From 6a96a151befd6ddb52399f43f0ced230bdfeba7a Mon Sep 17 00:00:00 2001
From: Hans Goudey <h.goudey@me.com>
Date: Wed, 15 Mar 2023 10:31:12 -0400
Subject: [PATCH] Fix: Dyntopo attribute data warning doesn't work

My PR https://projects.blender.org/blender/blender/pulls/104535
was committed as 88f9c55f7f5259c821b2 and the logic was changed
while adding support for face sets, making the logic incorrect and
the warning system disfunctional.

Restore the logic from the original PR with added support for face sets,
fix const correctness issues, improve variable naming, and remove a
check for empty names, since all attribute-type layers should have
names in a valid mesh.

Fixes #105780
---
 .../editors/sculpt_paint/sculpt_dyntopo.cc    | 45 +++++++++----------
 1 file changed, 20 insertions(+), 25 deletions(-)

diff --git a/source/blender/editors/sculpt_paint/sculpt_dyntopo.cc b/source/blender/editors/sculpt_paint/sculpt_dyntopo.cc
index 570e2e1cab3..3488c6f9533 100644
--- a/source/blender/editors/sculpt_paint/sculpt_dyntopo.cc
+++ b/source/blender/editors/sculpt_paint/sculpt_dyntopo.cc
@@ -309,37 +309,32 @@ static int dyntopo_warning_popup(bContext *C, wmOperatorType *ot, enum eDynTopoW
   return OPERATOR_INTERFACE;
 }
 
-static bool dyntopo_supports_customdata_layers(const blender::Span<CustomDataLayer> layers,
-                                               int totelem)
+static bool dyntopo_supports_layer(const CustomDataLayer &layer, const int elem_num)
 {
-  for (const CustomDataLayer &layer : layers) {
-    if (CD_TYPE_AS_MASK(layer.type) & CD_MASK_PROP_ALL) {
-      if (layer.name[0] == '\0') {
-        return false;
-      }
-
-      if (STREQ(layer.name, ".sculpt_face_sets") && totelem > 0) {
-        int *fsets = static_cast<int *>(layer.data);
-        int fset = fsets[0];
-
-        /* Check if only one face set exists. */
-        for (int i : IndexRange(totelem)) {
-          if (fsets[i] != fset) {
-            return false;
-          }
+  if (CD_TYPE_AS_MASK(layer.type) & CD_MASK_PROP_ALL) {
+    if (STREQ(layer.name, ".sculpt_face_set")) {
+      /* Check if only one face set exists. */
+      const blender::Span<int> face_sets(static_cast<const int *>(layer.data), elem_num);
+      for (const int i : face_sets.index_range()) {
+        if (face_sets[i] != face_sets.first()) {
+          return false;
         }
-
-        return true;
       }
-
-      /* Some data is stored as generic attributes on #Mesh but in flags or field on #BMesh. */
-      return BM_attribute_stored_in_bmesh_builtin(layer.name);
+      return true;
     }
-    /* Some layers just encode #Mesh topology or are handled as special cases for dyntopo. */
-    return ELEM(layer.type, CD_MEDGE, CD_MFACE, CD_MLOOP, CD_MPOLY, CD_PAINT_MASK, CD_ORIGINDEX);
+    /* Some data is stored as generic attributes on #Mesh but in flags or fields on #BMesh. */
+    return BM_attribute_stored_in_bmesh_builtin(layer.name);
   }
+  /* Some layers just encode #Mesh topology or are handled as special cases for dyntopo. */
+  return ELEM(layer.type, CD_MEDGE, CD_MPOLY, CD_MLOOP, CD_PAINT_MASK, CD_ORIGINDEX);
+}
 
-  return true;
+static bool dyntopo_supports_customdata_layers(const blender::Span<CustomDataLayer> layers,
+                                               const int elem_num)
+{
+  return std::all_of(layers.begin(), layers.end(), [&](const CustomDataLayer &layer) {
+    return dyntopo_supports_layer(layer, elem_num);
+  });
 }
 
 enum eDynTopoWarnFlag SCULPT_dynamic_topology_check(Scene *scene, Object *ob)