Refactor: move library linking arguments into a parameter struct

Move arguments to BLO_library_link_{begin/named_part/end} into
a single parameter struct, to ensure arguments always match.

This allows is to skip tagging ID's LIB_TAG_DOIT when it's not needed,
previously it was always cleared just in case it was needed.

This also makes it possible to remove BLO_library_link_named_part_ex
which was only used when tagging was needed.

5 files changed, 168 insertions, 88 deletions

diff --git a/source/blender/blenkernel/intern/blender_copybuffer.c b/source/blender/blenkernel/intern/blender_copybuffer.c
index e950e94655a..9f5e038fb82 100644
--- a/source/blender/blenkernel/intern/blender_copybuffer.c
+++ b/source/blender/blenkernel/intern/blender_copybuffer.c
@@ -93,9 +93,12 @@ bool BKE_copybuffer_read(Main *bmain_dst,
     return false;
   }
   /* Here appending/linking starts. */
-  Main *mainl = BLO_library_link_begin(bmain_dst, &bh, libname);
+  const int flag = 0;
+  struct LibraryLink_Params liblink_params;
+  BLO_library_link_params_init(&liblink_params, bmain_dst, flag);
+  Main *mainl = BLO_library_link_begin(&bh, libname, &liblink_params);
   BLO_library_link_copypaste(mainl, bh, id_types_mask);
-  BLO_library_link_end(mainl, &bh, 0, NULL, NULL, NULL, NULL);
+  BLO_library_link_end(mainl, &bh, &liblink_params);
   /* Mark all library linked objects to be updated. */
   BKE_main_lib_objects_recalc_all(bmain_dst);
   IMB_colormanagement_check_file_config(bmain_dst);
@@ -144,11 +147,13 @@ int BKE_copybuffer_paste(bContext *C,
   BKE_main_id_tag_all(bmain, LIB_TAG_PRE_EXISTING, true);
 
   /* here appending/linking starts */
-  mainl = BLO_library_link_begin(bmain, &bh, libname);
+  struct LibraryLink_Params liblink_params;
+  BLO_library_link_params_init_with_context(&liblink_params, bmain, flag, scene, view_layer, v3d);
+  mainl = BLO_library_link_begin(&bh, libname, &liblink_params);
 
   const int num_pasted = BLO_library_link_copypaste(mainl, bh, id_types_mask);
 
-  BLO_library_link_end(mainl, &bh, flag, bmain, scene, view_layer, v3d);
+  BLO_library_link_end(mainl, &bh, &liblink_params);
 
   /* mark all library linked objects to be updated */
   BKE_main_lib_objects_recalc_all(bmain);
diff --git a/source/blender/blenloader/BLO_readfile.h b/source/blender/blenloader/BLO_readfile.h
index c9e837eb3b5..c83d8e037c8 100644
--- a/source/blender/blenloader/BLO_readfile.h
+++ b/source/blender/blenloader/BLO_readfile.h
@@ -138,6 +138,10 @@ void BLO_blendhandle_close(BlendHandle *bh);
 bool BLO_has_bfile_extension(const char *str);
 bool BLO_library_path_explode(const char *path, char *r_dir, char **r_group, char **r_name);
 
+/* -------------------------------------------------------------------- */
+/** \name BLO Blend File Linking API
+ * \{ */
+
 /* Options controlling behavior of append/link code.
  * Note: merged with 'user-level' options from operators etc. in 16 lower bits
  *       (see eFileSel_Params_Flag in DNA_space_types.h). */
@@ -146,25 +150,63 @@ typedef enum BLO_LibLinkFlags {
   BLO_LIBLINK_USE_PLACEHOLDERS = 1 << 16,
   /* Force loaded ID to be tagged as LIB_TAG_INDIRECT (used in reload context only). */
   BLO_LIBLINK_FORCE_INDIRECT = 1 << 17,
+  /**
+   * When set, tag ID types that pass the internal check #library_link_idcode_needs_tag_check
+   *
+   * Currently this is only used to instantiate objects in the scene.
+   * Set this from #BLO_library_link_params_init_with_context so callers
+   * don't need to remember to set this flag.
+   */
+  BLO_LIBLINK_NEEDS_ID_TAG_DOIT = 1 << 18,
 } BLO_LinkFlags;
 
-struct Main *BLO_library_link_begin(struct Main *mainvar, BlendHandle **bh, const char *filepath);
+/**
+ * Struct for passing arguments to
+ * #BLO_library_link_begin, #BLO_library_link_named_part & #BLO_library_link_end.
+ * Wrap these in parameters since it's important both functions receive matching values.
+ */
+struct LibraryLink_Params {
+  /** The current main database, e.g. #G_MAIN or `CTX_data_main(C)`. */
+  struct Main *bmain;
+  /** Options for linking, used for instantiating. */
+  int flag;
+  /** Context for instancing objects (optional, no instantiation will be performed when NULL). */
+  struct {
+    /** The scene in which to instantiate objects/collections. */
+    struct Scene *scene;
+    /** The scene layer in which to instantiate objects/collections. */
+    struct ViewLayer *view_layer;
+    /** The active 3D viewport (only used to define local-view). */
+    const struct View3D *v3d;
+  } context;
+};
+
+void BLO_library_link_params_init(struct LibraryLink_Params *params,
+                                  struct Main *bmain,
+                                  const int flag);
+void BLO_library_link_params_init_with_context(struct LibraryLink_Params *params,
+                                               struct Main *bmain,
+                                               const int flag,
+                                               struct Scene *scene,
+                                               struct ViewLayer *view_layer,
+                                               const struct View3D *v3d);
+
+struct Main *BLO_library_link_begin(BlendHandle **bh,
+                                    const char *filepath,
+                                    const struct LibraryLink_Params *params);
 struct ID *BLO_library_link_named_part(struct Main *mainl,
                                        BlendHandle **bh,
                                        const short idcode,
-                                       const char *name);
-struct ID *BLO_library_link_named_part_ex(
-    struct Main *mainl, BlendHandle **bh, const short idcode, const char *name, const int flag);
+                                       const char *name,
+                                       const struct LibraryLink_Params *params);
 void BLO_library_link_end(struct Main *mainl,
                           BlendHandle **bh,
-                          int flag,
-                          struct Main *bmain,
-                          struct Scene *scene,
-                          struct ViewLayer *view_layer,
-                          const struct View3D *v3d);
+                          const struct LibraryLink_Params *params);
 
 int BLO_library_link_copypaste(struct Main *mainl, BlendHandle *bh, const uint64_t id_types_mask);
 
+/** \} */
+
 void *BLO_library_read_struct(struct FileData *fd, struct BHead *bh, const char *blockname);
 
 /* internal function but we need to expose it */
diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index 84cb898a426..35534963433 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -262,6 +262,7 @@ static void *read_struct(FileData *fd, BHead *bh, const char *blockname);
 static void direct_link_modifiers(BlendDataReader *reader, ListBase *lb, Object *ob);
 static BHead *find_bhead_from_code_name(FileData *fd, const short idcode, const char *name);
 static BHead *find_bhead_from_idname(FileData *fd, const char *idname);
+static bool library_link_idcode_needs_tag_check(const short idcode, const int flag);
 
 #ifdef USE_COLLECTION_COMPAT_28
 static void expand_scene_collection(BlendExpander *expander, SceneCollection *sc);
@@ -10469,6 +10470,14 @@ static ID *link_named_part(
   /* if we found the id but the id is NULL, this is really bad */
   BLI_assert(!((bhead != NULL) && (id == NULL)));
 
+  /* Tag as loose object (or data associated with objects)
+   * needing to be instantiated in #LibraryLink_Params.scene. */
+  if ((id != NULL) && (flag & BLO_LIBLINK_NEEDS_ID_TAG_DOIT)) {
+    if (library_link_idcode_needs_tag_check(idcode, flag)) {
+      id->tag |= LIB_TAG_DOIT;
+    }
+  }
+
   return id;
 }
 
@@ -10514,23 +10523,6 @@ int BLO_library_link_copypaste(Main *mainl, BlendHandle *bh, const uint64_t id_t
   return num_directly_linked;
 }
 
-static ID *link_named_part_ex(
-    Main *mainl, FileData *fd, const short idcode, const char *name, const int flag)
-{
-  ID *id = link_named_part(mainl, fd, idcode, name, flag);
-
-  if (id && (GS(id->name) == ID_OB)) {
-    /* Tag as loose object needing to be instantiated somewhere... */
-    id->tag |= LIB_TAG_DOIT;
-  }
-  else if (id && (GS(id->name) == ID_GR)) {
-    /* tag as needing to be instantiated or linked */
-    id->tag |= LIB_TAG_DOIT;
-  }
-
-  return id;
-}
-
 /**
  * Link a named data-block from an external blend file.
  *
@@ -10543,41 +10535,53 @@ static ID *link_named_part_ex(
 ID *BLO_library_link_named_part(Main *mainl,
                                 BlendHandle **bh,
                                 const short idcode,
-                                const char *name)
+                                const char *name,
+                                const struct LibraryLink_Params *params)
 {
   FileData *fd = (FileData *)(*bh);
-  return link_named_part(mainl, fd, idcode, name, 0);
+  return link_named_part(mainl, fd, idcode, name, params->flag);
 }
 
+/* common routine to append/link something from a library */
+
 /**
- * Link a named data-block from an external blend file.
- * Optionally instantiate the object/collection in the scene when the flags are set.
- *
- * \param mainl: The main database to link from (not the active one).
- * \param bh: The blender file handle.
- * \param idcode: The kind of data-block to link.
- * \param name: The name of the data-block (without the 2 char ID prefix).
- * \param flag: Options for linking, used for instantiating.
- * \return the linked ID when found.
+ * Checks if the \a idcode needs to be tagged with #LIB_TAG_DOIT when linking/appending.
  */
-ID *BLO_library_link_named_part_ex(
-    Main *mainl, BlendHandle **bh, const short idcode, const char *name, const int flag)
+static bool library_link_idcode_needs_tag_check(const short idcode, const int flag)
 {
-  FileData *fd = (FileData *)(*bh);
-  return link_named_part_ex(mainl, fd, idcode, name, flag);
+  if (flag & BLO_LIBLINK_NEEDS_ID_TAG_DOIT) {
+    /* Always true because of #add_loose_objects_to_scene & #add_collections_to_scene. */
+    if (ELEM(idcode, ID_OB, ID_GR)) {
+      return true;
+    }
+  }
+  return false;
 }
 
-/* common routine to append/link something from a library */
+/**
+ * Clears #LIB_TAG_DOIT based on the result of #library_link_idcode_needs_tag_check.
+ */
+static void library_link_clear_tag(Main *mainvar, const int flag)
+{
+  for (int i = 0; i < MAX_LIBARRAY; i++) {
+    const short idcode = BKE_idtype_idcode_from_index(i);
+    BLI_assert(idcode != -1);
+    if (library_link_idcode_needs_tag_check(idcode, flag)) {
+      BKE_main_id_tag_idcode(mainvar, idcode, LIB_TAG_DOIT, false);
+    }
+  }
+}
 
-static Main *library_link_begin(Main *mainvar, FileData **fd, const char *filepath)
+static Main *library_link_begin(Main *mainvar, FileData **fd, const char *filepath, const int flag)
 {
   Main *mainl;
 
   (*fd)->mainlist = MEM_callocN(sizeof(ListBase), "FileData.mainlist");
 
-  /* clear for objects and collections instantiating tag */
-  BKE_main_id_tag_listbase(&(mainvar->objects), LIB_TAG_DOIT, false);
-  BKE_main_id_tag_listbase(&(mainvar->collections), LIB_TAG_DOIT, false);
+  if (flag & BLO_LIBLINK_NEEDS_ID_TAG_DOIT) {
+    /* Clear for objects and collections instantiating tag. */
+    library_link_clear_tag(mainvar, flag);
+  }
 
   /* make mains */
   blo_split_main((*fd)->mainlist, mainvar);
@@ -10595,19 +10599,49 @@ static Main *library_link_begin(Main *mainvar, FileData **fd, const char *filepa
   return mainl;
 }
 
+void BLO_library_link_params_init(struct LibraryLink_Params *params,
+                                  struct Main *bmain,
+                                  const int flag)
+{
+  memset(params, 0, sizeof(*params));
+  params->bmain = bmain;
+  params->flag = flag;
+}
+
+void BLO_library_link_params_init_with_context(struct LibraryLink_Params *params,
+                                               struct Main *bmain,
+                                               const int flag,
+                                               /* Context arguments. */
+                                               struct Scene *scene,
+                                               struct ViewLayer *view_layer,
+                                               const struct View3D *v3d)
+{
+  BLO_library_link_params_init(params, bmain, flag);
+  if (scene != NULL) {
+    /* Tagging is needed for instancing. */
+    params->flag |= BLO_LIBLINK_NEEDS_ID_TAG_DOIT;
+
+    params->context.scene = scene;
+    params->context.view_layer = view_layer;
+    params->context.v3d = v3d;
+  }
+}
+
 /**
  * Initialize the #BlendHandle for linking library data.
  *
- * \param mainvar: The current main database, e.g. #G_MAIN or #CTX_data_main(C).
  * \param bh: A blender file handle as returned by
  * #BLO_blendhandle_from_file or #BLO_blendhandle_from_memory.
  * \param filepath: Used for relative linking, copied to the `lib->filepath`.
- * \return the library #Main, to be passed to #BLO_library_link_named_part_ex as \a mainl.
+ * \param params: Settings for linking that don't change from beginning to end of linking.
+ * \return the library #Main, to be passed to #BLO_library_link_named_part as \a mainl.
  */
-Main *BLO_library_link_begin(Main *mainvar, BlendHandle **bh, const char *filepath)
+Main *BLO_library_link_begin(BlendHandle **bh,
+                             const char *filepath,
+                             const struct LibraryLink_Params *params)
 {
   FileData *fd = (FileData *)(*bh);
-  return library_link_begin(mainvar, &fd, filepath);
+  return library_link_begin(params->bmain, &fd, filepath, params->flag);
 }
 
 static void split_main_newid(Main *mainptr, Main *main_newid)
@@ -10642,8 +10676,8 @@ static void split_main_newid(Main *mainptr, Main *main_newid)
  */
 static void library_link_end(Main *mainl,
                              FileData **fd,
-                             const short flag,
                              Main *bmain,
+                             const int flag,
                              Scene *scene,
                              ViewLayer *view_layer,
                              const View3D *v3d)
@@ -10720,19 +10754,18 @@ static void library_link_end(Main *mainl,
 
   /* Give a base to loose objects and collections.
    * Only directly linked objects & collections are instantiated by
-   * #BLO_library_link_named_part_ex & co,
+   * #BLO_library_link_named_part & co,
    * here we handle indirect ones and other possible edge-cases. */
-  if (scene) {
-    add_collections_to_scene(mainvar, bmain, scene, view_layer, v3d, curlib, flag);
-    add_loose_objects_to_scene(mainvar, bmain, scene, view_layer, v3d, curlib, flag);
-  }
-  else {
-    /* printf("library_append_end, scene is NULL (objects wont get bases)\n"); */
-  }
+  if (flag & BLO_LIBLINK_NEEDS_ID_TAG_DOIT) {
+    /* Should always be true. */
+    if (scene != NULL) {
+      add_collections_to_scene(mainvar, bmain, scene, view_layer, v3d, curlib, flag);
+      add_loose_objects_to_scene(mainvar, bmain, scene, view_layer, v3d, curlib, flag);
+    }
 
-  /* Clear objects and collections instantiating tag. */
-  BKE_main_id_tag_listbase(&(mainvar->objects), LIB_TAG_DOIT, false);
-  BKE_main_id_tag_listbase(&(mainvar->collections), LIB_TAG_DOIT, false);
+    /* Clear objects and collections instantiating tag. */
+    library_link_clear_tag(mainvar, flag);
+  }
 
   /* patch to prevent switch_endian happens twice */
   if ((*fd)->flags & FD_FLAGS_SWITCH_ENDIAN) {
@@ -10748,25 +10781,18 @@ static void library_link_end(Main *mainl,
  *
  * \param mainl: The main database to link from (not the active one).
  * \param bh: The blender file handle (WARNING! may be freed by this function!).
- * \param flag: Options for linking, used for instantiating.
- * \param bmain: The main database in which to instantiate objects/collections
- * \param scene: The scene in which to instantiate objects/collections
- * (if NULL, no instantiation is done).
- * \param view_layer: The scene layer in which to instantiate objects/collections
- * (if NULL, no instantiation is done).
- * \param v3d: The active 3D viewport
- * (only to define local-view for instantiated objects & groups, can be NULL).
+ * \param params: Settings for linking that don't change from beginning to end of linking.
  */
-void BLO_library_link_end(Main *mainl,
-                          BlendHandle **bh,
-                          int flag,
-                          Main *bmain,
-                          Scene *scene,
-                          ViewLayer *view_layer,
-                          const View3D *v3d)
+void BLO_library_link_end(Main *mainl, BlendHandle **bh, const struct LibraryLink_Params *params)
 {
   FileData *fd = (FileData *)(*bh);
-  library_link_end(mainl, &fd, flag, bmain, scene, view_layer, v3d);
+  library_link_end(mainl,
+                   &fd,
+                   params->bmain,
+                   params->flag,
+                   params->context.scene,
+                   params->context.view_layer,
+                   params->context.v3d);
   *bh = (BlendHandle *)fd;
 }
 
diff --git a/source/blender/python/intern/bpy_library_load.c b/source/blender/python/intern/bpy_library_load.c
index bdad4d03ae7..a3750d348f5 100644
--- a/source/blender/python/intern/bpy_library_load.c
+++ b/source/blender/python/intern/bpy_library_load.c
@@ -327,7 +327,10 @@ static PyObject *bpy_lib_exit(BPy_Library *self, PyObject *UNUSED(args))
   BKE_main_id_tag_all(bmain, LIB_TAG_PRE_EXISTING, true);
 
   /* here appending/linking starts */
-  mainl = BLO_library_link_begin(bmain, &(self->blo_handle), self->relpath);
+  struct LibraryLink_Params liblink_params;
+  BLO_library_link_params_init(&liblink_params, bmain, self->flag);
+
+  mainl = BLO_library_link_begin(&(self->blo_handle), self->relpath, &liblink_params);
 
   {
     int idcode_step = 0, idcode;
@@ -350,7 +353,7 @@ static PyObject *bpy_lib_exit(BPy_Library *self, PyObject *UNUSED(args))
 
             if (item_idname) {
               ID *id = BLO_library_link_named_part(
-                  mainl, &(self->blo_handle), idcode, item_idname);
+                  mainl, &(self->blo_handle), idcode, item_idname, &liblink_params);
               if (id) {
 #ifdef USE_RNA_DATABLOCKS
                 /* swap name for pointer to the id */
@@ -394,7 +397,7 @@ static PyObject *bpy_lib_exit(BPy_Library *self, PyObject *UNUSED(args))
   }
 
   Library *lib = mainl->curlib; /* newly added lib, assign before append end */
-  BLO_library_link_end(mainl, &(self->blo_handle), self->flag, NULL, NULL, NULL, NULL);
+  BLO_library_link_end(mainl, &(self->blo_handle), &liblink_params);
   BLO_blendhandle_close(self->blo_handle);
   self->blo_handle = NULL;
 
diff --git a/source/blender/windowmanager/intern/wm_files_link.c b/source/blender/windowmanager/intern/wm_files_link.c
index 6ccc5d79962..8c14055696c 100644
--- a/source/blender/windowmanager/intern/wm_files_link.c
+++ b/source/blender/windowmanager/intern/wm_files_link.c
@@ -250,7 +250,11 @@ static void wm_link_do(WMLinkAppendData *lapp_data,
     }
 
     /* here appending/linking starts */
-    mainl = BLO_library_link_begin(bmain, &bh, libname);
+    struct LibraryLink_Params liblink_params;
+    BLO_library_link_params_init_with_context(
+        &liblink_params, bmain, flag, scene, view_layer, v3d);
+
+    mainl = BLO_library_link_begin(&bh, libname, &liblink_params);
     lib = mainl->curlib;
     BLI_assert(lib);
     UNUSED_VARS_NDEBUG(lib);
@@ -276,7 +280,7 @@ static void wm_link_do(WMLinkAppendData *lapp_data,
         continue;
       }
 
-      new_id = BLO_library_link_named_part_ex(mainl, &bh, item->idcode, item->name, flag);
+      new_id = BLO_library_link_named_part(mainl, &bh, item->idcode, item->name, &liblink_params);
 
       if (new_id) {
         /* If the link is successful, clear item's libs 'todo' flags.
@@ -286,7 +290,7 @@ static void wm_link_do(WMLinkAppendData *lapp_data,
       }
     }
 
-    BLO_library_link_end(mainl, &bh, flag, bmain, scene, view_layer, v3d);
+    BLO_library_link_end(mainl, &bh, &liblink_params);
     BLO_blendhandle_close(bh);
   }
 }