re PR c++/32597 (New operation with empty parameter pack does not value-initialize)

2007-08-31 Douglas Gregor <doug.gregor@gmail.com>

	PR c++/32597
	* init.c (build_default_init): Make extern.
	* cp-tree.h (build_default_init): Declare here.
	* pt.c (tsubst_expr): When the instantiation of the initializer of
	a variable results in an empty list, default-initialize the
	variable.
	(tsubst_copy_and_build): When the instantiation of the initializer
	in a new expression results in an empty initializer list,
	default-initialize it.

2007-08-31 Douglas Gregor <doug.gregor@gmail.com>

	PR c++/32597
	* gcc/testsuite/g++.dg/cpp0x/variadic-new2.C: New.
	* gcc/testsuite/g++.dg/cpp0x/variadic-new.C: New.

From-SVN: r128000

gcc/cp/ChangeLog

@@ -1,3 +1,15 @@
+2007-08-31 Douglas Gregor <doug.gregor@gmail.com>
+
+	PR c++/32597
+	* init.c (build_default_init): Make extern.
+	* cp-tree.h (build_default_init): Declare here.
+	* pt.c (tsubst_expr): When the instantiation of the initializer of
+	a variable results in an empty list, default-initialize the
+	variable.
+	(tsubst_copy_and_build): When the instantiation of the initializer
+	in a new expression results in an empty initializer list,
+	default-initialize it.
+
 2007-08-31  Douglas Gregor  <doug.gregor@gmail.com>
 
 	* mangle.c (write_type): Change mangling of rvalue reference from

gcc/cp/cp-tree.h

@@ -4345,6 +4345,7 @@ extern tree build_zero_init			(tree, tree, bool);
 extern tree build_offset_ref			(tree, tree, bool);
 extern tree build_new				(tree, tree, tree, tree, int);
 extern tree build_vec_init			(tree, tree, tree, bool, int);
+extern tree build_default_init                  (tree, tree);
 extern tree build_delete			(tree, tree,
 						 special_function_kind,
 						 int, int);

gcc/cp/init.c

@@ -51,7 +51,6 @@ static tree initializing_context (tree);
 static void expand_cleanup_for_base (tree, tree);
 static tree get_temp_regvar (tree, tree);
 static tree dfs_initialize_vtbl_ptrs (tree, void *);
-static tree build_default_init (tree, tree);
 static tree build_dtor_call (tree, special_function_kind, int);
 static tree build_field_list (tree, tree, int *);
 static tree build_vtbl_address (tree);
@@ -275,7 +274,7 @@ build_zero_init (tree type, tree nelts, bool static_storage_p)
    returns NULL_TREE; the caller is responsible for arranging for the
    constructors to be called.  */
 
-static tree
+tree
 build_default_init (tree type, tree nelts)
 {
   /* [dcl.init]:

gcc/cp/pt.c

@@ -9885,7 +9885,23 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl,
 			init = cp_fname_init (name, &TREE_TYPE (decl));
 		      }
 		    else
-		      init = RECUR (init);
+		      {
+			tree t = RECUR (init);
+
+			if (init && !t)
+			  /* If we had an initializer but it
+			     instantiated to nothing,
+			     value-initialize the object.  This will
+			     only occur when the initializer was a
+			     pack expansion where the parameter packs
+			     used in that expansion were of length
+			     zero.  */
+			  init = build_default_init (TREE_TYPE (decl),
+                                                     NULL_TREE);
+			else
+			  init = t;
+		      }
+
 		    finish_decl (decl, init, NULL_TREE);
 		  }
 	      }
@@ -10489,12 +10505,25 @@ tsubst_copy_and_build (tree t,
       return build_x_arrow (op1);
 
     case NEW_EXPR:
-      return build_new
-	(RECUR (TREE_OPERAND (t, 0)),
-	 RECUR (TREE_OPERAND (t, 1)),
-	 RECUR (TREE_OPERAND (t, 2)),
-	 RECUR (TREE_OPERAND (t, 3)),
-	 NEW_EXPR_USE_GLOBAL (t));
+      {
+	tree init = RECUR (TREE_OPERAND (t, 3));
+
+	if (TREE_OPERAND (t, 3) && !init)
+	  /* If there was an initializer in the the original tree, but
+	     it instantiated to an empty list, then we should pass on
+	     VOID_ZERO_NODE to tell build_new that it was an empty
+	     initializer () rather than no initializer.  This can only
+	     happen when the initializer is a pack expansion whose
+	     parameter packs are of length zero.  */
+	  init = void_zero_node;
+
+	return build_new
+	  (RECUR (TREE_OPERAND (t, 0)),
+	   RECUR (TREE_OPERAND (t, 1)),
+	   RECUR (TREE_OPERAND (t, 2)),
+	   init,
+	   NEW_EXPR_USE_GLOBAL (t));
+      }
 
     case DELETE_EXPR:
      return delete_sanity

gcc/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2007-08-31 Douglas Gregor <doug.gregor@gmail.com>
+
+	PR c++/32597
+	* gcc/testsuite/g++.dg/cpp0x/variadic-new2.C: New.
+	* gcc/testsuite/g++.dg/cpp0x/variadic-new.C: New.
+
 2007-08-31  Tobias Burnus  <burnus@net-b.de>
 
 	PR fortran/33232

gcc/testsuite/g++.dg/cpp0x/variadic-new.C

@@ -0,0 +1,19 @@
+// { dg-do "run" }
+// { dg-options "-std=c++0x" }
+// Contributed by Peter Dimov
+// PR c++/32597
+#include <assert.h>
+#include <new>
+
+int k = 5;
+
+template< class... Args > void f( Args... args )
+{
+   new( &k ) int( args... );
+}
+
+int main()
+{
+   f();
+   assert( k == 0 );
+}

gcc/testsuite/g++.dg/cpp0x/variadic-new2.C

@@ -0,0 +1,24 @@
+// { dg-do "run" }
+// { dg-options "-std=c++0x" }
+// PR c++/32597
+#include <assert.h>
+#include <new>
+
+template< class... Args > void f( Args... args )
+{
+  { 
+    int x = 17;
+    (void)x;
+  }
+
+  {
+    int y(args...);
+    assert(y == 0);
+  }
+
+}
+
+int main()
+{
+   f();
+}