* lisp/progmodes/prog-mode.el (prettify-symbols--compose-symbol): Refine.

Fix handling of symbols with different syntax at beginning/end or with
symbol rather than word syntax.

1 files changed, 5 insertions, 3 deletions

diff --git a/lisp/progmodes/prog-mode.el b/lisp/progmodes/prog-mode.el
index 407466932d9..e0e57462405 100644
--- a/lisp/progmodes/prog-mode.el
+++ b/lisp/progmodes/prog-mode.el
@@ -66,11 +66,13 @@ Regexp match data 0 points to the chars."
   ;; Check that the chars should really be composed into a symbol.
   (let* ((start (match-beginning 0))
          (end (match-end 0))
-         (syntaxes (if (eq (char-syntax (char-after start)) ?w)
+         (syntaxes-beg (if (memq (char-syntax (char-after start)) '(?w ?_))
+                           '(?w ?_) '(?. ?\\)))
+         (syntaxes-end (if (memq (char-syntax (char-before end)) '(?w ?_))
                        '(?w ?_) '(?. ?\\)))
          match)
-    (if (or (memq (char-syntax (or (char-before start) ?\s)) syntaxes)
-            (memq (char-syntax (or (char-after end) ?\s)) syntaxes)
+    (if (or (memq (char-syntax (or (char-before start) ?\s)) syntaxes-beg)
+            (memq (char-syntax (or (char-after end) ?\s)) syntaxes-end)
             ;; syntax-ppss could modify the match data (bug#14595)
             (progn (setq match (match-string 0)) (nth 8 (syntax-ppss))))
         ;; No composition for you.  Let's actually remove any composition