parse.y: refine error messages

* parse.y: refine error messages for tSYMBEG and tSTRING_BEG, which
  can appear at invalid places.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66722 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

parse.y

@@ -900,7 +900,9 @@ static void token_info_warn(struct parser_params *p, const char *token, token_in
 %token tDSTAR		"**arg"
 %token tAMPER		"&"
 %token tLAMBDA		"->"
-%token tSYMBEG tSTRING_BEG tXSTRING_BEG tREGEXP_BEG tWORDS_BEG tQWORDS_BEG tSYMBOLS_BEG tQSYMBOLS_BEG
+%token tSYMBEG		"symbol literal"
+%token tSTRING_BEG	"string literal"
+%token tXSTRING_BEG tREGEXP_BEG tWORDS_BEG tQWORDS_BEG tSYMBOLS_BEG tQSYMBOLS_BEG
 %token tSTRING_DBEG tSTRING_DEND tSTRING_DVAR tSTRING_END tLAMBEG tLABEL_END
 
 /*

test/ruby/test_syntax.rb

@@ -905,6 +905,11 @@ eom
     assert_syntax_error(":#\n foo", /unexpected ':'/)
   end
 
+  def test_invalid_literal_message
+    assert_syntax_error("def :foo", /unexpected symbol literal/)
+    assert_syntax_error("def 'foo'", /unexpected string literal/)
+  end
+
   def test_fluent_dot
     assert_valid_syntax("a\n.foo")
     assert_valid_syntax("a\n&.foo")