[Bug libstdc++/58628] Incorrect std::isalpha results with UTF-8 locale on illumos

[alp at rsu dot ru]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58628

--- Comment #4 from Alexander Pyhalov <alp at rsu dot ru> ---
If it helps, the last comment from illumos-gate bug report says

"From what I can tell ctype<wchar_t>::_M_initialize_ctype() in
gcc-5.1.0/ibstdc++-v3/config/locale/generic/ctype_members.cc:248 is basically
just calling btowc(i) for all i <= 0 <= 255 and storing the result. If
std::locale::classic() is called before the setlocale() call in the test
program, things happen to work, but apparently the initialization uses whatever
the current locale is."