[Bug sanitizer/64741] Incorrect size of UBSan type descriptors

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64741

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The C FE does for vars with flexible array members with initializers:
      DECL_SIZE (decl)
        = size_binop (PLUS_EXPR, DECL_SIZE (decl), TYPE_SIZE (type));
      DECL_SIZE_UNIT (decl)
        = size_binop (PLUS_EXPR, DECL_SIZE_UNIT (decl), TYPE_SIZE_UNIT (type));
So what about doing the same (with type replaced by TREE_TYPE (str))?