Cleanup: dna_genfile API for accessing struct member offsets

- Rename `find_elem` to `elem_offset` (matching `elem_exists`).

- Remove unused `SDNA_StructMember` return argument.

- Return an offset instead of a pointer which was being converted
  back into an offset by one caller,
  in this case there was no way to tell the difference between
  and element that doesn't exist and a struct member
  at the start of the array.

Resolves UBSan warning raised in T81340.

1 files changed, 1 insertions, 0 deletions

diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index 5a995b3d750..ed35b5c5f8f 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -1118,6 +1118,7 @@ static bool read_file_dna(FileData *fd, const char **r_error_message)
             fd->filesdna, fd->memsdna, fd->compflags);
         /* used to retrieve ID names from (bhead+1) */
         fd->id_name_offs = DNA_elem_offset(fd->filesdna, "ID", "char", "name[]");
+        BLI_assert(fd->id_name_offs != -1);
 
         return true;
       }