Handle VS-16 correctly for non-emoji codepoints

* admin/unidata/blocks.awk: Remove emoji overrides for codepoints with
Emoji_Presentation = No, they're no longer necessary.
* lisp/composite.el: Remove #xFE0F (VS-16) from the range handled by
`compose-gstring-for-variation-glyph' so it can be handled by
`font_range'.
* src/composite.c (syms_of_composite): New variable
`auto-composition-emoji-eligible-codepoints'.
* admin/unidata/emoji-zwj.awk: Generate value for
`auto-composition-emoji-eligible-codepoints'.  Add
`composition-function-table' entries for 'codepoint + U+FE0F' for
them.
* src/font.c (codepoint_is_emoji_eligible): New function to check if
we should try to use the emoji font for a codepoint.
(font_range): Use it.

2 files changed, 29 insertions, 2 deletions

diff --git a/src/composite.c b/src/composite.c
index f456e7a835d..c170805d9dd 100644
--- a/src/composite.c
+++ b/src/composite.c
@@ -2124,6 +2124,17 @@ GSTRING, or modify GSTRING itself and return it.
 See also the documentation of `auto-composition-mode'.  */);
   Vcomposition_function_table = Fmake_char_table (Qnil, Qnil);
 
+  DEFVAR_LISP ("auto-composition-emoji-eligible-codepoints", Vauto_composition_emoji_eligible_codepoints,
+               doc: /* List of codepoints for which auto-composition will check for an emoji font.
+
+These are codepoints which have Emoji_Presentation = No, and thus by
+default are not displayed as emoji.  In certain circumstances, such as
+when followed by U+FE0F (VS-16) the emoji font should be used for
+them anyway.
+
+This list is auto-generated, you should not need to modify it.  */);
+  Vauto_composition_emoji_eligible_codepoints = Qnil;
+
   defsubr (&Scompose_region_internal);
   defsubr (&Scompose_string_internal);
   defsubr (&Sfind_composition_internal);
diff --git a/src/font.c b/src/font.c
index 83f0f8296ad..6cd4a6b5c11 100644
--- a/src/font.c
+++ b/src/font.c
@@ -3860,6 +3860,23 @@ font_at (int c, ptrdiff_t pos, struct face *face, struct window *w,
 
 #ifdef HAVE_WINDOW_SYSTEM
 
+/* Check if CH is a codepoint for which we should attempt to use the
+   emoji font, even if the codepoint itself has Emoji_Presentation =
+   No.  Vauto_composition_emoji_eligible_codepoints is filled in for
+   us by admin/unidata/emoji-zwj.awk.  */
+static bool
+codepoint_is_emoji_eligible (int ch)
+{
+  if (EQ (CHAR_TABLE_REF (Vchar_script_table, ch), Qemoji))
+    return true;
+
+  if (! NILP (Fmemq (make_fixnum (ch),
+                     Vauto_composition_emoji_eligible_codepoints)))
+    return true;
+
+  return false;
+}
+
 /* Check how many characters after character/byte position POS/POS_BYTE
    (at most to *LIMIT) can be displayed by the same font in the window W.
    FACE, if non-NULL, is the face selected for the character at POS.
@@ -3907,8 +3924,7 @@ font_range (ptrdiff_t pos, ptrdiff_t pos_byte, ptrdiff_t *limit,
   /* If the composition was triggered by an emoji, use a character
      from 'script-representative-chars', rather than the first
      character in the string, to determine the font to use.  */
-  if (EQ (CHAR_TABLE_REF (Vchar_script_table, ch),
-          Qemoji))
+  if (codepoint_is_emoji_eligible (ch))
     {
       Lisp_Object val = assq_no_quit (Qemoji, Vscript_representative_chars);
       if (CONSP (val))