From 7db777843ccba2596f3aa1817edc50156afe2fc3 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 69efbb99af47..d8fc647120e0 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2020-01-28  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.
+
 2020-01-27  Nathan Sidwell  <nathan@acm.org>
 
 	PR c++/91826
diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index 7b5ae9d3990d..8999c5ad4a74 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -7626,6 +7626,12 @@ 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 000000000000..faaff68b968f
--- /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;
+}
-- 
2.47.2