From 118ea5da764d581e29d944744a114a25bcb81db9 Mon Sep 17 00:00:00 2001
From: Henner Zeller <hzeller@google.com>
Date: Tue, 10 Oct 2023 12:08:33 -0700
Subject: [PATCH] C++20 preparation: make operator != non-ambiguous.

C++20 auto-generates the != operator from ==. However, if that
operator accepts a potentiallly different type, this might result in
an ambiguous operator (-Wambiguous-reversed-operator).
This provides the explicitly defined operator.
---
 common/util/tree_operations_test.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/common/util/tree_operations_test.cc b/common/util/tree_operations_test.cc
index 33d1160178..545a57cba3 100644
--- a/common/util/tree_operations_test.cc
+++ b/common/util/tree_operations_test.cc
@@ -143,6 +143,7 @@ class SimpleNode {
   void set_id(std::string&& new_id) { id_ = new_id; }
 
   bool operator==(const ThisType& other) const { return this == &other; }
+  bool operator!=(const ThisType& other) const { return !(*this == other); }
 
   friend std::ostream& operator<<(std::ostream& stream, const ThisType& self) {
     self.PrintRecursively(stream, 0);