From 96975b1159808defb222a57b369db02a0eab5fee Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Fri, 6 Apr 2018 14:09:53 -0400
Subject: [PATCH] PR c++/85214 - ICE with alias, generic lambda, constexpr if.

Here, since the condition for the constexpr if depends on the type of 'j',
it's still dependent when we are partially instantiating the inner lambda,
so we need to defer instantiating the constexpr if.  When we instantiated
the inner lambda, we tried to substitute into the typename, which failed
because we didn't have a declaration of 'i' available.

Fixed by teaching extract_locals_r to capture local typedefs such as 'ar';
if we have the typedef handy, we don't need to substitute into its
definition.

	* pt.c (extract_locals_r): Remember local typedefs.

From-SVN: r259185
---
 gcc/cp/ChangeLog                            |  5 +++++
 gcc/cp/pt.c                                 |  5 +++++
 gcc/testsuite/g++.dg/cpp1z/constexpr-if20.C | 17 +++++++++++++++++
 3 files changed, 27 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp1z/constexpr-if20.C

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index e71b4fbe9d8..ba323bf7c20 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2018-04-06  Jason Merrill  <jason@redhat.com>
+
+	PR c++/85214 - ICE with alias, generic lambda, constexpr if.
+	* pt.c (extract_locals_r): Remember local typedefs.
+
 2018-04-06  David Malcolm  <dmalcolm@redhat.com>
 
 	PR c++/84269
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 450ffaec9be..db3d7e38d85 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -11610,6 +11610,11 @@ extract_locals_r (tree *tp, int */*walk_subtrees*/, void *data_)
   el_data &data = *reinterpret_cast<el_data*>(data_);
   tree *extra = &data.extra;
   tsubst_flags_t complain = data.complain;
+
+  if (TYPE_P (*tp) && typedef_variant_p (*tp))
+    /* Remember local typedefs (85214).  */
+    tp = &TYPE_NAME (*tp);
+
   if (TREE_CODE (*tp) == DECL_EXPR)
     data.internal.add (DECL_EXPR_DECL (*tp));
   else if (tree spec = retrieve_local_specialization (*tp))
diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-if20.C b/gcc/testsuite/g++.dg/cpp1z/constexpr-if20.C
new file mode 100644
index 00000000000..24343adb748
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-if20.C
@@ -0,0 +1,17 @@
+// PR c++/85214
+// { dg-additional-options -std=c++17 }
+
+struct g {
+  constexpr operator int() { return true; }
+};
+template <typename T, typename U> constexpr bool m = true;
+template <long L> struct C { typedef double q; };
+void ao() {
+  [](auto i) {
+      using ar = typename C<i>::q;
+      [](auto j) {
+	using as = typename C<j>::q;
+	if constexpr (m<ar, as>) {}
+      }(g());
+  }(g());
+}
-- 
2.30.2