From: Jason Merrill <jason@redhat.com>
Date: Tue, 3 Apr 2012 22:51:08 +0000 (-0400)
Subject: re PR c++/52796 ([C++11] Initialization of primitive object with 0-length parameter... 
X-Git-Tag: releases/gcc-4.6.4~606
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f6f1732755cba4f352899e0517982eae5bf07e56;p=thirdparty%2Fgcc.git

re PR c++/52796 ([C++11] Initialization of primitive object with 0-length parameter pack fails to value-initialize)

	PR c++/52796
	* pt.c (tsubst_initializer_list): A pack expansion with no elements
	means value-initialization.

From-SVN: r186120
---

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index a365738c35c9..9dea1b5c1b40 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2012-04-03  Jason Merrill  <jason@redhat.com>
+
+	PR c++/52796
+	* pt.c (tsubst_initializer_list): A pack expansion with no elements
+	means value-initialization.
+
 2012-03-01  Release Manager
 
 	* GCC 4.6.3 released.
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 0760e9e23ca9..4defa853eaa6 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -17785,6 +17785,7 @@ tsubst_initializer_list (tree t, tree argvec)
             }
           else
             {
+	      tree tmp;
               decl = tsubst_copy (TREE_PURPOSE (t), argvec, 
                                   tf_warning_or_error, NULL_TREE);
 
@@ -17793,10 +17794,17 @@ tsubst_initializer_list (tree t, tree argvec)
                 in_base_initializer = 1;
 
 	      init = TREE_VALUE (t);
+	      tmp = init;
 	      if (init != void_type_node)
 		init = tsubst_expr (init, argvec,
 				    tf_warning_or_error, NULL_TREE,
 				    /*integral_constant_expression_p=*/false);
+	      if (init == NULL_TREE && tmp != NULL_TREE)
+		/* 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 = void_type_node;
               in_base_initializer = 0;
             }
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 9dcfc25b8891..a3a5f18e1180 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2012-04-03  Jason Merrill  <jason@redhat.com>
+
+	PR c++/52796
+	* g++.dg/cpp0x/variadic-value1.C: New.
+
 2012-03-28  Joey Ye  <joey.ye@arm.com>
 
 	Backported from mainline
diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic-value1.C b/gcc/testsuite/g++.dg/cpp0x/variadic-value1.C
new file mode 100644
index 000000000000..179919a5bc76
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic-value1.C
@@ -0,0 +1,24 @@
+// PR c++/52796
+// { dg-do run { target c++11 } }
+
+inline void *operator new(__SIZE_TYPE__ s, void *p) { return p; }
+
+struct A
+{
+  int i;
+  template<class... Ts>
+  A(Ts&&... ts): i(ts...) { }
+};
+
+static union {
+  unsigned char c[sizeof(A)];
+  int i;
+};
+
+int main()
+{
+  i = 0xdeadbeef;
+  new(c) A;
+  if (i != 0)
+    __builtin_abort();
+}