From 2e73a89bc9a73ef83b7b87fb65b8293c0ae8b693 Mon Sep 17 00:00:00 2001
From: Jakub Jelinek <jakub@redhat.com>
Date: Tue, 23 Jan 2018 08:46:05 +0100
Subject: [PATCH] re PR c++/83918 ([c++17] ICE on constexpr eval of datatype
 involving function and variadic template)

	PR c++/83918
	* tree.c (maybe_wrap_with_location): Use NON_LVALUE_EXPR rather than
	VIEW_CONVERT_EXPR to wrap CONST_DECLs.

	* g++.dg/cpp1z/pr83918.C: New test.

From-SVN: r256972
---
 gcc/ChangeLog                        |  6 ++++++
 gcc/testsuite/ChangeLog              |  5 +++++
 gcc/testsuite/g++.dg/cpp1z/pr83918.C | 32 ++++++++++++++++++++++++++++
 gcc/tree.c                           |  6 ++++--
 4 files changed, 47 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp1z/pr83918.C

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 507bb52dc82..a1307e34b50 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2018-01-23  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/83918
+	* tree.c (maybe_wrap_with_location): Use NON_LVALUE_EXPR rather than
+	VIEW_CONVERT_EXPR to wrap CONST_DECLs.
+
 2018-01-22  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/83957
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 82497ed9641..d22af7ab927 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-01-23  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/83918
+	* g++.dg/cpp1z/pr83918.C: New test.
+
 2018-01-22  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/83957
diff --git a/gcc/testsuite/g++.dg/cpp1z/pr83918.C b/gcc/testsuite/g++.dg/cpp1z/pr83918.C
new file mode 100644
index 00000000000..d4fe82631ed
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/pr83918.C
@@ -0,0 +1,32 @@
+// PR c++/83918
+// { dg-do compile }
+// { dg-options "-std=c++17" }
+
+constexpr unsigned
+foo (unsigned x, unsigned y)
+{
+  return x > y ? x : y;
+}
+
+template <typename, typename> struct A;
+template <auto ...> struct B;
+template <auto S, auto ... T, auto U, auto ... V>
+struct A <B <S, T...>, B <U, V...>>
+{
+  enum : unsigned
+  {
+    u = foo (sizeof (S), sizeof (U)),
+    v = A <B <T...>, B <V...>>::w,
+    w = foo (u, v)
+  };
+};
+
+template <>
+struct A <B <>, B <>>
+{
+  enum : unsigned { w = 0 };
+};
+
+constexpr static const auto v { A <B <1,2,3,4,5,6,7,8,9>,
+				   B <9,8,7,6,5,4,3,2,1>>::w };
+static_assert (v == sizeof (int));
diff --git a/gcc/tree.c b/gcc/tree.c
index b3e93b87eb2..452d3855a77 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -14085,8 +14085,10 @@ maybe_wrap_with_location (tree expr, location_t loc)
   if (EXCEPTIONAL_CLASS_P (expr))
     return expr;
 
-  tree_code code = (CONSTANT_CLASS_P (expr) && TREE_CODE (expr) != STRING_CST
-		    ? NON_LVALUE_EXPR : VIEW_CONVERT_EXPR);
+  tree_code code
+    = (((CONSTANT_CLASS_P (expr) && TREE_CODE (expr) != STRING_CST)
+	|| (TREE_CODE (expr) == CONST_DECL && !TREE_STATIC (expr)))
+       ? NON_LVALUE_EXPR : VIEW_CONVERT_EXPR);
   tree wrapper = build1_loc (loc, code, TREE_TYPE (expr), expr);
   /* Mark this node as being a wrapper.  */
   EXPR_LOCATION_WRAPPER_P (wrapper) = 1;
-- 
2.30.2