Fix T74897: VSE animation doesn't work

`seq_free_animdata()` removes fcurve pointers belonging to strips from
`Scene` CoW datablock's `AnimData` during `BKE_scene_graph_update_for_newframe`.
This causes problems with updating animation.

This worked before rBbe2e41c397ba, because `AnimData` was freed by `BKE_animdata_free()`
before `seq_free_animdata()` was executed, so it had no data to operate on and returned
on precondition `if (scene->adt == NULL || scene->adt->action == NULL)`

Reviewed By: mont29, brecht

Maniphest Tasks: T74897

Differential Revision: https://developer.blender.org/D7264

source/blender/blenkernel/BKE_sequencer.h

@@ -265,7 +265,7 @@ void BKE_sequencer_base_clipboard_pointers_free(struct ListBase *seqbase);
 void BKE_sequencer_base_clipboard_pointers_store(struct Main *bmain, struct ListBase *seqbase);
 void BKE_sequencer_base_clipboard_pointers_restore(struct ListBase *seqbase, struct Main *bmain);
 
-void BKE_sequence_free(struct Scene *scene, struct Sequence *seq);
+void BKE_sequence_free(struct Scene *scene, struct Sequence *seq, const bool do_clean_animdata);
 void BKE_sequence_free_anim(struct Sequence *seq);
 const char *BKE_sequence_give_name(struct Sequence *seq);
 ListBase *BKE_sequence_seqbase_get(struct Sequence *seq, int *r_offset);

source/blender/blenkernel/intern/sequencer.c

@@ -236,7 +236,8 @@ static void seq_free_strip(Strip *strip)
 static void BKE_sequence_free_ex(Scene *scene,
                                  Sequence *seq,
                                  const bool do_cache,
-                                 const bool do_id_user)
+                                 const bool do_id_user,
+                                 const bool do_clean_animdata)
 {
   if (seq->strip) {
     seq_free_strip(seq->strip);
@@ -271,7 +272,10 @@ static void BKE_sequence_free_ex(Scene *scene,
       BKE_sound_remove_scene_sound(scene, seq->scene_sound);
     }
 
-    seq_free_animdata(scene, seq);
+    /* XXX This must not be done in BKE code. */
+    if (do_clean_animdata) {
+      seq_free_animdata(scene, seq);
+    }
   }
 
   if (seq->prop) {
@@ -299,9 +303,9 @@ static void BKE_sequence_free_ex(Scene *scene,
   MEM_freeN(seq);
 }
 
-void BKE_sequence_free(Scene *scene, Sequence *seq)
+void BKE_sequence_free(Scene *scene, Sequence *seq, const bool do_clean_animdata)
 {
-  BKE_sequence_free_ex(scene, seq, true, true);
+  BKE_sequence_free_ex(scene, seq, true, true, do_clean_animdata);
 }
 
 /* Function to free imbuf and anim data on changes */
@@ -331,7 +335,7 @@ static void seq_free_sequence_recurse(Scene *scene, Sequence *seq, const bool do
     seq_free_sequence_recurse(scene, iseq, do_id_user);
   }
 
-  BKE_sequence_free_ex(scene, seq, false, do_id_user);
+  BKE_sequence_free_ex(scene, seq, false, do_id_user, true);
 }
 
 Editing *BKE_sequencer_editing_get(Scene *scene, bool alloc)
@@ -501,7 +505,7 @@ void BKE_sequencer_editing_free(Scene *scene, const bool do_id_user)
 
   SEQ_BEGIN (ed, seq) {
     /* handle cache freeing above */
-    BKE_sequence_free_ex(scene, seq, false, do_id_user);
+    BKE_sequence_free_ex(scene, seq, false, do_id_user, false);
   }
   SEQ_END;
 

source/blender/editors/space_sequencer/sequencer_edit.c

@@ -720,7 +720,7 @@ static void recurs_del_seq_flag(Scene *scene, ListBase *lb, short flag, short de
       if (seq->type == SEQ_TYPE_META) {
         recurs_del_seq_flag(scene, &seq->seqbase, flag, 1);
       }
-      BKE_sequence_free(scene, seq);
+      BKE_sequence_free(scene, seq, true);
     }
     seq = seqn;
   }
@@ -2641,7 +2641,7 @@ static int sequencer_separate_images_exec(bContext *C, wmOperator *op)
       }
 
       seq_next = seq->next;
-      BKE_sequence_free(scene, seq);
+      BKE_sequence_free(scene, seq, true);
       seq = seq_next;
     }
     else {
@@ -2866,7 +2866,7 @@ static int sequencer_meta_separate_exec(bContext *C, wmOperator *UNUSED(op))
   BLI_listbase_clear(&last_seq->seqbase);
 
   BLI_remlink(ed->seqbasep, last_seq);
-  BKE_sequence_free(scene, last_seq);
+  BKE_sequence_free(scene, last_seq, true);
 
   /* Empty meta strip, delete all effects depending on it. */
   for (seq = ed->seqbasep->first; seq; seq = seq->next) {

source/blender/makesrna/intern/rna_sequencer_api.c

@@ -193,7 +193,7 @@ static Sequence *rna_Sequences_new_image(ID *id,
   if (seq->strip->stripdata->name[0] == '\0') {
     BKE_report(reports, RPT_ERROR, "Sequences.new_image: unable to open image file");
     BLI_remlink(&ed->seqbase, seq);
-    BKE_sequence_free(scene, seq);
+    BKE_sequence_free(scene, seq, true);
     return NULL;
   }
 
@@ -382,7 +382,7 @@ static void rna_Sequences_remove(
     return;
   }
 
-  BKE_sequence_free(scene, seq);
+  BKE_sequence_free(scene, seq, true);
   RNA_POINTER_INVALIDATE(seq_ptr);
 
   DEG_relations_tag_update(bmain);