Fix (unreported) design flow in how workspace's relation data are read from .blend file.

Relying on pointer addresses across different data-blocks is extremely
not recommended (and should be strictly forbidden ideally), in
particular in direct_link step of blend file reading.
- It assumes a specific order in reading of data, which is not ensured
  in future, and is in any case a very bad, non explicit, hidden
  dependency on behaviors of other parts of the codebase.
- It is intrinsically unsafe (as in, it makes writing bad code and making
  mistakes easy, see e.g. fix in rB84b3f6e049b35f9).
- It makes advanced handling of data-blocks harder (thinking about
  partial undo code e.g., even though in this specific case it was not
  an issue as we do not re-read neither windowmanagers nor worspaces
  during undo).

New code uses windows' `winid` instead as 'anchor' to find again proper
workspace hook in windows at read time.

As a bonus, it will also cleanup the list of relations from any invalid
ones (afaict it was never done previously).

Differential Revision: https://developer.blender.org/D9073

1 files changed, 4 insertions, 1 deletions

diff --git a/source/blender/blenkernel/BKE_workspace.h b/source/blender/blenkernel/BKE_workspace.h
index 5ff1ba2c6f5..82a4e5fe08e 100644
--- a/source/blender/blenkernel/BKE_workspace.h
+++ b/source/blender/blenkernel/BKE_workspace.h
@@ -36,7 +36,8 @@ struct bToolRef;
 struct WorkSpace *BKE_workspace_add(struct Main *bmain, const char *name);
 void BKE_workspace_remove(struct Main *bmain, struct WorkSpace *workspace);
 
-struct WorkSpaceInstanceHook *BKE_workspace_instance_hook_create(const struct Main *bmain);
+struct WorkSpaceInstanceHook *BKE_workspace_instance_hook_create(const struct Main *bmain,
+                                                                 const int winid);
 void BKE_workspace_instance_hook_free(const struct Main *bmain,
                                       struct WorkSpaceInstanceHook *hook);
 
@@ -83,11 +84,13 @@ void BKE_workspace_active_set(struct WorkSpaceInstanceHook *hook,
 struct WorkSpaceLayout *BKE_workspace_active_layout_get(const struct WorkSpaceInstanceHook *hook)
     GETTER_ATTRS;
 void BKE_workspace_active_layout_set(struct WorkSpaceInstanceHook *hook,
+                                     const int winid,
                                      struct WorkSpace *workspace,
                                      struct WorkSpaceLayout *layout) SETTER_ATTRS;
 struct bScreen *BKE_workspace_active_screen_get(const struct WorkSpaceInstanceHook *hook)
     GETTER_ATTRS;
 void BKE_workspace_active_screen_set(struct WorkSpaceInstanceHook *hook,
+                                     const int winid,
                                      struct WorkSpace *workspace,
                                      struct bScreen *screen) SETTER_ATTRS;