* 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.

2 files changed, 11 insertions, 3 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 726d9b02ac8..ac36c059bd3 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2014-12-01  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        * progmodes/prog-mode.el (prettify-symbols--compose-symbol):
+        Fix handling of symbols with different syntax at beginning/end or with
+        symbol rather than word syntax.
+
 2014-11-30  Eli Zaretskii  <eliz@gnu.org>
 
         * simple.el (line-move): If noninteractive, call line-move-1, not
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