illumos gate

std::locale::classic() is apparently supposed to always use the "C" locale, but it appears not to be the case:

kekkonen ~ % cat alpha.cc         
#include <cctype>
#include <locale>
#include <stdio.h>

int main(void) {
        setlocale(LC_ALL, "");
        printf("is alpha: %d\n", (std::isalpha((char)0xe4, std::locale::classic()) ? 1 : 0));
        return 0;
}
kekkonen ~ % g++ -o alpha alpha.cc
kekkonen ~ % LC_CTYPE=C ./alpha               
is alpha: 0
kekkonen ~ % LC_CTYPE=fi_FI.ISO8859-15 ./alpha
is alpha: 1

On Linux this returns 0 regardless of locale.

http://en.cppreference.com/w/cpp/locale/locale/classic
https://github.com/rakshasa/rtorrent/pull/159#issuecomment-196716419