https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70178
Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |rguenth at gcc dot gnu.org --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- This is because we don't know that for struct string { char *data; } s; s->data doesn't point to &s->data and thus writing to s->data[i] may invalidate the pointer. Unfortunately 'char' aliases everything so writing to a char * object and then reading back as char * is valid from a TBAA perspective.