[C++ Patch] PR 60365

[Paolo Carlini]

Hi,

this issue is an accepts invalid about multiple noreturn in an 
attribute-list. The same issue exists for deprecated in C++14 (and will 
exist for carries_dependency when we'll implement it...). Of course it 
would be easy to imagine more efficient algorithms doing the check only 
once after the entire attribute-list is parsed, but the simple-minded 
check has the advantage that the locations are correct for free and I 
suppose should be good enough efficiency-wise for reasonable 
attribute-lists... Tested x86_64-linux.

Thanks,
Paolo.

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-------------- next part --------------
/cp
2015-06-30  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/60365
	* parser.c (cp_parser_check_std_attribute): New.
	(cp_parser_std_attribute_list): Call it.

/testsuite
2015-06-30  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/60365
	* g++.dg/cpp0x/gen-attrs-60.C: New.
	* g++.dg/cpp1y/attr-deprecated-2.C: Likewise.
-------------- next part --------------
Index: cp/parser.c
===================================================================
--- cp/parser.c	(revision 225177)
+++ cp/parser.c	(working copy)
@@ -22532,6 +22547,35 @@ cp_parser_std_attribute (cp_parser *parser)
   return attribute;
 }
 
+/* Check that the attribute ATTRIBUTE appears at most once in the
+   attribute-list ATTRIBUTES.  This is enforced for noreturn (7.6.3)
+   and deprecated (7.6.5).  Note that carries_dependency (7.6.4)
+   isn't implemented yet in GCC.  */
+
+static bool
+cp_parser_check_std_attribute (tree attributes, tree attribute)
+{
+  if (attributes)
+    {
+      tree name = get_attribute_name (attribute);
+      if (is_attribute_p ("noreturn", name)
+	  && lookup_attribute ("noreturn", attributes))
+	{
+	  error ("attribute noreturn can appear at most once "
+		 "in an attribute-list");
+	  return false;
+	}
+      else if (is_attribute_p ("deprecated", name)
+	       && lookup_attribute ("deprecated", attributes))
+	{
+	  error ("attribute deprecated can appear at most once "
+		 "in an attribute-list");
+	  return false;
+	}
+    }
+  return true;
+}
+
 /* Parse a list of standard C++-11 attributes.
 
    attribute-list:
@@ -22554,6 +22598,8 @@ cp_parser_std_attribute_list (cp_parser *parser)
 	break;
       if (attribute != NULL_TREE)
 	{
+	  if (!cp_parser_check_std_attribute (attributes, attribute))
+	    break;
 	  TREE_CHAIN (attribute) = attributes;
 	  attributes = attribute;
 	}
Index: testsuite/g++.dg/cpp0x/gen-attrs-60.C
===================================================================
--- testsuite/g++.dg/cpp0x/gen-attrs-60.C	(revision 0)
+++ testsuite/g++.dg/cpp0x/gen-attrs-60.C	(working copy)
@@ -0,0 +1,4 @@
+// PR c++/60365
+// { dg-do compile { target c++11 } }
+
+void func [[noreturn, noreturn]] ();     // { dg-error "at most once" }
Index: testsuite/g++.dg/cpp1y/attr-deprecated-2.C
===================================================================
--- testsuite/g++.dg/cpp1y/attr-deprecated-2.C	(revision 0)
+++ testsuite/g++.dg/cpp1y/attr-deprecated-2.C	(working copy)
@@ -0,0 +1,4 @@
+// PR c++/60365
+// { dg-do compile { target c++14 } }
+
+void func [[deprecated, deprecated]] (); // { dg-error "at most once" }