https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121520
--- Comment #17 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:f707c093dee0468a3ef837a6c40afcf4c7fa7e46 commit r16-3413-gf707c093dee0468a3ef837a6c40afcf4c7fa7e46 Author: Jakub Jelinek <ja...@redhat.com> Date: Wed Aug 27 14:00:51 2025 +0200 c++: Fix up cpp_warn on __STDCPP_FLOAT*_T__ [PR121520] I got the cpp_warn on __STDCPP_FLOAT*_T__ if we aren't predefining those wrong, so e.g. on powerpc64le we don't diagnose #undef __STDCPP_FLOAT16_T__. I've added it as else if on the if (c_dialect_cxx () && cxx_dialect > cxx20 && !floatn_nx_types[i].extended) condition, which means cpp_warn is called in case a target supports some extended type like _Float32x, cpp_warn is called on __STDCPP_FLOAT32_T__ (where when it supported _Float32 as well it did cpp_define_warn (pfile, "__STDCPP_FLOAT32_T__=1") earlier). On targets where the types aren't supported the earlier if (FLOATN_NX_TYPE_NODE (i) == NULL_TREE) continue; path is taken. This patch fixes it to cpp_warn on the non-extended types for C++23 if the target doesn't support them and cpp_define_warn as before if it does. 2025-08-27 Jakub Jelinek <ja...@redhat.com> PR target/121520 * c-cppbuiltin.cc (c_cpp_builtins): Properly call cpp_warn for __STDCPP_FLOAT<NN>_T__ if FLOATN_NX_TYPE_NODE (i) is NULL for C++23 for non-extended types and don't call cpp_warn for extended types.
