bug#9183: js-mode highlights quotes inside regexp character sets as string

[Stefan Monnier <monnier@IRO.UMontreal.CA>]

> The following is valid JavaScript:
> /[']/.test(str)

> js-mode erroneously highlights everything following `'' as a string.
> Same problem with `"'.

I installed the patch below which should fix this case and a few others.
But I don't know how to solve it completely because I don't know
Javascript enough to be sure exactly how to distinguish a /-division
from a /-regexp from a /-comment-starter in all cases:
- is something like

    x = 1 + /a/.test("foo");

  valid?  If so, is there a list of infix operators somewhere?

- I'm giving up on handling a /regexp/ that immediately follows an
  implicit semicolon.


        Stefan


=== modified file 'lisp/progmodes/js.el'
--- lisp/progmodes/js.el	2011-06-30 16:22:33 +0000
+++ lisp/progmodes/js.el	2011-08-05 16:52:20 +0000
@@ -1658,15 +1658,19 @@
 ;; below.
 (eval-and-compile
   (defconst js--regexp-literal
-    "[=(,:]\\(?:\\s-\\|\n\\)*\\(/\\)\\(?:\\\\.\\|[^/*\\]\\)\\(?:\\\\.\\|[^/\\]\\)*\\(/\\)"
+    (concat
+     ;; We want to match regular expressions only at the beginning of
+     ;; expressions.
+     ;; FIXME: Should we also allow /regexp/ after infix operators such as +,
+     ;; /, -, *, >, ...?
+     "\\(?:\\`\\|[=([{,:;]\\)\\(?:\\s-\\|\n\\)*"
+     "\\(/\\)\\(?:\\\\.\\|[^/*\\]\\)\\(?:\\\\.\\|[^/\\]\\)*\\(/\\)")
   "Regexp matching a JavaScript regular expression literal.
 Match groups 1 and 2 are the characters forming the beginning and
 end of the literal."))
 
 (defconst js-syntax-propertize-function
   (syntax-propertize-rules
-   ;; We want to match regular expressions only at the beginning of
-   ;; expressions.
    (js--regexp-literal (1 "\"") (2 "\""))))
 
 ;;; Indentation