ruby-mode: Change faces used for self, true, false and nil

Fixes: debbugs:17733

* lisp/progmodes/ruby-mode.el (ruby-font-lock-keywords): Use
`font-lock-constant-face' for nil, true and false.  Highlight
`self' as a keyword.

1 files changed, 4 insertions, 3 deletions

diff --git a/lisp/progmodes/ruby-mode.el b/lisp/progmodes/ruby-mode.el
index 4307109f654..4abc413f636 100644
--- a/lisp/progmodes/ruby-mode.el
+++ b/lisp/progmodes/ruby-mode.el
@@ -2053,8 +2053,9 @@ See `font-lock-syntax-table'.")
           "rescue"
           "retry"
           "return"
-          "then"
+          "self"
           "super"
+          "then"
           "unless"
           "undef"
           "until"
@@ -2149,8 +2150,8 @@ See `font-lock-syntax-table'.")
     "\\_<\\(?:BEGIN\\|END\\)\\_>\\|^__END__$"
     ;; Variables.
     (,(concat ruby-font-lock-keyword-beg-re
-              "\\_<\\(nil\\|self\\|true\\|false\\)\\_>")
-     1 font-lock-variable-name-face)
+              "\\_<\\(nil\\|true\\|false\\)\\_>")
+     1 font-lock-constant-face)
     ;; Keywords that evaluate to certain values.
     ("\\_<__\\(?:LINE\\|ENCODING\\|FILE\\)__\\_>"
      (0 font-lock-builtin-face))