From 85da7b57bc204c4cc6953156c1a9a4dc6e875541 Mon Sep 17 00:00:00 2001
From: Eli Zaretskii <eliz@gnu.org>
Date: Wed, 26 May 2021 20:08:47 +0300
Subject: [PATCH] Make 'string-width' auto-composition aware

* src/composite.c (find_automatic_composition): Now extern.
(char_composable_p): Don't assume 'unicode-category-table' is
always available.
* src/composite.h (find_automatic_composition): Add prototype.
* src/character.c (lisp_string_width): Support automatic
compositions; call 'find_automatic_composition' when
'auto-composition-mode' is ON.
---
 src/character.c | 17 +++++++++++++++++
 src/composite.c | 10 +++++++---
 src/composite.h |  4 ++++
 3 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/src/character.c b/src/character.c
index 41abb83a48b..e0978bb39fa 100644
--- a/src/character.c
+++ b/src/character.c
@@ -361,6 +361,23 @@ lisp_string_width (Lisp_Object string, ptrdiff_t from, ptrdiff_t to,
 	  chars = end - i;
 	  bytes = string_char_to_byte (string, end) - i_byte;
 	}
+      else if (!NILP (BVAR (current_buffer, enable_multibyte_characters))
+	       && ! NILP (Vauto_composition_mode)
+	       && find_automatic_composition (i, -1, &ignore, &end, &val, string)
+	       && end > i)
+	{
+	  int j;
+	  for (thiswidth = 0, j = 0; j < LGSTRING_GLYPH_LEN (val); j++)
+	    {
+	      Lisp_Object g = LGSTRING_GLYPH (val, j);
+
+	      if (NILP (g))
+		break;
+	      thiswidth += char_width (LGLYPH_CHAR (g), dp);
+	    }
+	  chars = end - i;
+	  bytes = string_char_to_byte (string, end) - i_byte;
+	}
       else
 	{
 	  int c;
diff --git a/src/composite.c b/src/composite.c
index f1c011223b2..17d5914e634 100644
--- a/src/composite.c
+++ b/src/composite.c
@@ -953,8 +953,12 @@ char_composable_p (int c)
   Lisp_Object val;
   return (c >= ' '
 	  && (c == ZERO_WIDTH_NON_JOINER || c == ZERO_WIDTH_JOINER
-	      || (val = CHAR_TABLE_REF (Vunicode_category_table, c),
-		  (FIXNUMP (val) && (XFIXNUM (val) <= UNICODE_CATEGORY_Zs)))));
+	      /* unicode-category-table may not be available during
+		 dumping.  */
+	      || (CHAR_TABLE_P (Vunicode_category_table)
+		  && (val = CHAR_TABLE_REF (Vunicode_category_table, c),
+		      (FIXNUMP (val)
+		       && (XFIXNUM (val) <= UNICODE_CATEGORY_Zs))))));
 }
 
 /* Update cmp_it->stop_pos to the next position after CHARPOS (and
@@ -1475,7 +1479,7 @@ struct position_record
    representing the composition, and return true.  Otherwise, *GSTRING to
    Qnil, and return false.  */
 
-static bool
+bool
 find_automatic_composition (ptrdiff_t pos, ptrdiff_t limit,
 			    ptrdiff_t *start, ptrdiff_t *end,
 			    Lisp_Object *gstring, Lisp_Object string)
diff --git a/src/composite.h b/src/composite.h
index c5d3c0faabb..75e5f9b9ecb 100644
--- a/src/composite.h
+++ b/src/composite.h
@@ -320,6 +320,10 @@ extern bool composition_gstring_p (Lisp_Object);
 extern int composition_gstring_width (Lisp_Object, ptrdiff_t, ptrdiff_t,
                                       struct font_metrics *);
 
+extern bool find_automatic_composition (ptrdiff_t, ptrdiff_t, ptrdiff_t *,
+					ptrdiff_t *, Lisp_Object *,
+					Lisp_Object);
+
 extern void composition_compute_stop_pos (struct composition_it *,
                                           ptrdiff_t, ptrdiff_t, ptrdiff_t,
                                           Lisp_Object);
-- 
2.39.5