Like, who's sabotaging who, or is buggy, wrt. locales?

[Alf P. Steinbach]

This can cause an exception or possibly just a crash or UB, in Windows:

std::locale{ setlocale( LC_ALL, nullptr ) }

Full example program:


-------------------------------------------------------------------------
#include <iostream>
#include <locale>
#include <locale.h>
#include <stdexcept>
#include <stdlib.h>

auto main()
-> int
{
setlocale( LC_ALL, "" ); // Default national locale (UTF-8 in *nix)
setlocale( LC_NUMERIC, "C" ); // Periods as fraction
separators, please.

std::cout << "C level locale = \"" << setlocale( LC_ALL, nullptr )
<< "\"\n";

try
{
const auto& loc = std::locale{ setlocale( LC_ALL, nullptr ) };
std::cout << "C++ level locale = " << loc.name() << "\n";
return EXIT_SUCCESS;
}
catch( std::exception const& x )
{
std::cerr << "!" << x.what() << "\n";
}
catch( ... )
{
std::cerr << "!!! non-standard exception\n";
}
return EXIT_FAILURE;
}
-------------------------------------------------------------------------


Results with respectively Visual C++ and MinGW g++, in that order:


-------------------------------------------------------------------------
[P:\temp]
> cl locale-sabotage.cpp /Feb
locale-sabotage.cpp

[P:\temp]
> b
C level locale = "LC_COLLATE=Norwegian Bokmål_Svalbard and Jan
Mayen.1252;LC_CTYPE=Norwegian Bokmål_Svalbard and Jan
Mayen.1252;LC_MONETARY=Norwegian Bokmål_Svalbard and Jan
Mayen.1252;LC_NUMERIC=C;LC_TIME=Norwegian Bokmål_Svalbard and Jan
Mayen.1252"
C++ level locale = LC_COLLATE=Norwegian Bokmål_Svalbard and Jan
Mayen.1252;LC_CTYPE=Norwegian Bokmål_Svalbard and Jan
Mayen.1252;LC_MONETARY=Norwegian Bokmål_Svalbard and Jan
Mayen.1252;LC_NUMERIC=C;LC_TIME=Norwegian Bokmål_Svalbard and Jan Mayen.1252

[P:\temp]
> g++ locale-sabotage.cpp

[P:\temp]
> a
C level locale = "LC_COLLATE=Norwegian Bokmål_Svalbard and Jan
Mayen.1252;LC_CTYPE=Norwegian Bokmål_Svalbard and Jan
Mayen.1252;LC_MONETARY=Norwegian Bokmål_Svalbard and Jan
Mayen.1252;LC_NUMERIC=C;LC_TIME=Norwegian Bokmål_Svalbard and Jan
Mayen.1252"
!locale::facet::_S_create_c_locale name not valid
-------------------------------------------------------------------------


This is in Windows 10. I seem to remember that locale names were like
"no_NB.1252", and not the long descriptive text above. Has something
changed?

Because I also remember g++'s C++ level locale handling to be missing or
screwed up, so that /could/ be the problem?


Cheers!,

- Alf

[Alf P. Steinbach]

On 20.07.2018 00:23, Alf P. Steinbach wrote:
> [snip]

> Because I also remember g++'s C++ level locale handling to be missing or
> screwed up, so that /could/ be the problem?

That was the problem.

Or rather /is/ the problem.

Not so nice to have all that inefficient locale stuff in the iostreams,
when actual use of it isn't portable to one of the main compilers. :(


-----------------------------------------------------------------------------
// Source encoding: utf-8 (π should be a greek "pi" char)

#include <iostream>
#include <locale>
#include <locale.h>
#include <stdexcept>
#include <stdlib.h>

auto main()
-> int
{

setlocale( LC_ALL, "" ); // Default national locale, for UTF-8
in Unix-land.
#ifdef PERIOD
setlocale( LC_NUMERIC, "C" ); // But periods as fraction
separators, please.
#endif

std::cout << "C level locale = \"" << setlocale( LC_ALL, nullptr )
<< "\"\n";

try
{
const auto& loc =
std::locale{ "" }

#ifdef PERIOD
.combine<std::numpunct<char>>( std::locale::classic() )
#endif

;
std::cout << "C++ level locale = \"" << loc.name() << "\"\n";

std::cout.imbue( loc );
printf( "printf blåbærsyltetøy, %g.\n", 3.14 );
std::cout << "cout blåbærsyltetøy, " << 3.14 << ".\n";

return EXIT_SUCCESS;
}
catch( std::exception const& x )
{
std::cerr << "!" << x.what() << "\n";
}
catch( ... )
{
std::cerr << "!!! non-standard exception\n";
}
return EXIT_FAILURE;
}

-----------------------------------------------------------------------------


Results with MinGW g++ 7.3.0 in Windows 10:


-----------------------------------------------------------------------------
[P:\temp]
> chcp
Active code page: 1252

[P:\temp]
> g++ locale-fix.cpp && a
C level locale = "Norwegian Bokmål_Svalbard and Jan Mayen.1252"
C++ level locale = "C"
printf blåbærsyltetøy, 3,14.
cout blåbærsyltetøy, 3.14.

[P:\temp]
> g++ locale-fix.cpp -D PERIOD && a

C level locale = "LC_COLLATE=Norwegian Bokmål_Svalbard and Jan
Mayen.1252;LC_CTYPE=Norwegian Bokmål_Svalbard and Jan
Mayen.1252;LC_MONETARY=Norwegian Bokmål_Svalbard and Jan
Mayen.1252;LC_NUMERIC=C;LC_TIME=Norwegian Bokmål_Svalbard and Jan
Mayen.1252"

C++ level locale = "C"
printf blåbærsyltetøy, 3.14.
cout blåbærsyltetøy, 3.14.
-----------------------------------------------------------------------------


The C++ level locale is unaffected by anything, it just remains as "C". :(

The code works with Visual C++.


Cheers & hope this info can be useful to someone, maybe,

- Alf

[Manfred]

Looks like a problem in MinGW: the following is the result on a real
Linux VM (gcc 8.1)

-------------------------------
[user@localhost]$ c++ locale.cc && ./a.out
C level locale = "de_DE.UTF-8"
C++ level locale = "de_DE.UTF-8"
printf blåbærsyltetøy, 3,14.
cout blåbærsyltetøy, 3,14.

[user@localhost]$ c++ -DPERIOD locale.cc && ./a.out
C level locale =
"LC_CTYPE=de_DE.UTF-8;LC_NUMERIC=C;LC_TIME=de_DE.UTF-8;LC_COLLATE=de_DE.UTF-8;LC_MONETARY=de_DE.UTF-8;LC_MESSAGES=de_DE.UTF-8;LC_PAPER=de_DE.UTF-8;LC_NAME=de_DE.UTF-8;LC_ADDRESS=de_DE.UTF-8;LC_TELEPHONE=de_DE.UTF-8;LC_MEASUREMENT=de_DE.UTF-8;LC_IDENTIFICATION=de_DE.UTF-8"
C++ level locale = "de_DE.UTF-8"
printf blåbærsyltetøy, 3.14.
cout blåbærsyltetøy, 3.14.

-------------------------------