https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69581
--- Comment #7 from Bernd Edlinger <bernd.edlinger at hotmail dot de> --- Thanks. Now about reversing the comments at the bottom of math.h ? Index: libstdc++-v3/include/c_compatibility/math.h =================================================================== --- libstdc++-v3/include/c_compatibility/math.h (revision 233023) +++ libstdc++-v3/include/c_compatibility/math.h (working copy) @@ -177,7 +177,6 @@ using std::sph_neumannl; using std::sph_neumann; #endif // __STDCPP_WANT_MATH_SPEC_FUNCS__ -#endif // __cplusplus - #endif // _GLIBCXX_MATH_H +#endif // __cplusplus