On 2023-09-21 23:56, Martin Wege via Cygwin wrote:
On Thu, Sep 21, 2023 at 9:07 PM Christian Franke via Cygwin
<cygwin@cygwin.com> wrote:
Brian Inglis via Cygwin wrote:
On 2023-09-21 10:28, Takashi Yano via Cygwin wrote:
On Fri, 22 Sep 2023 01:12:04 +0900
Takashi Yano wrote:
I wonder why the following code throws std::runtime_error
even though the LC_ALL is set to valid locale other than "C".
This does not occur only when LC_ALL is set to "C".
#include <locale>
int main()
{
std::locale("");
return 0;
}
In linux, this occurs only when the LC_ALL is set to invalid
locale (i.e. locale that is not registered in system).
Similarly,
std::locale("ja_JP.UTF-8")
throws std::runtime_error in cygwin.
Looks like the implementation does not like any default "" or explicit
"en_US.UTF-8" strings there! See example at link and below; results
are always the same:
https://en.cppreference.com/w/cpp/locale/locale
#include <iostream>
#include <locale>
int main()
{
std::wcout << "User-preferred locale setting is "
<< std::locale().name().c_str() << '\n';
// on startup, the global locale is the "C" locale
std::wcout << 1000.01 << '\n';
// replace the C++ global locale and the "C" locale with the
user-preferred locale
std::locale::global(std::locale(""));
// use the new global locale for future wide character output
std::wcout.imbue(std::locale());
// output the same number again
std::wcout << 1000.01 << '\n';
}
$ g++ -o c++locale{,.cc}
$ ./c++locale
User-preferred locale setting is C
1000.01
terminate called after throwing an instance of 'std::runtime_error'
what(): locale::facet::_S_create_c_locale name not valid
Aborted (core dumped)
According to libstdc++ source, the internal function
locale::facet::_S_create_c_locale() calls some __newlocale() which
apparently does not arrive at newlocale() from cygwin1.dll. But
cygstdc++-6.dll imports newlocale() from cygwin1.dll.
So this is a BUG?
Only standard locale "C" and its alias "POSIX" work with C++ std::locale().
The cygwin1.dll function newlocale() works as expected - except that it
does not set errno if the locale name is invalid.
As this is (presumably) conforming code from the reference website, this
certainly appears as if the current Cygwin implmentation may be non-conforming,
and less than useful for many users and uses.
--
Take care. Thanks, Brian Inglis Calgary, Alberta, Canada
La perfection est atteinte Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter not when there is no more to add
mais lorsqu'il n'y a plus rien à retirer but when there is no more to cut
-- Antoine de Saint-Exupéry
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