Re: Exception problem with locale with g++ on Windows

[Liu Hao <lh_mouse at 126 dot com>]

On 2017/2/21 3:33, Marvin Gülker wrote:
> the following program should switch to the current locale and then print
> the name of that locale:
> [...]
> It appears, however, that it doesn't do that on my 32-bits Windows 7.
> The program compiles fine, but when I execute it, I get this (after
> the usual "application has requested the runtime yadda yadda"):
>
>     terminate called after throwing an instance of 'std::runtime_error'
>       what(): locale::facet::_S_create_c_locale name not valid
>
> (That is, an std::runtime_error exception is thrown by the constructor
> of std::locale)
I compiled and ran the program and it didn't generate any exceptions on 
my 64-bit Windows 7:

    E:\Desktop>g++ test.cc -std=c++14 -Wall -Wextra -pedantic

    E:\Desktop>a.exe
    Locale is now: C

    E:\Desktop>g++ --version
    g++ (gcc-6-branch HEAD with MCF thread model, built by LH_Mouse.) 
6.3.1 20170218
    Copyright (C) 2016 Free Software Foundation, Inc.
    This is free software; see the source for copying conditions. There 
is NO
    warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR 
PURPOSE.

> I used the locale name "" (empty string), which should refer to the
> environment's locale and should be available on any platform (I even
> think it is required to do that, but I don't have a C++ standard at
> hand). Using the "C" locale works, but any other value causes the above
> problem.
You are right. See [locale.cons]/6:

    explicit locale(const char* std_name);
    6 Remarks: The set of valid string argument values is "C", "", and
      any implementation-defined values.

> Can someone please clarify what exactly is the problem with the C++
> variant of this program, and how one can get it to work on Windows?
>
>     $ g++ --version
>     g++.exe (Rev1, Built by MSYS2 project) 6.3.0
>     Copyright (C) 2016 Free Software Foundation, Inc.
>     This is free software; see the source for copying conditions.  There is NO
>     warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
I can't reproduce this problem. It seems that your environment is 
broken. I have CC'd this message to the MSYS2 mailing list. Hope it helps.

--
Best regards,
LH_Mouse