From 8b91e848130e45b427599ad30e99f96e447ea9aa Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Fri, 24 Jan 2020 18:20:56 -0500
Subject: [PATCH] c++: Fix ICE with lambda in member operator (PR93279)

Here the problem was that we were remembering the lookup in template scope,
and then trying to reuse that lookup in the instantiation without
substituting into it at all.  The simplest solution is to not try to
remember a lookup that finds a class-scope declaration, as in that case
doing the normal lookup again at instantiation time will always find the
right declarations.

	PR c++/93279 - ICE with lambda in member operator.
	* name-lookup.c (maybe_save_operator_binding): Don't remember
	class-scope bindings.
---
 gcc/cp/ChangeLog                                  |  6 ++++++
 gcc/cp/name-lookup.c                              |  6 ++++++
 .../g++.dg/cpp0x/lambda/lambda-template16.C       | 15 +++++++++++++++
 3 files changed, 27 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/lambda/lambda-template16.C

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index cddf169ea5b..764b9ccffa3 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2020-01-24  Jason Merrill  <jason@redhat.com>
+
+	PR c++/93279 - ICE with lambda in member operator.
+	* name-lookup.c (maybe_save_operator_binding): Don't remember
+	class-scope bindings.
+
 2020-01-24  Jason Merrill  <jason@redhat.com>
 
 	PR c++/93377 - ICE with member alias in constraint.
diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index cd7a5816e46..572100766cb 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -7616,6 +7616,12 @@ maybe_save_operator_binding (tree e)
 
   if (!fns && (fns = op_unqualified_lookup (fnname)))
     {
+      tree fn = get_first_fn (fns);
+      if (DECL_CLASS_SCOPE_P (fn))
+	/* We don't need to remember class-scope functions, normal unqualified
+	   lookup will find them again.  */
+	return;
+
       bindings = tree_cons (fnname, fns, bindings);
       if (attr)
 	TREE_VALUE (attr) = bindings;
diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-template16.C b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-template16.C
new file mode 100644
index 00000000000..faaff68b968
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-template16.C
@@ -0,0 +1,15 @@
+// PR c++/93279
+// { dg-do compile { target c++11 } }
+
+template <typename T> struct B { using f = int; };
+template <typename T, int N> struct E {
+  template <typename U, typename B<E>::f = 0>
+  void operator*(U l) { [l](T m) { m * l; }; }
+};
+
+int
+main ()
+{
+  E<E<float, 4>, 1> n;
+  n * 4.f;
+}
-- 
2.30.2