error.c: fix newline in syntax error

* error.c (rb_syntax_error_append): fix newline in syntax error
  message to the beginning, not after file name and line number.
  [Feature #11951]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55878 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Fri Aug 12 12:50:31 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* error.c (rb_syntax_error_append): fix newline in syntax error
+	  message to the beginning, not after file name and line number.
+	  [Feature #11951]
+
 Thu Aug 11 16:24:23 2016  nerdinand  <nerdinand@nerdinand.com>
 
 	* compar.c (cmp_clamp): Introduce Comparable#clamp.  [Feature #10594]

error.c

@@ -106,16 +106,16 @@ rb_syntax_error_append(VALUE exc, VALUE file, int line, int column,
     }
     else {
 	VALUE mesg;
-	const char *pre = NULL;
 	if (NIL_P(exc)) {
 	    mesg = rb_enc_str_new(0, 0, enc);
 	    exc = rb_class_new_instance(1, &mesg, rb_eSyntaxError);
 	}
 	else {
 	    mesg = rb_attr_get(exc, idMesg);
-	    pre = "\n";
+	    if (RSTRING_LEN(mesg) > 0 && *(RSTRING_END(mesg)-1) != '\n')
+		rb_str_cat_cstr(mesg, "\n");
 	}
-	err_vcatf(mesg, pre, fn, line, fmt, args);
+	err_vcatf(mesg, NULL, fn, line, fmt, args);
     }
 
     return exc;

test/ruby/test_iseq.rb

@@ -234,6 +234,9 @@ class TestISeq < Test::Unit::TestCase
       end
     end
     assert_equal([m1, e1.message], [m2, e2.message], feature11951)
+    e1, e2 = e1.message.lines
+    assert_send([e1, :start_with?, __FILE__])
+    assert_send([e2, :start_with?, __FILE__])
   end
 
   def test_translate_by_object