From 4fdfdd4f1bc3ad199abac6876d7228ccd30dc71e Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Thu, 30 Jul 2015 01:27:34 -0400
Subject: [PATCH] DR 1558 PR c++/67021

	DR 1558
	PR c++/67021
	* pt.c (tsubst_decl) [TYPE_DECL]: Clear TYPE_DEPENDENT_P_VALID.

From-SVN: r226381
---
 gcc/cp/ChangeLog                           |  6 ++++++
 gcc/cp/pt.c                                |  4 ++++
 gcc/testsuite/g++.dg/cpp0x/alias-decl-52.C | 24 ++++++++++++++++++++++
 3 files changed, 34 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/alias-decl-52.C

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 0fa0926cd5c..7356dff5ba2 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2015-07-30  Jason Merrill  <jason@redhat.com>
+
+	DR 1558
+	PR c++/67021
+	* pt.c (tsubst_decl) [TYPE_DECL]: Clear TYPE_DEPENDENT_P_VALID.
+
 2015-07-28  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	* call.c (build_op_delete_call, convert_like_real, build_over_call):
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index e92fefb416d..6bf3d23f2a7 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -11570,6 +11570,10 @@ tsubst_decl (tree t, tree args, tsubst_flags_t complain)
 	  {
 	    DECL_ORIGINAL_TYPE (r) = NULL_TREE;
 	    set_underlying_type (r);
+	    if (TYPE_DECL_ALIAS_P (r) && type != error_mark_node)
+	      /* An alias template specialization can be dependent
+		 even if its underlying type is not.  */
+	      TYPE_DEPENDENT_P_VALID (TREE_TYPE (r)) = false;
 	  }
 
 	layout_decl (r, 0);
diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-52.C b/gcc/testsuite/g++.dg/cpp0x/alias-decl-52.C
new file mode 100644
index 00000000000..27340753901
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-52.C
@@ -0,0 +1,24 @@
+// PR c++/67021
+// { dg-do compile { target c++11 } }
+
+template<typename> struct Dummy;
+template<> struct Dummy<int> {};
+
+template <class...>
+struct all_same { static constexpr bool value = true; };
+template <class T, class...Rest>
+struct all_same<T, T, Rest...> : all_same<T, Rest...> {};
+template <class T, class U, class...Rest>
+struct all_same<T, U, Rest...> { static constexpr bool value = false; };
+
+template <class R>
+using ValueType = int;
+
+template <class I>
+constexpr bool A(I i) {
+  return all_same<ValueType<I>, ValueType<decltype(i++)>>::value;
+}
+
+int main() {
+  static_assert(A(42), "");
+}
-- 
2.30.2