> perl -MPOSIX="setlocale" -le "$loc = setlocale( LC_ALL, 'Korean_Korea.949' ); print 'LOCALE: ' . $loc;"
Locale 'Korean_Korea.949' is unsupported, and may crash the interpreter.
LOCALE: Korean_Korea.949

##</code><code>##

### try.pl ###
use strict;
use warnings;

use Inline C => <<'EOC';

void foo() {
  Perl_ck_warner_d(aTHX_ packWARN(WARN_LOCALE),
                   "Locale is unsupported, and may crash the"
                   " interpreter.\n"
                  );
}

void bar() {
  Perl_ck_warner_d(aTHX_ packWARN(WARN_LOCALE),
                   "Locale is unsupported, and may crash the"
                   " interpreter"
                  );
}

EOC

foo();
bar();

__END__

Outputs:
Locale is unsupported, and may crash the interpreter.
Locale is unsupported, and may crash the interpreter at try.pl line 24.