re PR c++/47207 ([C++0x] ICE: in decl_constant_var_p, at cp/decl2.c:3563 on invalid code)

	PR c++/47207
	* decl2.c (decl_constant_var_p): A constexpr var needs an
	initializer to be constant.
	* semantics.c (cxx_eval_constant_expression): Complain about
	constexpr var used in its own initializer.
	* call.c (set_up_extended_ref_temp): Set
	DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P too.

From-SVN: r170365

gcc/cp/ChangeLog

+2011-02-21  Jason Merrill  <jason@redhat.com>
+
+	PR c++/47207
+	* decl2.c (decl_constant_var_p): A constexpr var needs an
+	initializer to be constant.
+	* semantics.c (cxx_eval_constant_expression): Complain about
+	constexpr var used in its own initializer.
+	* call.c (set_up_extended_ref_temp): Set
+	DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P too.
+
 2011-02-20  Jason Merrill  <jason@redhat.com>
 
 	PR c++/47199

gcc/cp/call.c

@@ -8149,6 +8149,7 @@ set_up_extended_ref_temp (tree decl, tree expr, tree *cleanup, tree *initp)
 	     Currently this is only useful for initializer_list temporaries,
 	     since reference vars can't appear in constant expressions.  */
 	  DECL_DECLARED_CONSTEXPR_P (var) = true;
+	  DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (var) = true;
 	  TREE_CONSTANT (var) = true;
 	}
       DECL_INITIAL (var) = init;

gcc/cp/decl2.c

@@ -3550,20 +3550,21 @@ decl_constant_var_p (tree decl)
   tree type = TREE_TYPE (decl);
   if (TREE_CODE (decl) != VAR_DECL)
     return false;
-  if (DECL_DECLARED_CONSTEXPR_P (decl))
-    ret = true;
-  else if (CP_TYPE_CONST_NON_VOLATILE_P (type)
-	   && INTEGRAL_OR_ENUMERATION_TYPE_P (type))
+  if (DECL_DECLARED_CONSTEXPR_P (decl)
+      || (CP_TYPE_CONST_NON_VOLATILE_P (type)
+	  && INTEGRAL_OR_ENUMERATION_TYPE_P (type)))
     {
       /* We don't know if a template static data member is initialized with
-	 a constant expression until we instantiate its initializer.  */
+	 a constant expression until we instantiate its initializer.  Even
+	 in the case of a constexpr variable, we can't treat it as a
+	 constant until its initializer is complete in case it's used in
+	 its own initializer.  */
       mark_used (decl);
       ret = DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (decl);
     }
   else
     ret = false;
 
-  gcc_assert (!ret || DECL_INITIAL (decl));
   return ret;
 }
 

gcc/cp/semantics.c

@@ -6768,7 +6768,10 @@ cxx_eval_constant_expression (const constexpr_call *call, tree t,
 	      tree type = TREE_TYPE (r);
 	      error ("the value of %qD is not usable in a constant "
 		     "expression", r);
-	      if (INTEGRAL_OR_ENUMERATION_TYPE_P (type))
+	      if (DECL_DECLARED_CONSTEXPR_P (r))
+		inform (DECL_SOURCE_LOCATION (r),
+			"%qD used in its own initializer", r);
+	      else if (INTEGRAL_OR_ENUMERATION_TYPE_P (type))
 		{
 		  if (!CP_TYPE_CONST_P (type))
 		    inform (DECL_SOURCE_LOCATION (r),

gcc/testsuite/ChangeLog

+2011-02-21  Jason Merrill  <jason@redhat.com>
+
+	* g++.dg/cpp0x/constexpr-diag2.C: New.
+
 2011-02-20  Jason Merrill  <jason@redhat.com>
 
 	* g++.dg/cpp0x/constexpr-ctor7.C: New.

gcc/testsuite/g++.dg/cpp0x/constexpr-diag2.C

+// PR c++/47207
+// { dg-options -std=c++0x }
+
+constexpr int X (X);		// { dg-error "not usable" }
+// { dg-message "own initializer" "" { target *-*-* } 4 }