Re: [musl] Question on C++ locale

["Érico Nogueira" <ericonr@disroot.org>]

On Mon Nov 30, 2020 at 8:35 AM -03, Szabolcs Nagy wrote:
> * Dong Brett <brett.browning.dong@gmail.com> [2020-11-30 18:41:33
> +0800]:
> > However, the following C++ code does not work (our software uses std::locale in C++ standard library for locale related stuff):
> > #include <langinfo.h>
> > #include <locale.h>
> > #include <locale>
> > using namespace std;
> > int main()
> > {
> >     std::locale::global(locale(""));
> >     initscr();
> >     printw("LC_ALL: %s\n", setlocale(LC_ALL, NULL));
> >     printw("C++ locale: %s\n", locale().name().c_str());
> >     printw("CODESET: %s\n", nl_langinfo(CODESET));
> >     printw("Hello, world!\n");
> >     printw("你好，世界!\n");
> >     refresh();
> >     getch();
> >     endwin();
> >     return 0;
> > }
>
> fwiw for me even the first line fails.
> i don't know how c++ locales are supposed to work.

From [1], it seems that C++ locales are supposed to affect the global
locale as well, so they should call setlocale() when appropriate.

- [1] https://www.cplusplus.com/reference/locale/locale/

Unfortunately, I assume libstdc++ uses their generic locale support on
musl...  From gcc-10.2.0/libstdc++-v3/config/locale/generic/c_locale.cc:

  void
  locale::facet::_S_create_c_locale(__c_locale& __cloc, const char* __s,
				    __c_locale)
  {
    // Currently, the generic model only supports the "C" locale.
    // See http://gcc.gnu.org/ml/libstdc++/2003-02/msg00345.html
    __cloc = 0;
    if (strcmp(__s, "C"))
      __throw_runtime_error(__N("locale::facet::_S_create_c_locale "
			    "name not valid"));
  }