From 29c5e2cea22f909af7d33b290ca0eb23c5ad6c00 Mon Sep 17 00:00:00 2001
From: Stefan Monnier <monnier@iro.umontreal.ca>
Date: Tue, 23 Dec 2014 11:17:55 -0500
Subject: [PATCH] (js-syntax-propertize-regexp): Recognize "slash in a
 character class"

Fixes: debbugs:19397

* lisp/progmodes/js.el (js--syntax-propertize-regexp-syntax-table): New var.
(js-syntax-propertize-regexp): Use it to recognize "slash in
a character class".
---
 lisp/ChangeLog       |  6 ++++++
 lisp/progmodes/js.el | 27 ++++++++++++++++++++++-----
 test/indent/js.js    |  5 +++++
 3 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index d8bb1c89f1f..12430b69fb7 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2014-12-23  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+	* progmodes/js.el (js--syntax-propertize-regexp-syntax-table): New var.
+	(js-syntax-propertize-regexp): Use it to recognize "slash in
+	a character class" (bug#19397).
+
 2014-12-22  Stefan Monnier  <monnier@iro.umontreal.ca>
 
 	* completion.el: Use post-self-insert-hook (bug#19400).
diff --git a/lisp/progmodes/js.el b/lisp/progmodes/js.el
index c2c45aa4ef8..45074d338d3 100644
--- a/lisp/progmodes/js.el
+++ b/lisp/progmodes/js.el
@@ -1637,12 +1637,29 @@ This performs fontification according to `js--class-styles'."
                                    js--font-lock-keywords-3)
   "Font lock keywords for `js-mode'.  See `font-lock-keywords'.")
 
+(defconst js--syntax-propertize-regexp-syntax-table
+  (let ((st (make-char-table 'syntax-table (string-to-syntax "."))))
+    (modify-syntax-entry ?\[ "(]" st)
+    (modify-syntax-entry ?\] ")[" st)
+    (modify-syntax-entry ?\\ "\\" st)
+    st))
+
 (defun js-syntax-propertize-regexp (end)
-  (when (eq (nth 3 (syntax-ppss)) ?/)
-    ;; A /.../ regexp.
-    (when (re-search-forward "\\(?:\\=\\|[^\\]\\)\\(?:\\\\\\\\\\)*/" end 'move)
-      (put-text-property (1- (point)) (point)
-                         'syntax-table (string-to-syntax "\"/")))))
+  (let ((ppss (syntax-ppss)))
+    (when (eq (nth 3 ppss) ?/)
+      ;; A /.../ regexp.
+      (while
+          (when (re-search-forward "\\(?:\\=\\|[^\\]\\)\\(?:\\\\\\\\\\)*/"
+                                   end 'move)
+            (if (nth 1 (with-syntax-table
+                           js--syntax-propertize-regexp-syntax-table
+                         (let ((parse-sexp-lookup-properties nil))
+                           (parse-partial-sexp (nth 8 ppss) (point)))))
+                ;; A / within a character class is not the end of a regexp.
+                t
+              (put-text-property (1- (point)) (point)
+                                 'syntax-table (string-to-syntax "\"/"))
+              nil))))))
 
 (defun js-syntax-propertize (start end)
   ;; Javascript allows immediate regular expression objects, written /.../.
diff --git a/test/indent/js.js b/test/indent/js.js
index 1924094e9d8..2d458e1b769 100644
--- a/test/indent/js.js
+++ b/test/indent/js.js
@@ -7,6 +7,11 @@ let c = 1,
 var e = 100500,
     + 1;
 
+function test ()
+{
+     return /[/]/.test ('/')     // (bug#19397)
+}
+
 var f = bar('/protocols/')
 baz();
 
-- 
2.39.2