From 1a69384e76e2b1ab11c87a582eb2cdf26386ac59 Mon Sep 17 00:00:00 2001
From: Asad-ullah Khan <kh4n>
Date: Fri, 3 Apr 2020 02:35:25 +0200
Subject: Fix T74205: crash cancelling transfrom operation in sculpt mode

Differential Revision: https://developer.blender.org/D7018
---
 source/blender/editors/sculpt_paint/sculpt.c        | 6 +++++-
 source/blender/editors/sculpt_paint/sculpt_intern.h | 1 +
 source/blender/editors/sculpt_paint/sculpt_undo.c   | 7 ++++++-
 3 files changed, 12 insertions(+), 2 deletions(-)

(limited to 'source')

diff --git a/source/blender/editors/sculpt_paint/sculpt.c b/source/blender/editors/sculpt_paint/sculpt.c
index 8d4870f5dd8..db138bb907d 100644
--- a/source/blender/editors/sculpt_paint/sculpt.c
+++ b/source/blender/editors/sculpt_paint/sculpt.c
@@ -11076,7 +11076,11 @@ void ED_sculpt_end_transform(struct bContext *C)
   if (ss->filter_cache) {
     sculpt_filter_cache_free(ss);
   }
-  SCULPT_undo_push_end();
+  /* Force undo push to happen even inside transform operator, since the sculpt
+   * undo system works separate from regular undo and this is require to properly
+   * finish an undo step also when cancelling. */
+  const bool use_nested_undo = true;
+  SCULPT_undo_push_end_ex(use_nested_undo);
   sculpt_flush_update_done(C, ob, SCULPT_UPDATE_COORDS);
 }
 
diff --git a/source/blender/editors/sculpt_paint/sculpt_intern.h b/source/blender/editors/sculpt_paint/sculpt_intern.h
index f0481582571..60b51ce17fd 100644
--- a/source/blender/editors/sculpt_paint/sculpt_intern.h
+++ b/source/blender/editors/sculpt_paint/sculpt_intern.h
@@ -726,6 +726,7 @@ SculptUndoNode *SCULPT_undo_push_node(Object *ob, PBVHNode *node, SculptUndoType
 SculptUndoNode *SCULPT_undo_get_node(PBVHNode *node);
 void SCULPT_undo_push_begin(const char *name);
 void SCULPT_undo_push_end(void);
+void SCULPT_undo_push_end_ex(const bool use_nested_undo);
 
 void SCULPT_vertcos_to_key(Object *ob, KeyBlock *kb, const float (*vertCos)[3]);
 
diff --git a/source/blender/editors/sculpt_paint/sculpt_undo.c b/source/blender/editors/sculpt_paint/sculpt_undo.c
index f6ed4fa21e0..f21bfe245dd 100644
--- a/source/blender/editors/sculpt_paint/sculpt_undo.c
+++ b/source/blender/editors/sculpt_paint/sculpt_undo.c
@@ -1289,6 +1289,11 @@ void SCULPT_undo_push_begin(const char *name)
 }
 
 void SCULPT_undo_push_end(void)
+{
+  SCULPT_undo_push_end_ex(false);
+}
+
+void SCULPT_undo_push_end_ex(const bool use_nested_undo)
 {
   UndoSculpt *usculpt = sculpt_undo_get_nodes();
   SculptUndoNode *unode;
@@ -1307,7 +1312,7 @@ void SCULPT_undo_push_end(void)
 
   /* We could remove this and enforce all callers run in an operator using 'OPTYPE_UNDO'. */
   wmWindowManager *wm = G_MAIN->wm.first;
-  if (wm->op_undo_depth == 0) {
+  if (wm->op_undo_depth == 0 || use_nested_undo) {
     UndoStack *ustack = ED_undo_stack_get();
     BKE_undosys_step_push(ustack, NULL, NULL);
     WM_file_tag_modified();
-- 
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