileData *fd, Main *mainvar, bNodeTree *ntree);
 static void expand_collection(FileData *fd, Main *mainvar, Collection *collection);
 
-static void expand_id_private_id(FileData *fd, Main *mainvar, ID *id)
+static void expand_id_embedded_id(FileData *fd, Main *mainvar, ID *id)
 {
   /* Handle 'private IDs'. */
   bNodeTree *nodetree = ntreeFromID(id);
@@ -10746,7 +10945,7 @@ static void expand_id(FileData *fd, Main *mainvar, ID *id)
     expand_animdata(fd, mainvar, adt);
   }
 
-  expand_id_private_id(fd, mainvar, id);
+  expand_id_embedded_id(fd, mainvar, id);
 }
 
 static void expand_action(FileData *fd, Main *mainvar, bAction *act)
@@ -10763,7 +10962,7 @@ static void expand_action(FileData *fd, Main *mainvar, bAction *act)
   /* F-Curves in Action */
   expand_fcurves(fd, mainvar, &act->curves);
 
-  for (TimeMarker *marker = act->markers.first; marker; marker = marker->next) {
+  LISTBASE_FOREACH (TimeMarker *, marker, &act->markers) {
     if (marker->camera) {
       expand_doit(fd, mainvar, marker->camera);
     }
@@ -10831,18 +11030,18 @@ static void expand_particlesettings(FileData *fd, Main *mainvar, ParticleSetting
     }
   }
 
-  for (ParticleDupliWeight *dw = part->instance_weights.first; dw; dw = dw->next) {
+  LISTBASE_FOREACH (ParticleDupliWeight *, dw, &part->instance_weights) {
     expand_doit(fd, mainvar, dw->ob);
   }
 }
 
 static void expand_collection(FileData *fd, Main *mainvar, Collection *collection)
 {
-  for (CollectionObject *cob = collection->gobject.first; cob; cob = cob->next) {
+  LISTBASE_FOREACH (CollectionObject *, cob, &collection->gobject) {
     expand_doit(fd, mainvar, cob->ob);
   }
 
-  for (CollectionChild *child = collection->children.first; child; child = child->next) {
+  LISTBASE_FOREACH (CollectionChild *, child, &collection->children) {
     expand_doit(fd, mainvar, child->collection);
   }
 
@@ -10858,10 +11057,51 @@ static void expand_key(FileData *fd, Main *mainvar, Key *key)
   expand_doit(fd, mainvar, key->ipo);  // XXX deprecated - old animation system
 }
 
+static void expand_node_socket(FileData *fd, Main *mainvar, bNodeSocket *sock)
+{
+  expand_idprops(fd, mainvar, sock->prop);
+
+  if (sock->default_value != NULL) {
+
+    switch ((eNodeSocketDatatype)sock->type) {
+      case SOCK_OBJECT: {
+        bNodeSocketValueObject *default_value = sock->default_value;
+        expand_doit(fd, mainvar, default_value->value);
+        break;
+      }
+      case SOCK_IMAGE: {
+        bNodeSocketValueImage *default_value = sock->default_value;
+        expand_doit(fd, mainvar, default_value->value);
+        break;
+      }
+      case SOCK_FLOAT:
+      case SOCK_VECTOR:
+      case SOCK_RGBA:
+      case SOCK_BOOLEAN:
+      case SOCK_INT:
+      case SOCK_STRING:
+      case __SOCK_MESH:
+      case SOCK_CUSTOM:
+      case SOCK_SHADER:
+      case SOCK_EMITTERS:
+      case SOCK_EVENTS:
+      case SOCK_FORCES:
+      case SOCK_CONTROL_FLOW:
+        break;
+    }
+  }
+}
+
+static void expand_node_sockets(FileData *fd, Main *mainvar, ListBase *sockets)
+{
+  LISTBASE_FOREACH (bNodeSocket *, sock, sockets) {
+    expand_node_socket(fd, mainvar, sock);
+  }
+}
+
 static void expand_nodetree(FileData *fd, Main *mainvar, bNodeTree *ntree)
 {
   bNode *node;
-  bNodeSocket *sock;
 
   if (ntree->gpd) {
     expand_doit(fd, mainvar, ntree->gpd);
@@ -10874,20 +11114,12 @@ static void expand_nodetree(FileData *fd, Main *mainvar, bNodeTree *ntree)
 
     expand_idprops(fd, mainvar, node->prop);
 
-    for (sock = node->inputs.first; sock; sock = sock->next) {
-      expand_idprops(fd, mainvar, sock->prop);
-    }
-    for (sock = node->outputs.first; sock; sock = sock->next) {
-      expand_idprops(fd, mainvar, sock->prop);
-    }
+    expand_node_sockets(fd, mainvar, &node->inputs);
+    expand_node_sockets(fd, mainvar, &node->outputs);
   }
 
-  for (sock = ntree->inputs.first; sock; sock = sock->next) {
-    expand_idprops(fd, mainvar, sock->prop);
-  }
-  for (sock = ntree->outputs.first; sock; sock = sock->next) {
-    expand_idprops(fd, mainvar, sock->prop);
-  }
+  expand_node_sockets(fd, mainvar, &ntree->inputs);
+  expand_node_sockets(fd, mainvar, &ntree->outputs);
 }
 
 static void expand_texture(FileData *fd, Main *mainvar, Tex *tex)
@@ -11027,14 +11259,14 @@ static void expand_bones(FileData *fd, Main *mainvar, Bone *bone)
 {
   expand_idprops(fd, mainvar, bone->prop);
 
-  for (Bone *curBone = bone->childbase.first; curBone; curBone = curBone->next) {
+  LISTBASE_FOREACH (Bone *, curBone, &bone->childbase) {
     expand_bones(fd, mainvar, curBone);
   }
 }
 
 static void expand_armature(FileData *fd, Main *mainvar, bArmature *arm)
 {
-  for (Bone *curBone = arm->bonebase.first; curBone; curBone = curBone->next) {
+  LISTBASE_FOREACH (Bone *, curBone, &arm->bonebase) {
     expand_bones(fd, mainvar, curBone);
   }
 }
@@ -11073,7 +11305,7 @@ static void expand_object(FileData *fd, Main *mainvar, Object *ob)
     data.fd = fd;
     data.mainvar = mainvar;
 
-    modifiers_foreachIDLink(ob, expand_object_expandModifiers, (void *)&data);
+    BKE_modifiers_foreach_ID_link(ob, expand_object_expandModifiers, (void *)&data);
   }
 
   /* expand_object_expandModifier() */
@@ -11085,7 +11317,7 @@ static void expand_object(FileData *fd, Main *mainvar, Object *ob)
     data.fd = fd;
     data.mainvar = mainvar;
 
-    BKE_gpencil_modifiers_foreachIDLink(ob, expand_object_expandModifiers, (void *)&data);
+    BKE_gpencil_modifiers_foreach_ID_link(ob, expand_object_expandModifiers, (void *)&data);
   }
 
   /* expand_object_expandShaderFx() */
@@ -11097,7 +11329,7 @@ static void expand_object(FileData *fd, Main *mainvar, Object *ob)
     data.fd = fd;
     data.mainvar = mainvar;
 
-    BKE_shaderfx_foreachIDLink(ob, expand_object_expandModifiers, (void *)&data);
+    BKE_shaderfx_foreach_ID_link(ob, expand_object_expandModifiers, (void *)&data);
   }
 
   expand_pose(fd, mainvar, ob->pose);
@@ -11172,11 +11404,11 @@ static void expand_object(FileData *fd, Main *mainvar, Object *ob)
 #ifdef USE_COLLECTION_COMPAT_28
 static void expand_scene_collection(FileData *fd, Main *mainvar, SceneCollection *sc)
 {
-  for (LinkData *link = sc->objects.first; link; link = link->next) {
+  LISTBASE_FOREACH (LinkData *, link, &sc->objects) {
     expand_doit(fd, mainvar, link->data);
   }
 
-  for (SceneCollection *nsc = sc->scene_collections.first; nsc; nsc = nsc->next) {
+  LISTBASE_FOREACH (SceneCollection *, nsc, &sc->scene_collections) {
     expand_scene_collection(fd, mainvar, nsc);
   }
 }
@@ -11188,7 +11420,7 @@ static void expand_scene(FileData *fd, Main *mainvar, Scene *sce)
   FreestyleModuleConfig *module;
   FreestyleLineSet *lineset;
 
-  for (Base *base_legacy = sce->base.first; base_legacy; base_legacy = base_legacy->next) {
+  LISTBASE_FOREACH (Base *, base_legacy, &sce->base) {
     expand_doit(fd, mainvar, base_legacy->object);
   }
   expand_doit(fd, mainvar, sce->camera);
@@ -11215,7 +11447,7 @@ static void expand_scene(FileData *fd, Main *mainvar, Scene *sce)
     }
   }
 
-  for (ViewLayer *view_layer = sce->view_layers.first; view_layer; view_layer = view_layer->next) {
+  LISTBASE_FOREACH (ViewLayer *, view_layer, &sce->view_layers) {
     expand_idprops(fd, mainvar, view_layer->id_properties);
 
     for (module = view_layer->freestyle_config.modules.first; module; module = module->next) {
@@ -11271,7 +11503,7 @@ static void expand_scene(FileData *fd, Main *mainvar, Scene *sce)
     expand_doit(fd, mainvar, sce->rigidbody_world->constraints);
   }
 
-  for (TimeMarker *marker = sce->markers.first; marker; marker = marker->next) {
+  LISTBASE_FOREACH (TimeMarker *, marker, &sce->markers) {
     if (marker->camera) {
       expand_doit(fd, mainvar, marker->camera);
     }
@@ -11294,7 +11526,7 @@ static void expand_camera(FileData *fd, Main *mainvar, Camera *ca)
 {
   expand_doit(fd, mainvar, ca->ipo);  // XXX deprecated - old animation system
 
-  for (CameraBGImage *bgpic = ca->bg_images.first; bgpic; bgpic = bgpic->next) {
+  LISTBASE_FOREACH (CameraBGImage *, bgpic, &ca->bg_images) {
     if (bgpic->source == CAM_BGIMG_SOURCE_IMAGE) {
       expand_doit(fd, mainvar, bgpic->ima);
     }
@@ -11398,9 +11630,7 @@ static void expand_gpencil(FileData *fd, Main *mainvar, bGPdata *gpd)
 
 static void expand_workspace(FileData *fd, Main *mainvar, WorkSpace *workspace)
 {
-  ListBase *layouts = BKE_workspace_layouts_get(workspace);
-
-  for (WorkSpaceLayout *layout = layouts->first; layout; layout = layout->next) {
+  LISTBASE_FOREACH (WorkSpaceLayout *, layout, &workspace->layouts) {
     expand_doit(fd, mainvar, BKE_workspace_layout_screen_get(layout));
   }
 }
@@ -11438,6 +11668,13 @@ static void expand_volume(FileData *fd, Main *mainvar, Volume *volume)
   }
 }
 
+static void expand_simulation(FileData *fd, Main *mainvar, Simulation *simulation)
+{
+  if (simulation->adt) {
+    expand_animdata(fd, mainvar, simulation->adt);
+  }
+}
+
 /**
  * Set the callback func used over all ID data found by \a BLO_expand_main func.
  *
@@ -11567,6 +11804,9 @@ void BLO_expand_main(void *fdhandle, Main *mainvar)
             case ID_VO:
               expand_volume(fd, mainvar, (Volume *)id);
               break;
+            case ID_SIM:
+              expand_simulation(fd, mainvar, (Simulation *)id);
+              break;
             default:
               break;
           }
@@ -11703,6 +11943,7 @@ static void add_collections_to_scene(Main *mainvar,
       /* BKE_object_add(...) messes with the selection. */
       Object *ob = BKE_object_add_only_object(bmain, OB_EMPTY, collection->id.name + 2);
       ob->type = OB_EMPTY;
+      ob->empty_drawsize = U.collection_instance_empty_size;
 
       BKE_collection_object_add(bmain, active_collection, ob);
       Base *base = BKE_view_layer_base_find(view_layer, ob);
@@ -12142,7 +12383,7 @@ static int has_linked_ids_to_read(Main *mainvar)
   int a = set_listbasepointers(mainvar, lbarray);
 
   while (a--) {
-    for (ID *id = lbarray[a]->first; id; id = id->next) {
+    LISTBASE_FOREACH (ID *, id, lbarray[a]) {
       if ((id->tag & LIB_TAG_ID_LINK_PLACEHOLDER) && !(id->flag & LIB_INDIRECT_WEAK_LINK)) {
         return true;
       }
@@ -12373,9 +12614,9 @@ static void read_libraries(FileData *basefd, ListBase *mainlist)
       /* Does this library have any more linked data-blocks we need to read? */
       if (has_linked_ids_to_read(mainptr)) {
 #if 0
-				printf("Reading linked data-blocks from %s (%s)\n",
-					mainptr->curlib->id.name,
-					mainptr->curlib->name);
+        printf("Reading linked data-blocks from %s (%s)\n",
+          mainptr->curlib->id.name,
+          mainptr->curlib->name);
 #endif
 
         /* Open file if it has not been done yet. */
@@ -12439,4 +12680,164 @@ static void read_libraries(FileData *basefd, ListBase *mainlist)
   BKE_main_free(main_newid);
 }
 
+void *BLO_read_get_new_data_address(BlendDataReader *reader, const void *old_address)
+{
+  return newdataadr(reader->fd, old_address);
+}
+
+ID *BLO_read_get_new_id_address(BlendLibReader *reader, Library *lib, ID *id)
+{
+  return newlibadr(reader->fd, lib, id);
+}
+
+bool BLO_read_requires_endian_switch(BlendDataReader *reader)
+{
+  return (reader->fd->flags & FD_FLAGS_SWITCH_ENDIAN) != 0;
+}
+
+/**
+ * Updates all ->prev and ->next pointers of the list elements.
+ * Updates the list->first and list->last pointers.
+ * When not NULL, calls the callback on every element.
+ */
+void BLO_read_list(BlendDataReader *reader, ListBase *list, BlendReadListFn callback)
+{
+  if (BLI_listbase_is_empty(list)) {
+    return;
+  }
+
+  BLO_read_data_address(reader, &list->first);
+  if (callback != NULL) {
+    callback(reader, list->first);
+  }
+  Link *ln = list->first;
+  Link *prev = NULL;
+  while (ln) {
+    BLO_read_data_address(reader, &ln->next);
+    if (ln->next != NULL && callback != NULL) {
+      callback(reader, ln->next);
+    }
+    ln->prev = prev;
+    prev = ln;
+    ln = ln->next;
+  }
+  list->last = prev;
+}
+
+void BLO_read_int32_array(BlendDataReader *reader, int array_size, int32_t **ptr_p)
+{
+  BLO_read_data_address(reader, ptr_p);
+  if (BLO_read_requires_endian_switch(reader)) {
+    BLI_endian_switch_int32_array(*ptr_p, array_size);
+  }
+}
+
+void BLO_read_uint32_array(BlendDataReader *reader, int array_size, uint32_t **ptr_p)
+{
+  BLO_read_data_address(reader, ptr_p);
+  if (BLO_read_requires_endian_switch(reader)) {
+    BLI_endian_switch_uint32_array(*ptr_p, array_size);
+  }
+}
+
+void BLO_read_float_array(BlendDataReader *reader, int array_size, float **ptr_p)
+{
+  BLO_read_data_address(reader, ptr_p);
+  if (BLO_read_requires_endian_switch(reader)) {
+    BLI_endian_switch_float_array(*ptr_p, array_size);
+  }
+}
+
+void BLO_read_float3_array(BlendDataReader *reader, int array_size, float **ptr_p)
+{
+  BLO_read_float_array(reader, array_size * 3, ptr_p);
+}
+
+void BLO_read_double_array(BlendDataReader *reader, int array_size, double **ptr_p)
+{
+  BLO_read_data_address(reader, ptr_p);
+  if (BLO_read_requires_endian_switch(reader)) {
+    BLI_endian_switch_double_array(*ptr_p, array_size);
+  }
+}
+
+static void convert_pointer_array_64_to_32(BlendDataReader *reader,
+                                           uint array_size,
+                                           const uint64_t *src,
+                                           uint32_t *dst)
+{
+  /* Match pointer conversion rules from bh4_from_bh8 and cast_pointer. */
+  if (BLO_read_requires_endian_switch(reader)) {
+    for (int i = 0; i < array_size; i++) {
+      uint64_t ptr = src[i];
+      BLI_endian_switch_uint64(&ptr);
+      dst[i] = (uint32_t)(ptr >> 3);
+    }
+  }
+  else {
+    for (int i = 0; i < array_size; i++) {
+      dst[i] = (uint32_t)(src[i] >> 3);
+    }
+  }
+}
+
+static void convert_pointer_array_32_to_64(BlendDataReader *UNUSED(reader),
+                                           uint array_size,
+                                           const uint32_t *src,
+                                           uint64_t *dst)
+{
+  /* Match pointer conversion rules from bh8_from_bh4 and cast_pointer. */
+  for (int i = 0; i < array_size; i++) {
+    dst[i] = src[i];
+  }
+}
+
+void BLO_read_pointer_array(BlendDataReader *reader, void **ptr_p)
+{
+  FileData *fd = reader->fd;
+
+  void *orig_array = newdataadr(fd, *ptr_p);
+  if (orig_array == NULL) {
+    *ptr_p = NULL;
+    return;
+  }
+
+  int file_pointer_size = fd->filesdna->pointer_size;
+  int current_pointer_size = fd->memsdna->pointer_size;
+
+  /* Overallocation is fine, but might be better to pass the length as parameter. */
+  int array_size = MEM_allocN_len(orig_array) / file_pointer_size;
+
+  void *final_array = NULL;
+
+  if (file_pointer_size == current_pointer_size) {
+    /* No pointer conversion necessary. */
+    final_array = orig_array;
+  }
+  else if (file_pointer_size == 8 && current_pointer_size == 4) {
+    /* Convert pointers from 64 to 32 bit. */
+    final_array = MEM_malloc_arrayN(array_size, 4, "new pointer array");
+    convert_pointer_array_64_to_32(
+        reader, array_size, (uint64_t *)orig_array, (uint32_t *)final_array);
+    MEM_freeN(orig_array);
+  }
+  else if (file_pointer_size == 4 && current_pointer_size == 8) {
+    /* Convert pointers from 32 to 64 bit. */
+    final_array = MEM_malloc_arrayN(array_size, 8, "new pointer array");
+    convert_pointer_array_32_to_64(
+        reader, array_size, (uint32_t *)orig_array, (uint64_t *)final_array);
+    MEM_freeN(orig_array);
+  }
+  else {
+    BLI_assert(false);
+  }
+
+  *ptr_p = final_array;
+}
+
+void BLO_expand_id(BlendExpander *expander, ID *id)
+{
+  expand_doit(expander->fd, expander->main, id);
+}
+
 /** \} */
diff --git a/source/blender/blenloader/intern/readfile.h b/source/blender/blenloader/intern/readfile.h
index 5be7e703d6b..f698d642e33 100644
--- a/source/blender/blenloader/intern/readfile.h
+++ b/source/blender/blenloader/intern/readfile.h
@@ -85,11 +85,6 @@ typedef struct FileData {
   const char *buffer;
   /** Variables needed for reading from memfile (undo). */
   struct MemFile *memfile;
-  /** Whether all data read from memfile so far was identical
-   * (i.e. shared with some previous undo step).
-   * Updated by `fd_read_from_memfile()`, user is responsible to reset it to true when needed.
-   * Used to detect unchanged IDs. */
-  bool are_memchunks_identical;
   /** Whether we are undoing (< 0) or redoing (> 0), used to choose which 'unchanged' flag to use
    * to detect unchanged data from memfile. */
   short undo_direction;
@@ -204,12 +199,14 @@ void blo_do_versions_250(struct FileData *fd, struct Library *lib, struct Main *
 void blo_do_versions_260(struct FileData *fd, struct Library *lib, struct Main *bmain);
 void blo_do_versions_270(struct FileData *fd, struct Library *lib, struct Main *bmain);
 void blo_do_versions_280(struct FileData *fd, struct Library *lib, struct Main *bmain);
+void blo_do_versions_290(struct FileData *fd, struct Library *lib, struct Main *bmain);
 void blo_do_versions_cycles(struct FileData *fd, struct Library *lib, struct Main *bmain);
 
 void do_versions_after_linking_250(struct Main *bmain);
 void do_versions_after_linking_260(struct Main *bmain);
 void do_versions_after_linking_270(struct Main *bmain);
-void do_versions_after_linking_280(struct Main *bmain, ReportList *reports);
+void do_versions_after_linking_280(struct Main *bmain, struct ReportList *reports);
+void do_versions_after_linking_290(struct Main *bmain, struct ReportList *reports);
 void do_versions_after_linking_cycles(struct Main *bmain);
 
 #endif
diff --git a/source/blender/blenloader/intern/undofile.c b/source/blender/blenloader/intern/undofile.c
index 06469a0c087..28b37c4a737 100644
--- a/source/blender/blenloader/intern/undofile.c
+++ b/source/blender/blenloader/intern/undofile.c
@@ -41,10 +41,12 @@
 #include "DNA_listBase.h"
 
 #include "BLI_blenlib.h"
+#include "BLI_ghash.h"
 
 #include "BLO_readfile.h"
 #include "BLO_undofile.h"
 
+#include "BKE_lib_id.h"
 #include "BKE_main.h"
 
 /* keep last */
@@ -92,13 +94,69 @@ void BLO_memfile_merge(MemFile *first, MemFile *second)
   BLO_memfile_free(first);
 }
 
-void memfile_chunk_add(MemFile *memfile, const char *buf, uint size, MemFileChunk **compchunk_step)
+/* Clear is_identical_future before adding next memfile. */
+void BLO_memfile_clear_future(MemFile *memfile)
 {
+  LISTBASE_FOREACH (MemFileChunk *, chunk, &memfile->chunks) {
+    chunk->is_identical_future = false;
+  }
+}
+
+void BLO_memfile_write_init(MemFileWriteData *mem_data,
+                            MemFile *written_memfile,
+                            MemFile *reference_memfile)
+{
+  mem_data->written_memfile = written_memfile;
+  mem_data->reference_memfile = reference_memfile;
+  mem_data->reference_current_chunk = reference_memfile ? reference_memfile->chunks.first : NULL;
+
+  /* If we have a reference memfile, we generate a mapping between the session_uuid's of the IDs
+   * stored in that previous undo step, and its first matching memchunk.
+   * This will allow us to easily find the existing undo memory storage of IDs even when some
+   * re-ordering in current Main data-base broke the order matching with the memchunks from
+   * previous step. */
+  if (reference_memfile != NULL) {
+    mem_data->id_session_uuid_mapping = BLI_ghash_new(
+        BLI_ghashutil_inthash_p_simple, BLI_ghashutil_intcmp, __func__);
+    uint current_session_uuid = MAIN_ID_SESSION_UUID_UNSET;
+    LISTBASE_FOREACH (MemFileChunk *, mem_chunk, &reference_memfile->chunks) {
+      if (!ELEM(mem_chunk->id_session_uuid, MAIN_ID_SESSION_UUID_UNSET, current_session_uuid)) {
+        current_session_uuid = mem_chunk->id_session_uuid;
+        void **entry;
+        if (!BLI_ghash_ensure_p(mem_data->id_session_uuid_mapping,
+                                POINTER_FROM_UINT(current_session_uuid),
+                                &entry)) {
+          *entry = mem_chunk;
+        }
+        else {
+          BLI_assert(0);
+        }
+      }
+    }
+  }
+}
+
+void BLO_memfile_write_finalize(MemFileWriteData *mem_data)
+{
+  if (mem_data->id_session_uuid_mapping != NULL) {
+    BLI_ghash_free(mem_data->id_session_uuid_mapping, NULL, NULL);
+  }
+}
+
+void BLO_memfile_chunk_add(MemFileWriteData *mem_data, const char *buf, uint size)
+{
+  MemFile *memfile = mem_data->written_memfile;
+  MemFileChunk **compchunk_step = &mem_data->reference_current_chunk;
+
   MemFileChunk *curchunk = MEM_mallocN(sizeof(MemFileChunk), "MemFileChunk");
   curchunk->size = size;
   curchunk->buf = NULL;
   curchunk->is_identical = false;
-  curchunk->is_identical_future = false;
+  /* This is unsafe in the sense that an app handler or other code that does not
+   * perform an undo push may make changes after the last undo push that
+   * will then not be undo. Though it's not entirely clear that is wrong behavior. */
+  curchunk->is_identical_future = true;
+  curchunk->id_session_uuid = mem_data->current_id_session_uuid;
   BLI_addtail(&memfile->chunks, curchunk);
 
   /* we compare compchunk with buf */
diff --git a/source/blender/blenloader/intern/versioning_250.c b/source/blender/blenloader/intern/versioning_250.c
index fed0cbda466..eaeef0d52c1 100644
--- a/source/blender/blenloader/intern/versioning_250.c
+++ b/source/blender/blenloader/intern/versioning_250.c
@@ -61,7 +61,8 @@
 #include "BLI_math.h"
 #include "BLI_utildefines.h"
 
-#include "BKE_anim.h"
+#include "BKE_anim_data.h"
+#include "BKE_anim_visualization.h"
 #include "BKE_armature.h"
 #include "BKE_colortools.h"
 #include "BKE_global.h"  // for G
@@ -88,13 +89,13 @@
 #define U (*((const UserDef *)&U))
 
 /* 2.50 patch */
-static void area_add_header_region(ScrArea *sa, ListBase *lb)
+static void area_add_header_region(ScrArea *area, ListBase *lb)
 {
   ARegion *region = MEM_callocN(sizeof(ARegion), "area region from do_versions");
 
   BLI_addtail(lb, region);
   region->regiontype = RGN_TYPE_HEADER;
-  if (sa->headertype == 1) {
+  if (area->headertype == 1) {
     region->alignment = RGN_ALIGN_BOTTOM;
   }
   else {
@@ -133,10 +134,10 @@ static void sequencer_init_preview_region(ARegion *region)
   region->v2d.keeptot = V2D_KEEPTOT_FREE;
 }
 
-static void area_add_window_regions(ScrArea *sa, SpaceLink *sl, ListBase *lb)
+static void area_add_window_regions(ScrArea *area, SpaceLink *sl, ListBase *lb)
 {
   ARegion *region;
-  ARegion *ar_main;
+  ARegion *region_main;
 
   if (sl) {
     /* first channels for ipo action nla... */
@@ -205,14 +206,14 @@ static void area_add_window_regions(ScrArea *sa, SpaceLink *sl, ListBase *lb)
         region->alignment = RGN_ALIGN_TOP;
         break;
       case SPACE_SEQ:
-        ar_main = (ARegion *)lb->first;
-        for (; ar_main; ar_main = ar_main->next) {
-          if (ar_main->regiontype == RGN_TYPE_WINDOW) {
+        region_main = (ARegion *)lb->first;
+        for (; region_main; region_main = region_main->next) {
+          if (region_main->regiontype == RGN_TYPE_WINDOW) {
             break;
           }
         }
         region = MEM_callocN(sizeof(ARegion), "preview area for sequencer");
-        BLI_insertlinkbefore(lb, ar_main, region);
+        BLI_insertlinkbefore(lb, region_main, region);
         sequencer_init_preview_region(region);
         break;
       case SPACE_VIEW3D:
@@ -256,7 +257,7 @@ static void area_add_window_regions(ScrArea *sa, SpaceLink *sl, ListBase *lb)
   region = MEM_callocN(sizeof(ARegion), "area region from do_versions");
 
   BLI_addtail(lb, region);
-  region->winrct = sa->totrct;
+  region->winrct = area->totrct;
 
   region->regiontype = RGN_TYPE_WINDOW;
 
@@ -303,7 +304,7 @@ static void area_add_window_regions(ScrArea *sa, SpaceLink *sl, ListBase *lb)
         SpaceNla *snla = (SpaceNla *)sl;
         memcpy(&region->v2d, &snla->v2d, sizeof(View2D));
 
-        region->v2d.tot.ymin = (float)(-sa->winy) / 3.0f;
+        region->v2d.tot.ymin = (float)(-area->winy) / 3.0f;
         region->v2d.tot.ymax = 0.0f;
 
         region->v2d.scroll |= (V2D_SCROLL_BOTTOM | V2D_SCROLL_HORIZONTAL_HANDLES);
@@ -318,8 +319,8 @@ static void area_add_window_regions(ScrArea *sa, SpaceLink *sl, ListBase *lb)
         /* We totally reinit the view for the Action Editor,
          * as some old instances had some weird cruft set. */
         region->v2d.tot.xmin = -20.0f;
-        region->v2d.tot.ymin = (float)(-sa->winy) / 3.0f;
-        region->v2d.tot.xmax = (float)((sa->winx > 120) ? (sa->winx) : 120);
+        region->v2d.tot.ymin = (float)(-area->winy) / 3.0f;
+        region->v2d.tot.xmax = (float)((area->winx > 120) ? (area->winx) : 120);
         region->v2d.tot.ymax = 0.0f;
 
         region->v2d.cur = region->v2d.tot;
@@ -397,40 +398,40 @@ static void area_add_window_regions(ScrArea *sa, SpaceLink *sl, ListBase *lb)
 
 static void do_versions_windowmanager_2_50(bScreen *screen)
 {
-  ScrArea *sa;
+  ScrArea *area;
   SpaceLink *sl;
 
   /* add regions */
-  for (sa = screen->areabase.first; sa; sa = sa->next) {
+  for (area = screen->areabase.first; area; area = area->next) {
     /* we keep headertype variable to convert old files only */
-    if (sa->headertype) {
-      area_add_header_region(sa, &sa->regionbase);
+    if (area->headertype) {
+      area_add_header_region(area, &area->regionbase);
     }
 
-    area_add_window_regions(sa, sa->spacedata.first, &sa->regionbase);
+    area_add_window_regions(area, area->spacedata.first, &area->regionbase);
 
     /* space imageselect is deprecated */
-    for (sl = sa->spacedata.first; sl; sl = sl->next) {
+    for (sl = area->spacedata.first; sl; sl = sl->next) {
       if (sl->spacetype == SPACE_IMASEL) {
         sl->spacetype = SPACE_EMPTY; /* spacedata then matches */
       }
     }
 
     /* space sound is deprecated */
-    for (sl = sa->spacedata.first; sl; sl = sl->next) {
+    for (sl = area->spacedata.first; sl; sl = sl->next) {
       if (sl->spacetype == SPACE_SOUND) {
         sl->spacetype = SPACE_EMPTY; /* spacedata then matches */
       }
     }
 
     /* pushed back spaces also need regions! */
-    if (sa->spacedata.first) {
-      sl = sa->spacedata.first;
+    if (area->spacedata.first) {
+      sl = area->spacedata.first;
       for (sl = sl->next; sl; sl = sl->next) {
-        if (sa->headertype) {
-          area_add_header_region(sa, &sl->regionbase);
+        if (area->headertype) {
+          area_add_header_region(area, &sl->regionbase);
         }
-        area_add_window_regions(sa, sl, &sl->regionbase);
+        area_add_window_regions(area, sl, &sl->regionbase);
       }
     }
   }
@@ -455,12 +456,12 @@ static void versions_gpencil_add_main(ListBase *lb, ID *id, const char *name)
 
 static void do_versions_gpencil_2_50(Main *main, bScreen *screen)
 {
-  ScrArea *sa;
+  ScrArea *area;
   SpaceLink *sl;
 
   /* add regions */
-  for (sa = screen->areabase.first; sa; sa = sa->next) {
-    for (sl = sa->spacedata.first; sl; sl = sl->next) {
+  for (area = screen->areabase.first; area; area = area->next) {
+    for (sl = area->spacedata.first; sl; sl = sl->next) {
       if (sl->spacetype == SPACE_VIEW3D) {
         View3D *v3d = (View3D *)sl;
         if (v3d->gpd) {
@@ -514,7 +515,7 @@ static void do_version_mdef_250(Main *main)
           mmd->bindcagecos = mmd->bindcos;
           mmd->bindcos = NULL;
 
-          modifier_mdef_compact_influences(md);
+          BKE_modifier_mdef_compact_influences(md);
         }
       }
     }
@@ -871,7 +872,7 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
 
     for (ob = bmain->objects.first; ob; ob = ob->id.next) {
       /* fluid-sim stuff */
-      FluidsimModifierData *fluidmd = (FluidsimModifierData *)modifiers_findByType(
+      FluidsimModifierData *fluidmd = (FluidsimModifierData *)BKE_modifiers_findby_type(
           ob, eModifierType_Fluidsim);
       if (fluidmd) {
         fluidmd->fss->fmd = fluidmd;
@@ -918,8 +919,8 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
 
       if (do_gravity) {
         for (md = ob->modifiers.first; md; md = md->next) {
-          ClothModifierData *clmd = (ClothModifierData *)modifiers_findByType(ob,
-                                                                              eModifierType_Cloth);
+          ClothModifierData *clmd = (ClothModifierData *)BKE_modifiers_findby_type(
+              ob, eModifierType_Cloth);
           if (clmd) {
             clmd->sim_parms->effector_weights->global_gravity = clmd->sim_parms->gravity[2] /
                                                                 -9.81f;
@@ -1079,12 +1080,12 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
 
     {
       bScreen *screen;
-      ScrArea *sa;
+      ScrArea *area;
       SpaceLink *sl;
 
       for (screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (sa = screen->areabase.first; sa; sa = sa->next) {
-          for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (area = screen->areabase.first; area; area = area->next) {
+          for (sl = area->spacedata.first; sl; sl = sl->next) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               if (v3d->drawtype == OB_MATERIAL) {
@@ -1154,7 +1155,7 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
       }
 
       for (ob = bmain->objects.first; ob; ob = ob->id.next) {
-        MultiresModifierData *mmd = (MultiresModifierData *)modifiers_findByType(
+        MultiresModifierData *mmd = (MultiresModifierData *)BKE_modifiers_findby_type(
             ob, eModifierType_Multires);
 
         if (mmd) {
@@ -1188,19 +1189,19 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
   if (bmain->versionfile == 250 && bmain->subversionfile == 10) {
     /* fix for new view type in sequencer */
     bScreen *screen;
-    ScrArea *sa;
+    ScrArea *area;
     SpaceLink *sl;
 
     /* remove all preview window in wrong spaces */
     for (screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (sa = screen->areabase.first; sa; sa = sa->next) {
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+      for (area = screen->areabase.first; area; area = area->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype != SPACE_SEQ) {
             ARegion *region;
             ListBase *regionbase;
 
-            if (sl == sa->spacedata.first) {
-              regionbase = &sa->regionbase;
+            if (sl == area->spacedata.first) {
+              regionbase = &area->regionbase;
             }
             else {
               regionbase = &sl->regionbase;
@@ -1227,20 +1228,20 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
     {
       /* fix for new view type in sequencer */
       bScreen *screen;
-      ScrArea *sa;
+      ScrArea *area;
       SpaceLink *sl;
 
       for (screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (sa = screen->areabase.first; sa; sa = sa->next) {
-          for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (area = screen->areabase.first; area; area = area->next) {
+          for (sl = area->spacedata.first; sl; sl = sl->next) {
             if (sl->spacetype == SPACE_SEQ) {
               ARegion *region;
-              ARegion *ar_main;
+              ARegion *region_main;
               ListBase *regionbase;
               SpaceSeq *sseq = (SpaceSeq *)sl;
 
-              if (sl == sa->spacedata.first) {
-                regionbase = &sa->regionbase;
+              if (sl == area->spacedata.first) {
+                regionbase = &area->regionbase;
               }
               else {
                 regionbase = &sl->regionbase;
@@ -1253,14 +1254,14 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
                 sseq->mainb = SEQ_DRAW_IMG_IMBUF;
               }
 
-              ar_main = (ARegion *)regionbase->first;
-              for (; ar_main; ar_main = ar_main->next) {
-                if (ar_main->regiontype == RGN_TYPE_WINDOW) {
+              region_main = (ARegion *)regionbase->first;
+              for (; region_main; region_main = region_main->next) {
+                if (region_main->regiontype == RGN_TYPE_WINDOW) {
                   break;
                 }
               }
               region = MEM_callocN(sizeof(ARegion), "preview area for sequencer");
-              BLI_insertlinkbefore(regionbase, ar_main, region);
+              BLI_insertlinkbefore(regionbase, region_main, region);
               sequencer_init_preview_region(region);
             }
           }
@@ -1360,17 +1361,17 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
   if (bmain->versionfile < 250 || (bmain->versionfile == 250 && bmain->subversionfile < 14)) {
     /* fix for bad View2D extents for Animation Editors */
     bScreen *screen;
-    ScrArea *sa;
+    ScrArea *area;
     SpaceLink *sl;
 
     for (screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (sa = screen->areabase.first; sa; sa = sa->next) {
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+      for (area = screen->areabase.first; area; area = area->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           ListBase *regionbase;
           ARegion *region;
 
-          if (sl == sa->spacedata.first) {
-            regionbase = &sa->regionbase;
+          if (sl == area->spacedata.first) {
+            regionbase = &area->regionbase;
           }
           else {
             regionbase = &sl->regionbase;
@@ -1380,7 +1381,7 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
             for (region = (ARegion *)regionbase->first; region; region = region->next) {
               if (region->regiontype == RGN_TYPE_WINDOW) {
                 region->v2d.cur.ymax = region->v2d.tot.ymax = 0.0f;
-                region->v2d.cur.ymin = region->v2d.tot.ymin = (float)(-sa->winy) / 3.0f;
+                region->v2d.cur.ymin = region->v2d.tot.ymin = (float)(-area->winy) / 3.0f;
               }
             }
           }
@@ -1426,31 +1427,31 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
     /* sequencer changes */
     {
       bScreen *screen;
-      ScrArea *sa;
+      ScrArea *area;
       SpaceLink *sl;
 
       for (screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (sa = screen->areabase.first; sa; sa = sa->next) {
-          for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (area = screen->areabase.first; area; area = area->next) {
+          for (sl = area->spacedata.first; sl; sl = sl->next) {
             if (sl->spacetype == SPACE_SEQ) {
-              ARegion *ar_preview;
+              ARegion *region_preview;
               ListBase *regionbase;
 
-              if (sl == sa->spacedata.first) {
-                regionbase = &sa->regionbase;
+              if (sl == area->spacedata.first) {
+                regionbase = &area->regionbase;
               }
               else {
                 regionbase = &sl->regionbase;
               }
 
-              ar_preview = (ARegion *)regionbase->first;
-              for (; ar_preview; ar_preview = ar_preview->next) {
-                if (ar_preview->regiontype == RGN_TYPE_PREVIEW) {
+              region_preview = (ARegion *)regionbase->first;
+              for (; region_preview; region_preview = region_preview->next) {
+                if (region_preview->regiontype == RGN_TYPE_PREVIEW) {
                   break;
                 }
               }
-              if (ar_preview && (ar_preview->regiontype == RGN_TYPE_PREVIEW)) {
-                sequencer_init_preview_region(ar_preview);
+              if (region_preview && (region_preview->regiontype == RGN_TYPE_PREVIEW)) {
+                sequencer_init_preview_region(region_preview);
               }
             }
           }
@@ -1460,17 +1461,17 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
   }
 
   if (bmain->versionfile <= 251) { /* 2.5.1 had no subversions */
-    bScreen *sc;
+    bScreen *screen;
 
     /* Blender 2.5.2 - subversion 0 introduced a new setting: V3D_HIDE_OVERLAYS.
      * This bit was used in the past for V3D_TRANSFORM_SNAP, which is now deprecated.
      * Here we clear it for old files so they don't come in with V3D_HIDE_OVERLAYS set,
      * which would cause cameras, lights, etc to become invisible */
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype == SPACE_VIEW3D) {
             View3D *v3d = (View3D *)sl;
             v3d->flag2 &= ~V3D_HIDE_OVERLAYS;
@@ -1547,16 +1548,16 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
   }
 
   if (bmain->versionfile < 252 || (bmain->versionfile == 252 && bmain->subversionfile < 5)) {
-    bScreen *sc;
+    bScreen *screen;
 
     /* Image editor scopes */
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
 
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
 
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype == SPACE_IMAGE) {
             SpaceImage *sima = (SpaceImage *)sl;
             BKE_scopes_new(&sima->scopes);
@@ -1569,23 +1570,23 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
   if (bmain->versionfile < 253) {
     Object *ob;
     Scene *scene;
-    bScreen *sc;
+    bScreen *screen;
     Tex *tex;
     Brush *brush;
 
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
 
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype == SPACE_NODE) {
             SpaceNode *snode = (SpaceNode *)sl;
             ListBase *regionbase;
             ARegion *region;
 
-            if (sl == sa->spacedata.first) {
-              regionbase = &sa->regionbase;
+            if (sl == area->spacedata.first) {
+              regionbase = &area->regionbase;
             }
             else {
               regionbase = &sl->regionbase;
@@ -1625,7 +1626,7 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
             ArmatureModifierData *amd;
             bArmature *arm = (bArmature *)blo_do_versions_newlibadr(fd, lib, parent->data);
 
-            amd = (ArmatureModifierData *)modifier_new(eModifierType_Armature);
+            amd = (ArmatureModifierData *)BKE_modifier_new(eModifierType_Armature);
             amd->object = ob->parent;
             BLI_addtail((ListBase *)&ob->modifiers, amd);
             amd->deformflag = arm->deformflag;
@@ -1634,7 +1635,7 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
           else if (parent->type == OB_LATTICE && ob->partype == PARSKEL) {
             LatticeModifierData *lmd;
 
-            lmd = (LatticeModifierData *)modifier_new(eModifierType_Lattice);
+            lmd = (LatticeModifierData *)BKE_modifier_new(eModifierType_Lattice);
             lmd->object = ob->parent;
             BLI_addtail((ListBase *)&ob->modifiers, lmd);
             ob->partype = PAROBJECT;
@@ -1642,7 +1643,7 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
           else if (parent->type == OB_CURVE && ob->partype == PARCURVE) {
             CurveModifierData *cmd;
 
-            cmd = (CurveModifierData *)modifier_new(eModifierType_Curve);
+            cmd = (CurveModifierData *)BKE_modifier_new(eModifierType_Curve);
             cmd->object = ob->parent;
             BLI_addtail((ListBase *)&ob->modifiers, cmd);
             ob->partype = PAROBJECT;
@@ -1833,7 +1834,7 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
   if (bmain->versionfile < 255 || (bmain->versionfile == 255 && bmain->subversionfile < 1)) {
     Brush *br;
     ParticleSettings *part;
-    bScreen *sc;
+    bScreen *screen;
 
     for (br = bmain->brushes.first; br; br = br->id.next) {
       if (br->ob_mode == 0) {
@@ -1850,18 +1851,18 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
       part->kink_amp_clump = 1.f;      /* keep old files looking similar */
     }
 
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype == SPACE_INFO) {
             SpaceInfo *sinfo = (SpaceInfo *)sl;
             ARegion *region;
 
             sinfo->rpt_mask = INFO_RPT_OP;
 
-            for (region = sa->regionbase.first; region; region = region->next) {
+            for (region = area->regionbase.first; region; region = region->next) {
               if (region->regiontype == RGN_TYPE_WINDOW) {
                 region->v2d.scroll = (V2D_SCROLL_RIGHT);
                 region->v2d.align = V2D_ALIGN_NO_NEG_X |
@@ -1896,16 +1897,16 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
   }
 
   if (bmain->versionfile < 256) {
-    bScreen *sc;
-    ScrArea *sa;
+    bScreen *screen;
+    ScrArea *area;
     Key *key;
 
     /* Fix for sample line scope initializing with no height */
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      sa = sc->areabase.first;
-      while (sa) {
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      area = screen->areabase.first;
+      while (area) {
         SpaceLink *sl;
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype == SPACE_IMAGE) {
             SpaceImage *sima = (SpaceImage *)sl;
             if (sima->sample_line_hist.height == 0) {
@@ -1913,7 +1914,7 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
             }
           }
         }
-        sa = sa->next;
+        area = area->next;
       }
     }
 
@@ -2040,18 +2041,18 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
   }
 
   if (bmain->versionfile < 256 || (bmain->versionfile == 256 && bmain->subversionfile < 3)) {
-    bScreen *sc;
+    bScreen *screen;
     Brush *brush;
     Object *ob;
     ParticleSettings *part;
 
     /* redraws flag in SpaceTime has been moved to Screen level */
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      if (sc->redraws_flag == 0) {
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      if (screen->redraws_flag == 0) {
         /* just initialize to default? */
         /* XXX: we could also have iterated through areas,
          * and taken them from the first timeline available... */
-        sc->redraws_flag = TIME_ALL_3D_WIN | TIME_ALL_ANIM_WIN;
+        screen->redraws_flag = TIME_ALL_3D_WIN | TIME_ALL_ANIM_WIN;
       }
     }
 
@@ -2117,13 +2118,13 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
     bScreen *screen;
 
     for (screen = bmain->screens.first; screen; screen = screen->id.next) {
-      ScrArea *sa;
+      ScrArea *area;
       /* add regions */
-      for (sa = screen->areabase.first; sa; sa = sa->next) {
-        SpaceLink *sl = sa->spacedata.first;
+      for (area = screen->areabase.first; area; area = area->next) {
+        SpaceLink *sl = area->spacedata.first;
         if (sl->spacetype == SPACE_IMAGE) {
           ARegion *region;
-          for (region = sa->regionbase.first; region; region = region->next) {
+          for (region = area->regionbase.first; region; region = region->next) {
             if (region->regiontype == RGN_TYPE_WINDOW) {
               View2D *v2d = &region->v2d;
               v2d->minzoom = v2d->maxzoom = v2d->scroll = v2d->keeptot = v2d->keepzoom =
@@ -2132,7 +2133,7 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
           }
         }
 
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype == SPACE_IMAGE) {
             ARegion *region;
             for (region = sl->regionbase.first; region; region = region->next) {
@@ -2174,14 +2175,14 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
     {
       bScreen *screen;
       for (screen = bmain->screens.first; screen; screen = screen->id.next) {
-        ScrArea *sa;
+        ScrArea *area;
 
         /* add regions */
-        for (sa = screen->areabase.first; sa; sa = sa->next) {
-          SpaceLink *sl = sa->spacedata.first;
+        for (area = screen->areabase.first; area; area = area->next) {
+          SpaceLink *sl = area->spacedata.first;
           if (sl->spacetype == SPACE_SEQ) {
             ARegion *region;
-            for (region = sa->regionbase.first; region; region = region->next) {
+            for (region = area->regionbase.first; region; region = region->next) {
               if (region->regiontype == RGN_TYPE_WINDOW) {
                 if (region->v2d.min[1] == 4.0f) {
                   region->v2d.min[1] = 0.5f;
@@ -2189,7 +2190,7 @@ void blo_do_versions_250(FileData *fd, Library *lib, Main *bmain)
               }
             }
           }
-          for (sl = sa->spacedata.first; sl; sl = sl->next) {
+          for (sl = area->spacedata.first; sl; sl = sl->next) {
             if (sl->spacetype == SPACE_SEQ) {
               ARegion *region;
               for (region = sl->regionbase.first; region; region = region->next) {
@@ -2352,4 +2353,32 @@ void do_versions_after_linking_250(Main *bmain)
     }
     FOREACH_NODETREE_END;
   }
+
+  if (!MAIN_VERSION_ATLEAST(bmain, 258, 0)) {
+    /* Some very old (original comments claim pre-2.57) versioning that was wrongly done in
+     * lib-linking code... Putting it here just to be sure (this is also checked at runtime anyway
+     * by `action_idcode_patch_check`). */
+    ID *id;
+    FOREACH_MAIN_ID_BEGIN (bmain, id) {
+      AnimData *adt = BKE_animdata_from_id(id);
+      if (adt != NULL) {
+        /* Fix actions' id-roots (i.e. if they come from a pre 2.57 .blend file). */
+        if ((adt->action) && (adt->action->idroot == 0)) {
+          adt->action->idroot = GS(id->name);
+        }
+        if ((adt->tmpact) && (adt->tmpact->idroot == 0)) {
+          adt->tmpact->idroot = GS(id->name);
+        }
+
+        LISTBASE_FOREACH (NlaTrack *, nla_track, &adt->nla_tracks) {
+          LISTBASE_FOREACH (NlaStrip *, nla_strip, &nla_track->strips) {
+            if ((nla_strip->act) && (nla_strip->act->idroot == 0)) {
+              nla_strip->act->idroot = GS(id->name);
+            }
+          }
+        }
+      }
+    }
+    FOREACH_MAIN_ID_END;
+  }
 }
diff --git a/source/blender/blenloader/intern/versioning_260.c b/source/blender/blenloader/intern/versioning_260.c
index 26de003dc17..98e10bef470 100644
--- a/source/blender/blenloader/intern/versioning_260.c
+++ b/source/blender/blenloader/intern/versioning_260.c
@@ -52,7 +52,7 @@
 
 #include "BLT_translation.h"
 
-#include "BKE_anim.h"
+#include "BKE_anim_visualization.h"
 #include "BKE_image.h"
 #include "BKE_main.h"  // for Main
 #include "BKE_mesh.h"  // for ME_ defines (patching)
@@ -765,14 +765,14 @@ void blo_do_versions_260(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     {
       /* Tomato compatibility code. */
-      bScreen *sc;
+      bScreen *screen;
       MovieClip *clip;
 
-      for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-        ScrArea *sa;
-        for (sa = sc->areabase.first; sa; sa = sa->next) {
+      for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+        ScrArea *area;
+        for (area = screen->areabase.first; area; area = area->next) {
           SpaceLink *sl;
-          for (sl = sa->spacedata.first; sl; sl = sl->next) {
+          for (sl = area->spacedata.first; sl; sl = sl->next) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               if (v3d->bundle_size == 0.0f) {
@@ -1188,20 +1188,20 @@ void blo_do_versions_260(FileData *fd, Library *UNUSED(lib), Main *bmain)
   }
 
   if (bmain->versionfile < 263 || (bmain->versionfile == 263 && bmain->subversionfile < 2)) {
-    bScreen *sc;
+    bScreen *screen;
 
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
 
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype == SPACE_CLIP) {
             SpaceClip *sclip = (SpaceClip *)sl;
             ARegion *region;
             bool hide = false;
 
-            for (region = sa->regionbase.first; region; region = region->next) {
+            for (region = area->regionbase.first; region; region = region->next) {
               if (region->regiontype == RGN_TYPE_PREVIEW) {
                 if (region->alignment != RGN_ALIGN_NONE) {
                   region->flag |= RGN_FLAG_HIDDEN;
@@ -1368,15 +1368,15 @@ void blo_do_versions_260(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
 
     {
-      bScreen *sc;
+      bScreen *screen;
 
-      for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-        ScrArea *sa;
+      for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+        ScrArea *area;
 
-        for (sa = sc->areabase.first; sa; sa = sa->next) {
+        for (area = screen->areabase.first; area; area = area->next) {
           SpaceLink *sl;
 
-          for (sl = sa->spacedata.first; sl; sl = sl->next) {
+          for (sl = area->spacedata.first; sl; sl = sl->next) {
             if (sl->spacetype == SPACE_CLIP) {
               SpaceClip *sclip = (SpaceClip *)sl;
 
@@ -1661,13 +1661,13 @@ void blo_do_versions_260(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     /* render border for viewport */
     {
-      bScreen *sc;
+      bScreen *screen;
 
-      for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-        ScrArea *sa;
-        for (sa = sc->areabase.first; sa; sa = sa->next) {
+      for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+        ScrArea *area;
+        for (area = screen->areabase.first; area; area = area->next) {
           SpaceLink *sl;
-          for (sl = sa->spacedata.first; sl; sl = sl->next) {
+          for (sl = area->spacedata.first; sl; sl = sl->next) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               if (v3d->render_border.xmin == 0.0f && v3d->render_border.ymin == 0.0f &&
@@ -1758,12 +1758,12 @@ void blo_do_versions_260(FileData *fd, Library *UNUSED(lib), Main *bmain)
   }
 
   if (bmain->versionfile < 265 || (bmain->versionfile == 265 && bmain->subversionfile < 3)) {
-    bScreen *sc;
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+    bScreen *screen;
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           switch (sl->spacetype) {
             case SPACE_VIEW3D: {
               View3D *v3d = (View3D *)sl;
@@ -1943,12 +1943,12 @@ void blo_do_versions_260(FileData *fd, Library *UNUSED(lib), Main *bmain)
   }
 
   if (MAIN_VERSION_OLDER(bmain, 266, 2)) {
-    bScreen *sc;
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+    bScreen *screen;
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype == SPACE_NODE) {
             SpaceNode *snode = (SpaceNode *)sl;
 
@@ -2119,10 +2119,10 @@ void blo_do_versions_260(FileData *fd, Library *UNUSED(lib), Main *bmain)
     bNodeInstanceKey active_viewer_key = {0};
     /* simply pick the first node space and use that for the active viewer key */
     for (screen = bmain->screens.first; screen; screen = screen->id.next) {
-      ScrArea *sa;
-      for (sa = screen->areabase.first; sa; sa = sa->next) {
+      ScrArea *area;
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype == SPACE_NODE) {
             SpaceNode *snode = (SpaceNode *)sl;
             bNodeTreePath *path = snode->treepath.last;
@@ -2199,7 +2199,7 @@ void blo_do_versions_260(FileData *fd, Library *UNUSED(lib), Main *bmain)
   }
 
   if (!MAIN_VERSION_ATLEAST(bmain, 268, 4)) {
-    bScreen *sc;
+    bScreen *screen;
     Object *ob;
 
     for (ob = bmain->objects.first; ob; ob = ob->id.next) {
@@ -2240,11 +2240,11 @@ void blo_do_versions_260(FileData *fd, Library *UNUSED(lib), Main *bmain)
      *
      * We moved this check to the do versions to be sure the value makes any sense.
      */
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype == SPACE_NODE) {
             SpaceNode *snode = (SpaceNode *)sl;
             if (snode->zoom < 0.02f) {
@@ -2257,23 +2257,23 @@ void blo_do_versions_260(FileData *fd, Library *UNUSED(lib), Main *bmain)
   }
 
   if (!MAIN_VERSION_ATLEAST(bmain, 268, 5)) {
-    bScreen *sc;
-    ScrArea *sa;
+    bScreen *screen;
+    ScrArea *area;
 
     /* add missing (+) expander in node editor */
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      for (area = screen->areabase.first; area; area = area->next) {
         ARegion *region, *arnew;
 
-        if (sa->spacetype == SPACE_NODE) {
-          region = BKE_area_find_region_type(sa, RGN_TYPE_TOOLS);
+        if (area->spacetype == SPACE_NODE) {
+          region = BKE_area_find_region_type(area, RGN_TYPE_TOOLS);
 
           if (region) {
             continue;
           }
 
           /* add subdiv level; after header */
-          region = BKE_area_find_region_type(sa, RGN_TYPE_HEADER);
+          region = BKE_area_find_region_type(area, RGN_TYPE_HEADER);
 
           /* is error! */
           if (region == NULL) {
@@ -2282,7 +2282,7 @@ void blo_do_versions_260(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
           arnew = MEM_callocN(sizeof(ARegion), "node tools");
 
-          BLI_insertlinkafter(&sa->regionbase, region, arnew);
+          BLI_insertlinkafter(&area->regionbase, region, arnew);
           arnew->regiontype = RGN_TYPE_TOOLS;
           arnew->alignment = RGN_ALIGN_LEFT;
 
@@ -2338,15 +2338,15 @@ void blo_do_versions_260(FileData *fd, Library *UNUSED(lib), Main *bmain)
   }
 
   if (!MAIN_VERSION_ATLEAST(bmain, 269, 3)) {
-    bScreen *sc;
-    ScrArea *sa;
+    bScreen *screen;
+    ScrArea *area;
     SpaceLink *sl;
     Scene *scene;
 
     /* Update files using invalid (outdated) outlinevis Outliner values. */
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      for (area = screen->areabase.first; area; area = area->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype == SPACE_OUTLINER) {
             SpaceOutliner *so = (SpaceOutliner *)sl;
 
@@ -2542,20 +2542,20 @@ void blo_do_versions_260(FileData *fd, Library *UNUSED(lib), Main *bmain)
   }
 
   if (!MAIN_VERSION_ATLEAST(bmain, 269, 11)) {
-    bScreen *sc;
+    bScreen *screen;
 
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *space_link;
 
-        for (space_link = sa->spacedata.first; space_link; space_link = space_link->next) {
+        for (space_link = area->spacedata.first; space_link; space_link = space_link->next) {
           if (space_link->spacetype == SPACE_IMAGE) {
             ARegion *region;
             ListBase *lb;
 
-            if (space_link == sa->spacedata.first) {
-              lb = &sa->regionbase;
+            if (space_link == area->spacedata.first) {
+              lb = &area->regionbase;
             }
             else {
               lb = &space_link->regionbase;
diff --git a/source/blender/blenloader/intern/versioning_270.c b/source/blender/blenloader/intern/versioning_270.c
index 80f75a7ac4a..0ca6fd34535 100644
--- a/source/blender/blenloader/intern/versioning_270.c
+++ b/source/blender/blenloader/intern/versioning_270.c
@@ -52,9 +52,10 @@
 
 #include "DNA_genfile.h"
 
+#include "BKE_anim_data.h"
 #include "BKE_animsys.h"
 #include "BKE_colortools.h"
-#include "BKE_fcurve.h"
+#include "BKE_fcurve_driver.h"
 #include "BKE_main.h"
 #include "BKE_mask.h"
 #include "BKE_modifier.h"
@@ -257,7 +258,7 @@ static void do_version_action_editor_properties_region(ListBase *regionbase)
 
 static void do_version_bones_super_bbone(ListBase *lb)
 {
-  for (Bone *bone = lb->first; bone; bone = bone->next) {
+  LISTBASE_FOREACH (Bone *, bone, lb) {
     bone->scale_in_x = bone->scale_in_y = 1.0f;
     bone->scale_out_x = bone->scale_out_y = 1.0f;
 
@@ -342,7 +343,7 @@ static void do_versions_compositor_render_passes_storage(bNode *node)
 
 static void do_versions_compositor_render_passes(bNodeTree *ntree)
 {
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node->type == CMP_NODE_R_LAYERS) {
       /* First we make sure existing sockets have proper names.
        * This is important because otherwise verification will
@@ -391,7 +392,7 @@ static void do_version_bbone_easing_fcurve_fix(ID *UNUSED(id),
 
   /* Driver -> Driver Vars (for bbone_in/out) */
   if (fcu->driver) {
-    for (DriverVar *dvar = fcu->driver->variables.first; dvar; dvar = dvar->next) {
+    LISTBASE_FOREACH (DriverVar *, dvar, &fcu->driver->variables) {
       DRIVER_TARGETS_LOOPER_BEGIN (dvar) {
         if (dtar->rna_path) {
           dtar->rna_path = replace_bbone_easing_rnapath(dtar->rna_path);
@@ -403,7 +404,7 @@ static void do_version_bbone_easing_fcurve_fix(ID *UNUSED(id),
 
   /* FModifiers -> Stepped (for frame_start/end) */
   if (fcu->modifiers.first) {
-    for (FModifier *fcm = fcu->modifiers.first; fcm; fcm = fcm->next) {
+    LISTBASE_FOREACH (FModifier *, fcm, &fcu->modifiers) {
       if (fcm->type == FMODIFIER_TYPE_STEPPED) {
         FMod_Stepped *data = fcm->data;
 
@@ -519,16 +520,16 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *bmain)
      * leading to corrupted files (see T39847).
      * This will always reset situation to a valid state.
      */
-    bScreen *sc;
+    bScreen *screen;
 
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
 
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           ARegion *region;
-          ListBase *lb = (sl == sa->spacedata.first) ? &sa->regionbase : &sl->regionbase;
+          ListBase *lb = (sl == area->spacedata.first) ? &area->regionbase : &sl->regionbase;
 
           for (region = lb->first; region; region = region->next) {
             BLI_listbase_clear(&region->ui_previews);
@@ -840,7 +841,7 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *bmain)
     for (ob = bmain->objects.first; ob != NULL; ob = ob->id.next) {
       ModifierData *md;
       for (md = ob->modifiers.last; md != NULL; md = md->prev) {
-        if (modifier_unique_name(&ob->modifiers, md)) {
+        if (BKE_modifier_unique_name(&ob->modifiers, md)) {
           printf(
               "Warning: Object '%s' had several modifiers with the "
               "same name, renamed one of them to '%s'.\n",
@@ -852,15 +853,15 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *bmain)
   }
 
   if (!MAIN_VERSION_ATLEAST(bmain, 273, 9)) {
-    bScreen *scr;
-    ScrArea *sa;
+    bScreen *screen;
+    ScrArea *area;
     SpaceLink *sl;
     ARegion *region;
 
     /* Make sure sequencer preview area limits zoom */
-    for (scr = bmain->screens.first; scr; scr = scr->id.next) {
-      for (sa = scr->areabase.first; sa; sa = sa->next) {
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      for (area = screen->areabase.first; area; area = area->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype == SPACE_SEQ) {
             for (region = sl->regionbase.first; region; region = region->next) {
               if (region->regiontype == RGN_TYPE_PREVIEW) {
@@ -942,11 +943,11 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
 
     for (screen = bmain->screens.first; screen; screen = screen->id.next) {
-      ScrArea *sa;
-      for (sa = screen->areabase.first; sa; sa = sa->next) {
+      ScrArea *area;
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
 
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           switch (sl->spacetype) {
             case SPACE_VIEW3D: {
               View3D *v3d = (View3D *)sl;
@@ -996,12 +997,12 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     if (!DNA_struct_elem_find(fd->filesdna, "FileSelectParams", "int", "thumbnail_size")) {
       for (screen = bmain->screens.first; screen; screen = screen->id.next) {
-        ScrArea *sa;
+        ScrArea *area;
 
-        for (sa = screen->areabase.first; sa; sa = sa->next) {
+        for (area = screen->areabase.first; area; area = area->next) {
           SpaceLink *sl;
 
-          for (sl = sa->spacedata.first; sl; sl = sl->next) {
+          for (sl = area->spacedata.first; sl; sl = sl->next) {
             if (sl->spacetype == SPACE_FILE) {
               SpaceFile *sfile = (SpaceFile *)sl;
 
@@ -1064,13 +1065,13 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *bmain)
       bScreen *screen;
 #define RV3D_VIEW_PERSPORTHO 7
       for (screen = bmain->screens.first; screen; screen = screen->id.next) {
-        ScrArea *sa;
-        for (sa = screen->areabase.first; sa; sa = sa->next) {
+        ScrArea *area;
+        for (area = screen->areabase.first; area; area = area->next) {
           SpaceLink *sl;
-          for (sl = sa->spacedata.first; sl; sl = sl->next) {
+          for (sl = area->spacedata.first; sl; sl = sl->next) {
             if (sl->spacetype == SPACE_VIEW3D) {
               ARegion *region;
-              ListBase *lb = (sl == sa->spacedata.first) ? &sa->regionbase : &sl->regionbase;
+              ListBase *lb = (sl == area->spacedata.first) ? &area->regionbase : &sl->regionbase;
               for (region = lb->first; region; region = region->next) {
                 if (region->regiontype == RGN_TYPE_WINDOW) {
                   if (region->regiondata) {
@@ -1152,7 +1153,7 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *bmain)
      * otherwise they could collide with any new persistent flag we may add in the future. */
     a = set_listbasepointers(bmain, lbarray);
     while (a--) {
-      for (ID *id = lbarray[a]->first; id; id = id->next) {
+      LISTBASE_FOREACH (ID *, id, lbarray[a]) {
         id->flag &= LIB_FAKEUSER;
       }
     }
@@ -1176,14 +1177,15 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
 
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-        for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
-          ListBase *regionbase = (sl == sa->spacedata.first) ? &sa->regionbase : &sl->regionbase;
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
+          ListBase *regionbase = (sl == area->spacedata.first) ? &area->regionbase :
+                                                                 &sl->regionbase;
           /* Bug: Was possible to add preview region to sequencer view by using AZones. */
           if (sl->spacetype == SPACE_SEQ) {
             SpaceSeq *sseq = (SpaceSeq *)sl;
             if (sseq->view == SEQ_VIEW_SEQUENCE) {
-              for (ARegion *region = regionbase->first; region; region = region->next) {
+              LISTBASE_FOREACH (ARegion *, region, regionbase) {
                 /* remove preview region for sequencer-only view! */
                 if (region->regiontype == RGN_TYPE_PREVIEW) {
                   region->flag |= RGN_FLAG_HIDDEN;
@@ -1195,7 +1197,7 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *bmain)
           }
           /* Remove old deprecated region from filebrowsers */
           else if (sl->spacetype == SPACE_FILE) {
-            for (ARegion *region = regionbase->first; region; region = region->next) {
+            LISTBASE_FOREACH (ARegion *, region, regionbase) {
               if (region->regiontype == RGN_TYPE_CHANNELS) {
                 /* Free old deprecated 'channel' region... */
                 BKE_area_region_free(NULL, region);
@@ -1243,9 +1245,9 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     /* Adding "Properties" region to DopeSheet */
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
         /* handle pushed-back space data first */
-        for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (sl->spacetype == SPACE_ACTION) {
             SpaceAction *saction = (SpaceAction *)sl;
             do_version_action_editor_properties_region(&saction->regionbase);
@@ -1253,8 +1255,8 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *bmain)
         }
 
         /* active spacedata info must be handled too... */
-        if (sa->spacetype == SPACE_ACTION) {
-          do_version_action_editor_properties_region(&sa->regionbase);
+        if (area->spacetype == SPACE_ACTION) {
+          do_version_action_editor_properties_region(&area->regionbase);
         }
       }
     }
@@ -1269,7 +1271,7 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *bmain)
     if (!DNA_struct_elem_find(fd->filesdna, "bPoseChannel", "float", "scaleIn")) {
       for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
         if (ob->pose) {
-          for (bPoseChannel *pchan = ob->pose->chanbase.first; pchan; pchan = pchan->next) {
+          LISTBASE_FOREACH (bPoseChannel *, pchan, &ob->pose->chanbase) {
             /* see do_version_bones_super_bbone()... */
             pchan->scale_in_x = pchan->scale_in_y = 1.0f;
             pchan->scale_out_x = pchan->scale_out_y = 1.0f;
@@ -1559,8 +1561,8 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *bmain)
   if (!MAIN_VERSION_ATLEAST(bmain, 278, 5)) {
     /* Mask primitive adding code was not initializing correctly id_type of its points' parent. */
     for (Mask *mask = bmain->masks.first; mask; mask = mask->id.next) {
-      for (MaskLayer *mlayer = mask->masklayers.first; mlayer; mlayer = mlayer->next) {
-        for (MaskSpline *mspline = mlayer->splines.first; mspline; mspline = mspline->next) {
+      LISTBASE_FOREACH (MaskLayer *, mlayer, &mask->masklayers) {
+        LISTBASE_FOREACH (MaskSpline *, mspline, &mlayer->splines) {
           int i = 0;
           for (MaskSplinePoint *mspoint = mspline->points; i < mspline->tot_point;
                mspoint++, i++) {
@@ -1577,7 +1579,7 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *bmain)
       FOREACH_NODETREE_BEGIN (bmain, ntree, id) {
         if (ntree->type == NTREE_COMPOSIT) {
           ntreeSetTypes(NULL, ntree);
-          for (bNode *node = ntree->nodes.first; node; node = node->next) {
+          LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
             if (node->type == CMP_NODE_GLARE) {
               NodeGlare *ndg = node->storage;
               switch (ndg->type) {
@@ -1599,7 +1601,7 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     if (!DNA_struct_elem_find(fd->filesdna, "SurfaceDeformModifierData", "float", "mat[4][4]")) {
       for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
-        for (ModifierData *md = ob->modifiers.first; md; md = md->next) {
+        LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
           if (md->type == eModifierType_SurfaceDeform) {
             SurfaceDeformModifierData *smd = (SurfaceDeformModifierData *)md;
             unit_m4(smd->mat);
@@ -1649,10 +1651,10 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
   if (!MAIN_VERSION_ATLEAST(bmain, 279, 4)) {
     /* Fix for invalid state of screen due to bug in older versions. */
-    for (bScreen *sc = bmain->screens.first; sc; sc = sc->id.next) {
-      for (ScrArea *sa = sc->areabase.first; sa; sa = sa->next) {
-        if (sa->full && sc->state == SCREENNORMAL) {
-          sa->full = NULL;
+    for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        if (area->full && screen->state == SCREENNORMAL) {
+          area->full = NULL;
         }
       }
     }
@@ -1681,7 +1683,7 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *bmain)
      * Must set previous defaults. */
     if (!DNA_struct_elem_find(fd->filesdna, "SimpleDeformModifierData", "char", "deform_axis")) {
       for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
-        for (ModifierData *md = ob->modifiers.first; md; md = md->next) {
+        LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
           if (md->type == eModifierType_SimpleDeform) {
             SimpleDeformModifierData *smd = (SimpleDeformModifierData *)md;
             smd->deform_axis = 2;
@@ -1710,7 +1712,7 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *bmain)
     if (!DNA_struct_elem_find(
             fd->filesdna, "ParticleInstanceModifierData", "float", "particle_amount")) {
       for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
-        for (ModifierData *md = ob->modifiers.first; md; md = md->next) {
+        LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
           if (md->type == eModifierType_ParticleInstance) {
             ParticleInstanceModifierData *pimd = (ParticleInstanceModifierData *)md;
             pimd->space = eParticleInstanceSpace_World;
@@ -1729,7 +1731,7 @@ void do_versions_after_linking_270(Main *bmain)
     FOREACH_NODETREE_BEGIN (bmain, ntree, id) {
       if (ntree->type == NTREE_COMPOSIT) {
         ntreeSetTypes(NULL, ntree);
-        for (bNode *node = ntree->nodes.first; node; node = node->next) {
+        LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
           if (node->type == CMP_NODE_HUE_SAT) {
             do_version_hue_sat_node(ntree, node);
           }
diff --git a/source/blender/blenloader/intern/versioning_280.c b/source/blender/blenloader/intern/versioning_280.c
index eda13dce084..6211c58d7d4 100644
--- a/source/blender/blenloader/intern/versioning_280.c
+++ b/source/blender/blenloader/intern/versioning_280.c
@@ -40,6 +40,7 @@
 #include "DNA_constraint_types.h"
 #include "DNA_curve_types.h"
 #include "DNA_curveprofile_types.h"
+#include "DNA_fluid_types.h"
 #include "DNA_freestyle_types.h"
 #include "DNA_genfile.h"
 #include "DNA_gpencil_modifier_types.h"
@@ -74,6 +75,7 @@
 #include "BKE_curveprofile.h"
 #include "BKE_customdata.h"
 #include "BKE_fcurve.h"
+#include "BKE_fcurve_driver.h"
 #include "BKE_freestyle.h"
 #include "BKE_global.h"
 #include "BKE_gpencil.h"
@@ -111,15 +113,44 @@
 /* Make preferences read-only, use versioning_userdef.c. */
 #define U (*((const UserDef *)&U))
 
+/**
+ * Rename if the ID doesn't exist.
+ */
+static ID *rename_id_for_versioning(Main *bmain,
+                                    const short id_type,
+                                    const char *name_src,
+                                    const char *name_dst)
+{
+  /* We can ignore libraries */
+  ListBase *lb = which_libbase(bmain, id_type);
+  ID *id = NULL;
+  LISTBASE_FOREACH (ID *, idtest, lb) {
+    if (idtest->lib == NULL) {
+      if (STREQ(idtest->name + 2, name_src)) {
+        id = idtest;
+      }
+      if (STREQ(idtest->name + 2, name_dst)) {
+        return NULL;
+      }
+    }
+  }
+  if (id != NULL) {
+    BLI_strncpy(id->name + 2, name_dst, sizeof(id->name) - 2);
+    /* We know it's unique, this just sorts. */
+    BLI_libblock_ensure_unique_name(bmain, id->name);
+  }
+  return id;
+}
+
 static bScreen *screen_parent_find(const bScreen *screen)
 {
   /* Can avoid lookup if screen state isn't maximized/full
    * (parent and child store the same state). */
   if (ELEM(screen->state, SCREENMAXIMIZED, SCREENFULL)) {
-    for (const ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-      if (sa->full && sa->full != screen) {
-        BLI_assert(sa->full->state == screen->state);
-        return sa->full;
+    LISTBASE_FOREACH (const ScrArea *, area, &screen->areabase) {
+      if (area->full && area->full != screen) {
+        BLI_assert(area->full->state == screen->state);
+        return area->full;
       }
     }
   }
@@ -129,6 +160,8 @@ static bScreen *screen_parent_find(const bScreen *screen)
 
 static void do_version_workspaces_create_from_screens(Main *bmain)
 {
+  bmain->is_locked_for_linking = false;
+
   for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
     const bScreen *screen_parent = screen_parent_find(screen);
     WorkSpace *workspace;
@@ -150,6 +183,8 @@ static void do_version_workspaces_create_from_screens(Main *bmain)
     }
     BKE_workspace_layout_add(bmain, workspace, screen, screen->id.name + 2);
   }
+
+  bmain->is_locked_for_linking = true;
 }
 
 static void do_version_area_change_space_to_space_action(ScrArea *area, const Scene *scene)
@@ -159,7 +194,7 @@ static void do_version_area_change_space_to_space_action(ScrArea *area, const Sc
   ARegion *region_channels;
 
   /* Properly free current regions */
-  for (ARegion *region = area->regionbase.first; region; region = region->next) {
+  LISTBASE_FOREACH (ARegion *, region, &area->regionbase) {
     BKE_area_region_free(area->type, region);
   }
   BLI_freelistN(&area->regionbase);
@@ -199,7 +234,7 @@ static void do_version_workspaces_after_lib_link(Main *bmain)
   do_version_workspaces_create_from_screens(bmain);
 
   for (wmWindowManager *wm = bmain->wm.first; wm; wm = wm->id.next) {
-    for (wmWindow *win = wm->windows.first; win; win = win->next) {
+    LISTBASE_FOREACH (wmWindow *, win, &wm->windows) {
       bScreen *screen_parent = screen_parent_find(win->screen);
       bScreen *screen = screen_parent ? screen_parent : win->screen;
 
@@ -222,7 +257,7 @@ static void do_version_workspaces_after_lib_link(Main *bmain)
       win->workspace_hook = BKE_workspace_instance_hook_create(bmain);
 
       BKE_workspace_active_set(win->workspace_hook, workspace);
-      BKE_workspace_active_layout_set(win->workspace_hook, layout);
+      BKE_workspace_active_layout_set(win->workspace_hook, workspace, layout);
 
       /* Move scene and view layer to window. */
       Scene *scene = screen->scene;
@@ -278,7 +313,7 @@ static void do_version_layer_collection_pre(ViewLayer *view_layer,
                                             GSet *selectable_set)
 {
   /* Convert from deprecated DISABLED to new layer collection and collection flags */
-  for (LayerCollection *lc = lb->first; lc; lc = lc->next) {
+  LISTBASE_FOREACH (LayerCollection *, lc, lb) {
     if (lc->scene_collection) {
       if (!(lc->flag & COLLECTION_DEPRECATED_DISABLED)) {
         BLI_gset_insert(enabled_set, lc->scene_collection);
@@ -300,7 +335,7 @@ static void do_version_layer_collection_post(ViewLayer *view_layer,
                                              GHash *collection_map)
 {
   /* Apply layer collection exclude flags. */
-  for (LayerCollection *lc = lb->first; lc; lc = lc->next) {
+  LISTBASE_FOREACH (LayerCollection *, lc, lb) {
     if (!(lc->collection->flag & COLLECTION_IS_MASTER)) {
       SceneCollection *sc = BLI_ghash_lookup(collection_map, lc->collection);
       const bool enabled = (sc && BLI_gset_haskey(enabled_set, sc));
@@ -334,7 +369,7 @@ static void do_version_scene_collection_convert(
     nsc = nsc_next;
   }
 
-  for (LinkData *link = sc->objects.first; link; link = link->next) {
+  LISTBASE_FOREACH (LinkData *, link, &sc->objects) {
     Object *ob = link->data;
     if (ob) {
       BKE_collection_object_add(bmain, collection, ob);
@@ -422,7 +457,7 @@ static void do_version_layers_to_collections(Main *bmain, Scene *scene)
   Collection *collections[20] = {NULL};
 
   for (int layer = 0; layer < 20; layer++) {
-    for (Base *base = scene->base.first; base; base = base->next) {
+    LISTBASE_FOREACH (Base *, base, &scene->base) {
       if (base->lay & (1 << layer)) {
         /* Create collections when needed only. */
         if (collections[layer] == NULL) {
@@ -461,7 +496,7 @@ static void do_version_layers_to_collections(Main *bmain, Scene *scene)
   bool have_override = false;
   const bool need_default_renderlayer = scene->r.layers.first == NULL;
 
-  for (SceneRenderLayer *srl = scene->r.layers.first; srl; srl = srl->next) {
+  LISTBASE_FOREACH (SceneRenderLayer *, srl, &scene->r.layers) {
     ViewLayer *view_layer = BKE_view_layer_add(scene, srl->name, NULL, VIEWLAYER_ADD_NEW);
 
     if (srl->layflag & SCE_LAY_DISABLE) {
@@ -493,7 +528,7 @@ static void do_version_layers_to_collections(Main *bmain, Scene *scene)
           /* Disable excluded layer. */
           have_override = true;
           lc->flag |= LAYER_COLLECTION_EXCLUDE;
-          for (LayerCollection *nlc = lc->layer_collections.first; nlc; nlc = nlc->next) {
+          LISTBASE_FOREACH (LayerCollection *, nlc, &lc->layer_collections) {
             nlc->flag |= LAYER_COLLECTION_EXCLUDE;
           }
         }
@@ -516,7 +551,7 @@ static void do_version_layers_to_collections(Main *bmain, Scene *scene)
       view_layer->basact = BKE_view_layer_base_find(view_layer, scene->basact->object);
     }
 
-    for (Base *base = view_layer->object_bases.first; base; base = base->next) {
+    LISTBASE_FOREACH (Base *, base, &view_layer->object_bases) {
       if ((base->flag & BASE_SELECTABLE) && (base->object->flag & SELECT)) {
         base->flag |= BASE_SELECTED;
       }
@@ -542,7 +577,7 @@ static void do_version_layers_to_collections(Main *bmain, Scene *scene)
     }
 
     /* convert selected bases */
-    for (Base *base = view_layer->object_bases.first; base; base = base->next) {
+    LISTBASE_FOREACH (Base *, base, &view_layer->object_bases) {
       if ((base->flag & BASE_SELECTABLE) && (base->object->flag & SELECT)) {
         base->flag |= BASE_SELECTED;
       }
@@ -553,7 +588,7 @@ static void do_version_layers_to_collections(Main *bmain, Scene *scene)
   }
 
   /* remove bases once and for all */
-  for (Base *base = scene->base.first; base; base = base->next) {
+  LISTBASE_FOREACH (Base *, base, &scene->base) {
     id_us_min(&base->object->id);
   }
 
@@ -577,8 +612,8 @@ static void do_version_collection_propagate_lib_to_children(Collection *collecti
 /** convert old annotations colors */
 static void do_versions_fix_annotations(bGPdata *gpd)
 {
-  for (const bGPDpalette *palette = gpd->palettes.first; palette; palette = palette->next) {
-    for (bGPDpalettecolor *palcolor = palette->colors.first; palcolor; palcolor = palcolor->next) {
+  LISTBASE_FOREACH (const bGPDpalette *, palette, &gpd->palettes) {
+    LISTBASE_FOREACH (bGPDpalettecolor *, palcolor, &palette->colors) {
       /* fix layers */
       LISTBASE_FOREACH (bGPDlayer *, gpl, &gpd->layers) {
         /* unlock/unhide layer */
@@ -609,9 +644,9 @@ static void do_versions_remove_region(ListBase *regionbase, ARegion *region)
 
 static void do_versions_remove_regions_by_type(ListBase *regionbase, int regiontype)
 {
-  ARegion *region, *ar_next;
-  for (region = regionbase->first; region; region = ar_next) {
-    ar_next = region->next;
+  ARegion *region, *region_next;
+  for (region = regionbase->first; region; region = region_next) {
+    region_next = region->next;
     if (region->regiontype == regiontype) {
       do_versions_remove_region(regionbase, region);
     }
@@ -620,7 +655,7 @@ static void do_versions_remove_regions_by_type(ListBase *regionbase, int regiont
 
 static ARegion *do_versions_find_region_or_null(ListBase *regionbase, int regiontype)
 {
-  for (ARegion *region = regionbase->first; region; region = region->next) {
+  LISTBASE_FOREACH (ARegion *, region, regionbase) {
     if (region->regiontype == regiontype) {
       return region;
     }
@@ -649,13 +684,14 @@ static void do_versions_area_ensure_tool_region(Main *bmain,
                                                 const short region_flag)
 {
   for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-    for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-      for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+    LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+      LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
         if (sl->spacetype == space_type) {
-          ListBase *regionbase = (sl == sa->spacedata.first) ? &sa->regionbase : &sl->regionbase;
-          ARegion *region = BKE_area_find_region_type(sa, RGN_TYPE_TOOLS);
+          ListBase *regionbase = (sl == area->spacedata.first) ? &area->regionbase :
+                                                                 &sl->regionbase;
+          ARegion *region = BKE_area_find_region_type(area, RGN_TYPE_TOOLS);
           if (!region) {
-            ARegion *header = BKE_area_find_region_type(sa, RGN_TYPE_HEADER);
+            ARegion *header = BKE_area_find_region_type(area, RGN_TYPE_HEADER);
             region = do_versions_add_region(RGN_TYPE_TOOLS, "tools region");
             BLI_insertlinkafter(regionbase, header, region);
             region->alignment = RGN_ALIGN_LEFT;
@@ -669,7 +705,7 @@ static void do_versions_area_ensure_tool_region(Main *bmain,
 
 static void do_version_bones_split_bbone_scale(ListBase *lb)
 {
-  for (Bone *bone = lb->first; bone; bone = bone->next) {
+  LISTBASE_FOREACH (Bone *, bone, lb) {
     bone->scale_in_y = bone->scale_in_x;
     bone->scale_out_y = bone->scale_out_x;
 
@@ -679,7 +715,7 @@ static void do_version_bones_split_bbone_scale(ListBase *lb)
 
 static void do_version_bones_inherit_scale(ListBase *lb)
 {
-  for (Bone *bone = lb->first; bone; bone = bone->next) {
+  LISTBASE_FOREACH (Bone *, bone, lb) {
     if (bone->flag & BONE_NO_SCALE) {
       bone->inherit_scale_mode = BONE_INHERIT_SCALE_NONE_LEGACY;
       bone->flag &= ~BONE_NO_SCALE;
@@ -723,7 +759,7 @@ static void do_version_bbone_scale_fcurve_fix(ListBase *curves, FCurve *fcu)
   /* Update F-Curve's path. */
   if (replace_bbone_scale_rnapath(&fcu->rna_path)) {
     /* If matched, duplicate the curve and tweak name. */
-    FCurve *second = copy_fcurve(fcu);
+    FCurve *second = BKE_fcurve_copy(fcu);
 
     second->rna_path[strlen(second->rna_path) - 1] = 'y';
 
@@ -749,7 +785,7 @@ static void do_version_bbone_scale_animdata_cb(ID *UNUSED(id),
 
 static void do_version_constraints_maintain_volume_mode_uniform(ListBase *lb)
 {
-  for (bConstraint *con = lb->first; con; con = con->next) {
+  LISTBASE_FOREACH (bConstraint *, con, lb) {
     if (con->type == CONSTRAINT_TYPE_SAMEVOL) {
       bSameVolumeConstraint *data = (bSameVolumeConstraint *)con->data;
       data->mode = SAMEVOL_UNIFORM;
@@ -759,7 +795,7 @@ static void do_version_constraints_maintain_volume_mode_uniform(ListBase *lb)
 
 static void do_version_constraints_copy_scale_power(ListBase *lb)
 {
-  for (bConstraint *con = lb->first; con; con = con->next) {
+  LISTBASE_FOREACH (bConstraint *, con, lb) {
     if (con->type == CONSTRAINT_TYPE_SIZELIKE) {
       bSizeLikeConstraint *data = (bSizeLikeConstraint *)con->data;
       data->power = 1.0f;
@@ -769,7 +805,7 @@ static void do_version_constraints_copy_scale_power(ListBase *lb)
 
 static void do_version_constraints_copy_rotation_mix_mode(ListBase *lb)
 {
-  for (bConstraint *con = lb->first; con; con = con->next) {
+  LISTBASE_FOREACH (bConstraint *, con, lb) {
     if (con->type == CONSTRAINT_TYPE_ROTLIKE) {
       bRotateLikeConstraint *data = (bRotateLikeConstraint *)con->data;
       data->mix_mode = (data->flag & ROTLIKE_OFFSET) ? ROTLIKE_MIX_OFFSET : ROTLIKE_MIX_REPLACE;
@@ -1243,8 +1279,8 @@ void do_versions_after_linking_280(Main *bmain, ReportList *UNUSED(reports))
        * so same layer as BKE_view_layer_default_view would return */
       ViewLayer *layer = screen->scene->view_layers.first;
 
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-        for (SpaceLink *space = sa->spacedata.first; space; space = space->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, space, &area->spacedata) {
           if (space->spacetype == SPACE_OUTLINER) {
             SpaceOutliner *soutliner = (SpaceOutliner *)space;
 
@@ -1273,8 +1309,8 @@ void do_versions_after_linking_280(Main *bmain, ReportList *UNUSED(reports))
 
   if (!MAIN_VERSION_ATLEAST(bmain, 280, 0)) {
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-        for (SpaceLink *space = sa->spacedata.first; space; space = space->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, space, &area->spacedata) {
           if (space->spacetype == SPACE_IMAGE) {
             SpaceImage *sima = (SpaceImage *)space;
             if ((sima) && (sima->gpd)) {
@@ -1304,7 +1340,7 @@ void do_versions_after_linking_280(Main *bmain, ReportList *UNUSED(reports))
     /* Cleanup any remaining SceneRenderLayer data for files that were created
      * with Blender 2.8 before the SceneRenderLayer > RenderLayer refactor. */
     for (Scene *scene = bmain->scenes.first; scene; scene = scene->id.next) {
-      for (SceneRenderLayer *srl = scene->r.layers.first; srl; srl = srl->next) {
+      LISTBASE_FOREACH (SceneRenderLayer *, srl, &scene->r.layers) {
         if (srl->prop) {
           IDP_FreeProperty(srl->prop);
         }
@@ -1319,7 +1355,7 @@ void do_versions_after_linking_280(Main *bmain, ReportList *UNUSED(reports))
      * no longer be visible.
      * Here we correct this by setting a default draw size for those files. */
     for (Object *object = bmain->objects.first; object; object = object->id.next) {
-      for (ParticleSystem *psys = object->particlesystem.first; psys; psys = psys->next) {
+      LISTBASE_FOREACH (ParticleSystem *, psys, &object->particlesystem) {
         if (psys->part->draw_size == 0.0f) {
           psys->part->draw_size = 0.1f;
         }
@@ -1331,7 +1367,7 @@ void do_versions_after_linking_280(Main *bmain, ReportList *UNUSED(reports))
     for (Object *object = bmain->objects.first; object; object = object->id.next) {
       if (object->particlesystem.first) {
         object->duplicator_visibility_flag = OB_DUPLI_FLAG_VIEWPORT;
-        for (ParticleSystem *psys = object->particlesystem.first; psys; psys = psys->next) {
+        LISTBASE_FOREACH (ParticleSystem *, psys, &object->particlesystem) {
           if (psys->part->draw & PART_DRAW_EMITTER) {
             object->duplicator_visibility_flag |= OB_DUPLI_FLAG_RENDER;
             break;
@@ -1362,9 +1398,9 @@ void do_versions_after_linking_280(Main *bmain, ReportList *UNUSED(reports))
        * screens using the active scene of the window they're displayed in.
        * Next, update remaining screens using first scene in main listbase. */
 
-      for (wmWindow *win = wm->windows.first; win; win = win->next) {
+      LISTBASE_FOREACH (wmWindow *, win, &wm->windows) {
         const bScreen *screen = BKE_workspace_active_screen_get(win->workspace_hook);
-        for (ScrArea *area = screen->areabase.first; area; area = area->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
           if (ELEM(area->butspacetype, SPACE_TIME, SPACE_LOGIC)) {
             do_version_area_change_space_to_space_action(area, win->scene);
 
@@ -1376,7 +1412,7 @@ void do_versions_after_linking_280(Main *bmain, ReportList *UNUSED(reports))
     }
     if (scene != NULL) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *area = screen->areabase.first; area; area = area->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
           if (ELEM(area->butspacetype, SPACE_TIME, SPACE_LOGIC)) {
             /* Areas that were already handled won't be handled again */
             do_version_area_change_space_to_space_action(area, scene);
@@ -1413,7 +1449,7 @@ void do_versions_after_linking_280(Main *bmain, ReportList *UNUSED(reports))
 
       int new_count = BKE_keyblock_curve_element_count(&cu->nurb);
 
-      for (KeyBlock *block = cu->key->block.first; block; block = block->next) {
+      LISTBASE_FOREACH (KeyBlock *, block, &cu->key->block) {
         int old_count = block->totelem;
         void *old_data = block->data;
 
@@ -1427,7 +1463,7 @@ void do_versions_after_linking_280(Main *bmain, ReportList *UNUSED(reports))
         float *oldptr = old_data;
         float(*newptr)[3] = block->data;
 
-        for (Nurb *nu = cu->nurb.first; nu; nu = nu->next) {
+        LISTBASE_FOREACH (Nurb *, nu, &cu->nurb) {
           if (nu->bezt) {
             BezTriple *bezt = nu->bezt;
 
@@ -1480,7 +1516,7 @@ void do_versions_after_linking_280(Main *bmain, ReportList *UNUSED(reports))
       if (ob->pose && arm && arm->id.lib == ob->id.lib) {
         bool rebuild = false;
 
-        for (bPoseChannel *pchan = ob->pose->chanbase.first; pchan; pchan = pchan->next) {
+        LISTBASE_FOREACH (bPoseChannel *, pchan, &ob->pose->chanbase) {
           /* If the 2.7 flag is enabled, processing is needed. */
           if (pchan->bone && (pchan->bboneflag & PCHAN_BBONE_CUSTOM_HANDLES)) {
             /* If the settings in the Bone are not set, copy. */
@@ -1632,14 +1668,42 @@ void do_versions_after_linking_280(Main *bmain, ReportList *UNUSED(reports))
 
   if (!MAIN_VERSION_ATLEAST(bmain, 282, 2)) {
     /* Init all Vertex/Sculpt and Weight Paint brushes. */
-    Brush *brush = BLI_findstring(&bmain->brushes, "Pencil", offsetof(ID, name) + 2);
+    Brush *brush;
+    Material *ma;
+    /* Pen Soft brush. */
+    brush = (Brush *)rename_id_for_versioning(bmain, ID_BR, "Draw Soft", "Pencil Soft");
+    if (brush) {
+      brush->gpencil_settings->icon_id = GP_BRUSH_ICON_PEN;
+    }
+    rename_id_for_versioning(bmain, ID_BR, "Draw Pencil", "Pencil");
+    rename_id_for_versioning(bmain, ID_BR, "Draw Pen", "Pen");
+    rename_id_for_versioning(bmain, ID_BR, "Draw Ink", "Ink Pen");
+    rename_id_for_versioning(bmain, ID_BR, "Draw Noise", "Ink Pen Rough");
+    rename_id_for_versioning(bmain, ID_BR, "Draw Marker", "Marker Bold");
+    rename_id_for_versioning(bmain, ID_BR, "Draw Block", "Marker Chisel");
+
+    ma = BLI_findstring(&bmain->materials, "Black", offsetof(ID, name) + 2);
+    if (ma && ma->gp_style) {
+      rename_id_for_versioning(bmain, ID_MA, "Black", "Solid Stroke");
+    }
+    ma = BLI_findstring(&bmain->materials, "Red", offsetof(ID, name) + 2);
+    if (ma && ma->gp_style) {
+      rename_id_for_versioning(bmain, ID_MA, "Red", "Squares Stroke");
+    }
+    ma = BLI_findstring(&bmain->materials, "Grey", offsetof(ID, name) + 2);
+    if (ma && ma->gp_style) {
+      rename_id_for_versioning(bmain, ID_MA, "Grey", "Solid Fill");
+    }
+    ma = BLI_findstring(&bmain->materials, "Black Dots", offsetof(ID, name) + 2);
+    if (ma && ma->gp_style) {
+      rename_id_for_versioning(bmain, ID_MA, "Black Dots", "Dots Stroke");
+    }
+
+    brush = BLI_findstring(&bmain->brushes, "Pencil", offsetof(ID, name) + 2);
+
     for (Scene *scene = bmain->scenes.first; scene; scene = scene->id.next) {
       ToolSettings *ts = scene->toolsettings;
 
-      BKE_brush_gpencil_vertex_presets(bmain, ts);
-      BKE_brush_gpencil_sculpt_presets(bmain, ts);
-      BKE_brush_gpencil_weight_presets(bmain, ts);
-
       /* Ensure new Paint modes. */
       BKE_paint_ensure_from_paintmode(scene, PAINT_MODE_GPENCIL);
       BKE_paint_ensure_from_paintmode(scene, PAINT_MODE_VERTEX_GPENCIL);
@@ -1653,8 +1717,6 @@ void do_versions_after_linking_280(Main *bmain, ReportList *UNUSED(reports))
         /* Enable cursor by default. */
         paint->flags |= PAINT_SHOW_BRUSH;
       }
-      /* Ensure Palette by default. */
-      BKE_gpencil_palette_ensure(bmain, scene);
     }
   }
 
@@ -1665,6 +1727,14 @@ void do_versions_after_linking_280(Main *bmain, ReportList *UNUSED(reports))
     LISTBASE_FOREACH (Object *, ob, &bmain->objects) {
       BKE_fcurves_id_cb(&ob->id, do_version_fcurve_hide_viewport_fix, NULL);
     }
+
+    /* Reset all grease pencil brushes. */
+    LISTBASE_FOREACH (Scene *, scene, &bmain->scenes) {
+      /* Ensure new Paint modes. */
+      BKE_paint_ensure_from_paintmode(scene, PAINT_MODE_VERTEX_GPENCIL);
+      BKE_paint_ensure_from_paintmode(scene, PAINT_MODE_SCULPT_GPENCIL);
+      BKE_paint_ensure_from_paintmode(scene, PAINT_MODE_WEIGHT_GPENCIL);
+    }
   }
 
   /**
@@ -1783,7 +1853,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     FOREACH_NODETREE_BEGIN (bmain, ntree, id) {
       if (ntree->type == NTREE_SHADER) {
-        for (bNode *node = ntree->nodes.first; node; node = node->next) {
+        LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
           if (node->type == 194 /* SH_NODE_EEVEE_METALLIC */ &&
               STREQ(node->idname, "ShaderNodeOutputMetallic")) {
             BLI_strncpy(node->idname, "ShaderNodeEeveeMetallic", sizeof(node->idname));
@@ -1912,8 +1982,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     /* init grease pencil grids and paper */
     if (!DNA_struct_elem_find(fd->filesdna, "View3DOverlay", "float", "gpencil_paper_color[3]")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *area = screen->areabase.first; area; area = area->next) {
-          for (SpaceLink *sl = area->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               v3d->overlay.gpencil_paper_opacity = 0.5f;
@@ -1927,14 +1997,14 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
   if (!MAIN_VERSION_ATLEAST(bmain, 280, 6)) {
     if (DNA_struct_elem_find(fd->filesdna, "SpaceOutliner", "int", "filter") == false) {
-      bScreen *sc;
-      ScrArea *sa;
+      bScreen *screen;
+      ScrArea *area;
       SpaceLink *sl;
 
       /* Update files using invalid (outdated) outlinevis Outliner values. */
-      for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-        for (sa = sc->areabase.first; sa; sa = sa->next) {
-          for (sl = sa->spacedata.first; sl; sl = sl->next) {
+      for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+        for (area = screen->areabase.first; area; area = area->next) {
+          for (sl = area->spacedata.first; sl; sl = sl->next) {
             if (sl->spacetype == SPACE_OUTLINER) {
               SpaceOutliner *so = (SpaceOutliner *)sl;
 
@@ -1972,9 +2042,9 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
       }
     }
 
-    for (bScreen *sc = bmain->screens.first; sc; sc = sc->id.next) {
-      for (ScrArea *sa = sc->areabase.first; sa; sa = sa->next) {
-        for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+    for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (sl->spacetype == SPACE_VIEW3D) {
             View3D *v3d = (View3D *)sl;
             v3d->shading.light = V3D_LIGHTING_STUDIO;
@@ -2026,7 +2096,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
       /* Calculate window width/height from screen vertices */
       int win_width = 0, win_height = 0;
-      for (ScrVert *vert = screen->vertbase.first; vert; vert = vert->next) {
+      LISTBASE_FOREACH (ScrVert *, vert, &screen->vertbase) {
         win_width = MAX2(win_width, vert->vec.x);
         win_height = MAX2(win_height, vert->vec.y);
       }
@@ -2066,10 +2136,11 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
   if (!MAIN_VERSION_ATLEAST(bmain, 280, 12)) {
     /* Remove tool property regions. */
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-        for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (ELEM(sl->spacetype, SPACE_VIEW3D, SPACE_CLIP)) {
-            ListBase *regionbase = (sl == sa->spacedata.first) ? &sa->regionbase : &sl->regionbase;
+            ListBase *regionbase = (sl == area->spacedata.first) ? &area->regionbase :
+                                                                   &sl->regionbase;
 
             for (ARegion *region = regionbase->first, *region_next; region; region = region_next) {
               region_next = region->next;
@@ -2095,8 +2166,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     /* Initialize new view3D options. */
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-        for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (sl->spacetype == SPACE_VIEW3D) {
             View3D *v3d = (View3D *)sl;
             v3d->shading.light = V3D_LIGHTING_STUDIO;
@@ -2320,8 +2391,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
       }
 
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_OUTLINER) {
               SpaceOutliner *soops = (SpaceOutliner *)sl;
               soops->filter_id_type = ID_GR;
@@ -2402,8 +2473,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
       }
 
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               v3d->shading.flag |= V3D_SHADING_SPECULAR_HIGHLIGHT;
@@ -2415,8 +2486,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     if (!DNA_struct_elem_find(fd->filesdna, "View3DShading", "float", "xray_alpha")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               v3d->shading.xray_alpha = 0.5f;
@@ -2430,8 +2501,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
       /* when loading the internal file is loaded before the matcaps */
       if (default_matcap) {
         for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-          for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-            for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+          LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+            LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
               if (sl->spacetype == SPACE_VIEW3D) {
                 View3D *v3d = (View3D *)sl;
                 BLI_strncpy(v3d->shading.matcap, default_matcap->name, FILE_MAXFILE);
@@ -2443,8 +2514,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
     if (!DNA_struct_elem_find(fd->filesdna, "View3DOverlay", "float", "wireframe_threshold")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               v3d->overlay.wireframe_threshold = 0.5f;
@@ -2455,8 +2526,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
     if (!DNA_struct_elem_find(fd->filesdna, "View3DShading", "float", "cavity_valley_factor")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               v3d->shading.cavity_valley_factor = 1.0f;
@@ -2468,8 +2539,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
     if (!DNA_struct_elem_find(fd->filesdna, "View3DOverlay", "float", "xray_alpha_bone")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               v3d->overlay.xray_alpha_bone = 0.5f;
@@ -2494,8 +2565,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
     if (!DNA_struct_elem_find(fd->filesdna, "SpaceAction", "char", "mode_prev")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_ACTION) {
               SpaceAction *saction = (SpaceAction *)sl;
               /* "Dopesheet" should be default here,
@@ -2510,8 +2581,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
 
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-        for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (sl->spacetype == SPACE_VIEW3D) {
             View3D *v3d = (View3D *)sl;
             if (v3d->drawtype == OB_TEXTURE) {
@@ -2535,8 +2606,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     if (!DNA_struct_elem_find(
             fd->filesdna, "View3DOverlay", "float", "texture_paint_mode_opacity")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               enum {
                 V3D_SHOW_MODE_SHADE_OVERRIDE = (1 << 15),
@@ -2554,8 +2625,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     if (!DNA_struct_elem_find(fd->filesdna, "View3DShading", "char", "background_type")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               copy_v3_fl(v3d->shading.background_color, 0.05f);
@@ -2619,8 +2690,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     if (!DNA_struct_elem_find(fd->filesdna, "View3DShading", "short", "type")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               if (v3d->drawtype == OB_RENDER) {
@@ -2641,9 +2712,9 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
     /* initialize grease pencil view data */
     if (!DNA_struct_elem_find(fd->filesdna, "SpaceView3D", "float", "vertex_opacity")) {
-      for (bScreen *sc = bmain->screens.first; sc; sc = sc->id.next) {
-        for (ScrArea *sa = sc->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+      for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               v3d->vertex_opacity = 1.0f;
@@ -2674,8 +2745,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
     if (!DNA_struct_elem_find(fd->filesdna, "View3DOverlay", "float", "gpencil_paper_opacity")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               v3d->overlay.gpencil_paper_opacity = 0.5f;
@@ -2686,8 +2757,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
     if (!DNA_struct_elem_find(fd->filesdna, "View3DOverlay", "float", "gpencil_grid_opacity")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               v3d->overlay.gpencil_grid_opacity = 0.5f;
@@ -2711,7 +2782,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     /* Versioning code for Subsurf modifier. */
     if (!DNA_struct_elem_find(fd->filesdna, "SubsurfModifier", "short", "uv_smooth")) {
       for (Object *object = bmain->objects.first; object != NULL; object = object->id.next) {
-        for (ModifierData *md = object->modifiers.first; md; md = md->next) {
+        LISTBASE_FOREACH (ModifierData *, md, &object->modifiers) {
           if (md->type == eModifierType_Subsurf) {
             SubsurfModifierData *smd = (SubsurfModifierData *)md;
             if (smd->flags & eSubsurfModifierFlag_SubsurfUv_DEPRECATED) {
@@ -2727,7 +2798,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     if (!DNA_struct_elem_find(fd->filesdna, "SubsurfModifier", "short", "quality")) {
       for (Object *object = bmain->objects.first; object != NULL; object = object->id.next) {
-        for (ModifierData *md = object->modifiers.first; md; md = md->next) {
+        LISTBASE_FOREACH (ModifierData *, md, &object->modifiers) {
           if (md->type == eModifierType_Subsurf) {
             SubsurfModifierData *smd = (SubsurfModifierData *)md;
             smd->quality = min_ii(smd->renderLevels, 3);
@@ -2738,7 +2809,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     /* Versioning code for Multires modifier. */
     if (!DNA_struct_elem_find(fd->filesdna, "MultiresModifier", "short", "quality")) {
       for (Object *object = bmain->objects.first; object != NULL; object = object->id.next) {
-        for (ModifierData *md = object->modifiers.first; md; md = md->next) {
+        LISTBASE_FOREACH (ModifierData *, md, &object->modifiers) {
           if (md->type == eModifierType_Multires) {
             MultiresModifierData *mmd = (MultiresModifierData *)md;
             mmd->quality = 3;
@@ -2755,7 +2826,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     if (!DNA_struct_elem_find(fd->filesdna, "ClothSimSettings", "short", "bending_model")) {
       for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
-        for (ModifierData *md = ob->modifiers.first; md; md = md->next) {
+        LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
           ClothModifierData *clmd = NULL;
           if (md->type == eModifierType_Cloth) {
             clmd = (ClothModifierData *)md;
@@ -2795,7 +2866,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
 
     for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
-      for (ModifierData *md = ob->modifiers.first; md; md = md->next) {
+      LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
         if (md->type == eModifierType_Cloth) {
           ClothModifierData *clmd = (ClothModifierData *)md;
 
@@ -2824,15 +2895,14 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
   if (!MAIN_VERSION_ATLEAST(bmain, 280, 24)) {
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-        for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (sl->spacetype == SPACE_VIEW3D) {
             View3D *v3d = (View3D *)sl;
             v3d->overlay.edit_flag |= V3D_OVERLAY_EDIT_FACES | V3D_OVERLAY_EDIT_SEAMS |
                                       V3D_OVERLAY_EDIT_SHARP | V3D_OVERLAY_EDIT_FREESTYLE_EDGE |
                                       V3D_OVERLAY_EDIT_FREESTYLE_FACE | V3D_OVERLAY_EDIT_EDGES |
-                                      V3D_OVERLAY_EDIT_CREASES | V3D_OVERLAY_EDIT_BWEIGHTS |
-                                      V3D_OVERLAY_EDIT_CU_HANDLES | V3D_OVERLAY_EDIT_CU_NORMALS;
+                                      V3D_OVERLAY_EDIT_CREASES | V3D_OVERLAY_EDIT_BWEIGHTS;
           }
         }
       }
@@ -2840,7 +2910,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     if (!DNA_struct_elem_find(fd->filesdna, "ShrinkwrapModifierData", "char", "shrinkMode")) {
       for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
-        for (ModifierData *md = ob->modifiers.first; md; md = md->next) {
+        LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
           if (md->type == eModifierType_Shrinkwrap) {
             ShrinkwrapModifierData *smd = (ShrinkwrapModifierData *)md;
             if (smd->shrinkOpts & MOD_SHRINKWRAP_KEEP_ABOVE_SURFACE) {
@@ -2858,7 +2928,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
           ob->pd->pdef_cfrict = 5.0f;
         }
 
-        for (ModifierData *md = ob->modifiers.first; md; md = md->next) {
+        LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
           if (md->type == eModifierType_Cloth) {
             ClothModifierData *clmd = (ClothModifierData *)md;
 
@@ -2870,8 +2940,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     if (!DNA_struct_elem_find(fd->filesdna, "View3DShading", "float", "xray_alpha_wire")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               v3d->shading.flag |= V3D_SHADING_XRAY_WIREFRAME;
@@ -2908,8 +2978,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
   if (!MAIN_VERSION_ATLEAST(bmain, 280, 29)) {
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-        for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (sl->spacetype == SPACE_VIEW3D) {
             enum { V3D_OCCLUDE_WIRE = (1 << 14) };
             View3D *v3d = (View3D *)sl;
@@ -2931,12 +3001,13 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
      */
     if (!MAIN_VERSION_ATLEAST(bmain, 283, 1)) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
-            ListBase *regionbase = (sl == sa->spacedata.first) ? &sa->regionbase : &sl->regionbase;
-            ARegion *ar_header = do_versions_find_region_or_null(regionbase, RGN_TYPE_HEADER);
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
+            ListBase *regionbase = (sl == area->spacedata.first) ? &area->regionbase :
+                                                                   &sl->regionbase;
+            ARegion *region_header = do_versions_find_region_or_null(regionbase, RGN_TYPE_HEADER);
 
-            if (!ar_header) {
+            if (!region_header) {
               /* Headers should always be first in the region list, except if there's also a
                * tool-header. These were only introduced in later versions though, so should be
                * fine to always insert headers first. */
@@ -2954,21 +3025,23 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
 
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-        for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (sl->spacetype == SPACE_PROPERTIES) {
-            ListBase *regionbase = (sl == sa->spacedata.first) ? &sa->regionbase : &sl->regionbase;
+            ListBase *regionbase = (sl == area->spacedata.first) ? &area->regionbase :
+                                                                   &sl->regionbase;
             ARegion *region = MEM_callocN(sizeof(ARegion), "navigation bar for properties");
-            ARegion *ar_header = NULL;
+            ARegion *region_header = NULL;
 
-            for (ar_header = regionbase->first; ar_header; ar_header = ar_header->next) {
-              if (ar_header->regiontype == RGN_TYPE_HEADER) {
+            for (region_header = regionbase->first; region_header;
+                 region_header = region_header->next) {
+              if (region_header->regiontype == RGN_TYPE_HEADER) {
                 break;
               }
             }
-            BLI_assert(ar_header);
+            BLI_assert(region_header);
 
-            BLI_insertlinkafter(regionbase, ar_header, region);
+            BLI_insertlinkafter(regionbase, region_header, region);
 
             region->regiontype = RGN_TYPE_NAV_BAR;
             region->alignment = RGN_ALIGN_LEFT;
@@ -2980,8 +3053,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     /* grease pencil fade layer opacity */
     if (!DNA_struct_elem_find(fd->filesdna, "View3DOverlay", "float", "gpencil_fade_layer")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               v3d->overlay.gpencil_fade_layer = 0.5f;
@@ -3185,8 +3258,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
   if (!MAIN_VERSION_ATLEAST(bmain, 280, 34)) {
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *area = screen->areabase.first; area; area = area->next) {
-        for (SpaceLink *slink = area->spacedata.first; slink; slink = slink->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, slink, &area->spacedata) {
           if (slink->spacetype == SPACE_USERPREF) {
             ARegion *navigation_region = BKE_spacedata_find_region_type(
                 slink, area, RGN_TYPE_NAV_BAR);
@@ -3214,8 +3287,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
   if (!MAIN_VERSION_ATLEAST(bmain, 280, 36)) {
     if (!DNA_struct_elem_find(fd->filesdna, "View3DShading", "float", "curvature_ridge_factor")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               v3d->shading.curvature_ridge_factor = 1.0f;
@@ -3246,8 +3319,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     /* Move studio_light selection to lookdev_light. */
     if (!DNA_struct_elem_find(fd->filesdna, "View3DShading", "char", "lookdev_light[256]")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               memcpy(v3d->shading.lookdev_light, v3d->shading.studio_light, sizeof(char) * 256);
@@ -3300,8 +3373,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
 
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *area = screen->areabase.first; area; area = area->next) {
-        for (SpaceLink *sl = area->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           switch (sl->spacetype) {
             case SPACE_IMAGE: {
               SpaceImage *sima = (SpaceImage *)sl;
@@ -3417,8 +3490,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
 
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *area = screen->areabase.first; area; area = area->next) {
-        for (SpaceLink *sl = area->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           switch (sl->spacetype) {
             case SPACE_VIEW3D: {
               enum { V3D_BACKFACE_CULLING = (1 << 10) };
@@ -3460,21 +3533,21 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
 
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *area = screen->areabase.first; area; area = area->next) {
-        for (SpaceLink *sl = area->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (sl->spacetype == SPACE_USERPREF) {
             ARegion *execute_region = BKE_spacedata_find_region_type(sl, area, RGN_TYPE_EXECUTE);
 
             if (!execute_region) {
               ListBase *regionbase = (sl == area->spacedata.first) ? &area->regionbase :
                                                                      &sl->regionbase;
-              ARegion *ar_navbar = BKE_spacedata_find_region_type(sl, area, RGN_TYPE_NAV_BAR);
+              ARegion *region_navbar = BKE_spacedata_find_region_type(sl, area, RGN_TYPE_NAV_BAR);
 
               execute_region = MEM_callocN(sizeof(ARegion), "execute region for properties");
 
-              BLI_assert(ar_navbar);
+              BLI_assert(region_navbar);
 
-              BLI_insertlinkafter(regionbase, ar_navbar, execute_region);
+              BLI_insertlinkafter(regionbase, region_navbar, execute_region);
 
               execute_region->regiontype = RGN_TYPE_EXECUTE;
               execute_region->alignment = RGN_ALIGN_BOTTOM | RGN_SPLIT_PREV;
@@ -3519,8 +3592,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     /* Add wireframe color. */
     if (!DNA_struct_elem_find(fd->filesdna, "View3DShading", "char", "wire_color_type")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               v3d->shading.wire_color_type = V3D_SHADING_SINGLE_COLOR;
@@ -3622,7 +3695,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     if (!DNA_struct_elem_find(fd->filesdna, "TriangulateModifierData", "int", "min_vertices")) {
       for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
-        for (ModifierData *md = ob->modifiers.first; md; md = md->next) {
+        LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
           if (md->type == eModifierType_Triangulate) {
             TriangulateModifierData *smd = (TriangulateModifierData *)md;
             smd->min_vertices = 4;
@@ -3633,7 +3706,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     FOREACH_NODETREE_BEGIN (bmain, ntree, id) {
       if (ntree->type == NTREE_SHADER) {
-        for (bNode *node = ntree->nodes.first; node; node = node->next) {
+        LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
           /* Fix missing version patching from earlier changes. */
           if (STREQ(node->idname, "ShaderNodeOutputLamp")) {
             STRNCPY(node->idname, "ShaderNodeOutputLight");
@@ -3672,7 +3745,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
   if (!MAIN_VERSION_ATLEAST(bmain, 280, 54)) {
     for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
       bool is_first_subdiv = true;
-      for (ModifierData *md = ob->modifiers.first; md; md = md->next) {
+      LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
         if (md->type == eModifierType_Subsurf) {
           SubsurfModifierData *smd = (SubsurfModifierData *)md;
           if (is_first_subdiv) {
@@ -3699,10 +3772,11 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
   if (!MAIN_VERSION_ATLEAST(bmain, 280, 55)) {
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-        for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (sl->spacetype == SPACE_TEXT) {
-            ListBase *regionbase = (sl == sa->spacedata.first) ? &sa->regionbase : &sl->regionbase;
+            ListBase *regionbase = (sl == area->spacedata.first) ? &area->regionbase :
+                                                                   &sl->regionbase;
 
             /* Remove multiple footers that were added by mistake. */
             do_versions_remove_regions_by_type(regionbase, RGN_TYPE_FOOTER);
@@ -3711,8 +3785,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
             ARegion *region = do_versions_add_region(RGN_TYPE_FOOTER, "footer for text");
             region->alignment = (U.uiflag & USER_HEADER_BOTTOM) ? RGN_ALIGN_TOP : RGN_ALIGN_BOTTOM;
 
-            ARegion *ar_header = do_versions_find_region(regionbase, RGN_TYPE_HEADER);
-            BLI_insertlinkafter(regionbase, ar_header, region);
+            ARegion *region_header = do_versions_find_region(regionbase, RGN_TYPE_HEADER);
+            BLI_insertlinkafter(regionbase, region_header, region);
           }
         }
       }
@@ -3721,8 +3795,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
   if (!MAIN_VERSION_ATLEAST(bmain, 280, 56)) {
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *area = screen->areabase.first; area; area = area->next) {
-        for (SpaceLink *sl = area->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (sl->spacetype == SPACE_VIEW3D) {
             View3D *v3d = (View3D *)sl;
             v3d->gizmo_show_armature = V3D_GIZMO_SHOW_ARMATURE_BBONE |
@@ -3739,8 +3813,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
   if (!MAIN_VERSION_ATLEAST(bmain, 280, 57)) {
     /* Enable Show Interpolation in dopesheet by default. */
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-        for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (sl->spacetype == SPACE_ACTION) {
             SpaceAction *saction = (SpaceAction *)sl;
             if ((saction->flag & SACTION_SHOW_EXTREMES) == 0) {
@@ -3778,8 +3852,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     /* enable the axis aligned ortho grid by default */
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *area = screen->areabase.first; area; area = area->next) {
-        for (SpaceLink *sl = area->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (sl->spacetype == SPACE_VIEW3D) {
             View3D *v3d = (View3D *)sl;
             v3d->gridflag |= V3D_SHOW_ORTHO_GRID;
@@ -3792,9 +3866,10 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
   /* Keep un-versioned until we're finished adding space types. */
   {
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-        for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
-          ListBase *regionbase = (sl == sa->spacedata.first) ? &sa->regionbase : &sl->regionbase;
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
+          ListBase *regionbase = (sl == area->spacedata.first) ? &area->regionbase :
+                                                                 &sl->regionbase;
           /* All spaces that use tools must be eventually added. */
           ARegion *region = NULL;
           if (ELEM(sl->spacetype, SPACE_VIEW3D, SPACE_IMAGE, SPACE_SEQ) &&
@@ -3804,8 +3879,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
             region = do_versions_add_region(RGN_TYPE_TOOL_HEADER, "tool header");
             region->alignment = (U.uiflag & USER_HEADER_BOTTOM) ? RGN_ALIGN_BOTTOM : RGN_ALIGN_TOP;
 
-            ARegion *ar_header = do_versions_find_region(regionbase, RGN_TYPE_HEADER);
-            BLI_insertlinkbefore(regionbase, ar_header, region);
+            ARegion *region_header = do_versions_find_region(regionbase, RGN_TYPE_HEADER);
+            BLI_insertlinkbefore(regionbase, region_header, region);
             /* Hide by default, enable for painting workspaces (startup only). */
             region->flag |= RGN_FLAG_HIDDEN | RGN_FLAG_HIDDEN_BY_USER;
           }
@@ -3822,8 +3897,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     if (!DNA_struct_elem_find(fd->filesdna, "bSplineIKConstraint", "short", "yScaleMode")) {
       for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
         if (ob->pose) {
-          for (bPoseChannel *pchan = ob->pose->chanbase.first; pchan; pchan = pchan->next) {
-            for (bConstraint *con = pchan->constraints.first; con; con = con->next) {
+          LISTBASE_FOREACH (bPoseChannel *, pchan, &ob->pose->chanbase) {
+            LISTBASE_FOREACH (bConstraint *, con, &pchan->constraints) {
               if (con->type == CONSTRAINT_TYPE_SPLINEIK) {
                 bSplineIKConstraint *data = (bSplineIKConstraint *)con->data;
                 if ((data->flag & CONSTRAINT_SPLINEIK_SCALE_LIMITED) == 0) {
@@ -3839,8 +3914,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     if (!DNA_struct_elem_find(
             fd->filesdna, "View3DOverlay", "float", "sculpt_mode_mask_opacity")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               v3d->overlay.sculpt_mode_mask_opacity = 0.75f;
@@ -3903,10 +3978,11 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
 
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-        for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (ELEM(sl->spacetype, SPACE_CLIP, SPACE_GRAPH, SPACE_SEQ)) {
-            ListBase *regionbase = (sl == sa->spacedata.first) ? &sa->regionbase : &sl->regionbase;
+            ListBase *regionbase = (sl == area->spacedata.first) ? &area->regionbase :
+                                                                   &sl->regionbase;
 
             ARegion *region = NULL;
             if (sl->spacetype == SPACE_CLIP) {
@@ -3928,8 +4004,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
 
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *area = screen->areabase.first; area; area = area->next) {
-        for (SpaceLink *sl = area->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (sl->spacetype != SPACE_OUTLINER) {
             continue;
           }
@@ -4039,7 +4115,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
   if (!MAIN_VERSION_ATLEAST(bmain, 281, 1)) {
     LISTBASE_FOREACH (Object *, ob, &bmain->objects) {
-      for (ModifierData *md = ob->modifiers.first; md; md = md->next) {
+      LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
         if (md->type == eModifierType_DataTransfer) {
           /* Now datatransfer's mix factor is multiplied with weights when any,
            * instead of being ignored,
@@ -4055,10 +4131,11 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
   if (!MAIN_VERSION_ATLEAST(bmain, 281, 3)) {
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-        for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (sl->spacetype == SPACE_TEXT) {
-            ListBase *regionbase = (sl == sa->spacedata.first) ? &sa->regionbase : &sl->regionbase;
+            ListBase *regionbase = (sl == area->spacedata.first) ? &area->regionbase :
+                                                                   &sl->regionbase;
             ARegion *region = do_versions_find_region_or_null(regionbase, RGN_TYPE_UI);
             if (region) {
               region->alignment = RGN_ALIGN_RIGHT;
@@ -4109,14 +4186,14 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
   if (!MAIN_VERSION_ATLEAST(bmain, 281, 6)) {
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-        for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (sl->spacetype == SPACE_VIEW3D) {
             View3D *v3d = (View3D *)sl;
             v3d->shading.flag |= V3D_SHADING_SCENE_LIGHTS_RENDER | V3D_SHADING_SCENE_WORLD_RENDER;
 
             /* files by default don't have studio lights selected unless interacted
-             * with the shading popover. When no studiolight could be read, we will
+             * with the shading popover. When no studio-light could be read, we will
              * select the default world one. */
             StudioLight *studio_light = BKE_studiolight_find(v3d->shading.lookdev_light,
                                                              STUDIOLIGHT_TYPE_WORLD);
@@ -4131,29 +4208,31 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
   if (!MAIN_VERSION_ATLEAST(bmain, 281, 9)) {
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-        for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (sl->spacetype == SPACE_FILE) {
             SpaceFile *sfile = (SpaceFile *)sl;
-            ListBase *regionbase = (sl == sa->spacedata.first) ? &sa->regionbase : &sl->regionbase;
-            ARegion *ar_ui = do_versions_find_region(regionbase, RGN_TYPE_UI);
-            ARegion *ar_header = do_versions_find_region(regionbase, RGN_TYPE_HEADER);
-            ARegion *ar_toolprops = do_versions_find_region_or_null(regionbase,
-                                                                    RGN_TYPE_TOOL_PROPS);
+            ListBase *regionbase = (sl == area->spacedata.first) ? &area->regionbase :
+                                                                   &sl->regionbase;
+            ARegion *region_ui = do_versions_find_region(regionbase, RGN_TYPE_UI);
+            ARegion *region_header = do_versions_find_region(regionbase, RGN_TYPE_HEADER);
+            ARegion *region_toolprops = do_versions_find_region_or_null(regionbase,
+                                                                        RGN_TYPE_TOOL_PROPS);
 
             /* Reinsert UI region so that it spawns entire area width */
-            BLI_remlink(regionbase, ar_ui);
-            BLI_insertlinkafter(regionbase, ar_header, ar_ui);
+            BLI_remlink(regionbase, region_ui);
+            BLI_insertlinkafter(regionbase, region_header, region_ui);
 
-            ar_ui->flag |= RGN_FLAG_DYNAMIC_SIZE;
+            region_ui->flag |= RGN_FLAG_DYNAMIC_SIZE;
 
-            if (ar_toolprops && (ar_toolprops->alignment == (RGN_ALIGN_BOTTOM | RGN_SPLIT_PREV))) {
+            if (region_toolprops &&
+                (region_toolprops->alignment == (RGN_ALIGN_BOTTOM | RGN_SPLIT_PREV))) {
               SpaceType *stype = BKE_spacetype_from_id(sl->spacetype);
 
               /* Remove empty region at old location. */
               BLI_assert(sfile->op == NULL);
-              BKE_area_region_free(stype, ar_toolprops);
-              BLI_freelinkN(regionbase, ar_toolprops);
+              BKE_area_region_free(stype, region_toolprops);
+              BLI_freelinkN(regionbase, region_toolprops);
             }
 
             if (sfile->params) {
@@ -4183,11 +4262,11 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
       }
     }
 
-    /* Added studiolight intensity */
+    /* Added studio-light intensity. */
     if (!DNA_struct_elem_find(fd->filesdna, "View3DShading", "float", "studiolight_intensity")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               v3d->shading.studiolight_intensity = 1.0f;
@@ -4224,14 +4303,13 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
 
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-        for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           if (sl->spacetype == SPACE_VIEW3D) {
             View3D *v3d = (View3D *)sl;
 
-            for (ScrArea *sa_other = screen->areabase.first; sa_other; sa_other = sa_other->next) {
-              for (SpaceLink *sl_other = sa_other->spacedata.first; sl_other;
-                   sl_other = sl_other->next) {
+            LISTBASE_FOREACH (ScrArea *, area_other, &screen->areabase) {
+              LISTBASE_FOREACH (SpaceLink *, sl_other, &area_other->spacedata) {
                 if (sl != sl_other && sl_other->spacetype == SPACE_VIEW3D) {
                   View3D *v3d_other = (View3D *)sl_other;
 
@@ -4243,25 +4321,27 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
             }
           }
           else if (sl->spacetype == SPACE_FILE) {
-            ListBase *regionbase = (sl == sa->spacedata.first) ? &sa->regionbase : &sl->regionbase;
-            ARegion *ar_tools = do_versions_find_region_or_null(regionbase, RGN_TYPE_TOOLS);
-            ARegion *ar_header = do_versions_find_region(regionbase, RGN_TYPE_HEADER);
+            ListBase *regionbase = (sl == area->spacedata.first) ? &area->regionbase :
+                                                                   &sl->regionbase;
+            ARegion *region_tools = do_versions_find_region_or_null(regionbase, RGN_TYPE_TOOLS);
+            ARegion *region_header = do_versions_find_region(regionbase, RGN_TYPE_HEADER);
 
-            if (ar_tools) {
-              ARegion *ar_next = ar_tools->next;
+            if (region_tools) {
+              ARegion *region_next = region_tools->next;
 
               /* We temporarily had two tools regions, get rid of the second one. */
-              if (ar_next && ar_next->regiontype == RGN_TYPE_TOOLS) {
-                do_versions_remove_region(regionbase, ar_next);
+              if (region_next && region_next->regiontype == RGN_TYPE_TOOLS) {
+                do_versions_remove_region(regionbase, region_next);
               }
 
-              BLI_remlink(regionbase, ar_tools);
-              BLI_insertlinkafter(regionbase, ar_header, ar_tools);
+              BLI_remlink(regionbase, region_tools);
+              BLI_insertlinkafter(regionbase, region_header, region_tools);
             }
             else {
-              ar_tools = do_versions_add_region(RGN_TYPE_TOOLS, "versioning file tools region");
-              BLI_insertlinkafter(regionbase, ar_header, ar_tools);
-              ar_tools->alignment = RGN_ALIGN_LEFT;
+              region_tools = do_versions_add_region(RGN_TYPE_TOOLS,
+                                                    "versioning file tools region");
+              BLI_insertlinkafter(regionbase, region_header, region_tools);
+              region_tools->alignment = RGN_ALIGN_LEFT;
             }
           }
         }
@@ -4279,8 +4359,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     do_version_curvemapping_walker(bmain, do_version_curvemapping_flag_extend_extrapolate);
 
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-        sa->flag &= ~AREA_FLAG_UNUSED_6;
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        area->flag &= ~AREA_FLAG_UNUSED_6;
       }
     }
 
@@ -4297,7 +4377,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     /* Add custom curve profile to bevel modifier */
     if (!DNA_struct_elem_find(fd->filesdna, "BevelModifier", "CurveProfile", "custom_profile")) {
       for (Object *object = bmain->objects.first; object != NULL; object = object->id.next) {
-        for (ModifierData *md = object->modifiers.first; md; md = md->next) {
+        LISTBASE_FOREACH (ModifierData *, md, &object->modifiers) {
           if (md->type == eModifierType_Bevel) {
             BevelModifierData *bmd = (BevelModifierData *)md;
             if (!bmd->custom_profile) {
@@ -4325,7 +4405,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     /* Cloth pressure */
     for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
-      for (ModifierData *md = ob->modifiers.first; md; md = md->next) {
+      LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
         if (md->type == eModifierType_Cloth) {
           ClothModifierData *clmd = (ClothModifierData *)md;
 
@@ -4350,8 +4430,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
       }
 
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               v3d->shading.render_pass = SCE_PASS_COMBINED;
@@ -4363,8 +4443,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 
     /* Make markers region visible by default. */
     for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-      for (ScrArea *area = screen->areabase.first; area; area = area->next) {
-        for (SpaceLink *sl = area->spacedata.first; sl; sl = sl->next) {
+      LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+        LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
           switch (sl->spacetype) {
             case SPACE_SEQ: {
               SpaceSeq *sseq = (SpaceSeq *)sl;
@@ -4393,13 +4473,26 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
   }
 
   if (!MAIN_VERSION_ATLEAST(bmain, 283, 3)) {
+    /* Color Management Look. */
+    for (Scene *scene = bmain->scenes.first; scene; scene = scene->id.next) {
+      ColorManagedViewSettings *view_settings;
+      view_settings = &scene->view_settings;
+      if (BLI_str_startswith(view_settings->look, "Filmic - ")) {
+        char *src = view_settings->look + strlen("Filmic - ");
+        memmove(view_settings->look, src, strlen(src) + 1);
+      }
+      else if (BLI_str_startswith(view_settings->look, "Standard - ")) {
+        char *src = view_settings->look + strlen("Standard - ");
+        memmove(view_settings->look, src, strlen(src) + 1);
+      }
+    }
 
     /* Sequencer Tool region */
     do_versions_area_ensure_tool_region(bmain, SPACE_SEQ, RGN_FLAG_HIDDEN);
 
     /* Cloth internal springs */
     for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
-      for (ModifierData *md = ob->modifiers.first; md; md = md->next) {
+      LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
         if (md->type == eModifierType_Cloth) {
           ClothModifierData *clmd = (ClothModifierData *)md;
 
@@ -4425,8 +4518,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     /* UDIM Image Editor change. */
     if (!DNA_struct_elem_find(fd->filesdna, "SpaceImage", "int", "tile_grid_shape[2]")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_IMAGE) {
               SpaceImage *sima = (SpaceImage *)sl;
               sima->tile_grid_shape[0] = 1;
@@ -4488,7 +4581,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     /* Add 2D transform to UV Warp modifier. */
     if (!DNA_struct_elem_find(fd->filesdna, "UVWarpModifierData", "float", "scale[2]")) {
       for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
-        for (ModifierData *md = ob->modifiers.first; md; md = md->next) {
+        LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
           if (md->type == eModifierType_UVWarp) {
             UVWarpModifierData *umd = (UVWarpModifierData *)md;
             copy_v2_fl(umd->scale, 1.0f);
@@ -4500,8 +4593,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     /* Add Lookdev blur property. */
     if (!DNA_struct_elem_find(fd->filesdna, "View3DShading", "float", "studiolight_blur")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               v3d->shading.studiolight_blur = 0.5f;
@@ -4541,8 +4634,6 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
             brush->gpencil_weight_tool = brush->gpencil_settings->brush_type;
           }
         }
-
-        BKE_paint_toolslots_init_from_main(bmain);
       }
 
       LISTBASE_FOREACH (Material *, mat, &bmain->materials) {
@@ -4774,8 +4865,8 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     if (!DNA_struct_elem_find(
             fd->filesdna, "View3DOverlay", "float", "sculpt_mode_face_sets_opacity")) {
       for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
-        for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-          for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
             if (sl->spacetype == SPACE_VIEW3D) {
               View3D *v3d = (View3D *)sl;
               v3d->overlay.sculpt_mode_face_sets_opacity = 1.0f;
@@ -4805,7 +4896,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     /* Corrective smooth modifier scale*/
     if (!DNA_struct_elem_find(fd->filesdna, "CorrectiveSmoothModifierData", "float", "scale")) {
       for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
-        for (ModifierData *md = ob->modifiers.first; md; md = md->next) {
+        LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
           if (md->type == eModifierType_CorrectiveSmooth) {
             CorrectiveSmoothModifierData *csmd = (CorrectiveSmoothModifierData *)md;
             csmd->scale = 1.0f;
@@ -4828,7 +4919,7 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
   if (!MAIN_VERSION_ATLEAST(bmain, 283, 11)) {
     if (!DNA_struct_elem_find(fd->filesdna, "OceanModifierData", "float", "fetch_jonswap")) {
       for (Object *object = bmain->objects.first; object != NULL; object = object->id.next) {
-        for (ModifierData *md = object->modifiers.first; md; md = md->next) {
+        LISTBASE_FOREACH (ModifierData *, md, &object->modifiers) {
           if (md->type == eModifierType_Ocean) {
             OceanModifierData *omd = (OceanModifierData *)md;
             omd->fetch_jonswap = 120.0f;
@@ -4852,6 +4943,125 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
         wm->xr.session_settings.flag = XR_SESSION_USE_POSITION_TRACKING;
       }
     }
+
+    /* Surface deform modifier strength*/
+    if (!DNA_struct_elem_find(fd->filesdna, "SurfaceDeformModifierData", "float", "strength")) {
+      for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
+        LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
+          if (md->type == eModifierType_SurfaceDeform) {
+            SurfaceDeformModifierData *sdmd = (SurfaceDeformModifierData *)md;
+            sdmd->strength = 1.0f;
+          }
+        }
+      }
+    }
+  }
+
+  if (!MAIN_VERSION_ATLEAST(bmain, 283, 12)) {
+    /* Activate f-curve drawing in the sequencer. */
+    for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
+      for (ScrArea *area = screen->areabase.first; area; area = area->next) {
+        for (SpaceLink *sl = area->spacedata.first; sl; sl = sl->next) {
+          if (sl->spacetype == SPACE_SEQ) {
+            SpaceSeq *sseq = (SpaceSeq *)sl;
+            sseq->flag |= SEQ_SHOW_FCURVES;
+          }
+        }
+      }
+    }
+
+    /* Remesh Modifier Voxel Mode. */
+    if (!DNA_struct_elem_find(fd->filesdna, "RemeshModifierData", "float", "voxel_size")) {
+      for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
+        LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
+          if (md->type == eModifierType_Remesh) {
+            RemeshModifierData *rmd = (RemeshModifierData *)md;
+            rmd->voxel_size = 0.1f;
+            rmd->adaptivity = 0.0f;
+          }
+        }
+      }
+    }
+  }
+
+  if (!MAIN_VERSION_ATLEAST(bmain, 283, 14)) {
+    /* Solidify modifier merge tolerance. */
+    if (!DNA_struct_elem_find(fd->filesdna, "SolidifyModifierData", "float", "merge_tolerance")) {
+      for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
+        for (ModifierData *md = ob->modifiers.first; md; md = md->next) {
+          if (md->type == eModifierType_Solidify) {
+            SolidifyModifierData *smd = (SolidifyModifierData *)md;
+            /* set to 0.0003 since that is what was used before, default now is 0.0001 */
+            smd->merge_tolerance = 0.0003f;
+          }
+        }
+      }
+    }
+
+    /* Enumerator was incorrect for a time in 2.83 development.
+     * Note that this only corrects values known to be invalid. */
+    for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
+      RigidBodyCon *rbc = ob->rigidbody_constraint;
+      if (rbc != NULL) {
+        enum {
+          INVALID_RBC_TYPE_SLIDER = 2,
+          INVALID_RBC_TYPE_6DOF_SPRING = 4,
+          INVALID_RBC_TYPE_MOTOR = 7,
+        };
+        switch (rbc->type) {
+          case INVALID_RBC_TYPE_SLIDER:
+            rbc->type = RBC_TYPE_SLIDER;
+            break;
+          case INVALID_RBC_TYPE_6DOF_SPRING:
+            rbc->type = RBC_TYPE_6DOF_SPRING;
+            break;
+          case INVALID_RBC_TYPE_MOTOR:
+            rbc->type = RBC_TYPE_MOTOR;
+            break;
+        }
+      }
+    }
+  }
+
+  /* Match scale of fluid modifier gravity with scene gravity. */
+  if (!MAIN_VERSION_ATLEAST(bmain, 283, 15)) {
+    for (Object *ob = bmain->objects.first; ob; ob = ob->id.next) {
+      for (ModifierData *md = ob->modifiers.first; md; md = md->next) {
+        if (md->type == eModifierType_Fluid) {
+          FluidModifierData *fmd = (FluidModifierData *)md;
+          if (fmd->domain != NULL) {
+            mul_v3_fl(fmd->domain->gravity, 9.81f);
+          }
+        }
+      }
+    }
+  }
+
+  if (!MAIN_VERSION_ATLEAST(bmain, 283, 16)) {
+    /* Init SMAA threshold for grease pencil render. */
+    LISTBASE_FOREACH (Scene *, scene, &bmain->scenes) {
+      scene->grease_pencil_settings.smaa_threshold = 1.0f;
+    }
+  }
+
+  if (!MAIN_VERSION_ATLEAST(bmain, 283, 17)) {
+    /* Reset the cloth mass to 1.0 in brushes with an invalid value. */
+    for (Brush *br = bmain->brushes.first; br; br = br->id.next) {
+      if (br->sculpt_tool == SCULPT_TOOL_CLOTH) {
+        if (br->cloth_mass == 0.0f) {
+          br->cloth_mass = 1.0f;
+        }
+      }
+    }
+
+    /* Set Brush default color for grease pencil. */
+    LISTBASE_FOREACH (Brush *, brush, &bmain->brushes) {
+      if (brush->gpencil_settings) {
+        brush->rgb[0] = 0.498f;
+        brush->rgb[1] = 1.0f;
+        brush->rgb[2] = 0.498f;
+      }
+    }
   }
 
   /**
diff --git a/source/blender/blenloader/intern/versioning_290.c b/source/blender/blenloader/intern/versioning_290.c
new file mode 100644
index 00000000000..ed23b69c623
--- /dev/null
+++ b/source/blender/blenloader/intern/versioning_290.c
@@ -0,0 +1,270 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+/** \file
+ * \ingroup blenloader
+ */
+/* allow readfile to use deprecated functionality */
+#define DNA_DEPRECATED_ALLOW
+
+#include "BLI_listbase.h"
+#include "BLI_utildefines.h"
+
+#include "DNA_brush_types.h"
+#include "DNA_genfile.h"
+#include "DNA_gpencil_modifier_types.h"
+#include "DNA_modifier_types.h"
+#include "DNA_object_types.h"
+#include "DNA_screen_types.h"
+
+#include "BKE_collection.h"
+#include "BKE_colortools.h"
+#include "BKE_lib_id.h"
+#include "BKE_main.h"
+
+#include "BLO_readfile.h"
+#include "readfile.h"
+
+/* Make preferences read-only, use versioning_userdef.c. */
+#define U (*((const UserDef *)&U))
+
+void do_versions_after_linking_290(Main *bmain, ReportList *UNUSED(reports))
+{
+  if (!MAIN_VERSION_ATLEAST(bmain, 290, 1)) {
+    /* Patch old grease pencil modifiers material filter. */
+    LISTBASE_FOREACH (Object *, ob, &bmain->objects) {
+      LISTBASE_FOREACH (GpencilModifierData *, md, &ob->greasepencil_modifiers) {
+        switch (md->type) {
+          case eGpencilModifierType_Array: {
+            ArrayGpencilModifierData *gpmd = (ArrayGpencilModifierData *)md;
+            if (gpmd->materialname[0] != '\0') {
+              gpmd->material = BLI_findstring(
+                  &bmain->materials, gpmd->materialname, offsetof(ID, name) + 2);
+              gpmd->materialname[0] = '\0';
+            }
+            break;
+          }
+          case eGpencilModifierType_Color: {
+            ColorGpencilModifierData *gpmd = (ColorGpencilModifierData *)md;
+            if (gpmd->materialname[0] != '\0') {
+              gpmd->material = BLI_findstring(
+                  &bmain->materials, gpmd->materialname, offsetof(ID, name) + 2);
+              gpmd->materialname[0] = '\0';
+            }
+            break;
+          }
+          case eGpencilModifierType_Hook: {
+            HookGpencilModifierData *gpmd = (HookGpencilModifierData *)md;
+            if (gpmd->materialname[0] != '\0') {
+              gpmd->material = BLI_findstring(
+                  &bmain->materials, gpmd->materialname, offsetof(ID, name) + 2);
+              gpmd->materialname[0] = '\0';
+            }
+            break;
+          }
+          case eGpencilModifierType_Lattice: {
+            LatticeGpencilModifierData *gpmd = (LatticeGpencilModifierData *)md;
+            if (gpmd->materialname[0] != '\0') {
+              gpmd->material = BLI_findstring(
+                  &bmain->materials, gpmd->materialname, offsetof(ID, name) + 2);
+              gpmd->materialname[0] = '\0';
+            }
+            break;
+          }
+          case eGpencilModifierType_Mirror: {
+            MirrorGpencilModifierData *gpmd = (MirrorGpencilModifierData *)md;
+            if (gpmd->materialname[0] != '\0') {
+              gpmd->material = BLI_findstring(
+                  &bmain->materials, gpmd->materialname, offsetof(ID, name) + 2);
+              gpmd->materialname[0] = '\0';
+            }
+            break;
+          }
+          case eGpencilModifierType_Multiply: {
+            MultiplyGpencilModifierData *gpmd = (MultiplyGpencilModifierData *)md;
+            if (gpmd->materialname[0] != '\0') {
+              gpmd->material = BLI_findstring(
+                  &bmain->materials, gpmd->materialname, offsetof(ID, name) + 2);
+              gpmd->materialname[0] = '\0';
+            }
+            break;
+          }
+          case eGpencilModifierType_Noise: {
+            NoiseGpencilModifierData *gpmd = (NoiseGpencilModifierData *)md;
+            if (gpmd->materialname[0] != '\0') {
+              gpmd->material = BLI_findstring(
+                  &bmain->materials, gpmd->materialname, offsetof(ID, name) + 2);
+              gpmd->materialname[0] = '\0';
+            }
+            break;
+          }
+          case eGpencilModifierType_Offset: {
+            OffsetGpencilModifierData *gpmd = (OffsetGpencilModifierData *)md;
+            if (gpmd->materialname[0] != '\0') {
+              gpmd->material = BLI_findstring(
+                  &bmain->materials, gpmd->materialname, offsetof(ID, name) + 2);
+              gpmd->materialname[0] = '\0';
+            }
+            break;
+          }
+          case eGpencilModifierType_Opacity: {
+            OpacityGpencilModifierData *gpmd = (OpacityGpencilModifierData *)md;
+            if (gpmd->materialname[0] != '\0') {
+              gpmd->material = BLI_findstring(
+                  &bmain->materials, gpmd->materialname, offsetof(ID, name) + 2);
+              gpmd->materialname[0] = '\0';
+            }
+            break;
+          }
+          case eGpencilModifierType_Simplify: {
+            SimplifyGpencilModifierData *gpmd = (SimplifyGpencilModifierData *)md;
+            if (gpmd->materialname[0] != '\0') {
+              gpmd->material = BLI_findstring(
+                  &bmain->materials, gpmd->materialname, offsetof(ID, name) + 2);
+              gpmd->materialname[0] = '\0';
+            }
+            break;
+          }
+          case eGpencilModifierType_Smooth: {
+            SmoothGpencilModifierData *gpmd = (SmoothGpencilModifierData *)md;
+            if (gpmd->materialname[0] != '\0') {
+              gpmd->material = BLI_findstring(
+                  &bmain->materials, gpmd->materialname, offsetof(ID, name) + 2);
+              gpmd->materialname[0] = '\0';
+            }
+            break;
+          }
+          case eGpencilModifierType_Subdiv: {
+            SubdivGpencilModifierData *gpmd = (SubdivGpencilModifierData *)md;
+            if (gpmd->materialname[0] != '\0') {
+              gpmd->material = BLI_findstring(
+                  &bmain->materials, gpmd->materialname, offsetof(ID, name) + 2);
+              gpmd->materialname[0] = '\0';
+            }
+            break;
+          }
+          case eGpencilModifierType_Texture: {
+            TextureGpencilModifierData *gpmd = (TextureGpencilModifierData *)md;
+            if (gpmd->materialname[0] != '\0') {
+              gpmd->material = BLI_findstring(
+                  &bmain->materials, gpmd->materialname, offsetof(ID, name) + 2);
+              gpmd->materialname[0] = '\0';
+            }
+            break;
+          }
+          case eGpencilModifierType_Thick: {
+            ThickGpencilModifierData *gpmd = (ThickGpencilModifierData *)md;
+            if (gpmd->materialname[0] != '\0') {
+              gpmd->material = BLI_findstring(
+                  &bmain->materials, gpmd->materialname, offsetof(ID, name) + 2);
+              gpmd->materialname[0] = '\0';
+            }
+            break;
+          }
+          default:
+            break;
+        }
+      }
+    }
+  }
+
+  /**
+   * Versioning code until next subversion bump goes here.
+   *
+   * \note Be sure to check when bumping the version:
+   * - #blo_do_versions_290 in this file.
+   * - "versioning_userdef.c", #BLO_version_defaults_userpref_blend
+   * - "versioning_userdef.c", #do_versions_theme
+   *
+   * \note Keep this message at the bottom of the function.
+   */
+  {
+    /* Keep this block, even when empty. */
+  }
+}
+
+void blo_do_versions_290(FileData *fd, Library *UNUSED(lib), Main *bmain)
+{
+  UNUSED_VARS(fd);
+
+  /** Repair files from duplicate brushes added to blend files, see: T76738. */
+  if (!MAIN_VERSION_ATLEAST(bmain, 290, 2)) {
+    {
+      short id_codes[] = {ID_BR, ID_PAL};
+      for (int i = 0; i < ARRAY_SIZE(id_codes); i++) {
+        ListBase *lb = which_libbase(bmain, id_codes[i]);
+        BKE_main_id_repair_duplicate_names_listbase(lb);
+      }
+    }
+
+    if (!DNA_struct_elem_find(fd->filesdna, "SpaceImage", "float", "uv_opacity")) {
+      for (bScreen *screen = bmain->screens.first; screen; screen = screen->id.next) {
+        LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+          LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
+            if (sl->spacetype == SPACE_IMAGE) {
+              SpaceImage *sima = (SpaceImage *)sl;
+              sima->uv_opacity = 1.0f;
+            }
+          }
+        }
+      }
+    }
+
+    /* Init Grease Pencil new random curves. */
+    if (!DNA_struct_elem_find(fd->filesdna, "BrushGpencilSettings", "float", "random_hue")) {
+      LISTBASE_FOREACH (Brush *, brush, &bmain->brushes) {
+        if ((brush->gpencil_settings) && (brush->gpencil_settings->curve_rand_pressure == NULL)) {
+          brush->gpencil_settings->curve_rand_pressure = BKE_curvemapping_add(
+              1, 0.0f, 0.0f, 1.0f, 1.0f);
+          brush->gpencil_settings->curve_rand_strength = BKE_curvemapping_add(
+              1, 0.0f, 0.0f, 1.0f, 1.0f);
+          brush->gpencil_settings->curve_rand_uv = BKE_curvemapping_add(1, 0.0f, 0.0f, 1.0f, 1.0f);
+          brush->gpencil_settings->curve_rand_hue = BKE_curvemapping_add(
+              1, 0.0f, 0.0f, 1.0f, 1.0f);
+          brush->gpencil_settings->curve_rand_saturation = BKE_curvemapping_add(
+              1, 0.0f, 0.0f, 1.0f, 1.0f);
+          brush->gpencil_settings->curve_rand_value = BKE_curvemapping_add(
+              1, 0.0f, 0.0f, 1.0f, 1.0f);
+        }
+      }
+    }
+  }
+
+  if (!MAIN_VERSION_ATLEAST(bmain, 290, 4)) {
+    /* Clear old deprecated bit-flag from edit weights modifiers, we now use it for something else.
+     */
+    LISTBASE_FOREACH (Object *, ob, &bmain->objects) {
+      LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
+        if (md->type == eModifierType_WeightVGEdit) {
+          ((WeightVGEditModifierData *)md)->edit_flags &= ~MOD_WVG_EDIT_WEIGHTS_NORMALIZE;
+        }
+      }
+    }
+  }
+
+  /**
+   * Versioning code until next subversion bump goes here.
+   *
+   * \note Be sure to check when bumping the version:
+   * - "versioning_userdef.c", #BLO_version_defaults_userpref_blend
+   * - "versioning_userdef.c", #do_versions_theme
+   *
+   * \note Keep this message at the bottom of the function.
+   */
+  {
+    /* Keep this block, even when empty. */
+  }
+}
diff --git a/source/blender/blenloader/intern/versioning_cycles.c b/source/blender/blenloader/intern/versioning_cycles.c
index 14a940b9297..ff3d4574561 100644
--- a/source/blender/blenloader/intern/versioning_cycles.c
+++ b/source/blender/blenloader/intern/versioning_cycles.c
@@ -173,7 +173,7 @@ static void square_roughness_node_insert(bNodeTree *ntree)
   bool need_update = false;
 
   /* Update default values */
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node_has_roughness(node)) {
       bNodeSocket *roughness_input = nodeFindSocket(node, SOCK_IN, "Roughness");
       float *roughness_value = cycles_node_socket_float_value(roughness_input);
@@ -256,7 +256,7 @@ static void ambient_occlusion_node_relink(bNodeTree *ntree)
   bool need_update = false;
 
   /* Set default values. */
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node->type == SH_NODE_AMBIENT_OCCLUSION) {
       node->custom1 = 1; /* samples */
       node->custom2 &= ~SHD_AO_LOCAL;
@@ -338,7 +338,7 @@ static void light_emission_node_to_energy(Light *light, float *energy, float col
   }
 
   bNode *emission_node = NULL;
-  for (bNodeLink *link = ntree->links.first; link; link = link->next) {
+  LISTBASE_FOREACH (bNodeLink *, link, &ntree->links) {
     if (link->tonode == output_node && link->fromnode->type == SH_NODE_EMISSION) {
       emission_node = link->fromnode;
       break;
@@ -410,7 +410,7 @@ static void update_math_node_single_operand_operators(bNodeTree *ntree)
 {
   bool need_update = false;
 
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node->type == SH_NODE_MATH) {
       if (ELEM(node->custom1,
                NODE_MATH_SQRT,
@@ -459,7 +459,7 @@ static void update_vector_math_node_add_and_subtract_operators(bNodeTree *ntree)
 {
   bool need_update = false;
 
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node->type == SH_NODE_VECTOR_MATH) {
       bNodeSocket *sockOutValue = nodeFindSocket(node, SOCK_OUT, "Value");
       if (socket_is_used(sockOutValue) &&
@@ -511,7 +511,7 @@ static void update_vector_math_node_dot_product_operator(bNodeTree *ntree)
 {
   bool need_update = false;
 
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node->type == SH_NODE_VECTOR_MATH) {
       bNodeSocket *sockOutVector = nodeFindSocket(node, SOCK_OUT, "Vector");
       if (socket_is_used(sockOutVector) && node->custom1 == NODE_VECTOR_MATH_DOT_PRODUCT) {
@@ -550,7 +550,7 @@ static void update_vector_math_node_cross_product_operator(bNodeTree *ntree)
 {
   bool need_update = false;
 
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node->type == SH_NODE_VECTOR_MATH) {
       if (node->custom1 == NODE_VECTOR_MATH_CROSS_PRODUCT) {
         bNodeSocket *sockOutVector = nodeFindSocket(node, SOCK_OUT, "Vector");
@@ -616,7 +616,7 @@ static void update_vector_math_node_normalize_operator(bNodeTree *ntree)
 {
   bool need_update = false;
 
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node->type == SH_NODE_VECTOR_MATH) {
       bNodeSocket *sockOutValue = nodeFindSocket(node, SOCK_OUT, "Value");
       if (node->custom1 == NODE_VECTOR_MATH_NORMALIZE && socket_is_used(sockOutValue)) {
@@ -675,7 +675,7 @@ static void update_vector_math_node_normalize_operator(bNodeTree *ntree)
  */
 static void update_vector_math_node_operators_enum_mapping(bNodeTree *ntree)
 {
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node->type == SH_NODE_VECTOR_MATH) {
       switch (node->custom1) {
         case 2:
@@ -702,7 +702,7 @@ static void update_vector_math_node_average_operator(bNodeTree *ntree)
 {
   bool need_update = false;
 
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node->type == SH_NODE_VECTOR_MATH) {
       /* See update_vector_math_node_operators_enum_mapping. */
       if (node->custom1 == -1) {
@@ -765,7 +765,7 @@ static void update_vector_math_node_average_operator(bNodeTree *ntree)
  */
 static void update_noise_node_dimensions(bNodeTree *ntree)
 {
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node->type == SH_NODE_TEX_NOISE && node->storage) {
       NodeTexNoise *tex = (NodeTexNoise *)node->storage;
       tex->dimensions = 3;
@@ -853,7 +853,7 @@ static void update_mapping_node_inputs_and_properties(bNodeTree *ntree)
 {
   bool need_update = false;
 
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     /* If node->storage is NULL, then conversion has already taken place.
      * This can happen if a file with the new mapping node [saved from (2, 81, 8) or newer]
      * is opened in a blender version prior to (2, 81, 8) and saved from there again. */
@@ -949,7 +949,7 @@ static void update_mapping_node_inputs_and_properties(bNodeTree *ntree)
  */
 static void update_musgrave_node_dimensions(bNodeTree *ntree)
 {
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node->type == SH_NODE_TEX_MUSGRAVE && node->storage) {
       NodeTexMusgrave *tex = (NodeTexMusgrave *)node->storage;
       tex->dimensions = 3;
@@ -977,7 +977,7 @@ static void update_musgrave_node_color_output(bNodeTree *ntree)
  */
 static void update_voronoi_node_dimensions(bNodeTree *ntree)
 {
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node->type == SH_NODE_TEX_VORONOI && node->storage) {
       NodeTexVoronoi *tex = (NodeTexVoronoi *)node->storage;
       tex->dimensions = 3;
@@ -992,7 +992,7 @@ static void update_voronoi_node_dimensions(bNodeTree *ntree)
  */
 static void update_voronoi_node_f3_and_f4(bNodeTree *ntree)
 {
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node->type == SH_NODE_TEX_VORONOI && node->storage) {
       NodeTexVoronoi *tex = (NodeTexVoronoi *)node->storage;
       if (ELEM(tex->feature, 2, 3)) {
@@ -1010,7 +1010,7 @@ static void update_voronoi_node_f3_and_f4(bNodeTree *ntree)
  */
 static void update_voronoi_node_fac_output(bNodeTree *ntree)
 {
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node->type == SH_NODE_TEX_VORONOI) {
       bNodeSocket *facOutput = BLI_findlink(&node->outputs, 1);
       strcpy(facOutput->identifier, "Distance");
@@ -1040,7 +1040,7 @@ static void update_voronoi_node_crackle(bNodeTree *ntree)
 {
   bool need_update = false;
 
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node->type == SH_NODE_TEX_VORONOI && node->storage) {
       NodeTexVoronoi *tex = (NodeTexVoronoi *)node->storage;
       bNodeSocket *sockDistance = nodeFindSocket(node, SOCK_OUT, "Distance");
@@ -1169,7 +1169,7 @@ static void update_voronoi_node_square_distance(bNodeTree *ntree)
 {
   bool need_update = false;
 
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node->type == SH_NODE_TEX_VORONOI && node->storage) {
       NodeTexVoronoi *tex = (NodeTexVoronoi *)node->storage;
       bNodeSocket *sockDistance = nodeFindSocket(node, SOCK_OUT, "Distance");
@@ -1213,7 +1213,7 @@ static void update_noise_and_wave_distortion(bNodeTree *ntree)
 {
   bool need_update = false;
 
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node->type == SH_NODE_TEX_NOISE || node->type == SH_NODE_TEX_WAVE) {
 
       bNodeSocket *sockDistortion = nodeFindSocket(node, SOCK_IN, "Distortion");
@@ -1262,7 +1262,7 @@ static void update_noise_and_wave_distortion(bNodeTree *ntree)
  */
 static void update_wave_node_directions_and_offset(bNodeTree *ntree)
 {
-  for (bNode *node = ntree->nodes.first; node; node = node->next) {
+  LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
     if (node->type == SH_NODE_TEX_WAVE) {
       NodeTexWave *tex = (NodeTexWave *)node->storage;
       tex->bands_direction = SHD_WAVE_BANDS_DIRECTION_DIAGONAL;
@@ -1351,13 +1351,13 @@ void do_versions_after_linking_cycles(Main *bmain)
 
       if (!MAIN_VERSION_ATLEAST(bmain, 273, 5)) {
         /* Euler order was ZYX in previous versions. */
-        for (bNode *node = ntree->nodes.first; node; node = node->next) {
+        LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
           mapping_node_order_flip(node);
         }
       }
 
       if (!MAIN_VERSION_ATLEAST(bmain, 276, 6)) {
-        for (bNode *node = ntree->nodes.first; node; node = node->next) {
+        LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
           vector_curve_node_remap(node);
         }
       }
@@ -1368,7 +1368,7 @@ void do_versions_after_linking_cycles(Main *bmain)
       }
 
       if (!MAIN_VERSION_ATLEAST(bmain, 279, 3)) {
-        for (bNode *node = ntree->nodes.first; node; node = node->next) {
+        LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
           displacement_principled_nodes(node);
         }
       }
@@ -1384,7 +1384,7 @@ void do_versions_after_linking_cycles(Main *bmain)
       }
 
       if (!MAIN_VERSION_ATLEAST(bmain, 280, 66)) {
-        for (bNode *node = ntree->nodes.first; node; node = node->next) {
+        LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
           image_node_colorspace(node);
         }
       }
diff --git a/source/blender/blenloader/intern/versioning_defaults.c b/source/blender/blenloader/intern/versioning_defaults.c
index 80395177100..91d89254c90 100644
--- a/source/blender/blenloader/intern/versioning_defaults.c
+++ b/source/blender/blenloader/intern/versioning_defaults.c
@@ -71,7 +71,7 @@ static ID *rename_id_for_versioning(Main *bmain,
   /* We can ignore libraries */
   ListBase *lb = which_libbase(bmain, id_type);
   ID *id = NULL;
-  for (ID *idtest = lb->first; idtest; idtest = idtest->next) {
+  LISTBASE_FOREACH (ID *, idtest, lb) {
     if (idtest->lib == NULL) {
       if (STREQ(idtest->name + 2, name_src)) {
         id = idtest;
@@ -101,8 +101,8 @@ static void blo_update_defaults_screen(bScreen *screen,
                                        const char *workspace_name)
 {
   /* For all app templates. */
-  for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-    for (ARegion *region = sa->regionbase.first; region; region = region->next) {
+  LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+    LISTBASE_FOREACH (ARegion *, region, &area->regionbase) {
       /* Some toolbars have been saved as initialized,
        * we don't want them to have odd zoom-level or scrolling set, see: T47047 */
       if (ELEM(region->regiontype, RGN_TYPE_UI, RGN_TYPE_TOOLS, RGN_TYPE_TOOL_PROPS)) {
@@ -111,7 +111,7 @@ static void blo_update_defaults_screen(bScreen *screen,
     }
 
     /* Set default folder. */
-    for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
+    LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
       if (sl->spacetype == SPACE_FILE) {
         SpaceFile *sfile = (SpaceFile *)sl;
         if (sfile->params) {
@@ -130,8 +130,8 @@ static void blo_update_defaults_screen(bScreen *screen,
     return;
   }
 
-  for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-    for (ARegion *region = sa->regionbase.first; region; region = region->next) {
+  LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+    LISTBASE_FOREACH (ARegion *, region, &area->regionbase) {
       /* Remove all stored panels, we want to use defaults
        * (order, open/closed) as defined by UI code here! */
       BKE_area_region_panels_free(&region->panels);
@@ -142,48 +142,48 @@ static void blo_update_defaults_screen(bScreen *screen,
       region->sizey = 0;
     }
 
-    if (sa->spacetype == SPACE_IMAGE) {
+    if (area->spacetype == SPACE_IMAGE) {
       if (STREQ(workspace_name, "UV Editing")) {
-        SpaceImage *sima = sa->spacedata.first;
+        SpaceImage *sima = area->spacedata.first;
         if (sima->mode == SI_MODE_VIEW) {
           sima->mode = SI_MODE_UV;
         }
       }
     }
-    else if (sa->spacetype == SPACE_ACTION) {
+    else if (area->spacetype == SPACE_ACTION) {
       /* Show markers region, hide channels and collapse summary in timelines. */
-      SpaceAction *saction = sa->spacedata.first;
+      SpaceAction *saction = area->spacedata.first;
       saction->flag |= SACTION_SHOW_MARKERS;
       if (saction->mode == SACTCONT_TIMELINE) {
         saction->ads.flag |= ADS_FLAG_SUMMARY_COLLAPSED;
 
-        for (ARegion *region = sa->regionbase.first; region; region = region->next) {
+        LISTBASE_FOREACH (ARegion *, region, &area->regionbase) {
           if (region->regiontype == RGN_TYPE_CHANNELS) {
             region->flag |= RGN_FLAG_HIDDEN;
           }
         }
       }
     }
-    else if (sa->spacetype == SPACE_GRAPH) {
-      SpaceGraph *sipo = sa->spacedata.first;
+    else if (area->spacetype == SPACE_GRAPH) {
+      SpaceGraph *sipo = area->spacedata.first;
       sipo->flag |= SIPO_SHOW_MARKERS;
     }
-    else if (sa->spacetype == SPACE_NLA) {
-      SpaceNla *snla = sa->spacedata.first;
+    else if (area->spacetype == SPACE_NLA) {
+      SpaceNla *snla = area->spacedata.first;
       snla->flag |= SNLA_SHOW_MARKERS;
     }
-    else if (sa->spacetype == SPACE_SEQ) {
-      SpaceSeq *seq = sa->spacedata.first;
-      seq->flag |= SEQ_SHOW_MARKERS;
+    else if (area->spacetype == SPACE_SEQ) {
+      SpaceSeq *seq = area->spacedata.first;
+      seq->flag |= SEQ_SHOW_MARKERS | SEQ_SHOW_FCURVES;
     }
-    else if (sa->spacetype == SPACE_TEXT) {
+    else if (area->spacetype == SPACE_TEXT) {
       /* Show syntax and line numbers in Script workspace text editor. */
-      SpaceText *stext = sa->spacedata.first;
+      SpaceText *stext = area->spacedata.first;
       stext->showsyntax = true;
       stext->showlinenrs = true;
     }
-    else if (sa->spacetype == SPACE_VIEW3D) {
-      View3D *v3d = sa->spacedata.first;
+    else if (area->spacetype == SPACE_VIEW3D) {
+      View3D *v3d = area->spacedata.first;
       /* Screen space cavity by default for faster performance. */
       v3d->shading.cavity_type = V3D_SHADING_CAVITY_CURVATURE;
       v3d->shading.flag |= V3D_SHADING_SPECULAR_HIGHLIGHT;
@@ -197,24 +197,27 @@ static void blo_update_defaults_screen(bScreen *screen,
       v3d->gp_flag |= V3D_GP_SHOW_EDIT_LINES;
       /* Remove dither pattern in wireframe mode. */
       v3d->shading.xray_alpha_wire = 0.0f;
+      v3d->clip_start = 0.01f;
       /* Skip startups that use the viewport color by default. */
       if (v3d->shading.background_type != V3D_SHADING_BACKGROUND_VIEWPORT) {
         copy_v3_fl(v3d->shading.background_color, 0.05f);
       }
+      /* Disable Curve Normals. */
+      v3d->overlay.edit_flag &= ~V3D_OVERLAY_EDIT_CU_NORMALS;
     }
-    else if (sa->spacetype == SPACE_CLIP) {
-      SpaceClip *sclip = sa->spacedata.first;
+    else if (area->spacetype == SPACE_CLIP) {
+      SpaceClip *sclip = area->spacedata.first;
       sclip->around = V3D_AROUND_CENTER_MEDIAN;
     }
   }
 
   /* Show tool-header by default (for most cases at least, hide for others). */
   const bool hide_image_tool_header = STREQ(workspace_name, "Rendering");
-  for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-    for (SpaceLink *sl = sa->spacedata.first; sl; sl = sl->next) {
-      ListBase *regionbase = (sl == sa->spacedata.first) ? &sa->regionbase : &sl->regionbase;
+  LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+    LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
+      ListBase *regionbase = (sl == area->spacedata.first) ? &area->regionbase : &sl->regionbase;
 
-      for (ARegion *region = regionbase->first; region; region = region->next) {
+      LISTBASE_FOREACH (ARegion *, region, regionbase) {
         if (region->regiontype == RGN_TYPE_TOOL_HEADER) {
           if ((sl->spacetype == SPACE_IMAGE) && hide_image_tool_header) {
             region->flag |= RGN_FLAG_HIDDEN;
@@ -229,20 +232,18 @@ static void blo_update_defaults_screen(bScreen *screen,
 
   /* 2D animation template. */
   if (app_template && STREQ(app_template, "2D_Animation")) {
-    for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-      for (ARegion *region = sa->regionbase.first; region; region = region->next) {
-        if (sa->spacetype == SPACE_ACTION) {
-          SpaceAction *saction = sa->spacedata.first;
-          /* Enable Sliders. */
-          saction->flag |= SACTION_SLIDERS;
-        }
-        else if (sa->spacetype == SPACE_VIEW3D) {
-          View3D *v3d = sa->spacedata.first;
-          /* Set Material Color by default. */
-          v3d->shading.color_type = V3D_SHADING_MATERIAL_COLOR;
-          /* Enable Annotations. */
-          v3d->flag2 |= V3D_SHOW_ANNOTATION;
-        }
+    LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+      if (area->spacetype == SPACE_ACTION) {
+        SpaceAction *saction = area->spacedata.first;
+        /* Enable Sliders. */
+        saction->flag |= SACTION_SLIDERS;
+      }
+      else if (area->spacetype == SPACE_VIEW3D) {
+        View3D *v3d = area->spacedata.first;
+        /* Set Material Color by default. */
+        v3d->shading.color_type = V3D_SHADING_MATERIAL_COLOR;
+        /* Enable Annotations. */
+        v3d->flag2 |= V3D_SHOW_ANNOTATION;
       }
     }
   }
@@ -250,8 +251,7 @@ static void blo_update_defaults_screen(bScreen *screen,
 
 void BLO_update_defaults_workspace(WorkSpace *workspace, const char *app_template)
 {
-  ListBase *layouts = BKE_workspace_layouts_get(workspace);
-  for (WorkSpaceLayout *layout = layouts->first; layout; layout = layout->next) {
+  LISTBASE_FOREACH (WorkSpaceLayout *, layout, &workspace->layouts) {
     if (layout->screen) {
       blo_update_defaults_screen(layout->screen, app_template, workspace->id.name + 2);
     }
@@ -270,13 +270,13 @@ void BLO_update_defaults_workspace(WorkSpace *workspace, const char *app_templat
 
     /* For Sculpting template. */
     if (STREQ(workspace->id.name + 2, "Sculpting")) {
-      for (WorkSpaceLayout *layout = layouts->first; layout; layout = layout->next) {
+      LISTBASE_FOREACH (WorkSpaceLayout *, layout, &workspace->layouts) {
         bScreen *screen = layout->screen;
         if (screen) {
-          for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
-            for (ARegion *region = sa->regionbase.first; region; region = region->next) {
-              if (sa->spacetype == SPACE_VIEW3D) {
-                View3D *v3d = sa->spacedata.first;
+          LISTBASE_FOREACH (ScrArea *, area, &screen->areabase) {
+            LISTBASE_FOREACH (ARegion *, region, &area->regionbase) {
+              if (area->spacetype == SPACE_VIEW3D) {
+                View3D *v3d = area->spacedata.first;
                 v3d->shading.flag &= ~V3D_SHADING_CAVITY;
                 copy_v3_fl(v3d->shading.single_color, 1.0f);
                 STRNCPY(v3d->shading.matcap, "basic_1");
@@ -297,7 +297,7 @@ static void blo_update_defaults_scene(Main *bmain, Scene *scene)
 
   /* Don't enable compositing nodes. */
   if (scene->nodetree) {
-    ntreeFreeNestedTree(scene->nodetree);
+    ntreeFreeEmbeddedTree(scene->nodetree);
     MEM_freeN(scene->nodetree);
     scene->nodetree = NULL;
     scene->use_nodes = false;
@@ -368,7 +368,13 @@ static void blo_update_defaults_scene(Main *bmain, Scene *scene)
 
 /**
  * Update defaults in startup.blend, without having to save and embed the file.
- * This function can be emptied each time the startup.blend is updated. */
+ * This function can be emptied each time the startup.blend is updated.
+ *
+ * \note Screen data may be cleared at this point, this will happen in the case
+ * an app-template's data needs to be versioned when read-file is called with "Load UI" disabled.
+ * Versioning the screen data can be safely skipped without "Load UI" since the screen data
+ * will have been versioned when it was first loaded.
+ */
 void BLO_update_defaults_startup_blend(Main *bmain, const char *app_template)
 {
   /* For all app templates. */
@@ -376,30 +382,132 @@ void BLO_update_defaults_startup_blend(Main *bmain, const char *app_template)
     BLO_update_defaults_workspace(workspace, app_template);
   }
 
+  /* New grease pencil brushes and vertex paint setup. */
+  {
+    /* Update Grease Pencil brushes. */
+    Brush *brush;
+
+    /* Pencil brush. */
+    rename_id_for_versioning(bmain, ID_BR, "Draw Pencil", "Pencil");
+
+    /* Pen brush. */
+    rename_id_for_versioning(bmain, ID_BR, "Draw Pen", "Pen");
+
+    /* Pen Soft brush. */
+    brush = (Brush *)rename_id_for_versioning(bmain, ID_BR, "Draw Soft", "Pencil Soft");
+    if (brush) {
+      brush->gpencil_settings->icon_id = GP_BRUSH_ICON_PEN;
+    }
+
+    /* Ink Pen brush. */
+    rename_id_for_versioning(bmain, ID_BR, "Draw Ink", "Ink Pen");
+
+    /* Ink Pen Rough brush. */
+    rename_id_for_versioning(bmain, ID_BR, "Draw Noise", "Ink Pen Rough");
+
+    /* Marker Bold brush. */
+    rename_id_for_versioning(bmain, ID_BR, "Draw Marker", "Marker Bold");
+
+    /* Marker Chisel brush. */
+    rename_id_for_versioning(bmain, ID_BR, "Draw Block", "Marker Chisel");
+
+    /* Remove useless Fill Area.001 brush. */
+    brush = BLI_findstring(&bmain->brushes, "Fill Area.001", offsetof(ID, name) + 2);
+    if (brush) {
+      BKE_id_delete(bmain, brush);
+    }
+
+    /* Rename and fix materials and enable default object lights on. */
+    if (app_template && STREQ(app_template, "2D_Animation")) {
+      Material *ma = NULL;
+      rename_id_for_versioning(bmain, ID_MA, "Black", "Solid Stroke");
+      rename_id_for_versioning(bmain, ID_MA, "Red", "Squares Stroke");
+      rename_id_for_versioning(bmain, ID_MA, "Grey", "Solid Fill");
+      rename_id_for_versioning(bmain, ID_MA, "Black Dots", "Dots Stroke");
+
+      /* Dots Stroke. */
+      ma = BLI_findstring(&bmain->materials, "Dots Stroke", offsetof(ID, name) + 2);
+      if (ma == NULL) {
+        ma = BKE_gpencil_material_add(bmain, "Dots Stroke");
+      }
+      ma->gp_style->mode = GP_MATERIAL_MODE_DOT;
+
+      /* Squares Stroke. */
+      ma = BLI_findstring(&bmain->materials, "Squares Stroke", offsetof(ID, name) + 2);
+      if (ma == NULL) {
+        ma = BKE_gpencil_material_add(bmain, "Squares Stroke");
+      }
+      ma->gp_style->mode = GP_MATERIAL_MODE_SQUARE;
+
+      /* Change Solid Stroke settings. */
+      ma = BLI_findstring(&bmain->materials, "Solid Stroke", offsetof(ID, name) + 2);
+      if (ma != NULL) {
+        ma->gp_style->mix_rgba[3] = 1.0f;
+        ma->gp_style->texture_offset[0] = -0.5f;
+        ma->gp_style->mix_factor = 0.5f;
+      }
+
+      /* Change Solid Fill settings. */
+      ma = BLI_findstring(&bmain->materials, "Solid Fill", offsetof(ID, name) + 2);
+      if (ma != NULL) {
+        ma->gp_style->flag &= ~GP_MATERIAL_STROKE_SHOW;
+        ma->gp_style->mix_rgba[3] = 1.0f;
+        ma->gp_style->texture_offset[0] = -0.5f;
+        ma->gp_style->mix_factor = 0.5f;
+      }
+
+      Object *ob = BLI_findstring(&bmain->objects, "Stroke", offsetof(ID, name) + 2);
+      if (ob && ob->type == OB_GPENCIL) {
+        ob->dtx |= OB_USE_GPENCIL_LIGHTS;
+      }
+    }
+
+    /* Reset all grease pencil brushes. */
+    Scene *scene = bmain->scenes.first;
+    BKE_brush_gpencil_paint_presets(bmain, scene->toolsettings, true);
+    BKE_brush_gpencil_sculpt_presets(bmain, scene->toolsettings, true);
+    BKE_brush_gpencil_vertex_presets(bmain, scene->toolsettings, true);
+    BKE_brush_gpencil_weight_presets(bmain, scene->toolsettings, true);
+
+    /* Ensure new Paint modes. */
+    BKE_paint_ensure_from_paintmode(scene, PAINT_MODE_VERTEX_GPENCIL);
+    BKE_paint_ensure_from_paintmode(scene, PAINT_MODE_SCULPT_GPENCIL);
+    BKE_paint_ensure_from_paintmode(scene, PAINT_MODE_WEIGHT_GPENCIL);
+
+    /* Enable cursor. */
+    GpPaint *gp_paint = scene->toolsettings->gp_paint;
+    gp_paint->paint.flags |= PAINT_SHOW_BRUSH;
+
+    /* Ensure Palette by default. */
+    BKE_gpencil_palette_ensure(bmain, scene);
+  }
+
   /* For builtin templates only. */
   if (!blo_is_builtin_template(app_template)) {
     return;
   }
 
   /* Workspaces. */
-  wmWindow *win = ((wmWindowManager *)bmain->wm.first)->windows.first;
-  for (WorkSpace *workspace = bmain->workspaces.first; workspace; workspace = workspace->id.next) {
-    WorkSpaceLayout *layout = BKE_workspace_hook_layout_for_workspace_get(win->workspace_hook,
-                                                                          workspace);
-
-    /* Name all screens by their workspaces (avoids 'Default.###' names). */
-    /* Default only has one window. */
-    if (layout->screen) {
-      bScreen *screen = layout->screen;
-      BLI_strncpy(screen->id.name + 2, workspace->id.name + 2, sizeof(screen->id.name) - 2);
-      BLI_libblock_ensure_unique_name(bmain, screen->id.name);
-    }
+  LISTBASE_FOREACH (wmWindowManager *, wm, &bmain->wm) {
+    LISTBASE_FOREACH (wmWindow *, win, &wm->windows) {
+      LISTBASE_FOREACH (WorkSpace *, workspace, &bmain->workspaces) {
+        WorkSpaceLayout *layout = BKE_workspace_active_layout_for_workspace_get(
+            win->workspace_hook, workspace);
+        /* Name all screens by their workspaces (avoids 'Default.###' names). */
+        /* Default only has one window. */
+        if (layout->screen) {
+          bScreen *screen = layout->screen;
+          BLI_strncpy(screen->id.name + 2, workspace->id.name + 2, sizeof(screen->id.name) - 2);
+          BLI_libblock_ensure_unique_name(bmain, screen->id.name);
+        }
 
-    /* For some reason we have unused screens, needed until re-saving.
-     * Clear unused layouts because they're visible in the outliner & Python API. */
-    LISTBASE_FOREACH_MUTABLE (WorkSpaceLayout *, layout_iter, &workspace->layouts) {
-      if (layout != layout_iter) {
-        BKE_workspace_layout_remove(bmain, workspace, layout_iter);
+        /* For some reason we have unused screens, needed until re-saving.
+         * Clear unused layouts because they're visible in the outliner & Python API. */
+        LISTBASE_FOREACH_MUTABLE (WorkSpaceLayout *, layout_iter, &workspace->layouts) {
+          if (layout != layout_iter) {
+            BKE_workspace_layout_remove(bmain, workspace, layout_iter);
+          }
+        }
       }
     }
   }
@@ -472,7 +580,7 @@ void BLO_update_defaults_startup_blend(Main *bmain, const char *app_template)
     ma->roughness = 0.4f;
 
     if (ma->nodetree) {
-      for (bNode *node = ma->nodetree->nodes.first; node; node = node->next) {
+      LISTBASE_FOREACH (bNode *, node, &ma->nodetree->nodes) {
         if (node->type == SH_NODE_BSDF_PRINCIPLED) {
           bNodeSocket *roughness_socket = nodeFindSocket(node, SOCK_IN, "Roughness");
           bNodeSocketValueFloat *roughness_data = roughness_socket->default_value;
@@ -598,90 +706,4 @@ void BLO_update_defaults_startup_blend(Main *bmain, const char *app_template)
       }
     }
   }
-
-  /* New grease pencil brushes and vertex paint setup. */
-  {
-    /* Update Grease Pencil brushes. */
-    Brush *brush;
-
-    /* Pencil brush. */
-    rename_id_for_versioning(bmain, ID_BR, "Draw Pencil", "Pencil");
-
-    /* Pen brush. */
-    rename_id_for_versioning(bmain, ID_BR, "Draw Pen", "Pen");
-
-    /* Pen Soft brush. */
-    brush = (Brush *)rename_id_for_versioning(bmain, ID_BR, "Draw Soft", "Pencil Soft");
-    if (brush) {
-      brush->gpencil_settings->icon_id = GP_BRUSH_ICON_PEN;
-    }
-
-    /* Ink Pen brush. */
-    rename_id_for_versioning(bmain, ID_BR, "Draw Ink", "Ink Pen");
-
-    /* Ink Pen Rough brush. */
-    rename_id_for_versioning(bmain, ID_BR, "Draw Noise", "Ink Pen Rough");
-
-    /* Marker Bold brush. */
-    rename_id_for_versioning(bmain, ID_BR, "Draw Marker", "Marker Bold");
-
-    /* Marker Chisel brush. */
-    rename_id_for_versioning(bmain, ID_BR, "Draw Block", "Marker Chisel");
-
-    /* Remove useless Fill Area.001 brush. */
-    brush = BLI_findstring(&bmain->brushes, "Fill Area.001", offsetof(ID, name) + 2);
-    if (brush) {
-      BKE_id_delete(bmain, brush);
-    }
-
-    /* Rename and fix materials and enable default object lights on. */
-    if (app_template && STREQ(app_template, "2D_Animation")) {
-      Material *ma = NULL;
-      rename_id_for_versioning(bmain, ID_MA, "Black", "Solid Stroke");
-      rename_id_for_versioning(bmain, ID_MA, "Red", "Squares Stroke");
-      rename_id_for_versioning(bmain, ID_MA, "Grey", "Solid Fill");
-      rename_id_for_versioning(bmain, ID_MA, "Black Dots", "Dots Stroke");
-
-      /* Dots Stroke. */
-      ma = BLI_findstring(&bmain->materials, "Dots Stroke", offsetof(ID, name) + 2);
-      if (ma == NULL) {
-        ma = BKE_gpencil_material_add(bmain, "Dots Stroke");
-      }
-      ma->gp_style->mode = GP_MATERIAL_MODE_DOT;
-
-      /* Squares Stroke. */
-      ma = BLI_findstring(&bmain->materials, "Squares Stroke", offsetof(ID, name) + 2);
-      if (ma == NULL) {
-        ma = BKE_gpencil_material_add(bmain, "Squares Stroke");
-      }
-      ma->gp_style->mode = GP_MATERIAL_MODE_SQUARE;
-
-      /* Change Solid Fill settings. */
-      ma = BLI_findstring(&bmain->materials, "Solid Fill", offsetof(ID, name) + 2);
-      if (ma != NULL) {
-        ma->gp_style->flag &= ~GP_MATERIAL_STROKE_SHOW;
-      }
-
-      Object *ob = BLI_findstring(&bmain->objects, "Stroke", offsetof(ID, name) + 2);
-      if (ob && ob->type == OB_GPENCIL) {
-        ob->dtx |= OB_USE_GPENCIL_LIGHTS;
-      }
-    }
-
-    /* Reset all grease pencil brushes. */
-    Scene *scene = bmain->scenes.first;
-    BKE_brush_gpencil_paint_presets(bmain, scene->toolsettings);
-
-    /* Ensure new Paint modes. */
-    BKE_paint_ensure_from_paintmode(scene, PAINT_MODE_VERTEX_GPENCIL);
-    BKE_paint_ensure_from_paintmode(scene, PAINT_MODE_SCULPT_GPENCIL);
-    BKE_paint_ensure_from_paintmode(scene, PAINT_MODE_WEIGHT_GPENCIL);
-
-    /* Enable cursor. */
-    GpPaint *gp_paint = scene->toolsettings->gp_paint;
-    gp_paint->paint.flags |= PAINT_SHOW_BRUSH;
-
-    /* Ensure Palette by default. */
-    BKE_gpencil_palette_ensure(bmain, scene);
-  }
 }
diff --git a/source/blender/blenloader/intern/versioning_legacy.c b/source/blender/blenloader/intern/versioning_legacy.c
index 29c4a0f3c9d..2cc811e213f 100644
--- a/source/blender/blenloader/intern/versioning_legacy.c
+++ b/source/blender/blenloader/intern/versioning_legacy.c
@@ -580,11 +580,11 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
 
   if (bmain->versionfile <= 109) {
     /* new variable: gridlines */
-    bScreen *sc = bmain->screens.first;
-    while (sc) {
-      ScrArea *sa = sc->areabase.first;
-      while (sa) {
-        SpaceLink *sl = sa->spacedata.first;
+    bScreen *screen = bmain->screens.first;
+    while (screen) {
+      ScrArea *area = screen->areabase.first;
+      while (area) {
+        SpaceLink *sl = area->spacedata.first;
         while (sl) {
           if (sl->spacetype == SPACE_VIEW3D) {
             View3D *v3d = (View3D *)sl;
@@ -595,9 +595,9 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
           }
           sl = sl->next;
         }
-        sa = sa->next;
+        area = area->next;
       }
-      sc = sc->id.next;
+      screen = screen->id.next;
     }
   }
 
@@ -694,11 +694,11 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
   }
 
   if (bmain->versionfile <= 169) {
-    bScreen *sc = bmain->screens.first;
-    while (sc) {
-      ScrArea *sa = sc->areabase.first;
-      while (sa) {
-        SpaceLink *sl = sa->spacedata.first;
+    bScreen *screen = bmain->screens.first;
+    while (screen) {
+      ScrArea *area = screen->areabase.first;
+      while (area) {
+        SpaceLink *sl = area->spacedata.first;
         while (sl) {
           if (sl->spacetype == SPACE_GRAPH) {
             SpaceGraph *sipo = (SpaceGraph *)sl;
@@ -706,9 +706,9 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
           }
           sl = sl->next;
         }
-        sa = sa->next;
+        area = area->next;
       }
-      sc = sc->id.next;
+      screen = screen->id.next;
     }
   }
 
@@ -727,11 +727,11 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
   }
 
   if (bmain->versionfile <= 171) {
-    bScreen *sc = bmain->screens.first;
-    while (sc) {
-      ScrArea *sa = sc->areabase.first;
-      while (sa) {
-        SpaceLink *sl = sa->spacedata.first;
+    bScreen *screen = bmain->screens.first;
+    while (screen) {
+      ScrArea *area = screen->areabase.first;
+      while (area) {
+        SpaceLink *sl = area->spacedata.first;
         while (sl) {
           if (sl->spacetype == SPACE_TEXT) {
             SpaceText *st = (SpaceText *)sl;
@@ -739,9 +739,9 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
           }
           sl = sl->next;
         }
-        sa = sa->next;
+        area = area->next;
       }
-      sc = sc->id.next;
+      screen = screen->id.next;
     }
   }
 
@@ -866,7 +866,7 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
     bSound *sound;
     Scene *sce;
     Mesh *me;
-    bScreen *sc;
+    bScreen *screen;
 
     for (sound = bmain->sounds.first; sound; sound = sound->id.next) {
       if (sound->packedfile) {
@@ -889,13 +889,13 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
     }
 
     /* some oldfile patch, moved from set_func_space */
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
 
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
 
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype == SPACE_GRAPH) {
             SpaceSeq *sseq = (SpaceSeq *)sl;
             sseq->v2d.keeptot = 0;
@@ -907,7 +907,7 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
 
   if (bmain->versionfile <= 227) {
     Scene *sce;
-    bScreen *sc;
+    bScreen *screen;
     Object *ob;
 
     /* As of now, this insures that the transition from the old Track system
@@ -962,13 +962,13 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
     }
 
     /* patch for old wrong max view2d settings, allows zooming out more */
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
 
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
 
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype == SPACE_ACTION) {
             SpaceAction *sac = (SpaceAction *)sl;
             sac->v2d.max[0] = 32000;
@@ -983,7 +983,7 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
   }
 
   if (bmain->versionfile <= 228) {
-    bScreen *sc;
+    bScreen *screen;
     Object *ob;
 
     /* As of now, this insures that the transition from the old Track system
@@ -1029,13 +1029,13 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
     }
 
     /* convert old mainb values for new button panels */
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
 
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
 
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype == SPACE_PROPERTIES) {
             SpaceProperties *sbuts = (SpaceProperties *)sl;
 
@@ -1096,16 +1096,16 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
    */
 
   if (bmain->versionfile <= 230) {
-    bScreen *sc;
+    bScreen *screen;
 
     /* new variable blockscale, for panels in any area */
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
 
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
 
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           /* added: 5x better zoom in for action */
           if (sl->spacetype == SPACE_ACTION) {
             SpaceAction *sac = (SpaceAction *)sl;
@@ -1117,14 +1117,14 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
   }
 
   if (bmain->versionfile <= 231) {
-    bScreen *sc = bmain->screens.first;
+    bScreen *screen = bmain->screens.first;
 
     /* new bit flags for showing/hiding grid floor and axes */
 
-    while (sc) {
-      ScrArea *sa = sc->areabase.first;
-      while (sa) {
-        SpaceLink *sl = sa->spacedata.first;
+    while (screen) {
+      ScrArea *area = screen->areabase.first;
+      while (area) {
+        SpaceLink *sl = area->spacedata.first;
         while (sl) {
           if (sl->spacetype == SPACE_VIEW3D) {
             View3D *v3d = (View3D *)sl;
@@ -1138,16 +1138,16 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
           }
           sl = sl->next;
         }
-        sa = sa->next;
+        area = area->next;
       }
-      sc = sc->id.next;
+      screen = screen->id.next;
     }
   }
 
   if (bmain->versionfile <= 232) {
     Tex *tex = bmain->textures.first;
     World *wrld = bmain->worlds.first;
-    bScreen *sc;
+    bScreen *screen;
 
     while (tex) {
       if ((tex->flag & (TEX_CHECKER_ODD + TEX_CHECKER_EVEN)) == 0) {
@@ -1184,11 +1184,11 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
     /* new variable blockscale, for panels in any area, do again because new
      * areas didn't initialize it to 0.7 yet
      */
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           /* added: 5x better zoom in for nla */
           if (sl->spacetype == SPACE_NLA) {
             SpaceNla *snla = (SpaceNla *)sl;
@@ -1200,13 +1200,13 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
   }
 
   if (bmain->versionfile <= 233) {
-    bScreen *sc;
+    bScreen *screen;
 
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype == SPACE_VIEW3D) {
             View3D *v3d = (View3D *)sl;
             v3d->flag |= V3D_SELECT_OUTLINE;
@@ -1217,13 +1217,13 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
   }
 
   if (bmain->versionfile <= 234) {
-    bScreen *sc;
+    bScreen *screen;
 
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype == SPACE_TEXT) {
             SpaceText *st = (SpaceText *)sl;
             if (st->tabnumber == 0) {
@@ -1351,7 +1351,8 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
         };
 
         if ((me->flag & ME_SUBSURF)) {
-          SubsurfModifierData *smd = (SubsurfModifierData *)modifier_new(eModifierType_Subsurf);
+          SubsurfModifierData *smd = (SubsurfModifierData *)BKE_modifier_new(
+              eModifierType_Subsurf);
 
           smd->levels = MAX2(1, me->subdiv);
           smd->renderLevels = MAX2(1, me->subdivr);
@@ -1371,7 +1372,7 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
 
           BLI_addtail(&ob->modifiers, smd);
 
-          modifier_unique_name(&ob->modifiers, (ModifierData *)smd);
+          BKE_modifier_unique_name(&ob->modifiers, (ModifierData *)smd);
         }
       }
 
@@ -1428,18 +1429,19 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
         }
       }
 
-      if ((ob->softflag & OB_SB_ENABLE) && !modifiers_findByType(ob, eModifierType_Softbody)) {
+      if ((ob->softflag & OB_SB_ENABLE) &&
+          !BKE_modifiers_findby_type(ob, eModifierType_Softbody)) {
         if (ob->softflag & OB_SB_POSTDEF) {
           md = ob->modifiers.first;
 
-          while (md && modifierType_getInfo(md->type)->type == eModifierTypeType_OnlyDeform) {
+          while (md && BKE_modifier_get_info(md->type)->type == eModifierTypeType_OnlyDeform) {
             md = md->next;
           }
 
-          BLI_insertlinkbefore(&ob->modifiers, md, modifier_new(eModifierType_Softbody));
+          BLI_insertlinkbefore(&ob->modifiers, md, BKE_modifier_new(eModifierType_Softbody));
         }
         else {
-          BLI_addhead(&ob->modifiers, modifier_new(eModifierType_Softbody));
+          BLI_addhead(&ob->modifiers, BKE_modifier_new(eModifierType_Softbody));
         }
 
         ob->softflag &= ~OB_SB_ENABLE;
@@ -1651,7 +1653,7 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
 
   if (bmain->versionfile <= 242) {
     Scene *sce;
-    bScreen *sc;
+    bScreen *screen;
     Object *ob;
     Curve *cu;
     Material *ma;
@@ -1663,13 +1665,13 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
     bNodeTree *ntree;
     int a;
 
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
-      sa = sc->areabase.first;
-      while (sa) {
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
+      area = screen->areabase.first;
+      while (area) {
         SpaceLink *sl;
 
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           if (sl->spacetype == SPACE_VIEW3D) {
             View3D *v3d = (View3D *)sl;
             if (v3d->gridsubdiv == 0) {
@@ -1677,7 +1679,7 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
             }
           }
         }
-        sa = sa->next;
+        area = area->next;
       }
     }
 
@@ -1922,17 +1924,17 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
   }
 
   if (bmain->versionfile <= 244) {
-    bScreen *sc;
+    bScreen *screen;
 
     if (bmain->versionfile != 244 || bmain->subversionfile < 2) {
       /* correct older action editors - incorrect scrolling */
-      for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-        ScrArea *sa;
-        sa = sc->areabase.first;
-        while (sa) {
+      for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+        ScrArea *area;
+        area = screen->areabase.first;
+        while (area) {
           SpaceLink *sl;
 
-          for (sl = sa->spacedata.first; sl; sl = sl->next) {
+          for (sl = area->spacedata.first; sl; sl = sl->next) {
             if (sl->spacetype == SPACE_ACTION) {
               SpaceAction *saction = (SpaceAction *)sl;
 
@@ -1943,7 +1945,7 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
               saction->v2d.cur.ymax = 5.0;
             }
           }
-          sa = sa->next;
+          area = area->next;
         }
       }
     }
@@ -2271,7 +2273,7 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
 
         BLI_addtail(&ob->particlesystem, psys);
 
-        md = modifier_new(eModifierType_ParticleSystem);
+        md = BKE_modifier_new(eModifierType_ParticleSystem);
         BLI_snprintf(md->name,
                      sizeof(md->name),
                      "ParticleSystem %i",
@@ -2357,7 +2359,7 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
         }
 
         {
-          FluidsimModifierData *fluidmd = (FluidsimModifierData *)modifiers_findByType(
+          FluidsimModifierData *fluidmd = (FluidsimModifierData *)BKE_modifiers_findby_type(
               ob, eModifierType_Fluidsim);
           if (fluidmd && fluidmd->fss && fluidmd->fss->type == OB_FLUIDSIM_PARTICLE) {
             part->type = PART_FLUID;
@@ -2483,7 +2485,7 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
 
     for (ob = bmain->objects.first; ob; ob = ob->id.next) {
       if (ob->fluidsimSettings) {
-        FluidsimModifierData *fluidmd = (FluidsimModifierData *)modifier_new(
+        FluidsimModifierData *fluidmd = (FluidsimModifierData *)BKE_modifier_new(
             eModifierType_Fluidsim);
         BLI_addhead(&ob->modifiers, (ModifierData *)fluidmd);
 
@@ -2540,16 +2542,16 @@ void blo_do_versions_pre250(FileData *fd, Library *lib, Main *bmain)
   }
 
   if (bmain->versionfile < 248 || (bmain->versionfile == 248 && bmain->subversionfile < 3)) {
-    bScreen *sc;
+    bScreen *screen;
 
     /* adjust default settings for Animation Editors */
-    for (sc = bmain->screens.first; sc; sc = sc->id.next) {
-      ScrArea *sa;
+    for (screen = bmain->screens.first; screen; screen = screen->id.next) {
+      ScrArea *area;
 
-      for (sa = sc->areabase.first; sa; sa = sa->next) {
+      for (area = screen->areabase.first; area; area = area->next) {
         SpaceLink *sl;
 
-        for (sl = sa->spacedata.first; sl; sl = sl->next) {
+        for (sl = area->spacedata.first; sl; sl = sl->next) {
           switch (sl->spacetype) {
             case SPACE_ACTION: {
               SpaceAction *sact = (SpaceAction *)sl;
diff --git a/source/blender/blenloader/intern/versioning_userdef.c b/source/blender/blenloader/intern/versioning_userdef.c
index a88e4e20d68..1b0e41ec54a 100644
--- a/source/blender/blenloader/intern/versioning_userdef.c
+++ b/source/blender/blenloader/intern/versioning_userdef.c
@@ -22,9 +22,14 @@
 #define DNA_DEPRECATED_ALLOW
 #include <string.h>
 
+#include "BLI_listbase.h"
 #include "BLI_math.h"
 #include "BLI_utildefines.h"
 
+#ifdef WITH_INTERNATIONAL
+#  include "BLT_translation.h"
+#endif
+
 #include "DNA_anim_types.h"
 #include "DNA_curve_types.h"
 #include "DNA_scene_types.h"
@@ -533,7 +538,7 @@ void BLO_version_defaults_userpref_blend(Main *bmain, UserDef *userdef)
     userdef->gpu_viewport_quality = 0.6f;
 
     /* Reset theme, old themes will not be compatible with minor version updates from now on. */
-    for (bTheme *btheme = userdef->themes.first; btheme; btheme = btheme->next) {
+    LISTBASE_FOREACH (bTheme *, btheme, &userdef->themes) {
       memcpy(btheme, &U_theme_default, sizeof(*btheme));
     }
 
@@ -551,8 +556,8 @@ void BLO_version_defaults_userpref_blend(Main *bmain, UserDef *userdef)
 
   if (!USER_VERSION_ATLEAST(280, 31)) {
     /* Remove select/action mouse from user defined keymaps. */
-    for (wmKeyMap *keymap = userdef->user_keymaps.first; keymap; keymap = keymap->next) {
-      for (wmKeyMapDiffItem *kmdi = keymap->diff_items.first; kmdi; kmdi = kmdi->next) {
+    LISTBASE_FOREACH (wmKeyMap *, keymap, &userdef->user_keymaps) {
+      LISTBASE_FOREACH (wmKeyMapDiffItem *, kmdi, &keymap->diff_items) {
         if (kmdi->remove_item) {
           do_version_select_mouse(userdef, kmdi->remove_item);
         }
@@ -561,7 +566,7 @@ void BLO_version_defaults_userpref_blend(Main *bmain, UserDef *userdef)
         }
       }
 
-      for (wmKeyMapItem *kmi = keymap->items.first; kmi; kmi = kmi->next) {
+      LISTBASE_FOREACH (wmKeyMapItem *, kmi, &keymap->items) {
         do_version_select_mouse(userdef, kmi);
       }
     }
@@ -739,6 +744,15 @@ void BLO_version_defaults_userpref_blend(Main *bmain, UserDef *userdef)
     userdef->gpu_flag |= USER_GPU_FLAG_OVERLAY_SMOOTH_WIRE;
   }
 
+  if (!USER_VERSION_ATLEAST(283, 13)) {
+    /* If Translations is off then language should default to English. */
+    if ((userdef->transopts & USER_DOTRANSLATE_DEPRECATED) == 0) {
+      userdef->language = ULANGUAGE_ENGLISH;
+    }
+    /* Clear this deprecated flag. */
+    userdef->transopts &= ~USER_DOTRANSLATE_DEPRECATED;
+  }
+
   /**
    * Versioning code until next subversion bump goes here.
    *
@@ -750,13 +764,17 @@ void BLO_version_defaults_userpref_blend(Main *bmain, UserDef *userdef)
    */
   {
     /* Keep this block, even when empty. */
+
+    if (userdef->collection_instance_empty_size == 0) {
+      userdef->collection_instance_empty_size = 1.0f;
+    }
   }
 
   if (userdef->pixelsize == 0.0f) {
     userdef->pixelsize = 1.0f;
   }
 
-  for (bTheme *btheme = userdef->themes.first; btheme; btheme = btheme->next) {
+  LISTBASE_FOREACH (bTheme *, btheme, &userdef->themes) {
     do_versions_theme(userdef, btheme);
   }
 #undef USER_VERSION_ATLEAST
diff --git a/source/blender/blenloader/intern/writefile.c b/source/blender/blenloader/intern/writefile.c
index 599e592c77d..73bab07a008 100644
--- a/source/blender/blenloader/intern/writefile.c
+++ b/source/blender/blenloader/intern/writefile.c
@@ -133,6 +133,7 @@
 #include "DNA_sdna_types.h"
 #include "DNA_sequence_types.h"
 #include "DNA_shader_fx_types.h"
+#include "DNA_simulation_types.h"
 #include "DNA_sound_types.h"
 #include "DNA_space_types.h"
 #include "DNA_speaker_types.h"
@@ -156,14 +157,17 @@
 #include "BKE_constraint.h"
 #include "BKE_curve.h"
 #include "BKE_fcurve.h"
+#include "BKE_fcurve_driver.h"
 #include "BKE_global.h"  // for G
 #include "BKE_gpencil_modifier.h"
 #include "BKE_idtype.h"
 #include "BKE_layer.h"
+#include "BKE_lib_id.h"
 #include "BKE_lib_override.h"
 #include "BKE_main.h"
 #include "BKE_modifier.h"
 #include "BKE_node.h"
+#include "BKE_object.h"
 #include "BKE_pointcache.h"
 #include "BKE_report.h"
 #include "BKE_sequencer.h"
@@ -173,6 +177,7 @@
 
 #include "BLO_blend_defs.h"
 #include "BLO_blend_validate.h"
+#include "BLO_read_write.h"
 #include "BLO_readfile.h"
 #include "BLO_undofile.h"
 #include "BLO_writefile.h"
@@ -323,12 +328,7 @@ typedef struct {
   bool error;
 
   /** #MemFile writing (used for undo). */
-  struct {
-    MemFile *current;
-    MemFile *compare;
-    /** Use to de-duplicate chunks when writing. */
-    MemFileChunk *compare_chunk;
-  } mem;
+  MemFileWriteData mem;
   /** When true, write to #WriteData.current, could also call 'is_undo'. */
   bool use_memfile;
 
@@ -340,6 +340,10 @@ typedef struct {
   WriteWrap *ww;
 } WriteData;
 
+typedef struct BlendWriter {
+  WriteData *wd;
+} BlendWriter;
+
 static WriteData *writedata_new(WriteWrap *ww)
 {
   WriteData *wd = MEM_callocN(sizeof(*wd), "writedata");
@@ -367,7 +371,7 @@ static void writedata_do_write(WriteData *wd, const void *mem, int memlen)
 
   /* memory based save */
   if (wd->use_memfile) {
-    memfile_chunk_add(wd->mem.current, mem, memlen, &wd->mem.compare_chunk);
+    BLO_memfile_chunk_add(&wd->mem, mem, memlen);
   }
   else {
     if (wd->ww->write(wd->ww, mem, memlen) != memlen) {
@@ -468,9 +472,7 @@ static WriteData *mywrite_begin(WriteWrap *ww, MemFile *compare, MemFile *curren
   WriteData *wd = writedata_new(ww);
 
   if (current != NULL) {
-    wd->mem.current = current;
-    wd->mem.compare = compare;
-    wd->mem.compare_chunk = compare ? compare->chunks.first : NULL;
+    BLO_memfile_write_init(&wd->mem, current, compare);
     wd->use_memfile = true;
   }
 
@@ -490,12 +492,58 @@ static bool mywrite_end(WriteData *wd)
     wd->buf_used_len = 0;
   }
 
+  if (wd->use_memfile) {
+    BLO_memfile_write_finalize(&wd->mem);
+  }
+
   const bool err = wd->error;
   writedata_free(wd);
 
   return err;
 }
 
+/**
+ * Start writing of data related to a single ID.
+ *
+ * Only does something when storing an undo step.
+ */
+static void mywrite_id_begin(WriteData *wd, ID *id)
+{
+  if (wd->use_memfile) {
+    wd->mem.current_id_session_uuid = id->session_uuid;
+
+    /* If current next memchunk does not match the ID we are about to write, try to find the
+     * correct memchunk in the mapping using ID's session_uuid. */
+    if (wd->mem.id_session_uuid_mapping != NULL &&
+        (wd->mem.reference_current_chunk == NULL ||
+         wd->mem.reference_current_chunk->id_session_uuid != id->session_uuid)) {
+      void *ref = BLI_ghash_lookup(wd->mem.id_session_uuid_mapping,
+                                   POINTER_FROM_UINT(id->session_uuid));
+      if (ref != NULL) {
+        wd->mem.reference_current_chunk = ref;
+      }
+      /* Else, no existing memchunk found, i.e. this is supposed to be a new ID. */
+    }
+    /* Otherwise, we try with the current memchunk in any case, whether it is matching current
+     * ID's session_uuid or not. */
+  }
+}
+
+/**
+ * Start writing of data related to a single ID.
+ *
+ * Only does something when storing an undo step.
+ */
+static void mywrite_id_end(WriteData *wd, ID *UNUSED(id))
+{
+  if (wd->use_memfile) {
+    /* Very important to do it after every ID write now, otherwise we cannot know whether a
+     * specific ID changed or not. */
+    mywrite_flush(wd);
+    wd->mem.current_id_session_uuid = MAIN_ID_SESSION_UUID_UNSET;
+  }
+}
+
 /** \} */
 
 /* -------------------------------------------------------------------- */
@@ -631,79 +679,86 @@ static void writelist_id(WriteData *wd, int filecode, const char *structname, co
  * These functions are used by blender's .blend system for file saving/loading.
  * \{ */
 
-void IDP_WriteProperty_OnlyData(const IDProperty *prop, void *wd);
-void IDP_WriteProperty(const IDProperty *prop, void *wd);
+void IDP_WriteProperty_OnlyData(const IDProperty *prop, BlendWriter *writer);
+void IDP_WriteProperty(const IDProperty *prop, WriteData *wd);
+void IDP_WriteProperty_new_api(const IDProperty *prop, BlendWriter *writer);
 
-static void IDP_WriteArray(const IDProperty *prop, void *wd)
+static void IDP_WriteArray(const IDProperty *prop, BlendWriter *writer)
 {
   /*REMEMBER to set totalen to len in the linking code!!*/
   if (prop->data.pointer) {
-    writedata(wd, DATA, MEM_allocN_len(prop->data.pointer), prop->data.pointer);
+    BLO_write_raw(writer, MEM_allocN_len(prop->data.pointer), prop->data.pointer);
 
     if (prop->subtype == IDP_GROUP) {
       IDProperty **array = prop->data.pointer;
       int a;
 
       for (a = 0; a < prop->len; a++) {
-        IDP_WriteProperty(array[a], wd);
+        IDP_WriteProperty_new_api(array[a], writer);
       }
     }
   }
 }
 
-static void IDP_WriteIDPArray(const IDProperty *prop, void *wd)
+static void IDP_WriteIDPArray(const IDProperty *prop, BlendWriter *writer)
 {
   /*REMEMBER to set totalen to len in the linking code!!*/
   if (prop->data.pointer) {
     const IDProperty *array = prop->data.pointer;
     int a;
 
-    writestruct(wd, DATA, IDProperty, prop->len, array);
+    BLO_write_struct_array(writer, IDProperty, prop->len, array);
 
     for (a = 0; a < prop->len; a++) {
-      IDP_WriteProperty_OnlyData(&array[a], wd);
+      IDP_WriteProperty_OnlyData(&array[a], writer);
     }
   }
 }
 
-static void IDP_WriteString(const IDProperty *prop, void *wd)
+static void IDP_WriteString(const IDProperty *prop, BlendWriter *writer)
 {
   /*REMEMBER to set totalen to len in the linking code!!*/
-  writedata(wd, DATA, prop->len, prop->data.pointer);
+  BLO_write_raw(writer, prop->len, prop->data.pointer);
 }
 
-static void IDP_WriteGroup(const IDProperty *prop, void *wd)
+static void IDP_WriteGroup(const IDProperty *prop, BlendWriter *writer)
 {
   IDProperty *loop;
 
   for (loop = prop->data.group.first; loop; loop = loop->next) {
-    IDP_WriteProperty(loop, wd);
+    IDP_WriteProperty_new_api(loop, writer);
   }
 }
 
 /* Functions to read/write ID Properties */
-void IDP_WriteProperty_OnlyData(const IDProperty *prop, void *wd)
+void IDP_WriteProperty_OnlyData(const IDProperty *prop, BlendWriter *writer)
 {
   switch (prop->type) {
     case IDP_GROUP:
-      IDP_WriteGroup(prop, wd);
+      IDP_WriteGroup(prop, writer);
       break;
     case IDP_STRING:
-      IDP_WriteString(prop, wd);
+      IDP_WriteString(prop, writer);
       break;
     case IDP_ARRAY:
-      IDP_WriteArray(prop, wd);
+      IDP_WriteArray(prop, writer);
       break;
     case IDP_IDPARRAY:
-      IDP_WriteIDPArray(prop, wd);
+      IDP_WriteIDPArray(prop, writer);
       break;
   }
 }
 
-void IDP_WriteProperty(const IDProperty *prop, void *wd)
+void IDP_WriteProperty_new_api(const IDProperty *prop, BlendWriter *writer)
 {
-  writestruct(wd, DATA, IDProperty, 1, prop);
-  IDP_WriteProperty_OnlyData(prop, wd);
+  BLO_write_struct(writer, IDProperty, prop);
+  IDP_WriteProperty_OnlyData(prop, writer);
+}
+
+void IDP_WriteProperty(const IDProperty *prop, WriteData *wd)
+{
+  BlendWriter writer = {wd};
+  IDP_WriteProperty_new_api(prop, &writer);
 }
 
 static void write_iddata(WriteData *wd, ID *id)
@@ -717,13 +772,11 @@ static void write_iddata(WriteData *wd, ID *id)
     writestruct(wd, DATA, IDOverrideLibrary, 1, id->override_library);
 
     writelist(wd, DATA, IDOverrideLibraryProperty, &id->override_library->properties);
-    for (IDOverrideLibraryProperty *op = id->override_library->properties.first; op;
-         op = op->next) {
+    LISTBASE_FOREACH (IDOverrideLibraryProperty *, op, &id->override_library->properties) {
       writedata(wd, DATA, strlen(op->rna_path) + 1, op->rna_path);
 
       writelist(wd, DATA, IDOverrideLibraryPropertyOperation, &op->operations);
-      for (IDOverrideLibraryPropertyOperation *opop = op->operations.first; opop;
-           opop = opop->next) {
+      LISTBASE_FOREACH (IDOverrideLibraryPropertyOperation *, opop, &op->operations) {
         if (opop->subitem_reference_name) {
           writedata(
               wd, DATA, strlen(opop->subitem_reference_name) + 1, opop->subitem_reference_name);
@@ -734,11 +787,6 @@ static void write_iddata(WriteData *wd, ID *id)
       }
     }
   }
-
-  /* Clear the accumulated recalc flags in case of undo step saving. */
-  if (wd->use_memfile) {
-    id->recalc_undo_accumulated = 0;
-  }
 }
 
 static void write_previews(WriteData *wd, const PreviewImage *prv_orig)
@@ -859,19 +907,19 @@ static void write_fcurves(WriteData *wd, ListBase *fcurves)
   }
 }
 
-static void write_action(WriteData *wd, bAction *act)
+static void write_action(WriteData *wd, bAction *act, const void *id_address)
 {
   if (act->id.us > 0 || wd->use_memfile) {
-    writestruct(wd, ID_AC, bAction, 1, act);
+    writestruct_at_address(wd, ID_AC, bAction, 1, id_address, act);
     write_iddata(wd, &act->id);
 
     write_fcurves(wd, &act->curves);
 
-    for (bActionGroup *grp = act->groups.first; grp; grp = grp->next) {
+    LISTBASE_FOREACH (bActionGroup *, grp, &act->groups) {
       writestruct(wd, DATA, bActionGroup, 1, grp);
     }
 
-    for (TimeMarker *marker = act->markers.first; marker; marker = marker->next) {
+    LISTBASE_FOREACH (TimeMarker *, marker, &act->markers) {
       writestruct(wd, DATA, TimeMarker, 1, marker);
     }
   }
@@ -996,9 +1044,19 @@ static void write_node_socket_default_value(WriteData *wd, bNodeSocket *sock)
     case SOCK_STRING:
       writestruct(wd, DATA, bNodeSocketValueString, 1, sock->default_value);
       break;
+    case SOCK_OBJECT:
+      writestruct(wd, DATA, bNodeSocketValueObject, 1, sock->default_value);
+      break;
+    case SOCK_IMAGE:
+      writestruct(wd, DATA, bNodeSocketValueImage, 1, sock->default_value);
+      break;
     case __SOCK_MESH:
     case SOCK_CUSTOM:
     case SOCK_SHADER:
+    case SOCK_EMITTERS:
+    case SOCK_EVENTS:
+    case SOCK_FORCES:
+    case SOCK_CONTROL_FLOW:
       BLI_assert(false);
       break;
   }
@@ -1139,11 +1197,6 @@ static void write_nodetree_nolib(WriteData *wd, bNodeTree *ntree)
   for (sock = ntree->outputs.first; sock; sock = sock->next) {
     write_node_socket_interface(wd, sock);
   }
-
-  /* Clear the accumulated recalc flags in case of undo step saving. */
-  if (wd->use_memfile) {
-    ntree->id.recalc_undo_accumulated = 0;
-  }
 }
 
 /**
@@ -1235,14 +1288,14 @@ static void write_userdef(WriteData *wd, const UserDef *userdef)
 {
   writestruct(wd, USER, UserDef, 1, userdef);
 
-  for (const bTheme *btheme = userdef->themes.first; btheme; btheme = btheme->next) {
+  LISTBASE_FOREACH (const bTheme *, btheme, &userdef->themes) {
     writestruct(wd, DATA, bTheme, 1, btheme);
   }
 
-  for (const wmKeyMap *keymap = userdef->user_keymaps.first; keymap; keymap = keymap->next) {
+  LISTBASE_FOREACH (const wmKeyMap *, keymap, &userdef->user_keymaps) {
     writestruct(wd, DATA, wmKeyMap, 1, keymap);
 
-    for (const wmKeyMapDiffItem *kmdi = keymap->diff_items.first; kmdi; kmdi = kmdi->next) {
+    LISTBASE_FOREACH (const wmKeyMapDiffItem *, kmdi, &keymap->diff_items) {
       writestruct(wd, DATA, wmKeyMapDiffItem, 1, kmdi);
       if (kmdi->remove_item) {
         write_keymapitem(wd, kmdi->remove_item);
@@ -1252,21 +1305,21 @@ static void write_userdef(WriteData *wd, const UserDef *userdef)
       }
     }
 
-    for (const wmKeyMapItem *kmi = keymap->items.first; kmi; kmi = kmi->next) {
+    LISTBASE_FOREACH (const wmKeyMapItem *, kmi, &keymap->items) {
       write_keymapitem(wd, kmi);
     }
   }
 
-  for (const wmKeyConfigPref *kpt = userdef->user_keyconfig_prefs.first; kpt; kpt = kpt->next) {
+  LISTBASE_FOREACH (const wmKeyConfigPref *, kpt, &userdef->user_keyconfig_prefs) {
     writestruct(wd, DATA, wmKeyConfigPref, 1, kpt);
     if (kpt->prop) {
       IDP_WriteProperty(kpt->prop, wd);
     }
   }
 
-  for (const bUserMenu *um = userdef->user_menus.first; um; um = um->next) {
+  LISTBASE_FOREACH (const bUserMenu *, um, &userdef->user_menus) {
     writestruct(wd, DATA, bUserMenu, 1, um);
-    for (const bUserMenuItem *umi = um->items.first; umi; umi = umi->next) {
+    LISTBASE_FOREACH (const bUserMenuItem *, umi, &um->items) {
       if (umi->type == USER_MENU_TYPE_OPERATOR) {
         const bUserMenuItem_Op *umi_op = (const bUserMenuItem_Op *)umi;
         writestruct(wd, DATA, bUserMenuItem_Op, 1, umi_op);
@@ -1288,19 +1341,18 @@ static void write_userdef(WriteData *wd, const UserDef *userdef)
     }
   }
 
-  for (const bAddon *bext = userdef->addons.first; bext; bext = bext->next) {
+  LISTBASE_FOREACH (const bAddon *, bext, &userdef->addons) {
     writestruct(wd, DATA, bAddon, 1, bext);
     if (bext->prop) {
       IDP_WriteProperty(bext->prop, wd);
     }
   }
 
-  for (const bPathCompare *path_cmp = userdef->autoexec_paths.first; path_cmp;
-       path_cmp = path_cmp->next) {
+  LISTBASE_FOREACH (const bPathCompare *, path_cmp, &userdef->autoexec_paths) {
     writestruct(wd, DATA, bPathCompare, 1, path_cmp);
   }
 
-  for (const uiStyle *style = userdef->uistyles.first; style; style = style->next) {
+  LISTBASE_FOREACH (const uiStyle *, style, &userdef->uistyles) {
     writestruct(wd, DATA, uiStyle, 1, style);
   }
 }
@@ -1396,11 +1448,11 @@ static void write_pointcaches(WriteData *wd, ListBase *ptcaches)
   }
 }
 
-static void write_particlesettings(WriteData *wd, ParticleSettings *part)
+static void write_particlesettings(WriteData *wd, ParticleSettings *part, const void *id_address)
 {
   if (part->id.us > 0 || wd->use_memfile) {
     /* write LibData */
-    writestruct(wd, ID_PA, ParticleSettings, 1, part);
+    writestruct_at_address(wd, ID_PA, ParticleSettings, 1, id_address, part);
     write_iddata(wd, &part->id);
 
     if (part->adt) {
@@ -1420,7 +1472,7 @@ static void write_particlesettings(WriteData *wd, ParticleSettings *part)
       write_curvemapping(wd, part->twistcurve);
     }
 
-    for (ParticleDupliWeight *dw = part->instance_weights.first; dw; dw = dw->next) {
+    LISTBASE_FOREACH (ParticleDupliWeight *, dw, &part->instance_weights) {
       /* update indices, but only if dw->ob is set (can be NULL after loading e.g.) */
       if (dw->ob != NULL) {
         dw->index = 0;
@@ -1440,7 +1492,7 @@ static void write_particlesettings(WriteData *wd, ParticleSettings *part)
     if (part->boids && part->phystype == PART_PHYS_BOIDS) {
       writestruct(wd, DATA, BoidSettings, 1, part->boids);
 
-      for (BoidState *state = part->boids->states.first; state; state = state->next) {
+      LISTBASE_FOREACH (BoidState *, state, &part->boids->states) {
         write_boid_state(wd, state);
       }
     }
@@ -1625,14 +1677,14 @@ static void write_pose(WriteData *wd, bPose *pose)
 
 static void write_defgroups(WriteData *wd, ListBase *defbase)
 {
-  for (bDeformGroup *defgroup = defbase->first; defgroup; defgroup = defgroup->next) {
+  LISTBASE_FOREACH (bDeformGroup *, defgroup, defbase) {
     writestruct(wd, DATA, bDeformGroup, 1, defgroup);
   }
 }
 
 static void write_fmaps(WriteData *wd, ListBase *fbase)
 {
-  for (bFaceMap *fmap = fbase->first; fmap; fmap = fmap->next) {
+  LISTBASE_FOREACH (bFaceMap *, fmap, fbase) {
     writestruct(wd, DATA, bFaceMap, 1, fmap);
   }
 }
@@ -1646,7 +1698,7 @@ static void write_modifiers(WriteData *wd, ListBase *modbase)
   }
 
   for (md = modbase->first; md; md = md->next) {
-    const ModifierTypeInfo *mti = modifierType_getInfo(md->type);
+    const ModifierTypeInfo *mti = BKE_modifier_get_info(md->type);
     if (mti == NULL) {
       return;
     }
@@ -1829,7 +1881,7 @@ static void write_gpencil_modifiers(WriteData *wd, ListBase *modbase)
   }
 
   for (md = modbase->first; md; md = md->next) {
-    const GpencilModifierTypeInfo *mti = BKE_gpencil_modifierType_getInfo(md->type);
+    const GpencilModifierTypeInfo *mti = BKE_gpencil_modifier_get_info(md->type);
     if (mti == NULL) {
       return;
     }
@@ -1896,7 +1948,7 @@ static void write_shaderfxs(WriteData *wd, ListBase *fxbase)
   }
 
   for (fx = fxbase->first; fx; fx = fx->next) {
-    const ShaderFxTypeInfo *fxi = BKE_shaderfxType_getInfo(fx->type);
+    const ShaderFxTypeInfo *fxi = BKE_shaderfx_get_info(fx->type);
     if (fxi == NULL) {
       return;
     }
@@ -1905,11 +1957,14 @@ static void write_shaderfxs(WriteData *wd, ListBase *fxbase)
   }
 }
 
-static void write_object(WriteData *wd, Object *ob)
+static void write_object(WriteData *wd, Object *ob, const void *id_address)
 {
   if (ob->id.us > 0 || wd->use_memfile) {
+    /* Clean up, important in undo case to reduce false detection of changed datablocks. */
+    BKE_object_runtime_reset(ob);
+
     /* write LibData */
-    writestruct(wd, ID_OB, Object, 1, ob);
+    writestruct_at_address(wd, ID_OB, Object, 1, id_address, ob);
     write_iddata(wd, &ob->id);
 
     if (ob->adt) {
@@ -1970,11 +2025,15 @@ static void write_object(WriteData *wd, Object *ob)
   }
 }
 
-static void write_vfont(WriteData *wd, VFont *vf)
+static void write_vfont(WriteData *wd, VFont *vf, const void *id_address)
 {
   if (vf->id.us > 0 || wd->use_memfile) {
+    /* Clean up, important in undo case to reduce false detection of changed datablocks. */
+    vf->data = NULL;
+    vf->temp_pf = NULL;
+
     /* write LibData */
-    writestruct(wd, ID_VF, VFont, 1, vf);
+    writestruct_at_address(wd, ID_VF, VFont, 1, id_address, vf);
     write_iddata(wd, &vf->id);
 
     /* direct data */
@@ -1986,11 +2045,11 @@ static void write_vfont(WriteData *wd, VFont *vf)
   }
 }
 
-static void write_key(WriteData *wd, Key *key)
+static void write_key(WriteData *wd, Key *key, const void *id_address)
 {
   if (key->id.us > 0 || wd->use_memfile) {
     /* write LibData */
-    writestruct(wd, ID_KE, Key, 1, key);
+    writestruct_at_address(wd, ID_KE, Key, 1, id_address, key);
     write_iddata(wd, &key->id);
 
     if (key->adt) {
@@ -1998,7 +2057,7 @@ static void write_key(WriteData *wd, Key *key)
     }
 
     /* direct data */
-    for (KeyBlock *kb = key->block.first; kb; kb = kb->next) {
+    LISTBASE_FOREACH (KeyBlock *, kb, &key->block) {
       writestruct(wd, DATA, KeyBlock, 1, kb);
       if (kb->data) {
         writedata(wd, DATA, kb->totelem * key->elemsize, kb->data);
@@ -2007,28 +2066,36 @@ static void write_key(WriteData *wd, Key *key)
   }
 }
 
-static void write_camera(WriteData *wd, Camera *cam)
+static void write_camera(WriteData *wd, Camera *cam, const void *id_address)
 {
   if (cam->id.us > 0 || wd->use_memfile) {
     /* write LibData */
-    writestruct(wd, ID_CA, Camera, 1, cam);
+    writestruct_at_address(wd, ID_CA, Camera, 1, id_address, cam);
     write_iddata(wd, &cam->id);
 
     if (cam->adt) {
       write_animdata(wd, cam->adt);
     }
 
-    for (CameraBGImage *bgpic = cam->bg_images.first; bgpic; bgpic = bgpic->next) {
+    LISTBASE_FOREACH (CameraBGImage *, bgpic, &cam->bg_images) {
       writestruct(wd, DATA, CameraBGImage, 1, bgpic);
     }
   }
 }
 
-static void write_mball(WriteData *wd, MetaBall *mb)
+static void write_mball(WriteData *wd, MetaBall *mb, const void *id_address)
 {
   if (mb->id.us > 0 || wd->use_memfile) {
+    /* Clean up, important in undo case to reduce false detection of changed datablocks. */
+    BLI_listbase_clear(&mb->disp);
+    mb->editelems = NULL;
+    /* Must always be cleared (meta's don't have their own edit-data). */
+    mb->needs_flush_to_id = 0;
+    mb->lastelem = NULL;
+    mb->batch_cache = NULL;
+
     /* write LibData */
-    writestruct(wd, ID_MB, MetaBall, 1, mb);
+    writestruct_at_address(wd, ID_MB, MetaBall, 1, id_address, mb);
     write_iddata(wd, &mb->id);
 
     /* direct data */
@@ -2037,17 +2104,22 @@ static void write_mball(WriteData *wd, MetaBall *mb)
       write_animdata(wd, mb->adt);
     }
 
-    for (MetaElem *ml = mb->elems.first; ml; ml = ml->next) {
+    LISTBASE_FOREACH (MetaElem *, ml, &mb->elems) {
       writestruct(wd, DATA, MetaElem, 1, ml);
     }
   }
 }
 
-static void write_curve(WriteData *wd, Curve *cu)
+static void write_curve(WriteData *wd, Curve *cu, const void *id_address)
 {
   if (cu->id.us > 0 || wd->use_memfile) {
+    /* Clean up, important in undo case to reduce false detection of changed datablocks. */
+    cu->editnurb = NULL;
+    cu->editfont = NULL;
+    cu->batch_cache = NULL;
+
     /* write LibData */
-    writestruct(wd, ID_CU, Curve, 1, cu);
+    writestruct_at_address(wd, ID_CU, Curve, 1, id_address, cu);
     write_iddata(wd, &cu->id);
 
     /* direct data */
@@ -2063,10 +2135,10 @@ static void write_curve(WriteData *wd, Curve *cu)
     }
     else {
       /* is also the order of reading */
-      for (Nurb *nu = cu->nurb.first; nu; nu = nu->next) {
+      LISTBASE_FOREACH (Nurb *, nu, &cu->nurb) {
         writestruct(wd, DATA, Nurb, 1, nu);
       }
-      for (Nurb *nu = cu->nurb.first; nu; nu = nu->next) {
+      LISTBASE_FOREACH (Nurb *, nu, &cu->nurb) {
         if (nu->type == CU_BEZIER) {
           writestruct(wd, DATA, BezTriple, nu->pntsu, nu->bezt);
         }
@@ -2186,7 +2258,7 @@ static void write_customdata(WriteData *wd,
         datasize = structnum * count;
         writestruct_id(wd, DATA, structname, datasize, layer->data);
       }
-      else {
+      else if (!wd->use_memfile) { /* Do not warn on undo. */
         printf("%s error: layer '%s':%d - can't be written to file\n",
                __func__,
                structname,
@@ -2200,19 +2272,14 @@ static void write_customdata(WriteData *wd,
   }
 }
 
-static void write_mesh(WriteData *wd, Mesh *mesh)
+static void write_mesh(WriteData *wd, Mesh *mesh, const void *id_address)
 {
   if (mesh->id.us > 0 || wd->use_memfile) {
-    /* Write a copy of the mesh with possibly reduced number of data layers.
-     * Don't edit the original since other threads might be reading it. */
-    Mesh *old_mesh = mesh;
-    Mesh copy_mesh = *mesh;
-    mesh = &copy_mesh;
-
     /* cache only - don't write */
     mesh->mface = NULL;
     mesh->totface = 0;
     memset(&mesh->fdata, 0, sizeof(mesh->fdata));
+    memset(&mesh->runtime, 0, sizeof(mesh->runtime));
 
     /* Reduce xdata layers, fill xlayers with layers to be written.
      * This makes xdata invalid for Blender, which is why we made a
@@ -2229,7 +2296,7 @@ static void write_mesh(WriteData *wd, Mesh *mesh)
     CustomData_file_write_prepare(&mesh->ldata, &llayers, llayers_buff, ARRAY_SIZE(llayers_buff));
     CustomData_file_write_prepare(&mesh->pdata, &players, players_buff, ARRAY_SIZE(players_buff));
 
-    writestruct_at_address(wd, ID_ME, Mesh, 1, old_mesh, mesh);
+    writestruct_at_address(wd, ID_ME, Mesh, 1, id_address, mesh);
     write_iddata(wd, &mesh->id);
 
     /* direct data */
@@ -2247,9 +2314,6 @@ static void write_mesh(WriteData *wd, Mesh *mesh)
     write_customdata(wd, &mesh->id, mesh->totloop, &mesh->ldata, llayers, CD_MASK_MESH.lmask);
     write_customdata(wd, &mesh->id, mesh->totpoly, &mesh->pdata, players, CD_MASK_MESH.pmask);
 
-    /* restore pointer */
-    mesh = old_mesh;
-
     /* free temporary data */
     if (vlayers && vlayers != vlayers_buff) {
       MEM_freeN(vlayers);
@@ -2269,11 +2333,15 @@ static void write_mesh(WriteData *wd, Mesh *mesh)
   }
 }
 
-static void write_lattice(WriteData *wd, Lattice *lt)
+static void write_lattice(WriteData *wd, Lattice *lt, const void *id_address)
 {
   if (lt->id.us > 0 || wd->use_memfile) {
+    /* Clean up, important in undo case to reduce false detection of changed datablocks. */
+    lt->editlatt = NULL;
+    lt->batch_cache = NULL;
+
     /* write LibData */
-    writestruct(wd, ID_LT, Lattice, 1, lt);
+    writestruct_at_address(wd, ID_LT, Lattice, 1, id_address, lt);
     write_iddata(wd, &lt->id);
 
     /* write animdata */
@@ -2288,7 +2356,7 @@ static void write_lattice(WriteData *wd, Lattice *lt)
   }
 }
 
-static void write_image(WriteData *wd, Image *ima)
+static void write_image(WriteData *wd, Image *ima, const void *id_address)
 {
   if (ima->id.us > 0 || wd->use_memfile) {
     ImagePackedFile *imapf;
@@ -2301,7 +2369,7 @@ static void write_image(WriteData *wd, Image *ima)
     }
 
     /* write LibData */
-    writestruct(wd, ID_IM, Image, 1, ima);
+    writestruct_at_address(wd, ID_IM, Image, 1, id_address, ima);
     write_iddata(wd, &ima->id);
 
     for (imapf = ima->packedfiles.first; imapf; imapf = imapf->next) {
@@ -2315,7 +2383,7 @@ static void write_image(WriteData *wd, Image *ima)
 
     write_previews(wd, ima->preview);
 
-    for (ImageView *iv = ima->views.first; iv; iv = iv->next) {
+    LISTBASE_FOREACH (ImageView *, iv, &ima->views) {
       writestruct(wd, DATA, ImageView, 1, iv);
     }
     writestruct(wd, DATA, Stereo3dFormat, 1, ima->stereo3d_format);
@@ -2328,11 +2396,11 @@ static void write_image(WriteData *wd, Image *ima)
   }
 }
 
-static void write_texture(WriteData *wd, Tex *tex)
+static void write_texture(WriteData *wd, Tex *tex, const void *id_address)
 {
   if (tex->id.us > 0 || wd->use_memfile) {
     /* write LibData */
-    writestruct(wd, ID_TE, Tex, 1, tex);
+    writestruct_at_address(wd, ID_TE, Tex, 1, id_address, tex);
     write_iddata(wd, &tex->id);
 
     if (tex->adt) {
@@ -2354,11 +2422,15 @@ static void write_texture(WriteData *wd, Tex *tex)
   }
 }
 
-static void write_material(WriteData *wd, Material *ma)
+static void write_material(WriteData *wd, Material *ma, const void *id_address)
 {
   if (ma->id.us > 0 || wd->use_memfile) {
+    /* Clean up, important in undo case to reduce false detection of changed datablocks. */
+    ma->texpaintslot = NULL;
+    BLI_listbase_clear(&ma->gpumaterial);
+
     /* write LibData */
-    writestruct(wd, ID_MA, Material, 1, ma);
+    writestruct_at_address(wd, ID_MA, Material, 1, id_address, ma);
     write_iddata(wd, &ma->id);
 
     if (ma->adt) {
@@ -2380,11 +2452,14 @@ static void write_material(WriteData *wd, Material *ma)
   }
 }
 
-static void write_world(WriteData *wd, World *wrld)
+static void write_world(WriteData *wd, World *wrld, const void *id_address)
 {
   if (wrld->id.us > 0 || wd->use_memfile) {
+    /* Clean up, important in undo case to reduce false detection of changed datablocks. */
+    BLI_listbase_clear(&wrld->gpumaterial);
+
     /* write LibData */
-    writestruct(wd, ID_WO, World, 1, wrld);
+    writestruct_at_address(wd, ID_WO, World, 1, id_address, wrld);
     write_iddata(wd, &wrld->id);
 
     if (wrld->adt) {
@@ -2401,11 +2476,11 @@ static void write_world(WriteData *wd, World *wrld)
   }
 }
 
-static void write_light(WriteData *wd, Light *la)
+static void write_light(WriteData *wd, Light *la, const void *id_address)
 {
   if (la->id.us > 0 || wd->use_memfile) {
     /* write LibData */
-    writestruct(wd, ID_LA, Light, 1, la);
+    writestruct_at_address(wd, ID_LA, Light, 1, id_address, la);
     write_iddata(wd, &la->id);
 
     if (la->adt) {
@@ -2431,25 +2506,26 @@ static void write_collection_nolib(WriteData *wd, Collection *collection)
   /* Shared function for collection data-blocks and scene master collection. */
   write_previews(wd, collection->preview);
 
-  for (CollectionObject *cob = collection->gobject.first; cob; cob = cob->next) {
+  LISTBASE_FOREACH (CollectionObject *, cob, &collection->gobject) {
     writestruct(wd, DATA, CollectionObject, 1, cob);
   }
 
-  for (CollectionChild *child = collection->children.first; child; child = child->next) {
+  LISTBASE_FOREACH (CollectionChild *, child, &collection->children) {
     writestruct(wd, DATA, CollectionChild, 1, child);
   }
-
-  /* Clear the accumulated recalc flags in case of undo step saving. */
-  if (wd->use_memfile) {
-    collection->id.recalc_undo_accumulated = 0;
-  }
 }
 
-static void write_collection(WriteData *wd, Collection *collection)
+static void write_collection(WriteData *wd, Collection *collection, const void *id_address)
 {
   if (collection->id.us > 0 || wd->use_memfile) {
+    /* Clean up, important in undo case to reduce false detection of changed datablocks. */
+    collection->flag &= ~COLLECTION_HAS_OBJECT_CACHE;
+    collection->tag = 0;
+    BLI_listbase_clear(&collection->object_cache);
+    BLI_listbase_clear(&collection->parents);
+
     /* write LibData */
-    writestruct(wd, ID_GR, Collection, 1, collection);
+    writestruct_at_address(wd, ID_GR, Collection, 1, id_address, collection);
     write_iddata(wd, &collection->id);
 
     write_collection_nolib(wd, collection);
@@ -2507,7 +2583,7 @@ static void write_paint(WriteData *wd, Paint *p)
 
 static void write_layer_collections(WriteData *wd, ListBase *lb)
 {
-  for (LayerCollection *lc = lb->first; lc; lc = lc->next) {
+  LISTBASE_FOREACH (LayerCollection *, lc, lb) {
     writestruct(wd, DATA, LayerCollection, 1, lc);
 
     write_layer_collections(wd, &lc->layer_collections);
@@ -2523,12 +2599,11 @@ static void write_view_layer(WriteData *wd, ViewLayer *view_layer)
     IDP_WriteProperty(view_layer->id_properties, wd);
   }
 
-  for (FreestyleModuleConfig *fmc = view_layer->freestyle_config.modules.first; fmc;
-       fmc = fmc->next) {
+  LISTBASE_FOREACH (FreestyleModuleConfig *, fmc, &view_layer->freestyle_config.modules) {
     writestruct(wd, DATA, FreestyleModuleConfig, 1, fmc);
   }
 
-  for (FreestyleLineSet *fls = view_layer->freestyle_config.linesets.first; fls; fls = fls->next) {
+  LISTBASE_FOREACH (FreestyleLineSet *, fls, &view_layer->freestyle_config.linesets) {
     writestruct(wd, DATA, FreestyleLineSet, 1, fls);
   }
   write_layer_collections(wd, &view_layer->layer_collections);
@@ -2564,10 +2639,16 @@ static void write_lightcache(WriteData *wd, LightCache *cache)
   writestruct(wd, DATA, LightProbeCache, cache->cube_len, cache->cube_data);
 }
 
-static void write_scene(WriteData *wd, Scene *sce)
+static void write_scene(WriteData *wd, Scene *sce, const void *id_address)
 {
+  if (wd->use_memfile) {
+    /* Clean up, important in undo case to reduce false detection of changed datablocks. */
+    /* XXX This UI data should not be stored in Scene at all... */
+    memset(&sce->cursor, 0, sizeof(sce->cursor));
+  }
+
   /* write LibData */
-  writestruct(wd, ID_SCE, Scene, 1, sce);
+  writestruct_at_address(wd, ID_SCE, Scene, 1, id_address, sce);
   write_iddata(wd, &sce->id);
 
   if (sce->adt) {
@@ -2714,7 +2795,7 @@ static void write_scene(WriteData *wd, Scene *sce)
     SEQ_END;
 
     /* new; meta stack too, even when its nasty restore code */
-    for (MetaStack *ms = ed->metastack.first; ms; ms = ms->next) {
+    LISTBASE_FOREACH (MetaStack *, ms, &ed->metastack) {
       writestruct(wd, DATA, MetaStack, 1, ms);
     }
   }
@@ -2733,17 +2814,17 @@ static void write_scene(WriteData *wd, Scene *sce)
   }
 
   /* writing dynamic list of TimeMarkers to the blend file */
-  for (TimeMarker *marker = sce->markers.first; marker; marker = marker->next) {
+  LISTBASE_FOREACH (TimeMarker *, marker, &sce->markers) {
     writestruct(wd, DATA, TimeMarker, 1, marker);
   }
 
   /* writing dynamic list of TransformOrientations to the blend file */
-  for (TransformOrientation *ts = sce->transform_spaces.first; ts; ts = ts->next) {
+  LISTBASE_FOREACH (TransformOrientation *, ts, &sce->transform_spaces) {
     writestruct(wd, DATA, TransformOrientation, 1, ts);
   }
 
   /* writing MultiView to the blend file */
-  for (SceneRenderView *srv = sce->r.views.first; srv; srv = srv->next) {
+  LISTBASE_FOREACH (SceneRenderView *, srv, &sce->r.views) {
     writestruct(wd, DATA, SceneRenderView, 1, srv);
   }
 
@@ -2769,7 +2850,7 @@ static void write_scene(WriteData *wd, Scene *sce)
   write_previews(wd, sce->preview);
   write_curvemapping_curves(wd, &sce->r.mblur_shutter_curve);
 
-  for (ViewLayer *view_layer = sce->view_layers.first; view_layer; view_layer = view_layer->next) {
+  LISTBASE_FOREACH (ViewLayer *, view_layer, &sce->view_layers) {
     write_view_layer(wd, view_layer);
   }
 
@@ -2790,11 +2871,19 @@ static void write_scene(WriteData *wd, Scene *sce)
   BLI_assert(sce->layer_properties == NULL);
 }
 
-static void write_gpencil(WriteData *wd, bGPdata *gpd)
+static void write_gpencil(WriteData *wd, bGPdata *gpd, const void *id_address)
 {
   if (gpd->id.us > 0 || wd->use_memfile) {
+    /* Clean up, important in undo case to reduce false detection of changed data-blocks. */
+    /* XXX not sure why the whole run-time data is not cleared in reading code,
+     * for now mimicking it here. */
+    gpd->runtime.sbuffer = NULL;
+    gpd->runtime.sbuffer_used = 0;
+    gpd->runtime.sbuffer_size = 0;
+    gpd->runtime.tot_cp_points = 0;
+
     /* write gpd data block to file */
-    writestruct(wd, ID_GD, bGPdata, 1, gpd);
+    writestruct_at_address(wd, ID_GD, bGPdata, 1, id_address, gpd);
     write_iddata(wd, &gpd->id);
 
     if (gpd->adt) {
@@ -2914,35 +3003,33 @@ static void write_soops(WriteData *wd, SpaceOutliner *so)
 
 static void write_panel_list(WriteData *wd, ListBase *lb)
 {
-  for (Panel *pa = lb->first; pa; pa = pa->next) {
-    writestruct(wd, DATA, Panel, 1, pa);
-    write_panel_list(wd, &pa->children);
+  LISTBASE_FOREACH (Panel *, panel, lb) {
+    writestruct(wd, DATA, Panel, 1, panel);
+    write_panel_list(wd, &panel->children);
   }
 }
 
 static void write_area_regions(WriteData *wd, ScrArea *area)
 {
-  for (ARegion *region = area->regionbase.first; region; region = region->next) {
+  LISTBASE_FOREACH (ARegion *, region, &area->regionbase) {
     write_region(wd, region, area->spacetype);
     write_panel_list(wd, &region->panels);
 
-    for (PanelCategoryStack *pc_act = region->panels_category_active.first; pc_act;
-         pc_act = pc_act->next) {
+    LISTBASE_FOREACH (PanelCategoryStack *, pc_act, &region->panels_category_active) {
       writestruct(wd, DATA, PanelCategoryStack, 1, pc_act);
     }
 
-    for (uiList *ui_list = region->ui_lists.first; ui_list; ui_list = ui_list->next) {
+    LISTBASE_FOREACH (uiList *, ui_list, &region->ui_lists) {
       write_uilist(wd, ui_list);
     }
 
-    for (uiPreview *ui_preview = region->ui_previews.first; ui_preview;
-         ui_preview = ui_preview->next) {
+    LISTBASE_FOREACH (uiPreview *, ui_preview, &region->ui_previews) {
       writestruct(wd, DATA, uiPreview, 1, ui_preview);
     }
   }
 
-  for (SpaceLink *sl = area->spacedata.first; sl; sl = sl->next) {
-    for (ARegion *region = sl->regionbase.first; region; region = region->next) {
+  LISTBASE_FOREACH (SpaceLink *, sl, &area->spacedata) {
+    LISTBASE_FOREACH (ARegion *, region, &sl->regionbase) {
       write_region(wd, region, sl->spacetype);
     }
 
@@ -3055,7 +3142,7 @@ static void write_area_map(WriteData *wd, ScrAreaMap *area_map)
 {
   writelist(wd, DATA, ScrVert, &area_map->vertbase);
   writelist(wd, DATA, ScrEdge, &area_map->edgebase);
-  for (ScrArea *area = area_map->areabase.first; area; area = area->next) {
+  LISTBASE_FOREACH (ScrArea *, area, &area_map->areabase) {
     area->butspacetype = area->spacetype; /* Just for compatibility, will be reset below. */
 
     writestruct(wd, DATA, ScrArea, 1, area);
@@ -3070,13 +3157,13 @@ static void write_area_map(WriteData *wd, ScrAreaMap *area_map)
   }
 }
 
-static void write_windowmanager(WriteData *wd, wmWindowManager *wm)
+static void write_windowmanager(BlendWriter *writer, wmWindowManager *wm, const void *id_address)
 {
-  writestruct(wd, ID_WM, wmWindowManager, 1, wm);
-  write_iddata(wd, &wm->id);
-  write_wm_xr_data(wd, &wm->xr);
+  BLO_write_id_struct(writer, wmWindowManager, id_address, &wm->id);
+  write_iddata(writer->wd, &wm->id);
+  write_wm_xr_data(writer->wd, &wm->xr);
 
-  for (wmWindow *win = wm->windows.first; win; win = win->next) {
+  LISTBASE_FOREACH (wmWindow *, win, &wm->windows) {
 #ifndef WITH_GLOBAL_AREA_WRITING
     /* Don't write global areas yet, while we make changes to them. */
     ScrAreaMap global_areas = win->global_areas;
@@ -3086,12 +3173,12 @@ static void write_windowmanager(WriteData *wd, wmWindowManager *wm)
     /* update deprecated screen member (for so loading in 2.7x uses the correct screen) */
     win->screen = BKE_workspace_active_screen_get(win->workspace_hook);
 
-    writestruct(wd, DATA, wmWindow, 1, win);
-    writestruct(wd, DATA, WorkSpaceInstanceHook, 1, win->workspace_hook);
-    writestruct(wd, DATA, Stereo3dFormat, 1, win->stereo3d_format);
+    BLO_write_struct(writer, wmWindow, win);
+    BLO_write_struct(writer, WorkSpaceInstanceHook, win->workspace_hook);
+    BLO_write_struct(writer, Stereo3dFormat, win->stereo3d_format);
 
 #ifdef WITH_GLOBAL_AREA_WRITING
-    write_area_map(wd, &win->global_areas);
+    write_area_map(writer->wd, &win->global_areas);
 #else
     win->global_areas = global_areas;
 #endif
@@ -3101,19 +3188,19 @@ static void write_windowmanager(WriteData *wd, wmWindowManager *wm)
   }
 }
 
-static void write_screen(WriteData *wd, bScreen *sc)
+static void write_screen(WriteData *wd, bScreen *screen, const void *id_address)
 {
   /* Screens are reference counted, only saved if used by a workspace. */
-  if (sc->id.us > 0 || wd->use_memfile) {
+  if (screen->id.us > 0 || wd->use_memfile) {
     /* write LibData */
     /* in 2.50+ files, the file identifier for screens is patched, forward compatibility */
-    writestruct(wd, ID_SCRN, bScreen, 1, sc);
-    write_iddata(wd, &sc->id);
+    writestruct_at_address(wd, ID_SCRN, bScreen, 1, id_address, screen);
+    write_iddata(wd, &screen->id);
 
-    write_previews(wd, sc->preview);
+    write_previews(wd, screen->preview);
 
     /* direct data */
-    write_area_map(wd, AREAMAP_FROM_SCREEN(sc));
+    write_area_map(wd, AREAMAP_FROM_SCREEN(screen));
   }
 }
 
@@ -3132,15 +3219,22 @@ static void write_bone(WriteData *wd, Bone *bone)
   }
 
   /* Write Children */
-  for (Bone *cbone = bone->childbase.first; cbone; cbone = cbone->next) {
+  LISTBASE_FOREACH (Bone *, cbone, &bone->childbase) {
     write_bone(wd, cbone);
   }
 }
 
-static void write_armature(WriteData *wd, bArmature *arm)
+static void write_armature(WriteData *wd, bArmature *arm, const void *id_address)
 {
   if (arm->id.us > 0 || wd->use_memfile) {
-    writestruct(wd, ID_AR, bArmature, 1, arm);
+    /* Clean up, important in undo case to reduce false detection of changed datablocks. */
+    arm->bonehash = NULL;
+    arm->edbo = NULL;
+    /* Must always be cleared (armatures don't have their own edit-data). */
+    arm->needs_flush_to_id = 0;
+    arm->act_edbone = NULL;
+
+    writestruct_at_address(wd, ID_AR, bArmature, 1, id_address, arm);
     write_iddata(wd, &arm->id);
 
     if (arm->adt) {
@@ -3148,20 +3242,24 @@ static void write_armature(WriteData *wd, bArmature *arm)
     }
 
     /* Direct data */
-    for (Bone *bone = arm->bonebase.first; bone; bone = bone->next) {
+    LISTBASE_FOREACH (Bone *, bone, &arm->bonebase) {
       write_bone(wd, bone);
     }
   }
 }
 
-static void write_text(WriteData *wd, Text *text)
+static void write_text(WriteData *wd, Text *text, const void *id_address)
 {
+  /* Note: we are clearing local temp data here, *not* the flag in the actual 'real' ID. */
   if ((text->flags & TXT_ISMEM) && (text->flags & TXT_ISEXT)) {
     text->flags &= ~TXT_ISEXT;
   }
 
+  /* Clean up, important in undo case to reduce false detection of changed datablocks. */
+  text->compiled = NULL;
+
   /* write LibData */
-  writestruct(wd, ID_TXT, Text, 1, text);
+  writestruct_at_address(wd, ID_TXT, Text, 1, id_address, text);
   write_iddata(wd, &text->id);
 
   if (text->name) {
@@ -3170,21 +3268,21 @@ static void write_text(WriteData *wd, Text *text)
 
   if (!(text->flags & TXT_ISEXT)) {
     /* now write the text data, in two steps for optimization in the readfunction */
-    for (TextLine *tmp = text->lines.first; tmp; tmp = tmp->next) {
+    LISTBASE_FOREACH (TextLine *, tmp, &text->lines) {
       writestruct(wd, DATA, TextLine, 1, tmp);
     }
 
-    for (TextLine *tmp = text->lines.first; tmp; tmp = tmp->next) {
+    LISTBASE_FOREACH (TextLine *, tmp, &text->lines) {
       writedata(wd, DATA, tmp->len + 1, tmp->line);
     }
   }
 }
 
-static void write_speaker(WriteData *wd, Speaker *spk)
+static void write_speaker(WriteData *wd, Speaker *spk, const void *id_address)
 {
   if (spk->id.us > 0 || wd->use_memfile) {
     /* write LibData */
-    writestruct(wd, ID_SPK, Speaker, 1, spk);
+    writestruct_at_address(wd, ID_SPK, Speaker, 1, id_address, spk);
     write_iddata(wd, &spk->id);
 
     if (spk->adt) {
@@ -3193,11 +3291,17 @@ static void write_speaker(WriteData *wd, Speaker *spk)
   }
 }
 
-static void write_sound(WriteData *wd, bSound *sound)
+static void write_sound(WriteData *wd, bSound *sound, const void *id_address)
 {
   if (sound->id.us > 0 || wd->use_memfile) {
+    /* Clean up, important in undo case to reduce false detection of changed datablocks. */
+    sound->tags = 0;
+    sound->handle = NULL;
+    sound->playback_handle = NULL;
+    sound->spinlock = NULL;
+
     /* write LibData */
-    writestruct(wd, ID_SO, bSound, 1, sound);
+    writestruct_at_address(wd, ID_SO, bSound, 1, id_address, sound);
     write_iddata(wd, &sound->id);
 
     if (sound->packedfile) {
@@ -3208,11 +3312,11 @@ static void write_sound(WriteData *wd, bSound *sound)
   }
 }
 
-static void write_probe(WriteData *wd, LightProbe *prb)
+static void write_probe(WriteData *wd, LightProbe *prb, const void *id_address)
 {
   if (prb->id.us > 0 || wd->use_memfile) {
     /* write LibData */
-    writestruct(wd, ID_LP, LightProbe, 1, prb);
+    writestruct_at_address(wd, ID_LP, LightProbe, 1, id_address, prb);
     write_iddata(wd, &prb->id);
 
     if (prb->adt) {
@@ -3221,10 +3325,18 @@ static void write_probe(WriteData *wd, LightProbe *prb)
   }
 }
 
-static void write_nodetree(WriteData *wd, bNodeTree *ntree)
+static void write_nodetree(WriteData *wd, bNodeTree *ntree, const void *id_address)
 {
   if (ntree->id.us > 0 || wd->use_memfile) {
-    writestruct(wd, ID_NT, bNodeTree, 1, ntree);
+    /* Clean up, important in undo case to reduce false detection of changed datablocks. */
+    ntree->init = 0; /* to set callbacks and force setting types */
+    ntree->is_updating = false;
+    ntree->typeinfo = NULL;
+    ntree->interface_type = NULL;
+    ntree->progress = NULL;
+    ntree->execdata = NULL;
+
+    writestruct_at_address(wd, ID_NT, bNodeTree, 1, id_address, ntree);
     /* Note that trees directly used by other IDs (materials etc.) are not 'real' ID, they cannot
      * be linked, etc., so we write actual id data here only, for 'real' ID trees. */
     write_iddata(wd, &ntree->id);
@@ -3233,10 +3345,10 @@ static void write_nodetree(WriteData *wd, bNodeTree *ntree)
   }
 }
 
-static void write_brush(WriteData *wd, Brush *brush)
+static void write_brush(WriteData *wd, Brush *brush, const void *id_address)
 {
   if (brush->id.us > 0 || wd->use_memfile) {
-    writestruct(wd, ID_BR, Brush, 1, brush);
+    writestruct_at_address(wd, ID_BR, Brush, 1, id_address, brush);
     write_iddata(wd, &brush->id);
 
     if (brush->curve) {
@@ -3255,6 +3367,24 @@ static void write_brush(WriteData *wd, Brush *brush)
       if (brush->gpencil_settings->curve_jitter) {
         write_curvemapping(wd, brush->gpencil_settings->curve_jitter);
       }
+      if (brush->gpencil_settings->curve_rand_pressure) {
+        write_curvemapping(wd, brush->gpencil_settings->curve_rand_pressure);
+      }
+      if (brush->gpencil_settings->curve_rand_strength) {
+        write_curvemapping(wd, brush->gpencil_settings->curve_rand_strength);
+      }
+      if (brush->gpencil_settings->curve_rand_uv) {
+        write_curvemapping(wd, brush->gpencil_settings->curve_rand_uv);
+      }
+      if (brush->gpencil_settings->curve_rand_hue) {
+        write_curvemapping(wd, brush->gpencil_settings->curve_rand_hue);
+      }
+      if (brush->gpencil_settings->curve_rand_saturation) {
+        write_curvemapping(wd, brush->gpencil_settings->curve_rand_saturation);
+      }
+      if (brush->gpencil_settings->curve_rand_value) {
+        write_curvemapping(wd, brush->gpencil_settings->curve_rand_value);
+      }
     }
     if (brush->gradient) {
       writestruct(wd, DATA, ColorBand, 1, brush->gradient);
@@ -3262,11 +3392,11 @@ static void write_brush(WriteData *wd, Brush *brush)
   }
 }
 
-static void write_palette(WriteData *wd, Palette *palette)
+static void write_palette(WriteData *wd, Palette *palette, const void *id_address)
 {
   if (palette->id.us > 0 || wd->use_memfile) {
     PaletteColor *color;
-    writestruct(wd, ID_PAL, Palette, 1, palette);
+    writestruct_at_address(wd, ID_PAL, Palette, 1, id_address, palette);
     write_iddata(wd, &palette->id);
 
     for (color = palette->colors.first; color; color = color->next) {
@@ -3275,10 +3405,10 @@ static void write_palette(WriteData *wd, Palette *palette)
   }
 }
 
-static void write_paintcurve(WriteData *wd, PaintCurve *pc)
+static void write_paintcurve(WriteData *wd, PaintCurve *pc, const void *id_address)
 {
   if (pc->id.us > 0 || wd->use_memfile) {
-    writestruct(wd, ID_PC, PaintCurve, 1, pc);
+    writestruct_at_address(wd, ID_PC, PaintCurve, 1, id_address, pc);
     write_iddata(wd, &pc->id);
 
     writestruct(wd, DATA, PaintCurvePoint, pc->tot_points, pc->points);
@@ -3324,13 +3454,18 @@ static void write_movieReconstruction(WriteData *wd, MovieTrackingReconstruction
   }
 }
 
-static void write_movieclip(WriteData *wd, MovieClip *clip)
+static void write_movieclip(WriteData *wd, MovieClip *clip, const void *id_address)
 {
   if (clip->id.us > 0 || wd->use_memfile) {
+    /* Clean up, important in undo case to reduce false detection of changed datablocks. */
+    clip->anim = NULL;
+    clip->tracking_context = NULL;
+    clip->tracking.stats = NULL;
+
     MovieTracking *tracking = &clip->tracking;
     MovieTrackingObject *object;
 
-    writestruct(wd, ID_MC, MovieClip, 1, clip);
+    writestruct_at_address(wd, ID_MC, MovieClip, 1, id_address, clip);
     write_iddata(wd, &clip->id);
 
     if (clip->adt) {
@@ -3354,12 +3489,12 @@ static void write_movieclip(WriteData *wd, MovieClip *clip)
   }
 }
 
-static void write_mask(WriteData *wd, Mask *mask)
+static void write_mask(WriteData *wd, Mask *mask, const void *id_address)
 {
   if (mask->id.us > 0 || wd->use_memfile) {
     MaskLayer *masklay;
 
-    writestruct(wd, ID_MSK, Mask, 1, mask);
+    writestruct_at_address(wd, ID_MSK, Mask, 1, id_address, mask);
     write_iddata(wd, &mask->id);
 
     if (mask->adt) {
@@ -3661,10 +3796,10 @@ static void write_linestyle_geometry_modifiers(WriteData *wd, ListBase *modifier
   }
 }
 
-static void write_linestyle(WriteData *wd, FreestyleLineStyle *linestyle)
+static void write_linestyle(WriteData *wd, FreestyleLineStyle *linestyle, const void *id_address)
 {
   if (linestyle->id.us > 0 || wd->use_memfile) {
-    writestruct(wd, ID_LS, FreestyleLineStyle, 1, linestyle);
+    writestruct_at_address(wd, ID_LS, FreestyleLineStyle, 1, id_address, linestyle);
     write_iddata(wd, &linestyle->id);
 
     if (linestyle->adt) {
@@ -3687,10 +3822,16 @@ static void write_linestyle(WriteData *wd, FreestyleLineStyle *linestyle)
   }
 }
 
-static void write_cachefile(WriteData *wd, CacheFile *cache_file)
+static void write_cachefile(WriteData *wd, CacheFile *cache_file, const void *id_address)
 {
   if (cache_file->id.us > 0 || wd->use_memfile) {
-    writestruct(wd, ID_CF, CacheFile, 1, cache_file);
+    /* Clean up, important in undo case to reduce false detection of changed datablocks. */
+    BLI_listbase_clear(&cache_file->object_paths);
+    cache_file->handle = NULL;
+    memset(cache_file->handle_filepath, 0, sizeof(cache_file->handle_filepath));
+    cache_file->handle_readers = NULL;
+
+    writestruct_at_address(wd, ID_CF, CacheFile, 1, id_address, cache_file);
 
     if (cache_file->adt) {
       write_animdata(wd, cache_file->adt);
@@ -3698,39 +3839,31 @@ static void write_cachefile(WriteData *wd, CacheFile *cache_file)
   }
 }
 
-static void write_workspace(WriteData *wd, WorkSpace *workspace)
+static void write_workspace(BlendWriter *writer, WorkSpace *workspace, const void *id_address)
 {
-  ListBase *layouts = BKE_workspace_layouts_get(workspace);
-
-  writestruct(wd, ID_WS, WorkSpace, 1, workspace);
-  write_iddata(wd, &workspace->id);
-  writelist(wd, DATA, WorkSpaceLayout, layouts);
-  writelist(wd, DATA, WorkSpaceDataRelation, &workspace->hook_layout_relations);
-  writelist(wd, DATA, wmOwnerID, &workspace->owner_ids);
-  writelist(wd, DATA, bToolRef, &workspace->tools);
-  for (bToolRef *tref = workspace->tools.first; tref; tref = tref->next) {
+  BLO_write_id_struct(writer, WorkSpace, id_address, &workspace->id);
+  write_iddata(writer->wd, &workspace->id);
+  BLO_write_struct_list(writer, WorkSpaceLayout, &workspace->layouts);
+  BLO_write_struct_list(writer, WorkSpaceDataRelation, &workspace->hook_layout_relations);
+  BLO_write_struct_list(writer, wmOwnerID, &workspace->owner_ids);
+  BLO_write_struct_list(writer, bToolRef, &workspace->tools);
+  LISTBASE_FOREACH (bToolRef *, tref, &workspace->tools) {
     if (tref->properties) {
-      IDP_WriteProperty(tref->properties, wd);
+      IDP_WriteProperty_new_api(tref->properties, writer);
     }
   }
 }
 
-static void write_hair(WriteData *wd, Hair *hair)
+static void write_hair(WriteData *wd, Hair *hair, const void *id_address)
 {
   if (hair->id.us > 0 || wd->use_memfile) {
-    /* Write a copy of the hair with possibly reduced number of data layers.
-     * Don't edit the original since other threads might be reading it. */
-    Hair *old_hair = hair;
-    Hair copy_hair = *hair;
-    hair = &copy_hair;
-
     CustomDataLayer *players = NULL, players_buff[CD_TEMP_CHUNK_SIZE];
     CustomDataLayer *clayers = NULL, clayers_buff[CD_TEMP_CHUNK_SIZE];
     CustomData_file_write_prepare(&hair->pdata, &players, players_buff, ARRAY_SIZE(players_buff));
     CustomData_file_write_prepare(&hair->cdata, &clayers, clayers_buff, ARRAY_SIZE(clayers_buff));
 
     /* Write LibData */
-    writestruct_at_address(wd, ID_HA, Hair, 1, old_hair, hair);
+    writestruct_at_address(wd, ID_HA, Hair, 1, id_address, hair);
     write_iddata(wd, &hair->id);
 
     /* Direct data */
@@ -3748,27 +3881,18 @@ static void write_hair(WriteData *wd, Hair *hair)
     if (clayers && clayers != clayers_buff) {
       MEM_freeN(clayers);
     }
-
-    /* restore pointer */
-    hair = old_hair;
   }
 }
 
-static void write_pointcloud(WriteData *wd, PointCloud *pointcloud)
+static void write_pointcloud(WriteData *wd, PointCloud *pointcloud, const void *id_address)
 {
   if (pointcloud->id.us > 0 || wd->use_memfile) {
-    /* Write a copy of the pointcloud with possibly reduced number of data layers.
-     * Don't edit the original since other threads might be reading it. */
-    PointCloud *old_pointcloud = pointcloud;
-    PointCloud copy_pointcloud = *pointcloud;
-    pointcloud = &copy_pointcloud;
-
     CustomDataLayer *players = NULL, players_buff[CD_TEMP_CHUNK_SIZE];
     CustomData_file_write_prepare(
         &pointcloud->pdata, &players, players_buff, ARRAY_SIZE(players_buff));
 
     /* Write LibData */
-    writestruct_at_address(wd, ID_PT, PointCloud, 1, old_pointcloud, pointcloud);
+    writestruct_at_address(wd, ID_PT, PointCloud, 1, id_address, pointcloud);
     write_iddata(wd, &pointcloud->id);
 
     /* Direct data */
@@ -3786,11 +3910,14 @@ static void write_pointcloud(WriteData *wd, PointCloud *pointcloud)
   }
 }
 
-static void write_volume(WriteData *wd, Volume *volume)
+static void write_volume(WriteData *wd, Volume *volume, const void *id_address)
 {
   if (volume->id.us > 0 || wd->use_memfile) {
+    /* Clean up, important in undo case to reduce false detection of changed datablocks. */
+    volume->runtime.grids = 0;
+
     /* write LibData */
-    writestruct(wd, ID_VO, Volume, 1, volume);
+    writestruct_at_address(wd, ID_VO, Volume, 1, id_address, volume);
     write_iddata(wd, &volume->id);
 
     /* direct data */
@@ -3807,6 +3934,24 @@ static void write_volume(WriteData *wd, Volume *volume)
   }
 }
 
+static void write_simulation(WriteData *wd, Simulation *simulation)
+{
+  if (simulation->id.us > 0 || wd->use_memfile) {
+    writestruct(wd, ID_SIM, Simulation, 1, simulation);
+    write_iddata(wd, &simulation->id);
+
+    if (simulation->adt) {
+      write_animdata(wd, simulation->adt);
+    }
+
+    /* nodetree is integral part of simulation, no libdata */
+    if (simulation->nodetree) {
+      writestruct(wd, DATA, bNodeTree, 1, simulation->nodetree);
+      write_nodetree_nolib(wd, simulation->nodetree);
+    }
+  }
+}
+
 /* Keep it last of write_foodata functions. */
 static void write_libraries(WriteData *wd, Main *main)
 {
@@ -3822,6 +3967,11 @@ static void write_libraries(WriteData *wd, Main *main)
     if (main->curlib && main->curlib->packedfile) {
       found_one = true;
     }
+    else if (wd->use_memfile) {
+      /* When writing undo step we always write all existing libraries, makes reading undo step
+       * much easier when dealing with purely indirectly used libraries. */
+      found_one = true;
+    }
     else {
       found_one = false;
       while (!found_one && tot--) {
@@ -3909,12 +4059,12 @@ static void write_global(WriteData *wd, int fileflags, Main *mainvar)
 
   fg.globalf = G.f;
   BLI_strncpy(fg.filename, mainvar->name, sizeof(fg.filename));
-  sprintf(subvstr, "%4d", BLENDER_SUBVERSION);
+  sprintf(subvstr, "%4d", BLENDER_FILE_SUBVERSION);
   memcpy(fg.subvstr, subvstr, 4);
 
-  fg.subversion = BLENDER_SUBVERSION;
-  fg.minversion = BLENDER_MINVERSION;
-  fg.minsubversion = BLENDER_MINSUBVERSION;
+  fg.subversion = BLENDER_FILE_SUBVERSION;
+  fg.minversion = BLENDER_FILE_MIN_VERSION;
+  fg.minsubversion = BLENDER_FILE_MIN_SUBVERSION;
 #ifdef WITH_BUILDINFO
   {
     extern unsigned long build_commit_timestamp;
@@ -3968,7 +4118,7 @@ static bool write_file_handle(Main *mainvar,
           "BLENDER%c%c%.3d",
           (sizeof(void *) == 8) ? '-' : '_',
           (ENDIAN_ORDER == B_ENDIAN) ? 'V' : 'v',
-          BLENDER_VERSION);
+          BLENDER_FILE_VERSION);
 
   mywrite(wd, buf, 12);
 
@@ -3983,6 +4133,7 @@ static bool write_file_handle(Main *mainvar,
   OverrideLibraryStorage *override_storage =
       wd->use_memfile ? NULL : BKE_lib_override_library_operations_store_initialize();
 
+#define ID_BUFFER_STATIC_SIZE 8192
   /* This outer loop allows to save first data-blocks from real mainvar,
    * then the temp ones from override process,
    * if needed, without duplicating whole code. */
@@ -3993,10 +4144,18 @@ static bool write_file_handle(Main *mainvar,
     while (a--) {
       ID *id = lbarray[a]->first;
 
-      if (id && GS(id->name) == ID_LI) {
+      if (id == NULL || GS(id->name) == ID_LI) {
         continue; /* Libraries are handled separately below. */
       }
 
+      char id_buffer_static[ID_BUFFER_STATIC_SIZE];
+      void *id_buffer = id_buffer_static;
+      const size_t idtype_struct_size = BKE_idtype_get_info_from_id(id)->struct_size;
+      if (idtype_struct_size > ID_BUFFER_STATIC_SIZE) {
+        BLI_assert(0);
+        id_buffer = MEM_mallocN(idtype_struct_size, __func__);
+      }
+
       for (; id; id = id->next) {
         /* We should never attempt to write non-regular IDs
          * (i.e. all kind of temp/runtime ones). */
@@ -4009,117 +4168,155 @@ static bool write_file_handle(Main *mainvar,
           BKE_lib_override_library_operations_store_start(bmain, override_storage, id);
         }
 
+        if (wd->use_memfile) {
+          /* Record the changes that happened up to this undo push in
+           * recalc_up_to_undo_push, and clear recalc_after_undo_push again
+           * to start accumulating for the next undo push. */
+          id->recalc_up_to_undo_push = id->recalc_after_undo_push;
+          id->recalc_after_undo_push = 0;
+
+          bNodeTree *nodetree = ntreeFromID(id);
+          if (nodetree != NULL) {
+            nodetree->id.recalc_up_to_undo_push = nodetree->id.recalc_after_undo_push;
+            nodetree->id.recalc_after_undo_push = 0;
+          }
+          if (GS(id->name) == ID_SCE) {
+            Scene *scene = (Scene *)id;
+            if (scene->master_collection != NULL) {
+              scene->master_collection->id.recalc_up_to_undo_push =
+                  scene->master_collection->id.recalc_after_undo_push;
+              scene->master_collection->id.recalc_after_undo_push = 0;
+            }
+          }
+        }
+
+        mywrite_id_begin(wd, id);
+
+        memcpy(id_buffer, id, idtype_struct_size);
+
+        ((ID *)id_buffer)->tag = 0;
+        /* Those listbase data change every time we add/remove an ID, and also often when renaming
+         * one (due to re-sorting). This avoids generating a lot of false 'is changed' detections
+         * between undo steps. */
+        ((ID *)id_buffer)->prev = NULL;
+        ((ID *)id_buffer)->next = NULL;
+
+        BlendWriter writer = {wd};
+
         switch ((ID_Type)GS(id->name)) {
           case ID_WM:
-            write_windowmanager(wd, (wmWindowManager *)id);
+            write_windowmanager(&writer, (wmWindowManager *)id_buffer, id);
             break;
           case ID_WS:
-            write_workspace(wd, (WorkSpace *)id);
+            write_workspace(&writer, (WorkSpace *)id_buffer, id);
             break;
           case ID_SCR:
-            write_screen(wd, (bScreen *)id);
+            write_screen(wd, (bScreen *)id_buffer, id);
             break;
           case ID_MC:
-            write_movieclip(wd, (MovieClip *)id);
+            write_movieclip(wd, (MovieClip *)id_buffer, id);
             break;
           case ID_MSK:
-            write_mask(wd, (Mask *)id);
+            write_mask(wd, (Mask *)id_buffer, id);
             break;
           case ID_SCE:
-            write_scene(wd, (Scene *)id);
+            write_scene(wd, (Scene *)id_buffer, id);
             break;
           case ID_CU:
-            write_curve(wd, (Curve *)id);
+            write_curve(wd, (Curve *)id_buffer, id);
             break;
           case ID_MB:
-            write_mball(wd, (MetaBall *)id);
+            write_mball(wd, (MetaBall *)id_buffer, id);
             break;
           case ID_IM:
-            write_image(wd, (Image *)id);
+            write_image(wd, (Image *)id_buffer, id);
             break;
           case ID_CA:
-            write_camera(wd, (Camera *)id);
+            write_camera(wd, (Camera *)id_buffer, id);
             break;
           case ID_LA:
-            write_light(wd, (Light *)id);
+            write_light(wd, (Light *)id_buffer, id);
             break;
           case ID_LT:
-            write_lattice(wd, (Lattice *)id);
+            write_lattice(wd, (Lattice *)id_buffer, id);
             break;
           case ID_VF:
-            write_vfont(wd, (VFont *)id);
+            write_vfont(wd, (VFont *)id_buffer, id);
             break;
           case ID_KE:
-            write_key(wd, (Key *)id);
+            write_key(wd, (Key *)id_buffer, id);
             break;
           case ID_WO:
-            write_world(wd, (World *)id);
+            write_world(wd, (World *)id_buffer, id);
             break;
           case ID_TXT:
-            write_text(wd, (Text *)id);
+            write_text(wd, (Text *)id_buffer, id);
             break;
           case ID_SPK:
-            write_speaker(wd, (Speaker *)id);
+            write_speaker(wd, (Speaker *)id_buffer, id);
             break;
           case ID_LP:
-            write_probe(wd, (LightProbe *)id);
+            write_probe(wd, (LightProbe *)id_buffer, id);
             break;
           case ID_SO:
-            write_sound(wd, (bSound *)id);
+            write_sound(wd, (bSound *)id_buffer, id);
             break;
           case ID_GR:
-            write_collection(wd, (Collection *)id);
+            write_collection(wd, (Collection *)id_buffer, id);
             break;
           case ID_AR:
-            write_armature(wd, (bArmature *)id);
+            write_armature(wd, (bArmature *)id_buffer, id);
             break;
           case ID_AC:
-            write_action(wd, (bAction *)id);
+            write_action(wd, (bAction *)id_buffer, id);
             break;
           case ID_OB:
-            write_object(wd, (Object *)id);
+            write_object(wd, (Object *)id_buffer, id);
             break;
           case ID_MA:
-            write_material(wd, (Material *)id);
+            write_material(wd, (Material *)id_buffer, id);
             break;
           case ID_TE:
-            write_texture(wd, (Tex *)id);
+            write_texture(wd, (Tex *)id_buffer, id);
             break;
           case ID_ME:
-            write_mesh(wd, (Mesh *)id);
+            write_mesh(wd, (Mesh *)id_buffer, id);
             break;
           case ID_PA:
-            write_particlesettings(wd, (ParticleSettings *)id);
+            write_particlesettings(wd, (ParticleSettings *)id_buffer, id);
             break;
           case ID_NT:
-            write_nodetree(wd, (bNodeTree *)id);
+            write_nodetree(wd, (bNodeTree *)id_buffer, id);
             break;
           case ID_BR:
-            write_brush(wd, (Brush *)id);
+            write_brush(wd, (Brush *)id_buffer, id);
             break;
           case ID_PAL:
-            write_palette(wd, (Palette *)id);
+            write_palette(wd, (Palette *)id_buffer, id);
             break;
           case ID_PC:
-            write_paintcurve(wd, (PaintCurve *)id);
+            write_paintcurve(wd, (PaintCurve *)id_buffer, id);
             break;
           case ID_GD:
-            write_gpencil(wd, (bGPdata *)id);
+            write_gpencil(wd, (bGPdata *)id_buffer, id);
             break;
           case ID_LS:
-            write_linestyle(wd, (FreestyleLineStyle *)id);
+            write_linestyle(wd, (FreestyleLineStyle *)id_buffer, id);
             break;
           case ID_CF:
-            write_cachefile(wd, (CacheFile *)id);
+            write_cachefile(wd, (CacheFile *)id_buffer, id);
             break;
           case ID_HA:
-            write_hair(wd, (Hair *)id);
+            write_hair(wd, (Hair *)id_buffer, id);
             break;
           case ID_PT:
-            write_pointcloud(wd, (PointCloud *)id);
+            write_pointcloud(wd, (PointCloud *)id_buffer, id);
             break;
           case ID_VO:
-            write_volume(wd, (Volume *)id);
+            write_volume(wd, (Volume *)id_buffer, id);
+            break;
+          case ID_SIM:
+            write_simulation(wd, (Simulation *)id);
             break;
           case ID_LI:
             /* Do nothing, handled below - and should never be reached. */
@@ -4138,11 +4335,11 @@ static bool write_file_handle(Main *mainvar,
           BKE_lib_override_library_operations_store_end(override_storage, id);
         }
 
-        if (wd->use_memfile) {
-          /* Very important to do it after every ID write now, otherwise we cannot know whether a
-           * specific ID changed or not. */
-          mywrite_flush(wd);
-        }
+        mywrite_id_end(wd, id);
+      }
+
+      if (id_buffer != id_buffer_static) {
+        MEM_SAFE_FREE(id_buffer);
       }
 
       mywrite_flush(wd);
@@ -4277,8 +4474,8 @@ bool BLO_write_file(Main *mainvar,
     BLI_split_dir_part(filepath, dir_dst, sizeof(dir_dst));
 
     /* Just in case there is some subtle difference. */
-    BLI_cleanup_path(mainvar->name, dir_dst);
-    BLI_cleanup_path(mainvar->name, dir_src);
+    BLI_path_normalize(mainvar->name, dir_dst);
+    BLI_path_normalize(mainvar->name, dir_src);
 
     if (G.relbase_valid && (BLI_path_cmp(dir_dst, dir_src) == 0)) {
       /* Saved to same path. Nothing to do. */
@@ -4353,4 +4550,98 @@ bool BLO_write_file_mem(Main *mainvar, MemFile *compare, MemFile *current, int w
   return (err == 0);
 }
 
+void BLO_write_raw(BlendWriter *writer, int size_in_bytes, const void *data_ptr)
+{
+  writedata(writer->wd, DATA, size_in_bytes, data_ptr);
+}
+
+void BLO_write_struct_by_name(BlendWriter *writer, const char *struct_name, const void *data_ptr)
+{
+  int struct_id = BLO_get_struct_id_by_name(writer, struct_name);
+  BLO_write_struct_by_id(writer, struct_id, data_ptr);
+}
+
+void BLO_write_struct_array_by_name(BlendWriter *writer,
+                                    const char *struct_name,
+                                    int array_size,
+                                    const void *data_ptr)
+{
+  int struct_id = BLO_get_struct_id_by_name(writer, struct_name);
+  BLO_write_struct_array_by_id(writer, struct_id, array_size, data_ptr);
+}
+
+void BLO_write_struct_by_id(BlendWriter *writer, int struct_id, const void *data_ptr)
+{
+  writestruct_nr(writer->wd, DATA, struct_id, 1, data_ptr);
+}
+
+void BLO_write_struct_array_by_id(BlendWriter *writer,
+                                  int struct_id,
+                                  int array_size,
+                                  const void *data_ptr)
+{
+  writestruct_nr(writer->wd, DATA, struct_id, array_size, data_ptr);
+}
+
+void BLO_write_struct_list_by_id(BlendWriter *writer, int struct_id, ListBase *list)
+{
+  writelist_nr(writer->wd, DATA, struct_id, list);
+}
+
+void BLO_write_struct_list_by_name(BlendWriter *writer, const char *struct_name, ListBase *list)
+{
+  BLO_write_struct_list_by_id(writer, BLO_get_struct_id_by_name(writer, struct_name), list);
+}
+
+void blo_write_id_struct(BlendWriter *writer, int struct_id, const void *id_address, const ID *id)
+{
+  writestruct_at_address_nr(writer->wd, GS(id->name), struct_id, 1, id_address, id);
+}
+
+int BLO_get_struct_id_by_name(BlendWriter *writer, const char *struct_name)
+{
+  int struct_id = DNA_struct_find_nr(writer->wd->sdna, struct_name);
+  BLI_assert(struct_id >= 0);
+  return struct_id;
+}
+
+void BLO_write_int32_array(BlendWriter *writer, int size, const int32_t *data_ptr)
+{
+  BLO_write_raw(writer, sizeof(int32_t) * size, data_ptr);
+}
+
+void BLO_write_uint32_array(BlendWriter *writer, int size, const uint32_t *data_ptr)
+{
+  BLO_write_raw(writer, sizeof(uint32_t) * size, data_ptr);
+}
+
+void BLO_write_float_array(BlendWriter *writer, int size, const float *data_ptr)
+{
+  BLO_write_raw(writer, sizeof(float) * size, data_ptr);
+}
+
+void BLO_write_float3_array(BlendWriter *writer, int size, const float *data_ptr)
+{
+  BLO_write_raw(writer, sizeof(float) * 3 * size, data_ptr);
+}
+
+/**
+ * Write a null terminated string.
+ */
+void BLO_write_string(BlendWriter *writer, const char *str)
+{
+  if (str != NULL) {
+    BLO_write_raw(writer, strlen(str) + 1, str);
+  }
+}
+
+/**
+ * Sometimes different data is written depending on whether the file is saved to disk or used for
+ * undo. This function returns true when the current file-writing is done for undo.
+ */
+bool BLO_write_is_undo(BlendWriter *writer)
+{
+  return writer->wd->use_memfile;
+}
+
 /** \} */