https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63622
--- Comment #16 from howarth at bromo dot med.uc.edu --- (In reply to Jonathan Wakely from comment #15) > (In reply to howarth from comment #14) > > which produces as set of warnings that don't appear in the build of > > libstdc++-v3/src/c++98/streambuf-inst.cc. These are... > > > > ./../../../../gcc-5.0-20141105/libstdc++-v3/src/c++11/streambuf-inst.cc:63:1: > > warning: alias definitions not supported in Mach-O; ignored > > I have no idea what that means or why building the file with -std=c++11 > instead of -std=c++98 causes it, and I don't have any way to check what is > different on darwin. This sounds similar to thread https://gcc.gnu.org/ml/gcc/2010-05/msg00164.html. The fact that we see the same warnings indicate the use of -std=c++11 is triggering the use aliases on darwin which is unsupported. The fact that the attached preprocessed source code from gcc trunk doesn't show any instances of '__alias__' makes me wondering if the middle-end is automatically doing this somehow when -std=c++11 is invoked.
