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, 41 insertions, 26 deletions

diff --git a/admin/unidata/blocks.awk b/admin/unidata/blocks.awk
index 96b0413875d..314ac3e9394 100755
--- a/admin/unidata/blocks.awk
+++ b/admin/unidata/blocks.awk
@@ -221,31 +221,9 @@ FILENAME ~ "emoji-data.txt" && /^[0-9A-F].*; Emoji_Presentation / {
 }
 
 END {
-    ## These codepoints have Emoji_Presentation = No, but they are
-    ## used in emoji-sequences.txt and emoji-zwj-sequences.txt (with a
-    ## Variation Selector), so force them into the emoji script so
-    ## they will get composed correctly.  FIXME: delete this when we
-    ## can change the font used for a codepoint based on whether it's
-    ## followed by a VS (usually VS-16)
     idx = 0
-    override_start[idx] = "1F3CB"
-    override_end[idx] = "1F3CC"
-    idx++
-    override_start[idx] = "1F3F3"
-    override_end[idx] = "1F3F4"
-    idx++
-    override_start[idx] = "1F441"
-    override_end[idx] = "1F441"
-    idx++
-    override_start[idx] = "1F574"
-    override_end[idx] = "1F575"
-    idx++
-    override_start[idx] = "1F590"
-    override_end[idx] = "1F590"
-
-    ## These are here so that font_range can choose Emoji presentation
-    ## for the preceding codepoint when it encounters a VS
-    idx++
+    # ## These are here so that font_range can choose Emoji presentation
+    # ## for the preceding codepoint when it encounters a VS
     override_start[idx] = "FE00"
     override_end[idx] = "FE0F"
 
diff --git a/admin/unidata/emoji-zwj.awk b/admin/unidata/emoji-zwj.awk
index 5aca157cbd4..d4e2944ca34 100644
--- a/admin/unidata/emoji-zwj.awk
+++ b/admin/unidata/emoji-zwj.awk
@@ -64,6 +64,44 @@ END {
      print ";;; emoji-zwj.el --- emoji zwj character composition table  -*- lexical-binding:t -*-"
      print ";;; Automatically generated from admin/unidata/emoji-{zwj-,}sequences.txt"
      print "(eval-when-compile (require 'regexp-opt))"
+
+     # The following codepoints are not emoji, but they are part of
+     # emoji sequences.  We have code in font.c:font_range that will
+     # try to display them with the emoji font anyway.
+
+     trigger_codepoints[1] = "261D"
+     trigger_codepoints[2] = "26F9"
+     trigger_codepoints[3] = "270C"
+     trigger_codepoints[4] = "270D"
+     trigger_codepoints[5] = "2764"
+     trigger_codepoints[6] = "1F3CB"
+     trigger_codepoints[7] = "1F3CC"
+     trigger_codepoints[8] = "1F3F3"
+     trigger_codepoints[9] = "1F3F4"
+     trigger_codepoints[10] = "1F441"
+     trigger_codepoints[11] = "1F574"
+     trigger_codepoints[12] = "1F575"
+     trigger_codepoints[13] = "1F590"
+
+     printf "(setq auto-composition-emoji-eligible-codepoints\n"
+     printf "'("
+
+     for (trig in trigger_codepoints)
+     {
+         printf("\n?\\N{U+%s}", trigger_codepoints[trig])
+     }
+     printf "\n))\n\n"
+
+     #  We add entries for 'codepoint U+FE0F' here to ensure that the
+     # code in font_range is triggered.
+
+     for (trig in trigger_codepoints)
+     {
+         codepoint = trigger_codepoints[trig]
+         c = sprintf("\\N{U+%s}", codepoint)
+         vec[codepoint] = vec[codepoint] "\n\"" c "\\N{U+FE0F}\""
+     }
+
      print "(dolist (elt `("
 
      for (elt in ch)
@@ -98,6 +136,5 @@ END {
      print "                                           0"
      print "                                    'compose-gstring-for-graphic))))"
 
-     print "\n"
-     print "(provide 'emoji-zwj)"
+     printf "\n(provide 'emoji-zwj)"
 }