https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89615
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> --- Oh, but it's not failing because of the -finput-charset=ascii option, just because it includes <bits/extc++.h>, and one of the extension ehaders includes <iconv.h>. OK, so then maybe something like this: --- a/libstdc++-v3/include/ext/codecvt_specializations.h +++ b/libstdc++-v3/include/ext/codecvt_specializations.h @@ -35,6 +35,7 @@ #ifndef _EXT_CODECVT_SPECIALIZATIONS_H #define _EXT_CODECVT_SPECIALIZATIONS_H 1 +#if defined __has_include && __has_include(<iconv.h>) #include <bits/c++config.h> #include <locale> #include <iconv.h> @@ -513,3 +514,4 @@ _GLIBCXX_END_NAMESPACE_VERSION } // namespace #endif +#endif