c++: support C++11 attributes in C++98

I don't see any reason why we can't allow the [[]] attribute syntax in C++98
mode with a pedwarn just like many other C++11 features.  In fact, we
already do support it in some places in the grammar, but not in places that
check cp_nth_tokens_can_be_std_attribute_p.

Let's also follow the C front-end's lead in only warning about them when
-pedantic.

It still isn't necessary for this function to guard against Objective-C
message passing syntax; we handle that with tentative parsing in
cp_parser_statement, and we don't call this function in that context anyway.

gcc/cp/ChangeLog:

	* parser.cc (cp_nth_tokens_can_be_std_attribute_p): Don't check
	cxx_dialect.
	* error.cc (maybe_warn_cpp0x): Only complain about C++11 attributes
	if pedantic.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/gen-attrs-1.C: Also run in C++98 mode.
	* g++.dg/cpp0x/gen-attrs-11.C: Likewise.
	* g++.dg/cpp0x/gen-attrs-13.C: Likewise.
	* g++.dg/cpp0x/gen-attrs-15.C: Likewise.
	* g++.dg/cpp0x/gen-attrs-75.C: Don't expect C++98 warning after
	__extension__.

7 files changed, 17 insertions, 17 deletions

diff --git a/gcc/cp/error.cc b/gcc/cp/error.cc
index 57cd76c..4a9e9aa 100644
--- a/gcc/cp/error.cc
+++ b/gcc/cp/error.cc
@@ -4735,9 +4735,10 @@ maybe_warn_cpp0x (cpp0x_warn_str str, location_t loc/*=input_location*/)
 		 "only available with %<-std=c++11%> or %<-std=gnu++11%>");
         break;
       case CPP0X_ATTRIBUTES:
-	pedwarn (loc, OPT_Wc__11_extensions,
-		 "C++11 attributes "
-		 "only available with %<-std=c++11%> or %<-std=gnu++11%>");
+	if (pedantic)
+	  pedwarn (loc, OPT_Wc__11_extensions,
+		   "C++11 attributes "
+		   "only available with %<-std=c++11%> or %<-std=gnu++11%>");
 	break;
       case CPP0X_REF_QUALIFIER:
 	pedwarn (loc, OPT_Wc__11_extensions,
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index edfa5a4..64122d9 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -29924,11 +29924,10 @@ cp_nth_tokens_can_be_std_attribute_p (cp_parser *parser, size_t n)
 {
   cp_token *token = cp_lexer_peek_nth_token (parser->lexer, n);
 
-  return (cxx_dialect >= cxx11
-	  && ((token->type == CPP_KEYWORD && token->keyword == RID_ALIGNAS)
-	      || (token->type == CPP_OPEN_SQUARE
-		  && (token = cp_lexer_peek_nth_token (parser->lexer, n + 1))
-		  && token->type == CPP_OPEN_SQUARE)));
+  return ((token->type == CPP_KEYWORD && token->keyword == RID_ALIGNAS)
+	  || (token->type == CPP_OPEN_SQUARE
+	      && (token = cp_lexer_peek_nth_token (parser->lexer, n + 1))
+	      && token->type == CPP_OPEN_SQUARE));
 }
 
 /* Return TRUE iff the next Nth tokens in the stream are possibly the
diff --git a/gcc/testsuite/g++.dg/cpp0x/gen-attrs-1.C b/gcc/testsuite/g++.dg/cpp0x/gen-attrs-1.C
index c2cf912..b1625d9 100644
--- a/gcc/testsuite/g++.dg/cpp0x/gen-attrs-1.C
+++ b/gcc/testsuite/g++.dg/cpp0x/gen-attrs-1.C
@@ -1,3 +1,3 @@
-// { dg-do compile { target c++11 } }
+// { dg-additional-options "-Wno-c++11-extensions" }
 
 int **** [[gnu::format(printf, 1, 2)]] foo(const char *, ...); // { dg-warning "only applies to function types" }
diff --git a/gcc/testsuite/g++.dg/cpp0x/gen-attrs-11.C b/gcc/testsuite/g++.dg/cpp0x/gen-attrs-11.C
index 504b456..040f15c 100644
--- a/gcc/testsuite/g++.dg/cpp0x/gen-attrs-11.C
+++ b/gcc/testsuite/g++.dg/cpp0x/gen-attrs-11.C
@@ -1,4 +1,4 @@
-// { dg-do compile { target c++11 } }
+// { dg-additional-options "-Wno-c++11-extensions" }
 // PR c++/13791
 
 template <typename T> struct O {
diff --git a/gcc/testsuite/g++.dg/cpp0x/gen-attrs-13.C b/gcc/testsuite/g++.dg/cpp0x/gen-attrs-13.C
index a1b4a84..8997b84 100644
--- a/gcc/testsuite/g++.dg/cpp0x/gen-attrs-13.C
+++ b/gcc/testsuite/g++.dg/cpp0x/gen-attrs-13.C
@@ -1,4 +1,4 @@
-// { dg-do compile { target c++11 } }
+// { dg-additional-options "-Wno-c++11-extensions" }
 // PR c++/13854
 
 extern char *rindex [[gnu::__pure__]] (__const char *__s, int __c) throw ();
diff --git a/gcc/testsuite/g++.dg/cpp0x/gen-attrs-15.C b/gcc/testsuite/g++.dg/cpp0x/gen-attrs-15.C
index bf05dbe..8b552ca 100644
--- a/gcc/testsuite/g++.dg/cpp0x/gen-attrs-15.C
+++ b/gcc/testsuite/g++.dg/cpp0x/gen-attrs-15.C
@@ -1,4 +1,4 @@
-// { dg-do compile { target c++11 } }
+// { dg-additional-options "-Wno-c++11-extensions" }
 // PR c++/15317
 
 struct A
diff --git a/gcc/testsuite/g++.dg/cpp0x/gen-attrs-75.C b/gcc/testsuite/g++.dg/cpp0x/gen-attrs-75.C
index bac80aa..c2a328c 100644
--- a/gcc/testsuite/g++.dg/cpp0x/gen-attrs-75.C
+++ b/gcc/testsuite/g++.dg/cpp0x/gen-attrs-75.C
@@ -1,6 +1,6 @@
 // PR c++/101582
 // { dg-do compile }
-// { dg-options "" }
+// { dg-options "-pedantic -Wno-extra-semi" }
 
 ;
 [[]] [[]] [[]];	// { dg-warning "attributes only available with" "" { target c++98_only } }
@@ -12,9 +12,9 @@ extern "C" [[]];	// { dg-warning "attributes only available with" "" { target c+
 extern "C" extern "C" ;
 extern "C" extern "C" [[]][[]][[]];	// { dg-warning "attributes only available with" "" { target c++98_only } }
 __extension__ ;
-__extension__ [[]];			// { dg-warning "attributes only available with" "" { target c++98_only } }
+__extension__ [[]];
 __extension__ __extension__ ;
-__extension__ __extension__ [[]][[]];	// { dg-warning "attributes only available with" "" { target c++98_only } }
+__extension__ __extension__ [[]][[]];
 
 namespace N {
 
@@ -28,8 +28,8 @@ extern "C" [[]];	// { dg-warning "attributes only available with" "" { target c+
 extern "C" extern "C" ;
 extern "C" extern "C" [[]][[]][[]];	// { dg-warning "attributes only available with" "" { target c++98_only } }
 __extension__ ;
-__extension__ [[]];			// { dg-warning "attributes only available with" "" { target c++98_only } }
+__extension__ [[]];
 __extension__ __extension__ ;
-__extension__ __extension__ [[]][[]];	// { dg-warning "attributes only available with" "" { target c++98_only } }
+__extension__ __extension__ [[]][[]];
 
 }