C++ PATCH for c++/49520 (bogus error with using in constexpr)

C++ PATCH for c++/49520 (bogus error with using in constexpr)

[Jason Merrill]

[-- Attachment #1: Type: text/plain, Size: 132 bytes --]

A CLEANUP_POINT_EXPR wraps each statement, so we need to strip it at a 
lower level.

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

[-- Attachment #2: 49520.patch --]
[-- Type: text/x-patch, Size: 2153 bytes --]

commit 505b4baa3619375d81b409f9ff2bde95cce0f50a
Author: Jason Merrill <jason@redhat.com>
Date:   Wed Jun 29 12:43:19 2011 -0400

    	PR c++/49520
    	* semantics.c (constexpr_fn_retval): Handle CLEANUP_POINT_EXPR here.
    	(massage_constexpr_body): Not here.

diff --git a/gcc/cp/cp-tree.def b/gcc/cp/cp-tree.def
index 12c01cb..bb1b753 100644
--- a/gcc/cp/cp-tree.def
+++ b/gcc/cp/cp-tree.def
@@ -207,7 +207,7 @@ DEFTREECODE (UNBOUND_CLASS_TEMPLATE, "unbound_class_template", tcc_type, 0)
 DEFTREECODE (USING_DECL, "using_decl", tcc_declaration, 0)
 
 /* A using directive. The operand is USING_STMT_NAMESPACE.  */
-DEFTREECODE (USING_STMT, "using_directive", tcc_statement, 1)
+DEFTREECODE (USING_STMT, "using_stmt", tcc_statement, 1)
 
 /* An un-parsed default argument.  Holds a vector of input tokens and
    a vector of places where the argument was instantiated before
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index fb984d4..ad68a01 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -5657,6 +5657,9 @@ constexpr_fn_retval (tree body)
 	return NULL_TREE;
       return error_mark_node;
 
+    case CLEANUP_POINT_EXPR:
+      return constexpr_fn_retval (TREE_OPERAND (body, 0));
+
     case USING_STMT:
       return NULL_TREE;
 
@@ -5683,8 +5686,6 @@ massage_constexpr_body (tree fun, tree body)
         body = EH_SPEC_STMTS (body);
       if (TREE_CODE (body) == MUST_NOT_THROW_EXPR)
 	body = TREE_OPERAND (body, 0);
-      if (TREE_CODE (body) == CLEANUP_POINT_EXPR)
-        body = TREE_OPERAND (body, 0);
       body = constexpr_fn_retval (body);
     }
   return body;
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-using2.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-using2.C
new file mode 100644
index 0000000..6b28281
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-using2.C
@@ -0,0 +1,18 @@
+// PR c++/49520
+// { dg-options -std=c++0x }
+
+namespace x { void foo(); }
+
+template<typename T>
+struct traits
+{
+    static constexpr bool f() { return true; }
+
+    static constexpr bool g()
+    {
+        using x::foo;
+        return f() && noexcept(foo());
+    }
+};
+
+template struct traits<int>;