24861 (with tweaks): logic to use alternative wcwidth() if needed;

slightly improve test for overwriting with combining characters.

12 files changed, 434 insertions, 27 deletions

diff --git a/ChangeLog b/ChangeLog
index 3f8cbad7a..be81c4cbc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2008-04-22  Peter Stephenson  <pws@csr.com>
+
+	* 24861: configure.ac, Src/builtin.c, Src/compat.c, Src/prompt.c,
+	Src/utils.c, Src/zsh.h, Src/zle/complist.c, Src/Zle/zle_misc.c
+	(slightly rewritten), Src/zle/zle_refresh.c, Src/Zle/zle_tricky.c:
+	use alternative wcwidth() if configure suggests the library
+	version is returning non-zero when it shouldn't; also improve the
+	overwriting test for combining characters.
+
 2008-04-21  Peter Stephenson  <pws@csr.com>
 
 	* 24860: Src/Zle/zle_misc.c, Src/Zle/zle_utils.c: better
diff --git a/Src/Zle/complist.c b/Src/Zle/complist.c
index 651a5103c..1543a1506 100644
--- a/Src/Zle/complist.c
+++ b/Src/Zle/complist.c
@@ -1017,7 +1017,7 @@ compprintfmt(char *fmt, int n, int dopr, int doesc, int ml, int *stop)
 	}
 	else
 #endif
-	    width = WCWIDTH(cchar);
+	    width = WCWIDTH_WINT(cchar);
 
 	if (doesc && cchar == ZWC('%')) {
 	    p += len;
diff --git a/Src/Zle/zle_hist.c b/Src/Zle/zle_hist.c
index 5af482f9e..91d2d1016 100644
--- a/Src/Zle/zle_hist.c
+++ b/Src/Zle/zle_hist.c
@@ -1045,6 +1045,7 @@ doisearch(char **args, int dir)
 		free(last_line);
 	    last_line = ztrdup(zt.text);
 
+	    sbuf[sbptr] = '\0';
 	    for (;;) {
 		char *t;
 
@@ -1076,7 +1077,6 @@ doisearch(char **args, int dir)
 		 * First search for a(nother) match within the
 		 * current line, unless we've been told to skip it.
 		 */
-		sbuf[sbptr] = '\0';
 		if (!skip_line && ((sbuf[0] == '^') ?
 				   (t = (zlinecmp(zt.text, sbuf + 1) < sens
 					 ? zt.text : NULL)) :
diff --git a/Src/Zle/zle_misc.c b/Src/Zle/zle_misc.c
index d3a9413f3..554830244 100644
--- a/Src/Zle/zle_misc.c
+++ b/Src/Zle/zle_misc.c
@@ -59,10 +59,16 @@ doinsert(ZLE_STRING_T zstr, int len)
 	 * (i.e. even if control, or double width, or with combining
 	 * characters) is treated as 1 for the purpose of replacing
 	 * what's there already.
+	 *
+	 * This can cause inserting of a combining character in
+	 * places where it should overwrite, such as the start
+	 * of a line.  However, combining characters aren't
+	 * useful there anyway and this doesn't cause any
+	 * particular harm.
 	 */
 	for (i = 0, count = 0; i < len; i++) {
-	    int width = wcwidth(zstr[i]);
-	    count += (width != 0) ? 1 : 0;
+	    if (!IS_COMBINING(zstr[i]))
+		count++;
 	}
 	/*
 	 * Ensure we replace a complete combining character
diff --git a/Src/Zle/zle_refresh.c b/Src/Zle/zle_refresh.c
index a9bc017f8..66cae9f97 100644
--- a/Src/Zle/zle_refresh.c
+++ b/Src/Zle/zle_refresh.c
@@ -1222,7 +1222,7 @@ zrefresh(void)
 	    }
 	}
 #ifdef MULTIBYTE_SUPPORT
-	else if (iswprint(*t) && (width = wcwidth(*t)) > 0) {
+	else if (iswprint(*t) && (width = WCWIDTH(*t)) > 0) {
 	    int ichars;
 	    if (width > rpms.sen - rpms.s) {
 		int started = 0;
@@ -1397,7 +1397,7 @@ zrefresh(void)
 	for (; u < outputline + outll; u++) {
 #ifdef MULTIBYTE_SUPPORT
 	    if (iswprint(*u)) {
-		int width = wcwidth(*u);
+		int width = WCWIDTH(*u);
 		/* Handle wide characters as above */
 		if (width > rpms.sen - rpms.s) {
 		    do {
@@ -2144,7 +2144,7 @@ tc_rightcurs(int ct)
    characters occupying more than one column.  We could flag that
    this has happened (since it's not that common to have characters
    wider than one column), but for now it's easier not to use the
-   trick if we are using wcwidth() on the prompt.  It's not that
+   trick if we are using WCWIDTH() on the prompt.  It's not that
    common to be editing in the middle of the prompt anyway, I would
    think.
    */
@@ -2264,7 +2264,7 @@ singlerefresh(ZLE_STRING_T tmpline, int tmpll, int tmpcs)
 	if (tmpline[t0] == ZWC('\t'))
 	    vsiz = (vsiz | 7) + 2;
 #ifdef MULTIBYTE_SUPPORT
-	else if (iswprint(tmpline[t0]) && (width = wcwidth(tmpline[t0]) > 0)) {
+	else if (iswprint(tmpline[t0]) && (width = WCWIDTH(tmpline[t0]) > 0)) {
 	    vsiz += width;
 	    if (isset(COMBININGCHARS) && IS_BASECHAR(tmpline[t0])) {
 		while (t0 < tmpll-1 && IS_COMBINING(tmpline[t0+1]))
@@ -2340,7 +2340,7 @@ singlerefresh(ZLE_STRING_T tmpline, int tmpll, int tmpcs)
 	    vp++;
 #ifdef MULTIBYTE_SUPPORT
 	} else if (iswprint(tmpline[t0]) &&
-		   (width = wcwidth(tmpline[t0])) > 0) {
+		   (width = WCWIDTH(tmpline[t0])) > 0) {
 	    int ichars;
 	    if (isset(COMBININGCHARS) && IS_BASECHAR(tmpline[t0])) {
 		/*
diff --git a/Src/Zle/zle_tricky.c b/Src/Zle/zle_tricky.c
index d7c17676b..a6083764b 100644
--- a/Src/Zle/zle_tricky.c
+++ b/Src/Zle/zle_tricky.c
@@ -2375,7 +2375,7 @@ printfmt(char *fmt, int n, int dopr, int doesc)
 		    }
 		} else
 		    p += clen;
-		cc += WCWIDTH(cchar);
+		cc += WCWIDTH_WINT(cchar);
 		if (dopr && !(cc % columns))
 			fputs(" \010", shout);
 	    }
diff --git a/Src/builtin.c b/Src/builtin.c
index 75dd19d54..a9f181419 100644
--- a/Src/builtin.c
+++ b/Src/builtin.c
@@ -3668,7 +3668,7 @@ bin_print(char *name, char **args, Options ops, int func)
 			width += l;
 			break;
 		    }
-		    wcw = wcwidth(wc);
+		    wcw = WCWIDTH(wc);
 		    /* treat unprintable as 0 */
 		    if (wcw > 0)
 			width += wcw;
diff --git a/Src/compat.c b/Src/compat.c
index 334af45a5..38f24d7fe 100644
--- a/Src/compat.c
+++ b/Src/compat.c
@@ -549,4 +549,327 @@ strtoul(nptr, endptr, base)
 		*endptr = any ? s - 1 : nptr;
 	return (acc);
 }
-#endif
+#endif /* HAVE_STRTOUL */
+
+/**/
+#ifdef BROKEN_WCWIDTH
+
+/*
+ * This is an implementation of wcwidth() and wcswidth() (defined in
+ * IEEE Std 1002.1-2001) for Unicode.
+ *
+ * http://www.opengroup.org/onlinepubs/007904975/functions/wcwidth.html
+ * http://www.opengroup.org/onlinepubs/007904975/functions/wcswidth.html
+ *
+ * In fixed-width output devices, Latin characters all occupy a single
+ * "cell" position of equal width, whereas ideographic CJK characters
+ * occupy two such cells. Interoperability between terminal-line
+ * applications and (teletype-style) character terminals using the
+ * UTF-8 encoding requires agreement on which character should advance
+ * the cursor by how many cell positions. No established formal
+ * standards exist at present on which Unicode character shall occupy
+ * how many cell positions on character terminals. These routines are
+ * a first attempt of defining such behavior based on simple rules
+ * applied to data provided by the Unicode Consortium.
+ *
+ * For some graphical characters, the Unicode standard explicitly
+ * defines a character-cell width via the definition of the East Asian
+ * FullWidth (F), Wide (W), Half-width (H), and Narrow (Na) classes.
+ * In all these cases, there is no ambiguity about which width a
+ * terminal shall use. For characters in the East Asian Ambiguous (A)
+ * class, the width choice depends purely on a preference of backward
+ * compatibility with either historic CJK or Western practice.
+ * Choosing single-width for these characters is easy to justify as
+ * the appropriate long-term solution, as the CJK practice of
+ * displaying these characters as double-width comes from historic
+ * implementation simplicity (8-bit encoded characters were displayed
+ * single-width and 16-bit ones double-width, even for Greek,
+ * Cyrillic, etc.) and not any typographic considerations.
+ *
+ * Much less clear is the choice of width for the Not East Asian
+ * (Neutral) class. Existing practice does not dictate a width for any
+ * of these characters. It would nevertheless make sense
+ * typographically to allocate two character cells to characters such
+ * as for instance EM SPACE or VOLUME INTEGRAL, which cannot be
+ * represented adequately with a single-width glyph. The following
+ * routines at present merely assign a single-cell width to all
+ * neutral characters, in the interest of simplicity. This is not
+ * entirely satisfactory and should be reconsidered before
+ * establishing a formal standard in this area. At the moment, the
+ * decision which Not East Asian (Neutral) characters should be
+ * represented by double-width glyphs cannot yet be answered by
+ * applying a simple rule from the Unicode database content. Setting
+ * up a proper standard for the behavior of UTF-8 character terminals
+ * will require a careful analysis not only of each Unicode character,
+ * but also of each presentation form, something the author of these
+ * routines has avoided to do so far.
+ *
+ * http://www.unicode.org/unicode/reports/tr11/
+ *
+ * Markus Kuhn -- 2007-05-26 (Unicode 5.0)
+ *
+ * Permission to use, copy, modify, and distribute this software
+ * for any purpose and without fee is hereby granted. The author
+ * disclaims all warranties with regard to this software.
+ *
+ * Latest version: http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c
+ */
+
+struct interval {
+  int first;
+  int last;
+};
+
+/* auxiliary function for binary search in interval table */
+static int bisearch(wchar_t ucs, const struct interval *table, int max) {
+  int min = 0;
+  int mid;
+
+  if (ucs < table[0].first || ucs > table[max].last)
+    return 0;
+  while (max >= min) {
+    mid = (min + max) / 2;
+    if (ucs > table[mid].last)
+      min = mid + 1;
+    else if (ucs < table[mid].first)
+      max = mid - 1;
+    else
+      return 1;
+  }
+
+  return 0;
+}
+
+
+/* The following two functions define the column width of an ISO 10646
+ * character as follows:
+ *
+ *    - The null character (U+0000) has a column width of 0.
+ *
+ *    - Other C0/C1 control characters and DEL will lead to a return
+ *      value of -1.
+ *
+ *    - Non-spacing and enclosing combining characters (general
+ *      category code Mn or Me in the Unicode database) have a
+ *      column width of 0.
+ *
+ *    - SOFT HYPHEN (U+00AD) has a column width of 1.
+ *
+ *    - Other format characters (general category code Cf in the Unicode
+ *      database) and ZERO WIDTH SPACE (U+200B) have a column width of 0.
+ *
+ *    - Hangul Jamo medial vowels and final consonants (U+1160-U+11FF)
+ *      have a column width of 0.
+ *
+ *    - Spacing characters in the East Asian Wide (W) or East Asian
+ *      Full-width (F) category as defined in Unicode Technical
+ *      Report #11 have a column width of 2.
+ *
+ *    - All remaining characters (including all printable
+ *      ISO 8859-1 and WGL4 characters, Unicode control characters,
+ *      etc.) have a column width of 1.
+ *
+ * This implementation assumes that wchar_t characters are encoded
+ * in ISO 10646.
+ */
+
+/**/
+int
+mk_wcwidth(wchar_t ucs)
+{
+  /* sorted list of non-overlapping intervals of non-spacing characters */
+  /* generated by "uniset +cat=Me +cat=Mn +cat=Cf -00AD +1160-11FF +200B c" */
+  static const struct interval combining[] = {
+    { 0x0300, 0x036F }, { 0x0483, 0x0486 }, { 0x0488, 0x0489 },
+    { 0x0591, 0x05BD }, { 0x05BF, 0x05BF }, { 0x05C1, 0x05C2 },
+    { 0x05C4, 0x05C5 }, { 0x05C7, 0x05C7 }, { 0x0600, 0x0603 },
+    { 0x0610, 0x0615 }, { 0x064B, 0x065E }, { 0x0670, 0x0670 },
+    { 0x06D6, 0x06E4 }, { 0x06E7, 0x06E8 }, { 0x06EA, 0x06ED },
+    { 0x070F, 0x070F }, { 0x0711, 0x0711 }, { 0x0730, 0x074A },
+    { 0x07A6, 0x07B0 }, { 0x07EB, 0x07F3 }, { 0x0901, 0x0902 },
+    { 0x093C, 0x093C }, { 0x0941, 0x0948 }, { 0x094D, 0x094D },
+    { 0x0951, 0x0954 }, { 0x0962, 0x0963 }, { 0x0981, 0x0981 },
+    { 0x09BC, 0x09BC }, { 0x09C1, 0x09C4 }, { 0x09CD, 0x09CD },
+    { 0x09E2, 0x09E3 }, { 0x0A01, 0x0A02 }, { 0x0A3C, 0x0A3C },
+    { 0x0A41, 0x0A42 }, { 0x0A47, 0x0A48 }, { 0x0A4B, 0x0A4D },
+    { 0x0A70, 0x0A71 }, { 0x0A81, 0x0A82 }, { 0x0ABC, 0x0ABC },
+    { 0x0AC1, 0x0AC5 }, { 0x0AC7, 0x0AC8 }, { 0x0ACD, 0x0ACD },
+    { 0x0AE2, 0x0AE3 }, { 0x0B01, 0x0B01 }, { 0x0B3C, 0x0B3C },
+    { 0x0B3F, 0x0B3F }, { 0x0B41, 0x0B43 }, { 0x0B4D, 0x0B4D },
+    { 0x0B56, 0x0B56 }, { 0x0B82, 0x0B82 }, { 0x0BC0, 0x0BC0 },
+    { 0x0BCD, 0x0BCD }, { 0x0C3E, 0x0C40 }, { 0x0C46, 0x0C48 },
+    { 0x0C4A, 0x0C4D }, { 0x0C55, 0x0C56 }, { 0x0CBC, 0x0CBC },
+    { 0x0CBF, 0x0CBF }, { 0x0CC6, 0x0CC6 }, { 0x0CCC, 0x0CCD },
+    { 0x0CE2, 0x0CE3 }, { 0x0D41, 0x0D43 }, { 0x0D4D, 0x0D4D },
+    { 0x0DCA, 0x0DCA }, { 0x0DD2, 0x0DD4 }, { 0x0DD6, 0x0DD6 },
+    { 0x0E31, 0x0E31 }, { 0x0E34, 0x0E3A }, { 0x0E47, 0x0E4E },
+    { 0x0EB1, 0x0EB1 }, { 0x0EB4, 0x0EB9 }, { 0x0EBB, 0x0EBC },
+    { 0x0EC8, 0x0ECD }, { 0x0F18, 0x0F19 }, { 0x0F35, 0x0F35 },
+    { 0x0F37, 0x0F37 }, { 0x0F39, 0x0F39 }, { 0x0F71, 0x0F7E },
+    { 0x0F80, 0x0F84 }, { 0x0F86, 0x0F87 }, { 0x0F90, 0x0F97 },
+    { 0x0F99, 0x0FBC }, { 0x0FC6, 0x0FC6 }, { 0x102D, 0x1030 },
+    { 0x1032, 0x1032 }, { 0x1036, 0x1037 }, { 0x1039, 0x1039 },
+    { 0x1058, 0x1059 }, { 0x1160, 0x11FF }, { 0x135F, 0x135F },
+    { 0x1712, 0x1714 }, { 0x1732, 0x1734 }, { 0x1752, 0x1753 },
+    { 0x1772, 0x1773 }, { 0x17B4, 0x17B5 }, { 0x17B7, 0x17BD },
+    { 0x17C6, 0x17C6 }, { 0x17C9, 0x17D3 }, { 0x17DD, 0x17DD },
+    { 0x180B, 0x180D }, { 0x18A9, 0x18A9 }, { 0x1920, 0x1922 },
+    { 0x1927, 0x1928 }, { 0x1932, 0x1932 }, { 0x1939, 0x193B },
+    { 0x1A17, 0x1A18 }, { 0x1B00, 0x1B03 }, { 0x1B34, 0x1B34 },
+    { 0x1B36, 0x1B3A }, { 0x1B3C, 0x1B3C }, { 0x1B42, 0x1B42 },
+    { 0x1B6B, 0x1B73 }, { 0x1DC0, 0x1DCA }, { 0x1DFE, 0x1DFF },
+    { 0x200B, 0x200F }, { 0x202A, 0x202E }, { 0x2060, 0x2063 },
+    { 0x206A, 0x206F }, { 0x20D0, 0x20EF }, { 0x302A, 0x302F },
+    { 0x3099, 0x309A }, { 0xA806, 0xA806 }, { 0xA80B, 0xA80B },
+    { 0xA825, 0xA826 }, { 0xFB1E, 0xFB1E }, { 0xFE00, 0xFE0F },
+    { 0xFE20, 0xFE23 }, { 0xFEFF, 0xFEFF }, { 0xFFF9, 0xFFFB },
+    { 0x10A01, 0x10A03 }, { 0x10A05, 0x10A06 }, { 0x10A0C, 0x10A0F },
+    { 0x10A38, 0x10A3A }, { 0x10A3F, 0x10A3F }, { 0x1D167, 0x1D169 },
+    { 0x1D173, 0x1D182 }, { 0x1D185, 0x1D18B }, { 0x1D1AA, 0x1D1AD },
+    { 0x1D242, 0x1D244 }, { 0xE0001, 0xE0001 }, { 0xE0020, 0xE007F },
+    { 0xE0100, 0xE01EF }
+  };
+
+  /* test for 8-bit control characters */
+  if (ucs == 0)
+    return 0;
+  if (ucs < 32 || (ucs >= 0x7f && ucs < 0xa0))
+    return -1;
+
+  /* binary search in table of non-spacing characters */
+  if (bisearch(ucs, combining,
+	       sizeof(combining) / sizeof(struct interval) - 1))
+    return 0;
+
+  /* if we arrive here, ucs is not a combining or C0/C1 control character */
+
+  return 1 + 
+    (ucs >= 0x1100 &&
+     (ucs <= 0x115f ||                    /* Hangul Jamo init. consonants */
+      ucs == 0x2329 || ucs == 0x232a ||
+      (ucs >= 0x2e80 && ucs <= 0xa4cf &&
+       ucs != 0x303f) ||                  /* CJK ... Yi */
+      (ucs >= 0xac00 && ucs <= 0xd7a3) || /* Hangul Syllables */
+      (ucs >= 0xf900 && ucs <= 0xfaff) || /* CJK Compatibility Ideographs */
+      (ucs >= 0xfe10 && ucs <= 0xfe19) || /* Vertical forms */
+      (ucs >= 0xfe30 && ucs <= 0xfe6f) || /* CJK Compatibility Forms */
+      (ucs >= 0xff00 && ucs <= 0xff60) || /* Fullwidth Forms */
+      (ucs >= 0xffe0 && ucs <= 0xffe6) ||
+      (ucs >= 0x20000 && ucs <= 0x2fffd) ||
+      (ucs >= 0x30000 && ucs <= 0x3fffd)));
+}
+
+
+/*
+ * The following functions are part of the original wcwidth.c:
+ * we don't use them but I've kept them in case - pws.
+ */
+#if 0
+int mk_wcswidth(const wchar_t *pwcs, size_t n)
+{
+  int w, width = 0;
+
+  for (;*pwcs && n-- > 0; pwcs++)
+    if ((w = mk_wcwidth(*pwcs)) < 0)
+      return -1;
+    else
+      width += w;
+
+  return width;
+}
+
+
+/*
+ * The following functions are the same as mk_wcwidth() and
+ * mk_wcswidth(), except that spacing characters in the East Asian
+ * Ambiguous (A) category as defined in Unicode Technical Report #11
+ * have a column width of 2. This variant might be useful for users of
+ * CJK legacy encodings who want to migrate to UCS without changing
+ * the traditional terminal character-width behaviour. It is not
+ * otherwise recommended for general use.
+ */
+int mk_wcwidth_cjk(wchar_t ucs)
+{
+  /* sorted list of non-overlapping intervals of East Asian Ambiguous
+   * characters, generated by "uniset +WIDTH-A -cat=Me -cat=Mn -cat=Cf c" */
+  static const struct interval ambiguous[] = {
+    { 0x00A1, 0x00A1 }, { 0x00A4, 0x00A4 }, { 0x00A7, 0x00A8 },
+    { 0x00AA, 0x00AA }, { 0x00AE, 0x00AE }, { 0x00B0, 0x00B4 },
+    { 0x00B6, 0x00BA }, { 0x00BC, 0x00BF }, { 0x00C6, 0x00C6 },
+    { 0x00D0, 0x00D0 }, { 0x00D7, 0x00D8 }, { 0x00DE, 0x00E1 },
+    { 0x00E6, 0x00E6 }, { 0x00E8, 0x00EA }, { 0x00EC, 0x00ED },
+    { 0x00F0, 0x00F0 }, { 0x00F2, 0x00F3 }, { 0x00F7, 0x00FA },
+    { 0x00FC, 0x00FC }, { 0x00FE, 0x00FE }, { 0x0101, 0x0101 },
+    { 0x0111, 0x0111 }, { 0x0113, 0x0113 }, { 0x011B, 0x011B },
+    { 0x0126, 0x0127 }, { 0x012B, 0x012B }, { 0x0131, 0x0133 },
+    { 0x0138, 0x0138 }, { 0x013F, 0x0142 }, { 0x0144, 0x0144 },
+    { 0x0148, 0x014B }, { 0x014D, 0x014D }, { 0x0152, 0x0153 },
+    { 0x0166, 0x0167 }, { 0x016B, 0x016B }, { 0x01CE, 0x01CE },
+    { 0x01D0, 0x01D0 }, { 0x01D2, 0x01D2 }, { 0x01D4, 0x01D4 },
+    { 0x01D6, 0x01D6 }, { 0x01D8, 0x01D8 }, { 0x01DA, 0x01DA },
+    { 0x01DC, 0x01DC }, { 0x0251, 0x0251 }, { 0x0261, 0x0261 },
+    { 0x02C4, 0x02C4 }, { 0x02C7, 0x02C7 }, { 0x02C9, 0x02CB },
+    { 0x02CD, 0x02CD }, { 0x02D0, 0x02D0 }, { 0x02D8, 0x02DB },
+    { 0x02DD, 0x02DD }, { 0x02DF, 0x02DF }, { 0x0391, 0x03A1 },
+    { 0x03A3, 0x03A9 }, { 0x03B1, 0x03C1 }, { 0x03C3, 0x03C9 },
+    { 0x0401, 0x0401 }, { 0x0410, 0x044F }, { 0x0451, 0x0451 },
+    { 0x2010, 0x2010 }, { 0x2013, 0x2016 }, { 0x2018, 0x2019 },
+    { 0x201C, 0x201D }, { 0x2020, 0x2022 }, { 0x2024, 0x2027 },
+    { 0x2030, 0x2030 }, { 0x2032, 0x2033 }, { 0x2035, 0x2035 },
+    { 0x203B, 0x203B }, { 0x203E, 0x203E }, { 0x2074, 0x2074 },
+    { 0x207F, 0x207F }, { 0x2081, 0x2084 }, { 0x20AC, 0x20AC },
+    { 0x2103, 0x2103 }, { 0x2105, 0x2105 }, { 0x2109, 0x2109 },
+    { 0x2113, 0x2113 }, { 0x2116, 0x2116 }, { 0x2121, 0x2122 },
+    { 0x2126, 0x2126 }, { 0x212B, 0x212B }, { 0x2153, 0x2154 },
+    { 0x215B, 0x215E }, { 0x2160, 0x216B }, { 0x2170, 0x2179 },
+    { 0x2190, 0x2199 }, { 0x21B8, 0x21B9 }, { 0x21D2, 0x21D2 },
+    { 0x21D4, 0x21D4 }, { 0x21E7, 0x21E7 }, { 0x2200, 0x2200 },
+    { 0x2202, 0x2203 }, { 0x2207, 0x2208 }, { 0x220B, 0x220B },
+    { 0x220F, 0x220F }, { 0x2211, 0x2211 }, { 0x2215, 0x2215 },
+    { 0x221A, 0x221A }, { 0x221D, 0x2220 }, { 0x2223, 0x2223 },
+    { 0x2225, 0x2225 }, { 0x2227, 0x222C }, { 0x222E, 0x222E },
+    { 0x2234, 0x2237 }, { 0x223C, 0x223D }, { 0x2248, 0x2248 },
+    { 0x224C, 0x224C }, { 0x2252, 0x2252 }, { 0x2260, 0x2261 },
+    { 0x2264, 0x2267 }, { 0x226A, 0x226B }, { 0x226E, 0x226F },
+    { 0x2282, 0x2283 }, { 0x2286, 0x2287 }, { 0x2295, 0x2295 },
+    { 0x2299, 0x2299 }, { 0x22A5, 0x22A5 }, { 0x22BF, 0x22BF },
+    { 0x2312, 0x2312 }, { 0x2460, 0x24E9 }, { 0x24EB, 0x254B },
+    { 0x2550, 0x2573 }, { 0x2580, 0x258F }, { 0x2592, 0x2595 },
+    { 0x25A0, 0x25A1 }, { 0x25A3, 0x25A9 }, { 0x25B2, 0x25B3 },
+    { 0x25B6, 0x25B7 }, { 0x25BC, 0x25BD }, { 0x25C0, 0x25C1 },
+    { 0x25C6, 0x25C8 }, { 0x25CB, 0x25CB }, { 0x25CE, 0x25D1 },
+    { 0x25E2, 0x25E5 }, { 0x25EF, 0x25EF }, { 0x2605, 0x2606 },
+    { 0x2609, 0x2609 }, { 0x260E, 0x260F }, { 0x2614, 0x2615 },
+    { 0x261C, 0x261C }, { 0x261E, 0x261E }, { 0x2640, 0x2640 },
+    { 0x2642, 0x2642 }, { 0x2660, 0x2661 }, { 0x2663, 0x2665 },
+    { 0x2667, 0x266A }, { 0x266C, 0x266D }, { 0x266F, 0x266F },
+    { 0x273D, 0x273D }, { 0x2776, 0x277F }, { 0xE000, 0xF8FF },
+    { 0xFFFD, 0xFFFD }, { 0xF0000, 0xFFFFD }, { 0x100000, 0x10FFFD }
+  };
+
+  /* binary search in table of non-spacing characters */
+  if (bisearch(ucs, ambiguous,
+	       sizeof(ambiguous) / sizeof(struct interval) - 1))
+    return 2;
+
+  return mk_wcwidth(ucs);
+}
+
+
+int mk_wcswidth_cjk(const wchar_t *pwcs, size_t n)
+{
+  int w, width = 0;
+
+  for (;*pwcs && n-- > 0; pwcs++)
+    if ((w = mk_wcwidth_cjk(*pwcs)) < 0)
+      return -1;
+    else
+      width += w;
+
+  return width;
+}
+#endif /* 0 */
+
+/**/
+#endif /* BROKEN_WCWIDTH */
+
diff --git a/Src/prompt.c b/Src/prompt.c
index 63b048083..319759874 100644
--- a/Src/prompt.c
+++ b/Src/prompt.c
@@ -960,10 +960,10 @@ countprompt(char *str, int *wp, int *hp, int overf)
 		break;
 	    default:
 		/*
-		 * If the character isn't printable, wcwidth() returns
+		 * If the character isn't printable, WCWIDTH() returns
 		 * -1.  We assume width 1.
 		 */
-		wcw = wcwidth(wc);
+		wcw = WCWIDTH(wc);
 		if (wcw >= 0)
 		    w += wcw;
 		else
@@ -1177,7 +1177,7 @@ prompttrunc(int arg, int truncchar, int doprint, int endchar)
 				remw--;
 				break;
 			    default:
-				wcw = wcwidth(cc);
+				wcw = WCWIDTH(cc);
 				if (wcw >= 0)
 				    remw -= wcw;
 				else
@@ -1249,7 +1249,7 @@ prompttrunc(int arg, int truncchar, int doprint, int endchar)
 				maxwidth--;
 				break;
 			    default:
-				wcw = wcwidth(cc);
+				wcw = WCWIDTH(cc);
 				if (wcw >= 0)
 				    maxwidth -= wcw;
 				else
diff --git a/Src/utils.c b/Src/utils.c
index 24e709c24..30162a71e 100644
--- a/Src/utils.c
+++ b/Src/utils.c
@@ -548,7 +548,7 @@ wcs_nicechar(wchar_t c, size_t *widthp, char **swidep)
     }
 
     if (widthp) {
-	int wcw = wcwidth(c);
+	int wcw = WCWIDTH(c);
 	*widthp = (s - buf);
 	if (wcw >= 0)
 	    *widthp += wcw;
@@ -581,7 +581,7 @@ zwcwidth(wint_t wc)
     /* assume a single-byte character if not valid */
     if (wc == WEOF || unset(MULTIBYTE))
 	return 1;
-    wcw = wcwidth(wc);
+    wcw = WCWIDTH(wc);
     /* if not printable, assume width 1 */
     if (wcw < 0)
 	return 1;
@@ -4097,7 +4097,7 @@ mb_metastrlen(char *ptr, int width)
 		 * Returns -1 if not a printable character.  We
 		 * turn this into 1 for backward compatibility.
 		 */
-		int wcw = wcwidth(wc);
+		int wcw = WCWIDTH(wc);
 		if (wcw >= 0)
 		    num += wcw;
 		else
diff --git a/Src/zsh.h b/Src/zsh.h
index eaeacad8e..727dcefd6 100644
--- a/Src/zsh.h
+++ b/Src/zsh.h
@@ -2256,12 +2256,21 @@ typedef wint_t convchar_t;
 #define MB_METASTRWIDTH(str)	mb_metastrlen(str, 1)
 #define MB_METASTRLEN2(str, widthp)	mb_metastrlen(str, widthp)
 
+#ifdef BROKEN_WCWIDTH
+#define WCWIDTH(wc)	wcwidth_mk(wc)
+#else
+#define WCWIDTH(wc)	wcwidth(wc)
+#endif
 /*
- * Note WCWIDTH() takes wint_t, typically as a convchar_t.
+ * Note WCWIDTH_WINT() takes wint_t, typically as a convchar_t.
  * It's written to use the wint_t from mb_metacharlenconv() without
  * further tests.
+ *
+ * This version has a non-multibyte definition that simply returns
+ * 1.  We never expose WCWIDTH() in the non-multibyte world since
+ * it's just a proxy for wcwidth() itself.
  */
-#define WCWIDTH(wc)	zwcwidth(wc)
+#define WCWIDTH_WINT(wc)	zwcwidth(wc)
 
 #define MB_INCOMPLETE	((size_t)-2)
 #define MB_INVALID	((size_t)-1)
@@ -2286,9 +2295,6 @@ typedef wint_t convchar_t;
  *
  * wc is assumed to be a wchar_t (i.e. we don't need zwcwidth).
  *
- * This may need to be more careful if we import a wcwidth() for
- * compatibility to try to avoid clashes with the system library.
- *
  * Pedantic note: in Unicode, a combining character need not be
  * zero length.  However, we are concerned here about display;
  * we simply need to know whether the character will be displayed
@@ -2296,7 +2302,15 @@ typedef wint_t convchar_t;
  * sense throughout the shell.  I am not aware of a way of
  * detecting the Unicode trait in standard libraries.
  */
-#define IS_COMBINING(wc)	(wcwidth(wc) == 0)
+#ifdef BROKEN_WCWIDTH
+/*
+ * We can't be quite sure the wcwidth we've provided is entirely
+ * in agreement with the system's, so be extra safe.
+ */
+#define IS_COMBINING(wc)	(WCWIDTH(wc) == 0 && !iswcntrl(wc))
+#else
+#define IS_COMBINING(wc)	(WCWIDTH(wc) == 0)
+#endif
 /*
  * Test for the base of a combining character.
  *
@@ -2305,7 +2319,7 @@ typedef wint_t convchar_t;
  * is, as long as it has non-zero width.  We need to avoid all forms of
  * space because the shell will split words on any whitespace.
  */
-#define IS_BASECHAR(wc)		(iswgraph(wc) && wcwidth(wc) > 0)
+#define IS_BASECHAR(wc)		(iswgraph(wc) && WCWIDTH(wc) > 0)
 
 #else /* not MULTIBYTE_SUPPORT */
 
@@ -2317,7 +2331,7 @@ typedef int convchar_t;
 #define MB_METASTRWIDTH(str)	ztrlen(str)
 #define MB_METASTRLEN2(str, widthp)	ztrlen(str)
 
-#define WCWIDTH(c)	(1)
+#define WCWIDTH_WINT(c)	(1)
 
 /* Leave character or string as is. */
 #define ZWC(c)	c
diff --git a/configure.ac b/configure.ac
index c14f6562d..247f4f062 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2266,8 +2266,63 @@ wmemcpy wmemmove wmemset; do
 ])
 AH_TEMPLATE([MULTIBYTE_SUPPORT],
 [Define to 1 if you want support for multibyte character sets.])
+AH_TEMPLATE([BROKEN_WCWIDTH],
+[Define to 1 if the wcwidth() function is present but broken.])
 if test x$zsh_cv_c_unicode_support = xyes; then
   AC_DEFINE(MULTIBYTE_SUPPORT)
+
+  dnl Test for a wcwidth() implementation that gives the wrong width for
+  dnl zero-width combining characters.
+  dnl For the test we use a combining acute accent (\u0301).
+  dnl We input it as UTF-8 since that is the standard we can rely
+  dnl upon most:  we can't rely on a wchar_t being stored as a
+  dnl Unicode code point on all systems.
+  dnl The programme returns 0 only if all the conditions for brokenness
+  dnl are met:
+  dnl - the programme compiled, linked and ran
+  dnl - we successfully set a UTF-8 locale
+  dnl - the locale we set plausibly converted the UTF-8 string
+  dnl   for a zero-width combining character (the only way to be
+  dnl   100% sure would be to output it and ask if it looked right)
+  dnl - the converted wide character gave a non-zero width.
+  dnl locale -a is a fallback; on most systems we should find en_US.UTF-8.
+  [locale_prog='char *my_locales[] = {
+  "en_US.UTF-8", "en_GB.UTF-8", "en.UTF-8", '
+  locale_prog="$locale_prog"`locale -a 2>/dev/null | \
+    sed -e 's/utf8/UTF-8/' | grep UTF-8 | \
+    while read line; do echo " \"$line\","; done;`
+  locale_prog="$locale_prog 0 };
+  #define _XOPEN_SOURCE
+  #include <stdlib.h>
+  #include <locale.h>
+  #include <wchar.h>
+
+  int main() {
+    char **localep;
+    char comb_acute_mb[] = { (char)0xcc, (char)0x81 };
+    wchar_t wc;
+
+    for (localep = my_locales; *localep; localep++)
+      if (setlocale(LC_ALL, *localep) &&
+          mbtowc(&wc, comb_acute_mb, 2) == 2)
+	  break;
+    if (!*localep)
+      return 1;
+    if (wcwidth(wc) == 0)
+      return 1;
+    return 0;
+  }
+  "]
+
+  AC_CACHE_CHECK(if the wcwidth() function is broken,
+  zsh_cv_c_broken_wcwidth,
+  [AC_TRY_RUN([$locale_prog],
+  zsh_cv_c_broken_wcwidth=yes,
+  zsh_cv_c_broken_wcwidth=no,
+  zsh_cv_c_broken_wcwidth=no)])
+  if test x$zsh_cv_c_broken_wcwdith = xyes; then
+    AC_DEFINE(BROKEN_WCWIDTH)
+  fi
 fi
 
 dnl