Fix T67999: calling Mesh.materials.clear() crashes Blender

The `BKE_material_pop_id()` and `BKE_material_clear_id()` functions had
a parameter `update_data` that, when `false`, would cause the mesh polys
to keep their material index, even when the indexed material slots were
removed. This behaviour was never used in the C code and not supported
by the drawing code, making polygons disappear and causing crashes. The
Python binding in RNA, however, defaulted to `update_data=False`.

This commit removes the `update_data` parameter altogether, and makes
the functions always fix up the material indices.

Reviewed by: mont29, brecht

1 files changed, 4 insertions, 9 deletions

diff --git a/source/blender/makesrna/intern/rna_ID.c b/source/blender/makesrna/intern/rna_ID.c
index 57cdbbadeb8..7996750a1b8 100644
--- a/source/blender/makesrna/intern/rna_ID.c
+++ b/source/blender/makesrna/intern/rna_ID.c
@@ -642,8 +642,7 @@ static void rna_IDMaterials_append_id(ID *id, Main *bmain, Material *ma)
   WM_main_add_notifier(NC_OBJECT | ND_OB_SHADING, id);
 }
 
-static Material *rna_IDMaterials_pop_id(
-    ID *id, Main *bmain, ReportList *reports, int index_i, bool remove_material_slot)
+static Material *rna_IDMaterials_pop_id(ID *id, Main *bmain, ReportList *reports, int index_i)
 {
   Material *ma;
   short *totcol = give_totcolp_id(id);
@@ -657,7 +656,7 @@ static Material *rna_IDMaterials_pop_id(
     return NULL;
   }
 
-  ma = BKE_material_pop_id(bmain, id, index_i, remove_material_slot);
+  ma = BKE_material_pop_id(bmain, id, index_i);
 
   if (*totcol == totcol_orig) {
     BKE_report(reports, RPT_ERROR, "No material to removed");
@@ -671,9 +670,9 @@ static Material *rna_IDMaterials_pop_id(
   return ma;
 }
 
-static void rna_IDMaterials_clear_id(ID *id, Main *bmain, bool remove_material_slot)
+static void rna_IDMaterials_clear_id(ID *id, Main *bmain)
 {
-  BKE_material_clear_id(bmain, id, remove_material_slot);
+  BKE_material_clear_id(bmain, id);
 
   DEG_id_tag_update(id, ID_RECALC_GEOMETRY);
   WM_main_add_notifier(NC_OBJECT | ND_DRAW, id);
@@ -1116,16 +1115,12 @@ static void rna_def_ID_materials(BlenderRNA *brna)
   RNA_def_function_ui_description(func, "Remove a material from the data-block");
   parm = RNA_def_int(
       func, "index", -1, -MAXMAT, MAXMAT, "", "Index of material to remove", 0, MAXMAT);
-  RNA_def_boolean(
-      func, "update_data", 0, "", "Update data by re-adjusting the material slots assigned");
   parm = RNA_def_pointer(func, "material", "Material", "", "Material to remove");
   RNA_def_function_return(func, parm);
 
   func = RNA_def_function(srna, "clear", "rna_IDMaterials_clear_id");
   RNA_def_function_flag(func, FUNC_USE_MAIN);
   RNA_def_function_ui_description(func, "Remove all materials from the data-block");
-  RNA_def_boolean(
-      func, "update_data", 0, "", "Update data by re-adjusting the material slots assigned");
 }
 
 static void rna_def_image_preview(BlenderRNA *brna)