From 3db4aa63d6850f44758d06d5f075c76de6d4c1e9 Mon Sep 17 00:00:00 2001
From: jason <jason@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Fri, 6 May 2011 21:58:22 +0000
Subject: [PATCH] 	PR c++/48089
 	* semantics.c (potential_constant_expression_1): Don't allow *this
 	in a constructor.
 	(register_constexpr_fundef): Use potential_rvalue_constant_expression.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_6-branch@173513 138bc75d-0d04-0410-961f-82ee72b054a4

index f43649e..8f621b9 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -5704,11 +5704,11 @@ register_constexpr_fundef (tree fun, tree body)
       body = unshare_expr (TREE_OPERAND (body, 0));
     }
 
-  if (!potential_constant_expression (body))
+  if (!potential_rvalue_constant_expression (body))
     {
       DECL_DECLARED_CONSTEXPR_P (fun) = false;
       if (!DECL_TEMPLATE_INSTANTIATION (fun))
-	require_potential_constant_expression (body);
+	require_potential_rvalue_constant_expression (body);
       return NULL;
     }
   fundef->body = body;
@@ -7560,7 +7560,16 @@ potential_constant_expression_1 (tree t, bool want_rval, tsubst_flags_t flags)
         tree x = TREE_OPERAND (t, 0);
         STRIP_NOPS (x);
         if (is_this_parameter (x))
-	  return true;
+	  {
+	    if (DECL_CONSTRUCTOR_P (DECL_CONTEXT (x)) && want_rval)
+	      {
+		if (flags & tf_error)
+		  sorry ("use of the value of the object being constructed "
+			 "in a constant expression");
+		return false;
+	      }
+	    return true;
+	  }
 	return potential_constant_expression_1 (x, rval, flags);
       }
 
new file mode 100644
index 0000000..fc69cfe
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-48089.C
@@ -0,0 +1,24 @@
+// PR c++/48089
+// { dg-options -std=c++0x }
+
+// bang is ill-formed (diagnostic required) because its initializer is
+// non-constant, because it uses the value of an uninitialized object.
+
+// s() is ill-formed (no diagnostic required) because there is no set of
+// arguments that would produce a constant expression.
+
+// R() is well-formed because i is initialized before j.
+
+struct s {
+  constexpr s() : v(v) { }	// { dg-message "" }
+  int v;
+};
+
+constexpr s bang;		// { dg-error "" }
+
+struct R {
+  int i,j;
+  constexpr R() : i(42),j(i) { } // { dg-bogus "" "" { xfail *-*-* } }
+};
+
+constexpr R r;			// { dg-bogus "" "" { xfail *-*-* } }
-- 
1.7.0.4