C++ FE: Show both locations in string literal concatenation error

gcc/cp/ChangeLog:
	* parser.c (cp_parser_string_literal): Convert non-standard
	concatenation error to directly use a rich_location, and
	use that to add the location of the first literal to the
	diagnostic.

gcc/testsuite/ChangeLog:
	* g++.dg/diagnostic/string-literal-concat.C: New test case.

From-SVN: r237608

gcc/cp/ChangeLog

+2016-06-20  David Malcolm  <dmalcolm@redhat.com>
+
+	* parser.c (cp_parser_string_literal): Convert non-standard
+	concatenation error to directly use a rich_location, and
+	use that to add the location of the first literal to the
+	diagnostic.
+
 2016-06-17  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	* decl.c (validate_constexpr_redeclaration): Change pair of errors

gcc/cp/parser.c

@@ -3893,13 +3893,12 @@ cp_parser_string_literal (cp_parser *parser, bool translate, bool wide_ok,
     }
   else
     {
-      location_t last_tok_loc;
+      location_t last_tok_loc = tok->location;
       gcc_obstack_init (&str_ob);
       count = 0;
 
       do
 	{
-	  last_tok_loc = tok->location;
 	  cp_lexer_consume_token (parser->lexer);
 	  count++;
 	  str.text = (const unsigned char *)TREE_STRING_POINTER (string_tree);
@@ -3931,13 +3930,19 @@ cp_parser_string_literal (cp_parser *parser, bool translate, bool wide_ok,
 	      if (type == CPP_STRING)
 		type = curr_type;
 	      else if (curr_type != CPP_STRING)
-		error_at (tok->location,
-			  "unsupported non-standard concatenation "
-			  "of string literals");
+		{
+		  rich_location rich_loc (line_table, tok->location);
+		  rich_loc.add_range (last_tok_loc, false);
+		  error_at_rich_loc (&rich_loc,
+				     "unsupported non-standard concatenation "
+				     "of string literals");
+		}
 	    }
 
 	  obstack_grow (&str_ob, &str, sizeof (cpp_string));
 
+	  last_tok_loc = tok->location;
+
 	  tok = cp_lexer_peek_token (parser->lexer);
 	  if (cpp_userdef_string_p (tok->type))
 	    {

gcc/testsuite/ChangeLog

+2016-06-20  David Malcolm  <dmalcolm@redhat.com>
+
+	* g++.dg/diagnostic/string-literal-concat.C: New test case.
+
 2016-06-20  Martin Sebor  <msebor@redhat.com>
 
 	PR c/69507

gcc/testsuite/g++.dg/diagnostic/string-literal-concat.C

+/* { dg-options "-fdiagnostics-show-caret -std=c++11" } */
+
+const void *s = u8"a"  u"b";  // { dg-error "24: non-standard concatenation" }
+/* { dg-begin-multiline-output "" }
+ const void *s = u8"a"  u"b";
+                 ~~~~~  ^~~~
+   { dg-end-multiline-output "" } */
+
+const void *s2 = u"a"  u"b"  u8"c";  // { dg-error "30: non-standard concatenation" }
+/* { dg-begin-multiline-output "" }
+ const void *s2 = u"a"  u"b"  u8"c";
+                        ~~~~  ^~~~~
+  { dg-end-multiline-output "" } */
+
+#define TEST_U8_LITERAL u8"a"
+
+const void *s3 = TEST_U8_LITERAL u8"b";
+
+const void *s4 = TEST_U8_LITERAL u"b"; // { dg-error "34: non-standard concatenation" }
+/* { dg-begin-multiline-output "" }
+ const void *s4 = TEST_U8_LITERAL u"b";
+                                  ^~~~
+  { dg-end-multiline-output "" } */