Disambiguate nested objc-message-expressions and c++11 attributes

A couple of obj-c++ tests were failing[1] because the tokens '[[' can
either be the beginning of a c++11 attribute (that is itself at the
beginning of a statement), or the beginning of a nested
objc-message-expression.  This patch resolves the ambiguity by
tentatively parsing the c++11 attribute and if it fails, then consider
the objc-message-expression.

I missed this initially because it didn't occur to me that
--enable-languages=all,ada does not include obj-c++.  Shame on me.  I
have now updated my compile farm scripts to use
--enable-language=all,ada,obj-c++,go and I

[1]:

FAIL: obj-c++.dg/syntax-error-6.mm -fgnu-runtime  (test for errors, line 11)
FAIL: obj-c++.dg/syntax-error-6.mm -fgnu-runtime (test for excess errors)
FAIL: obj-c++.dg/template-8.mm -fgnu-runtime (test for excess errors)

Tested on x86_64-unknown-linux-gnu against trunk.

gcc/cp/

	* parser (cp_parser_statement):  Parse c++11 attributes tentatively.
	(cp_parser_std_attribute_spec_seq): Do not warn too early about
	using c++11 attributes in non c++11 mode.

From-SVN: r192299

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 68ebb96a7c3164c90fb2efec1e1a28195434a5ba..208d305e60470207e3925c4c6896214cf2ed9afc 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,10 @@
+2012-10-10  Dodji Seketeli  <dodji@redhat.com>
+
+       * parser (cp_parser_statement): Parse c++11 attributes
+       tentatively.
+       (cp_parser_std_attribute_spec_seq): Do not warn too early about
+       using c++11 attributes in non c++11 mode.
+
 2012-10-10  Dehao Chen  <dehao@google.com>
 
        * cp-gimplify.c (cp_genericize_r): Set location for TRY expr.

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index e2b355a246f6dbc5eccf392f9440d74241ce2387..a7939c87647dbfde8ae761205e7c3b9d60aaafeb 100644 (file)
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -8718,7 +8718,17 @@ cp_parser_statement (cp_parser* parser, tree in_statement_expr,
 
   cp_lexer_save_tokens (parser->lexer);
   attrs_location = cp_lexer_peek_token (parser->lexer)->location;
+  if (c_dialect_objc ())
+    /* In obj-c++, seing '[[' might be the either the beginning of
+       c++11 attributes, or a nested objc-message-expression.  So
+       let's parse the c++11 attributes tentatively.  */
+    cp_parser_parse_tentatively (parser);
   std_attrs = cp_parser_std_attribute_spec_seq (parser);
+  if (c_dialect_objc ())
+    {
+      if (!cp_parser_parse_definitely (parser))
+       std_attrs = NULL_TREE;
+    }
 
   /* Peek at the next token.  */
   token = cp_lexer_peek_token (parser->lexer);
@@ -20703,7 +20713,6 @@ cp_parser_std_attribute_spec (cp_parser *parser)
       && cp_lexer_peek_nth_token (parser->lexer, 2)->type == CPP_OPEN_SQUARE)
     {
       cp_lexer_consume_token (parser->lexer);
-      maybe_warn_cpp0x (CPP0X_ATTRIBUTES);
       cp_lexer_consume_token (parser->lexer);
 
       attributes = cp_parser_std_attribute_list (parser);
@@ -20711,6 +20720,10 @@ cp_parser_std_attribute_spec (cp_parser *parser)
       if (!cp_parser_require (parser, CPP_CLOSE_SQUARE, RT_CLOSE_SQUARE)
          || !cp_parser_require (parser, CPP_CLOSE_SQUARE, RT_CLOSE_SQUARE))
        cp_parser_skip_to_end_of_statement (parser);
+      else
+       /* Warn about parsing c++11 attribute in non-c++1 mode, only
+          when we are sure that we have actually parsed them.  */
+       maybe_warn_cpp0x (CPP0X_ATTRIBUTES);
     }
   else
     {