https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65892
--- Comment #41 from rguenther at suse dot de <rguenther at suse dot de> --- On April 29, 2018 1:51:58 PM GMT+02:00, "aph at gcc dot gnu.org" <gcc-bugzi...@gcc.gnu.org> wrote: >https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65892 > >--- Comment #40 from Andrew Haley <aph at gcc dot gnu.org> --- >(In reply to rguent...@suse.de from comment #29) > >> Note I repeatedly said this part of the standard is just stupid. It >makes >> most if not all type-based alias analysis useless. > >I don't think so. It does mean that we'd have to feed all declared >union types (or, at least the ones containing structs with common >initial sequences) into the alias oracle. While unpleasant, in that >simply declaring a type without even declaring an object of that type >changes code generation, it doesn't render all type-based alias >analysis useless. How do you handle this within the LTO framework? >> Which means I'll refuse any patches implementing it in a way that >affects >> default behavior. > >Maybe --pedantic or even --pedantic-aliasing? Whatever you call it I doubt any working solution will fit nicely into our existing TBAA framework. When I read the language text then a union declaration in between two accesses will change the semantic of the second?
