patch 8.0.1234: MS-Windows: composing chars are not shown properly

Problem:    MS-Windows: composing characters are not shown properly.
Solution:   Pass base character and composing characters to the renderer at
            once. (Ken Takata, closes #2206)

src/gui.c

@@ -2429,9 +2429,14 @@ gui_outstr_nowrap(
 	int	cl;		/* byte length of current char */
 	int	comping;	/* current char is composing */
 	int	scol = col;	/* screen column */
-	int	curr_wide;	/* use 'guifontwide' */
+	int	curr_wide = FALSE;  /* use 'guifontwide' */
 	int	prev_wide = FALSE;
 	int	wide_changed;
+#  ifdef WIN3264
+	int	sep_comp = FALSE;   /* Don't separate composing chars. */
+#  else
+	int	sep_comp = TRUE;    /* Separate composing chars. */
+#  endif
 
 	/* Break the string at a composing character, it has to be drawn on
 	 * top of the previous character. */
@@ -2441,6 +2446,11 @@ gui_outstr_nowrap(
 	{
 	    c = utf_ptr2char(s + i);
 	    cn = utf_char2cells(c);
+	    comping = utf_iscomposing(c);
+	    if (!comping)	/* count cells from non-composing chars */
+		cells += cn;
+	    if (!comping || sep_comp)
+	    {
 		if (cn > 1
 #  ifdef FEAT_XFONTSET
 			&& fontset == NOFONTSET
@@ -2449,9 +2459,7 @@ gui_outstr_nowrap(
 		    curr_wide = TRUE;
 		else
 		    curr_wide = FALSE;
-	    comping = utf_iscomposing(c);
+	    }
-	    if (!comping)	/* count cells from non-composing chars */
-		cells += cn;
 	    cl = utf_ptr2len(s + i);
 	    if (cl == 0)	/* hit end of string */
 		len = i + cl;	/* len must be wrong "cannot happen" */
@@ -2460,7 +2468,8 @@ gui_outstr_nowrap(
 
 	    /* Print the string so far if it's the last character or there is
 	     * a composing character. */
-	    if (i + cl >= len || (comping && i > start) || wide_changed
+	    if (i + cl >= len || (comping && sep_comp && i > start)
+		    || wide_changed
 #  if defined(FEAT_GUI_X11)
 		    || (cn > 1
 #   ifdef FEAT_XFONTSET
@@ -2472,7 +2481,7 @@ gui_outstr_nowrap(
 #  endif
 	       )
 	    {
-		if (comping || wide_changed)
+		if ((comping && sep_comp) || wide_changed)
 		    thislen = i - start;
 		else
 		    thislen = i - start + cl;
@@ -2490,7 +2499,7 @@ gui_outstr_nowrap(
 		cells = 0;
 		/* Adjust to not draw a character which width is changed
 		 * against with last one. */
-		if (wide_changed && !comping)
+		if (wide_changed && !(comping && sep_comp))
 		{
 		    scol -= cn;
 		    cl = 0;
@@ -2509,7 +2518,7 @@ gui_outstr_nowrap(
 #  endif
 	    }
 	    /* Draw a composing char on top of the previous char. */
-	    if (comping)
+	    if (comping && sep_comp)
 	    {
 #  if (defined(__APPLE_CC__) || defined(__MRC__)) && TARGET_API_MAC_CARBON
 		/* Carbon ATSUI autodraws composing char over previous char */

src/gui_w32.c

@@ -6295,8 +6295,8 @@ gui_mch_draw_string(
 
     if (enc_utf8 && n < len && unicodebuf != NULL)
     {
-	/* Output UTF-8 characters.  Caller has already separated
+	/* Output UTF-8 characters.  Composing characters should be
-	 * composing characters. */
+	 * handled here. */
 	int		i;
 	int		wlen;	/* string length in words */
 	int		clen;	/* string length in characters */
@@ -6320,9 +6320,16 @@ gui_mch_draw_string(
 	    {
 		unicodebuf[wlen++] = c;
 	    }
+
+	    if (utf_iscomposing(c))
+		cw = 0;
+	    else
+	    {
 		cw = utf_char2cells(c);
 		if (cw > 2)		/* don't use 4 for unprintable char */
 		    cw = 1;
+	    }
+
 	    if (unicodepdy != NULL)
 	    {
 		/* Use unicodepdy to make characters fit as we expect, even
@@ -6337,7 +6344,7 @@ gui_mch_draw_string(
 		    unicodepdy[wlen - 1] = cw * gui.char_width;
 	    }
 	    cells += cw;
-	    i += utfc_ptr2len_len(text + i, len - i);
+	    i += utf_ptr2len_len(text + i, len - i);
 	    ++clen;
 	}
 #if defined(FEAT_DIRECTX)

src/version.c

@@ -761,6 +761,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1234,
 /**/
     1233,
 /**/