Implement locale-sensitive string collation for MS-Windows. (Bug#18051)

 src/w32proc.c (get_lcid_callback, get_lcid, w32_compare_strings):
 New functions.
 src/w32.h (w32_compare_strings): Add prototype.
 src/w32.c <g_b_init_compare_string_w>: New global flag.
 (globals_of_w32): Initialize it.
 src/sysdep.c (str_collate) [WINDOWSNT]: Implementation for MS-Windows.
 src/fns.c (Fstring_collate_lessp, Fstring_collate_equalp)
 [WINDOWSNT]: Call str_collate on MS-Windows.

 etc/NEWS: Mention that string-collate-* functions are supported on
 MS-Windows as well.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/sysdep.c b/src/sysdep.c
index 856d668bb71..25bec264f46 100644
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -3592,3 +3592,15 @@ str_collate (Lisp_Object s1, Lisp_Object s2)
   return res;
 }
 #endif /* __STDC_ISO_10646__ */
+
+#ifdef WINDOWSNT
+ptrdiff_t
+str_collate (Lisp_Object s1, Lisp_Object s2)
+{
+  Lisp_Object lc_collate =
+    Fgetenv_internal (build_string ("LC_COLLATE"), Vprocess_environment);
+  char *loc = STRINGP (lc_collate) ? SSDATA (lc_collate) : NULL;
+
+  return w32_compare_strings (SDATA (s1), SDATA (s2), loc);
+}
+#endif  /* WINDOWSNT */