From 0398c18360a7b4a4024b1cc0fee3e3fcb9293e09 Mon Sep 17 00:00:00 2001
From: Ryan Burn <contact@rnburn.com>
Date: Thu, 19 Nov 2015 18:25:38 +0000
Subject: [PATCH] re PR c++/68396 (function auto-deduced return types get
 incorrectly classified as parameter packs)

	PR c++/68396

2015-11-19  Ryan Burn  <contact@rnburn.com>

	* pt.c (find_parameter_packs_r) [DECLTYPE_TYPE]: When traversing
	the DECLTYPE_TYPE_EXPR, set type_pack_expansion_p to false.

From-SVN: r230620
---
 gcc/cp/ChangeLog                     |  6 ++++++
 gcc/cp/pt.c                          | 14 ++++++++++++++
 gcc/testsuite/g++.dg/cpp1y/pr68396.C | 15 +++++++++++++++
 3 files changed, 35 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp1y/pr68396.C

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 024290c16d0..d7804a0edae 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2015-11-19  Ryan Burn  <contact@rnburn.com>
+
+	PR c++/68396
+	* pt.c (find_parameter_packs_r) [DECLTYPE_TYPE]: When traversing
+	the DECLTYPE_TYPE_EXPR, set type_pack_expansion_p to false.
+
 2015-11-19  Cesar Philippidis  <cesar@codesourcery.com>
 
 	* parser.h (struct cp_omp_declare_simd_data): Add clauses member.
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 29046572b2c..b4a5e71b521 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -3551,6 +3551,20 @@ find_parameter_packs_r (tree *tp, int *walk_subtrees, void* data)
       *walk_subtrees = 0;
       return NULL_TREE;
 
+    case DECLTYPE_TYPE:
+      {
+	/* When traversing a DECLTYPE_TYPE_EXPR, we need to set
+	   type_pack_expansion_p to false so that any placeholders
+	   within the expression don't get marked as parameter packs.  */
+	bool type_pack_expansion_p = ppd->type_pack_expansion_p;
+	ppd->type_pack_expansion_p = false;
+	cp_walk_tree (&DECLTYPE_TYPE_EXPR (t), &find_parameter_packs_r,
+		      ppd, ppd->visited);
+	ppd->type_pack_expansion_p = type_pack_expansion_p;
+	*walk_subtrees = 0;
+	return NULL_TREE;
+      }
+
     default:
       return NULL_TREE;
     }
diff --git a/gcc/testsuite/g++.dg/cpp1y/pr68396.C b/gcc/testsuite/g++.dg/cpp1y/pr68396.C
new file mode 100644
index 00000000000..2027d6ef967
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/pr68396.C
@@ -0,0 +1,15 @@
+// { dg-do compile { target c++14 } }
+
+template <unsigned>
+auto f () {
+  return 2;
+}
+
+template <class>
+class A {};
+
+template <int... Ix>
+auto g () {
+  A<decltype(f<Ix> ())...>();
+  return f<2> ();
+}
-- 
2.30.2