From 5498361c0f4822b2c48f19835963afa5a630175b Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Thu, 21 Feb 2019 18:07:12 -0500
Subject: [PATCH] PR c++/88419 - C++17 ICE with class template arg deduction.

Just like in make_constrained_auto, we need to defer setting TYPE_CANONICAL
until we've set fields that will affect structural_comptypes.

	* pt.c (make_template_placeholder): Set TYPE_CANONICAL after
	CLASS_PLACEHOLDER_TEMPLATE.

From-SVN: r269080
---
 gcc/cp/ChangeLog                              |  6 +++++
 gcc/cp/pt.c                                   |  4 +++-
 .../g++.dg/cpp1z/class-deduction62.C          | 22 +++++++++++++++++++
 3 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp1z/class-deduction62.C

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 824d007d36c..228100ab21f 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2019-02-21  Jason Merrill  <jason@redhat.com>
+
+	PR c++/88419 - C++17 ICE with class template arg deduction.
+	* pt.c (make_template_placeholder): Set TYPE_CANONICAL after
+	CLASS_PLACEHOLDER_TEMPLATE.
+
 2019-02-21  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/89285
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index a212be8c747..bd0a3d13bbe 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -26619,8 +26619,10 @@ make_auto (void)
 tree
 make_template_placeholder (tree tmpl)
 {
-  tree t = make_auto_1 (auto_identifier, true);
+  tree t = make_auto_1 (auto_identifier, false);
   CLASS_PLACEHOLDER_TEMPLATE (t) = tmpl;
+  /* Our canonical type depends on the placeholder.  */
+  TYPE_CANONICAL (t) = canonical_type_parameter (t);
   return t;
 }
 
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction62.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction62.C
new file mode 100644
index 00000000000..2baa3acb8c1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction62.C
@@ -0,0 +1,22 @@
+// PR c++/88419
+// { dg-do compile { target c++17 } }
+
+template<class> struct ref_view {
+  template<class T> ref_view(T&&);
+};
+
+template<class R> ref_view(R&) -> ref_view<R>;
+
+struct ref_fn {
+  template<class R> auto operator()(R r) const
+    noexcept(noexcept(ref_view{r}));
+};
+
+template<class R> struct indirect_view {
+  indirect_view(R);
+};
+
+struct indirect_fn {
+  template<class R> auto operator()(R r) const
+    noexcept(noexcept(indirect_view{r}));
+};
-- 
2.30.2