* lisp/progmodes/ruby-mode.el (ruby-font-lock-keywords): Highlight

regexp options.

Fixes: debbugs:16914

lisp/ChangeLog

@@ -1,3 +1,8 @@
+2014-03-01  Dmitry Gutov  <dgutov@yandex.ru>
+
+	* progmodes/ruby-mode.el (ruby-font-lock-keywords): Highlight
+	regexp options.  (Bug#16914)
+
 2014-03-01  Martin Rudalics  <rudalics@gmx.at>
 
 	* window.el (window--max-delta-1): Round down when calculating

lisp/progmodes/ruby-mode.el

@@ -2132,6 +2132,16 @@ See `font-lock-syntax-table'.")
     ;; Character literals.
     ;; FIXME: Support longer escape sequences.
     ("\\_<\\?\\\\?\\S " 0 font-lock-string-face)
+    ;; Regexp options.
+    ("\\(?:\\s|\\|/\\)\\([imxo]+\\)"
+     1 (when (save-excursion
+               (let ((state (syntax-ppss (match-beginning 0))))
+                 (and (nth 3 state)
+                      (or (eq (char-after) ?/)
+                          (progn
+                            (goto-char (nth 8 state))
+                            (looking-at "%r"))))))
+         font-lock-preprocessor-face))
     )
   "Additional expressions to highlight in Ruby mode.")
 

test/indent/ruby.rb

@@ -29,6 +29,10 @@ a = asub / aslb + bsub / bslb;
 # Highlight the regexp after "if".
 x = toto / foo if /do bar/ =~ "dobar"
 
+# Regexp options are highlighted.
+
+/foo/xi != %r{bar}mo.tee
+
 bar(class: XXX) do              # ruby-indent-keyword-label
   foo
 end