https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104395
--- Comment #11 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-14 branch has been updated by Jonathan Wakely <r...@gcc.gnu.org>: https://gcc.gnu.org/g:3b9885ac4df2e83cec2080d5a7013b71345a7a7b commit r14-11362-g3b9885ac4df2e83cec2080d5a7013b71345a7a7b Author: Jonathan Wakely <jwak...@redhat.com> Date: Wed Jun 26 14:09:07 2024 +0100 libstdc++: Do not use C++11 alignof in C++98 mode [PR104395] When -faligned-new (or Clang's -faligned-allocation) is used our allocators try to support extended alignments, gated on the __cpp_aligned_new macro. However, because they use alignof(_Tp) which is not a keyword in C++98 mode, using -std=c++98 -faligned-new results in errors from <memory> and other headers. We could change them to use __alignof__ instead of alignof, but that would potentially alter the result of the conditions, because e.g. alignof(long long) != __alignof__(long long) on some targets. That's probably not an issue for any types with extended alignment, so maybe it would be a safe change. For now, it seems acceptable to just disable the extended alignment support in C++98 mode, so that -faligned-new enables std::align_val_t and the corresponding operator new overloads, but doesn't affect std::allocator, __gnu_cxx::__bitmap_allocator etc. libstdc++-v3/ChangeLog: PR libstdc++/104395 * include/bits/new_allocator.h: Disable extended alignment support in C++98 mode. * include/bits/stl_tempbuf.h: Likewise. * include/ext/bitmap_allocator.h: Likewise. * include/ext/malloc_allocator.h: Likewise. * include/ext/mt_allocator.h: Likewise. * include/ext/pool_allocator.h: Likewise. * testsuite/ext/104395.cc: New test. (cherry picked from commit 03d3aeb0e0fa7dec9bd702cabf57ef73cdc32704)
