C++ PATCH for c++/45401 (losing __restrict on reference squashing)

C++ PATCH for c++/45401 (losing __restrict on reference squashing)

[Jason Merrill]

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There are no standardized semantics for __restrict on references, but it 
seems reasonable to do as the submitter requests and return the original 
reference type unchanged when adding &&.

Tested x86_64-pc-linux-gnu, applying to trunk.

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commit abb9429bb160d33b268bb45b9538ba83d920b0f2
Author: Jason Merrill <jason@redhat.com>
Date:   Wed May 25 16:19:21 2011 -0400

    	PR c++/45401
    	* decl.c (grokdeclarator): Don't change type when adding rvalue ref
    	to another reference type.

diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 7fc1945..d53fa26 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -9200,13 +9200,18 @@ grokdeclarator (const cp_declarator *declarator,
 		 to create the type "rvalue reference to cv TD' creates the
 		 type TD."
               */
-	      if (!VOID_TYPE_P (type))
+	      if (VOID_TYPE_P (type))
+		/* We already gave an error.  */;
+	      else if (TREE_CODE (type) == REFERENCE_TYPE)
+		{
+		  if (declarator->u.reference.rvalue_ref)
+		    /* Leave type alone.  */;
+		  else
+		    type = cp_build_reference_type (TREE_TYPE (type), false);
+		}
+	      else
 		type = cp_build_reference_type
-		       ((TREE_CODE (type) == REFERENCE_TYPE
-			 ? TREE_TYPE (type) : type),
-			(declarator->u.reference.rvalue_ref
-			 && (TREE_CODE(type) != REFERENCE_TYPE
-			     || TYPE_REF_IS_RVALUE (type))));
+		  (type, declarator->u.reference.rvalue_ref);
 
 	      /* In C++0x, we need this check for direct reference to
 		 reference declarations, which are forbidden by
diff --git a/gcc/testsuite/g++.dg/cpp0x/rv-restrict.C b/gcc/testsuite/g++.dg/cpp0x/rv-restrict.C
new file mode 100644
index 0000000..569ee5b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/rv-restrict.C
@@ -0,0 +1,6 @@
+// PR c++/45401
+// { dg-options -std=c++0x }
+
+typedef int &__restrict restrictLvref;
+typedef restrictLvref &&rvrefToRestrictLvref;
+typedef restrictLvref rvrefToRestrictLvref;