BMesh: ensure iterator macros assign to valid types

note, this is for C++ code which expects a cast, (will be added later)
also add a macro for nop-expressions (EXPR_NOP),
when we never want an expression to be evaluated, but it should still be valid.

1 files changed, 19 insertions, 9 deletions

diff --git a/source/blender/bmesh/intern/bmesh_iterators.h b/source/blender/bmesh/intern/bmesh_iterators.h
index 792a9cdfe0d..49e511bdcb5 100644
--- a/source/blender/bmesh/intern/bmesh_iterators.h
+++ b/source/blender/bmesh/intern/bmesh_iterators.h
@@ -84,30 +84,40 @@ typedef enum BMIterType {
 extern const char bm_iter_itype_htype_map[BM_ITYPE_MAX];
 
 #define BM_ITER_MESH(ele, iter, bm, itype) \
-	for (ele = BM_iter_new(iter, bm, itype, NULL); ele; ele = BM_iter_step(iter))
+	for (BM_CHECK_TYPE_ELEM_ASSIGN(ele) = BM_iter_new(iter, bm, itype, NULL); \
+	     ele; \
+	     BM_CHECK_TYPE_ELEM_ASSIGN(ele) = BM_iter_step(iter))
 
 #define BM_ITER_MESH_INDEX(ele, iter, bm, itype, indexvar) \
-	for (ele = BM_iter_new(iter, bm, itype, NULL), indexvar = 0; ele; ele = BM_iter_step(iter), (indexvar)++)
+	for (BM_CHECK_TYPE_ELEM_ASSIGN(ele) = BM_iter_new(iter, bm, itype, NULL), indexvar = 0; \
+	     ele; \
+	     BM_CHECK_TYPE_ELEM_ASSIGN(ele) = BM_iter_step(iter), (indexvar)++)
 
 /* a version of BM_ITER_MESH which keeps the next item in storage
  * so we can delete the current item, see bug [#36923] */
 #ifdef DEBUG
 #  define BM_ITER_MESH_MUTABLE(ele, ele_next, iter, bm, itype) \
-	for (ele = BM_iter_new(iter, bm, itype, NULL); \
-	ele ? ((void)((iter)->count = BM_iter_mesh_count(itype, bm)), \
-	       (void)(ele_next = BM_iter_step(iter)), 1) : 0; \
-	ele = ele_next)
+	for (BM_CHECK_TYPE_ELEM_ASSIGN(ele) = BM_iter_new(iter, bm, itype, NULL); \
+	     ele ? ((void)((iter)->count = BM_iter_mesh_count(itype, bm)), \
+	            (void)(ele_next = BM_iter_step(iter)), 1) : 0; \
+	     BM_CHECK_TYPE_ELEM_ASSIGN(ele) = ele_next)
 #else
 #  define BM_ITER_MESH_MUTABLE(ele, ele_next, iter, bm, itype) \
-	for (ele = BM_iter_new(iter, bm, itype, NULL); ele ? ((ele_next = BM_iter_step(iter)), 1) : 0; ele = ele_next)
+	for (BM_CHECK_TYPE_ELEM_ASSIGN(ele) = BM_iter_new(iter, bm, itype, NULL); \
+	     ele ? ((BM_CHECK_TYPE_ELEM_ASSIGN(ele_next) = BM_iter_step(iter)), 1) : 0; \
+	     ele = ele_next)
 #endif
 
 
 #define BM_ITER_ELEM(ele, iter, data, itype) \
-	for (ele = BM_iter_new(iter, NULL, itype, data); ele; ele = BM_iter_step(iter))
+	for (BM_CHECK_TYPE_ELEM_ASSIGN(ele) = BM_iter_new(iter, NULL, itype, data); \
+	     ele; \
+	     BM_CHECK_TYPE_ELEM_ASSIGN(ele) = BM_iter_step(iter))
 
 #define BM_ITER_ELEM_INDEX(ele, iter, data, itype, indexvar) \
-	for (ele = BM_iter_new(iter, NULL, itype, data), indexvar = 0; ele; ele = BM_iter_step(iter), (indexvar)++)
+	for (BM_CHECK_TYPE_ELEM_ASSIGN(ele) = BM_iter_new(iter, NULL, itype, data), indexvar = 0; \
+	     ele; \
+	     BM_CHECK_TYPE_ELEM_ASSIGN(ele) = BM_iter_step(iter), (indexvar)++)
 
 /* iterator type structs */
 struct BMIter__elem_of_mesh {