Improve locale and language environment setting at startup

* lisp/international/mule-cmds.el (locale-language-names): Add
more locales and their language environments.
(set-locale-environment): Use w32-multibyte-code-page, if
non-zero, as locale-coding-system.  (Bug#34684)

* src/w32fns.c (globals_of_w32fns) <w32-multibyte-code-page>:
New variable.

* etc/NEWS: Mention w32-multibyte-code-page.

1 files changed, 10 insertions, 0 deletions

diff --git a/src/w32fns.c b/src/w32fns.c
index 4f53d93d8b4..1fbf32760dd 100644
--- a/src/w32fns.c
+++ b/src/w32fns.c
@@ -48,6 +48,7 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 
 #ifdef WINDOWSNT
 #include <mbstring.h>
+#include <mbctype.h>    /* for _getmbcp */
 #endif /* WINDOWSNT */
 
 #if CYGWIN
@@ -10908,6 +10909,15 @@ globals_of_w32fns (void)
               doc: /* The ANSI code page used by the system.  */);
   w32_ansi_code_page = GetACP ();
 
+#ifndef CYGWIN
+  DEFVAR_INT ("w32-multibyte-code-page",
+              w32_multibyte_code_page,
+              doc: /* The current multibyte code page used by the system.
+A value of zero indicates that the single-byte code page is in use,
+see `w32-ansi-code-page'.  */);
+  w32_multibyte_code_page = _getmbcp ();
+#endif
+
   if (os_subtype == OS_NT)
     w32_unicode_gui = 1;
   else