From 83059741a0a58b6cccb105522bf7f07813a55c23 Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
Date: Wed, 7 Jun 2017 12:34:36 +0100
Subject: [PATCH] PR c++/80990 use cv-qualifiers in class template argument
 deduction

gcc/cp:

	PR c++/80990
	* pt.c (do_class_deduction): Build qualified type.

gcc/testsuite:

	PR c++/80990
	* g++.dg/cpp1z/class-deduction39.C: New.

From-SVN: r248966
---
 gcc/cp/ChangeLog                               |  5 +++++
 gcc/cp/pt.c                                    |  2 +-
 gcc/testsuite/ChangeLog                        |  5 +++++
 gcc/testsuite/g++.dg/cpp1z/class-deduction39.C | 15 +++++++++++++++
 4 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp1z/class-deduction39.C

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 8375ceedd49..e47c4299748 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2017-06-07  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR c++/80990
+	* pt.c (do_class_deduction): Build qualified type.
+
 2017-06-06  Nathan Sidwell  <nathan@acm.org>
 
 	* name-lookup.c (suggest_alternatives_for): Use qualified lookup
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index a04f2e0a762..ada94bd65ed 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -25367,7 +25367,7 @@ do_class_deduction (tree ptype, tree tmpl, tree init, int flags,
   --cp_unevaluated_operand;
   release_tree_vector (args);
 
-  return TREE_TYPE (t);
+  return cp_build_qualified_type (TREE_TYPE (t), cp_type_quals (ptype));
 }
 
 /* Replace occurrences of 'auto' in TYPE with the appropriate type deduced
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 990e10ac327..e5a4dbd229b 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2017-06-07  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR c++/80990
+	* g++.dg/cpp1z/class-deduction39.C: New.
+
 2017-06-07  Marek Polacek  <polacek@redhat.com>
 
 	PR sanitizer/80932
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction39.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction39.C
new file mode 100644
index 00000000000..98a3664f5b2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction39.C
@@ -0,0 +1,15 @@
+// { dg-options -std=c++1z }
+
+template <class T> struct A { };
+
+A<int> a;
+const A c = a;
+volatile A v = a;
+const volatile A cv = a;
+
+template <class,class> struct same;
+template <class T> struct same<T,T> {};
+
+same<decltype(c), const A<int>> s1;
+same<decltype(v), volatile A<int>> s2;
+same<decltype(cv), const volatile A<int>> s3;
-- 
2.30.2