https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84829
--- Comment #8 from Carlos O'Donell <carlos at redhat dot com> --- (In reply to Florian Weimer from comment #6) > (In reply to Jakub Jelinek from comment #5) > > -mieee-fp does affect code generation on x86 and m68k, but I don't see how > > it is related to any changes in glibc. > > And besides code generation changes it affects whether -lieee is linked in > > or not. > > It matters from the users' point of view. I think it's better to give them > a build error when they use unsupported functionality, rather than giving > the wrong results at run time. The overloaded nature of -mieee-fp makes > this difficult to achieve, though. I agree. My own opinion is that I would rather see a link-time failure for user applications that use any interfaces that are no longer supported for building new programs. Therefore it is that -mieee-fp is no longer supported with glibc 2.27, you cannot use it, and it will not work. You must XFAIL any such tests if you are using a glibc with the obsoleted matherr, _LIB_VERSION, and libieee.a functionality. Opinions vary though, since -mieee-fp is intended to require IEEE semantics, and that is now the default in glibc, we could just keep silently supporting -mieee-fp as the default. I think that Joseph will need to comment on thoughts about the behaviour of using deprecated interfaces.