https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95349
--- Comment #32 from rguenther at suse dot de <rguenther at suse dot de> --- On Thu, 4 Jun 2020, andrew2085 at gmail dot com wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95349 > > --- Comment #31 from Andrew Downing <andrew2085 at gmail dot com> --- > What would you say is the solution here? There's a disconnect between what the > c++ standard says should work, and what actually works. I think C++ standards people must come to realize that designing how TBAA works in a compiler isn't something that can be turned around every now and then so changing requirements in the standard every now and then does not work. I think people will have to live with the reality of existing implementations. Because massive changes like this cannot be brought to older releases nor can I give any estimate on what future release of GCC might "support" this "feature" of the standard. There's the workaround of disabling type-based alias anaysis via -fno-strict-aliasing of course. Mind it took GCC about 4 to 5 major releases to get placement new work correctly. Well, to the reading of the C++11 standard. So expect us to be ready with C++20 in about 5 years. The message to the standards people should also be that C++ does not live in isolation and modern technology like link-time optimization has to cope with input from multiple source languages which means that compilers intermediate language has to cope with all of them and do optimizations expected by people using different languages.
