re PR c++/49528 (g++ fails to destroy temporary object when subobject is used to…

re PR c++/49528 (g++ fails to destroy temporary object when subobject is used to initialize a reference)

	PR c++/49528
	* semantics.c (potential_constant_expression_1): A TARGET_EXPR
	with a cleanup isn't constant.
	(cxx_eval_constant_expression): Likewise.
	* init.c (expand_default_init): Use maybe_constant_init.

From-SVN: r175409

gcc/cp/ChangeLog

+2011-06-26  Jason Merrill  <jason@redhat.com>
+
+	PR c++/49528
+	* semantics.c (potential_constant_expression_1): A TARGET_EXPR
+	with a cleanup isn't constant.
+	(cxx_eval_constant_expression): Likewise.
+	* init.c (expand_default_init): Use maybe_constant_init.
+
 2011-06-24  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/46400

gcc/cp/init.c

@@ -1514,7 +1514,7 @@ expand_default_init (tree binfo, tree true_exp, tree exp, tree init, int flags,
       tree fn = get_callee_fndecl (rval);
       if (fn && DECL_DECLARED_CONSTEXPR_P (fn))
 	{
-	  tree e = maybe_constant_value (rval);
+	  tree e = maybe_constant_init (rval);
 	  if (TREE_CONSTANT (e))
 	    rval = build2 (INIT_EXPR, type, exp, e);
 	}

gcc/cp/semantics.c

@@ -7020,6 +7020,16 @@ cxx_eval_constant_expression (const constexpr_call *call, tree t,
       break;
 
     case TARGET_EXPR:
+      /* A cleanup isn't constant.  */
+      if (TARGET_EXPR_CLEANUP (t))
+	{
+	  if (!allow_non_constant)
+	    error ("temporary of type %qT needing destruction in a "
+		   "constant expression", TREE_TYPE (t));
+	  *non_constant_p = true;
+	  break;
+	}
+      /* else fall through.  */
     case INIT_EXPR:
       /* Pass false for 'addr' because these codes indicate
 	 initialization of a temporary.  */
@@ -7840,8 +7850,16 @@ potential_constant_expression_1 (tree t, bool want_rval, tsubst_flags_t flags)
       return potential_constant_expression_1 (TREE_OPERAND (t, 1),
 					      want_rval, flags);
 
-    case INIT_EXPR:
     case TARGET_EXPR:
+      /* A cleanup isn't constant.  */
+      if (TARGET_EXPR_CLEANUP (t))
+	{
+	  if (flags & tf_error)
+	    error ("temporary of type %qT needing destruction in a "
+		   "constant expression", TREE_TYPE (t));
+	  return false;
+	}
+    case INIT_EXPR:
       return potential_constant_expression_1 (TREE_OPERAND (t, 1),
 					      rval, flags);
 

gcc/testsuite/ChangeLog

+2011-06-26  Jason Merrill  <jason@redhat.com>
+
+	PR c++/49528
+	* g++.dg/init/ref19.C: New.
+	* g++.dg/cpp0x/constexpr-cleanup.C: New.
+
 2011-06-26  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/48377

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

+// { dg-options -std=c++0x }
+
+struct A
+{
+  int i;
+  ~A();
+};
+
+constexpr int i = A().i;	// { dg-error "destruction" }

gcc/testsuite/g++.dg/init/ref19.C

+// PR c++/49528
+// { dg-do run }
+
+int d;
+
+struct A
+{
+  int i;
+  ~A() { ++d; };
+};
+
+int main()
+{
+  const int &r = A().i;
+  if (d != 1)
+    return 1;
+}