From fdf2ad76c9aff11d53494dbde03521478c4daf51 Mon Sep 17 00:00:00 2001
From: Bryce Arden <arden.bryce@gmail.com>
Date: Wed, 10 Aug 2022 22:25:36 -0500
Subject: [PATCH] build: fix IWYU error in instruments.h (#1555)

---
 sdk/include/opentelemetry/sdk/metrics/instruments.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sdk/include/opentelemetry/sdk/metrics/instruments.h b/sdk/include/opentelemetry/sdk/metrics/instruments.h
index 565fd05d95..22fdba2879 100644
--- a/sdk/include/opentelemetry/sdk/metrics/instruments.h
+++ b/sdk/include/opentelemetry/sdk/metrics/instruments.h
@@ -3,6 +3,7 @@
 
 #pragma once
 #ifndef ENABLE_METRICS_PREVIEW
+#  include <functional>
 #  include "opentelemetry/sdk/common/attribute_utils.h"
 OPENTELEMETRY_BEGIN_NAMESPACE
 namespace sdk