emacs-28 3da9fa8 1/2: Make hieroglyphs display correctly with existing fonts

[Eli Zaretskii]

branch: emacs-28
commit 3da9fa875bbfceee41df38d9f97e06013484a791
Author: Gregory Heytings <gregory@heytings.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    Make hieroglyphs display correctly with existing fonts
    
    * etc/HELLO: Remove hieroglyph format control characters.
    
    * lisp/language/misc-lang.el: Add a rule to compose Egyptian
    hieroglyphs even without Unicode format control characters.
---
 etc/HELLO                  |  2 +-
 lisp/language/misc-lang.el | 15 ++++++++++++++-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/etc/HELLO b/etc/HELLO
index 577c282..8bd489f 100644
--- a/etc/HELLO
+++ b/etc/HELLO
@@ -38,7 +38,7 @@ Czech (čeština)       Dobrý den
 Danish (dansk) Hej / Goddag / Halløj
 Dutch (Nederlands)     Hallo / Dag
 Efik  /ˈɛfɪk/  Mɔkɔm
-Egyptian Hieroglyphs (𓂋𓐰𓏤𓈖𓆎𓅓𓏏𓐰𓊖)       𓅓𓊵𓐰𓐷𓏏𓊪𓐸, 𓇍𓇋𓂻𓍘𓇋
+Egyptian Hieroglyphs (𓂋𓏤𓈖𓆎𓅓‌𓏏𓊖)        𓅓𓊵𓏏𓊪, 𓇍𓇋𓂻𓍘𓇋
 Emacs  emacs --no-splash -f view-hello-file
 Emoji  👋
 English /ˈɪŋɡlɪʃ/      Hello
diff --git a/lisp/language/misc-lang.el b/lisp/language/misc-lang.el
index a2ca678..de4f092 100644
--- a/lisp/language/misc-lang.el
+++ b/lisp/language/misc-lang.el
@@ -192,7 +192,20 @@ thin (i.e. 1-dot width) space."
    composition-function-table
    #x13437
    (list (vector "\U00013437[\U00013000-\U0001343F]+"
-                 0 #'egyptian-shape-grouping))))
+                 0 #'egyptian-shape-grouping)))
+  ;; As of late 2021, Egyptian Hieroglyph Format Controls are not yet
+  ;; supported in existing fonts and shaping engines, but some fonts
+  ;; do provide ligatures with which texts in Egyptian Hieroglyphs are
+  ;; correctly displayed.  If and when these format controls are
+  ;; supported, the five lines below (which cancel the effect of the
+  ;; above lines) can be removed, and the entry in etc/HELLO can be
+  ;; restored to:
+  ;; Egyptian Hieroglyphs (𓂋𓐰𓏤𓈖𓆎𓅓𓏏𓐰𓊖)  𓅓𓊵𓐰𓐷𓏏𓊪𓐸, 𓇍𓇋𓂻𓍘𓇋
+  (set-char-table-range
+   composition-function-table
+   '(#x13000 . #x1342E)
+   (list (vector "[\U00013000-\U0001342E]+"
+                 0 #'font-shape-gstring))))
 
 (provide 'misc-lang)