https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78201
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- DECL_SIZE is always sizetype (unsigned), so using tree_to_shwi looks odd. Of course this is a local object on the stack which never should use anchors so the fix should be in the caller (which you omit from the stack trace).
