newlocale: Linux incompatibility

[Ken Brown]

I'm reporting this here rather than the newlib list because the behavior 
is compatible with Posix but not Linux, so I think it's a Cygwin issue.

Consider the following test case:

$ cat locale_test.c
#include <stdio.h>
#include <locale.h>

int main ()
{
   const char *locale = "en_DE.UTF-8";
   locale_t loc = newlocale (LC_COLLATE_MASK | LC_CTYPE_MASK, locale, 0);
   if (!loc)
     perror ("newlocale");
   else
     printf ("newlocale succeeded on invalid locale %s\n", locale);
}

$ gcc -o locale_test locale_test.c

$ ./locale_test.exe
newlocale succeeded on invalid locale en_DE.UTF-8

On Linux, the newlocale call fails with ENOENT, as is documented on the 
man page.  Posix doesn't say what should happen on an invalid locale, so 
this is not, strictly speaking, a bug.

Ken

P.S. I noticed this because of a failing Emacs test.  No one else has 
reported this test failure, so it seems that newlocale fails on an 
invalid locale on all platforms supported by Emacs other than Cygwin.