Implement case-insensitive and Unicode-compliant collation on MS-Windows.

 src/fns.c (Fstring_collate_lessp, Fstring_collate_equalp): Doc fix.
 src/w32proc.c (w32_compare_strings): Accept additional argument
 IGNORE_CASE.  Set up the flags for CompareStringW to ignore case
 if requested.  If w32-collate-ignore-punctuation is non-nil, add
 NORM_IGNORESYMBOLS to the flags.
 (LINGUISTIC_IGNORECASE): Define if not already defined.
 (syms_of_ntproc) <Vw32_collate_ignore_punctuation>: New variable.
 src/sysdep.c (str_collate) [WINDOWSNT]: Adapt to the interface
 change.
 src/w32.h: Adjust prototype of w32_compare_strings.

 etc/NEWS: Mention w32-collate-ignore-punctuation.

Fixes: debbugs:18051

5 files changed, 69 insertions, 14 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 66588bc3e67..181a43d058f 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,17 @@
+2014-08-29  Eli Zaretskii  <eliz@gnu.org>
+
+        * fns.c (Fstring_collate_lessp, Fstring_collate_equalp): Doc fix.
+
+        * w32proc.c (w32_compare_strings): Accept additional argument
+        IGNORE_CASE.  Set up the flags for CompareStringW to ignore case
+        if requested.  If w32-collate-ignore-punctuation is non-nil, add
+        NORM_IGNORESYMBOLS to the flags.
+        (LINGUISTIC_IGNORECASE): Define if not already defined.
+        (syms_of_ntproc) <Vw32_collate_ignore_punctuation>: New variable.
+
+        * sysdep.c (str_collate) [WINDOWSNT]: Adapt to the interface
+        change.
+
 2014-08-29  Michael Albinus  <michael.albinus@gmx.de>
 
         * sysdep.c (LC_CTYPE, LC_CTYPE_MASK, towlower_l):
diff --git a/src/fns.c b/src/fns.c
index 3cca40df50f..f838599230b 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -350,7 +350,7 @@ Symbols are also allowed; their print names are used instead.
 
 This function obeys the conventions for collation order in your
 locale settings.  For example, punctuation and whitespace characters
-are considered less significant for sorting:
+might be considered less significant for sorting:
 
 \(sort '\("11" "12" "1 1" "1 2" "1.1" "1.2") 'string-collate-lessp)
   => \("11" "1 1" "1.1" "12" "1 2" "1.2")
@@ -358,11 +358,15 @@ are considered less significant for sorting:
 The optional argument LOCALE, a string, overrides the setting of your
 current locale identifier for collation.  The value is system
 dependent; a LOCALE \"en_US.UTF-8\" is applicable on POSIX systems,
-while it would be \"English_USA.1252\" on MS Windows systems.
+while it would be, e.g., \"enu_USA.1252\" on MS-Windows systems.
 
 If IGNORE-CASE is non-nil, characters are converted to lower-case
 before comparing them.
 
+To emulate Unicode-compliant collation on MS-Windows systems,
+bind `w32-collate-ignore-punctuation' to a non-nil value, since
+the codeset part of the locale cannot be \"UTF-8\" on MS-Windows.
+
 If your system does not support a locale environment, this function
 behaves like `string-lessp'.  */)
   (Lisp_Object s1, Lisp_Object s2, Lisp_Object locale, Lisp_Object ignore_case)
@@ -391,8 +395,8 @@ Symbols are also allowed; their print names are used instead.
 
 This function obeys the conventions for collation order in your locale
 settings.  For example, characters with different coding points but
-the same meaning are considered as equal, like different grave accent
-unicode characters:
+the same meaning might be considered as equal, like different grave
+accent Unicode characters:
 
 \(string-collate-equalp \(string ?\\uFF40) \(string ?\\u1FEF))
   => t
@@ -400,13 +404,20 @@ unicode characters:
 The optional argument LOCALE, a string, overrides the setting of your
 current locale identifier for collation.  The value is system
 dependent; a LOCALE \"en_US.UTF-8\" is applicable on POSIX systems,
-while it would be \"English_USA.1252\" on MS Windows systems.
+while it would be \"enu_USA.1252\" on MS Windows systems.
 
 If IGNORE-CASE is non-nil, characters are converted to lower-case
 before comparing them.
 
+To emulate Unicode-compliant collation on MS-Windows systems,
+bind `w32-collate-ignore-punctuation' to a non-nil value, since
+the codeset part of the locale cannot be \"UTF-8\" on MS-Windows.
+
 If your system does not support a locale environment, this function
-behaves like `string-equal'.  */)
+behaves like `string-equal'.
+
+Do NOT use this function to compare file names for equality, only
+for sorting them.  */)
   (Lisp_Object s1, Lisp_Object s2, Lisp_Object locale, Lisp_Object ignore_case)
 {
 #if defined __STDC_ISO_10646__ || defined WINDOWSNT
diff --git a/src/sysdep.c b/src/sysdep.c
index 7993a59e721..52a72385f46 100644
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -3796,6 +3796,6 @@ str_collate (Lisp_Object s1, Lisp_Object s2,
 
   char *loc = STRINGP (locale) ? SSDATA (locale) : NULL;
 
-  return w32_compare_strings (SDATA (s1), SDATA (s2), loc);
+  return w32_compare_strings (SDATA (s1), SDATA (s2), loc, !NILP (ignore_case));
 }
 #endif  /* WINDOWSNT */
diff --git a/src/w32.h b/src/w32.h
index 68ee14c70e3..2cc179a0c36 100644
--- a/src/w32.h
+++ b/src/w32.h
@@ -211,7 +211,7 @@ extern int w32_memory_info (unsigned long long *, unsigned long long *,
                             unsigned long long *, unsigned long long *);
 
 /* Compare 2 UTF-8 strings in locale-dependent fashion.  */
-extern int w32_compare_strings (const char *, const char *, char *);
+extern int w32_compare_strings (const char *, const char *, char *, int);
 
 #ifdef HAVE_GNUTLS
 #include <gnutls/gnutls.h>
diff --git a/src/w32proc.c b/src/w32proc.c
index ed62de02433..0b441d45186 100644
--- a/src/w32proc.c
+++ b/src/w32proc.c
@@ -3213,15 +3213,20 @@ get_lcid (const char *locale_name)
 #ifndef _NSLCMPERROR
 # define _NSLCMPERROR INT_MAX
 #endif
+#ifndef LINGUISTIC_IGNORECASE
+# define LINGUISTIC_IGNORECASE  0x00000010
+#endif
 
 int
-w32_compare_strings (const char *s1, const char *s2, char *locname)
+w32_compare_strings (const char *s1, const char *s2, char *locname,
+                     int ignore_case)
 {
   LCID lcid = GetThreadLocale ();
   wchar_t *string1_w, *string2_w;
   int val, needed;
   extern BOOL g_b_init_compare_string_w;
   static int (WINAPI *pCompareStringW)(LCID, DWORD, LPCWSTR, int, LPCWSTR, int);
+  DWORD flags = 0;
 
   USE_SAFE_ALLOCA;
 
@@ -3284,11 +3289,22 @@ w32_compare_strings (const char *s1, const char *s2, char *locname)
         lcid = new_lcid;
     }
 
-  /* FIXME: Need a way to control the FLAGS argument, perhaps via the
-     CODESET part of LOCNAME.  In particular, ls-lisp will want
-     NORM_IGNORESYMBOLS and sometimes LINGUISTIC_IGNORECASE or
-     NORM_IGNORECASE.  */
-  val = pCompareStringW (lcid, 0, string1_w, -1, string2_w, -1);
+  if (ignore_case)
+    {
+      /* NORM_IGNORECASE ignores any tertiary distinction, not just
+         case variants.  LINGUISTIC_IGNORECASE is more selective, and
+         is sensitive to the locale's language, but it is not
+         available before Vista.  */
+      if (w32_major_version >= 6)
+        flags |= LINGUISTIC_IGNORECASE;
+      else
+        flags |= NORM_IGNORECASE;
+    }
+  /* This approximates what glibc collation functions do when the
+     locale's codeset is UTF-8.  */
+  if (!NILP (Vw32_collate_ignore_punctuation))
+    flags |= NORM_IGNORESYMBOLS;
+  val = pCompareStringW (lcid, flags, string1_w, -1, string2_w, -1);
   SAFE_FREE ();
   if (!val)
     {
@@ -3408,6 +3424,20 @@ Any other non-nil value means do this even on remote and removable drives
 where the performance impact may be noticeable even on modern hardware.  */);
   Vw32_get_true_file_attributes = Qlocal;
 
+  DEFVAR_LISP ("w32-collate-ignore-punctuation",
+               Vw32_collate_ignore_punctuation,
+               doc: /* Non-nil causes string collation functions ignore punctuation on MS-Windows.
+On Posix platforms, `string-collate-lessp' and `string-collate-equalp'
+ignore punctuation characters when they compare strings, if the
+locale's codeset is UTF-8, as in \"en_US.UTF-8\".  Binding this option
+to a non-nil value will achieve a similar effect on MS-Windows, where
+locales with UTF-8 codeset are not supported.
+
+Note that setting this to non-nil will also ignore blanks and symbols
+in the strings.  So do NOT use this option when comparing file names
+for equality, only when you need to sort them.  */);
+  Vw32_collate_ignore_punctuation = Qnil;
+
   staticpro (&Vw32_valid_locale_ids);
   staticpro (&Vw32_valid_codepages);
 }