ligatures.diff

--- a/src/gui_gtk_x11.c
+++ b/src/gui_gtk_x11.c
@@ -5232,7 +5232,7 @@ get_styled_font_variants(void)
 static PangoEngineShape *default_shape_engine = NULL;
 
 /*
- * Create a map from ASCII characters in the range [32,126] to glyphs
+ * Create a map from ASCII characters [ ,0-9,a-z,A-Z] to glyphs
  * of the current font.  This is used by gui_gtk2_draw_string() to skip
  * the itemize and shaping process for the most common case.
  */
@@ -5256,7 +5256,7 @@ ascii_glyph_table_init(void)
      * Put a space between characters to avoid shaping. */
     for (i = 0; i < 128; ++i)
     {
-       if (i >= 32 && i < 127)
+        if (i == 32 || (i >= 48 && i <= 57) || (i >= 65 && i <= 90) || (i >= 97 && i <= 122))
            ascii_chars[2 * i] = i;
        else
            ascii_chars[2 * i] = '?';
@@ -5933,8 +5933,9 @@ gui_gtk2_draw_string(int row, int col, c
 
     /*
      * Optimization hack:  If possible, skip the itemize and shaping process
-     * for pure ASCII strings. This optimization is particularly effective
-     * because Vim draws space characters to clear parts of the screen.
+     * for pure alphanumeric ASCII strings.
+     * This optimization is particularly effective because Vim draws space
+     * characters to clear parts of the screen.
      */
     if (!(flags & DRAW_ITALIC)
            && !((flags & DRAW_BOLD) && gui.font_can_bold)
@@ -5943,7 +5944,7 @@ gui_gtk2_draw_string(int row, int col, c
        char_u *p;
 
        for (p = s; p < s + len; ++p)
-           if (*p & 0x80)
+           if (*p != 32 && (*p < 48 || *p > 57) && (*p < 65 || *p > 90) && (*p < 97 || *p > 122))
                goto not_ascii;
 
        pango_glyph_string_set_size(glyphs, len);

Copy of https://paste.fedoraproject.org/427667/73785436/