From c75a0d4c575edcc7288ec9423968921a6ad2ef58 Mon Sep 17 00:00:00 2001
From: fanquake <fanquake@gmail.com>
Date: Fri, 5 Jan 2024 10:51:05 +0000
Subject: [PATCH] Merge bitcoin/bitcoin#29177: build: Fix check whether
 `-latomic` needed

f8ca1357c8205ceff732dcfb0d2bad79b40b611b build: Fix check whether `-latomic` needed (Hennadii Stepanov)

Pull request description:

  Clang >=15 still might need linking against `libatomic`.

  We use `std::atomic<std::chrono::seconds>::compare_exchange_strong` in `net_processing.cpp`.

  Addresses the https://github.com/bitcoin/bitcoin/pull/29165#discussion_r1440293694.

ACKs for top commit:
  maflcko:
    lgtm ACK f8ca1357c8205ceff732dcfb0d2bad79b40b611b
  fanquake:
    ACK f8ca1357c8205ceff732dcfb0d2bad79b40b611b

Tree-SHA512: ba8b6a88fd3471a206d068e8a000a053c99cb46d26bd04624418ddb066b3b9664a569ec8a1569af67c96b3e27f13dccbd5e24f985290ac072b6d74c92524e35d
---
 build-aux/m4/l_atomic.m4 | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/build-aux/m4/l_atomic.m4 b/build-aux/m4/l_atomic.m4
index c04a271a56..9a9a31dd8a 100644
--- a/build-aux/m4/l_atomic.m4
+++ b/build-aux/m4/l_atomic.m4
@@ -4,7 +4,7 @@ dnl permitted in any medium without royalty provided the copyright notice
 dnl and this notice are preserved. This file is offered as-is, without any
 dnl warranty.
 
-# Clang prior to version 15, when building for 32-bit,
+# Clang, when building for 32-bit,
 # and linking against libstdc++, requires linking with
 # -latomic if using the C++ atomic library.
 # Can be tested with: clang++ test.cpp -m32
@@ -24,6 +24,8 @@ m4_define([_CHECK_ATOMIC_testbody], [[
 
     std::atomic<std::chrono::seconds> t{0s};
     t.store(2s);
+    auto t1 = t.load();
+    t.compare_exchange_strong(t1, 3s);
 
     std::atomic<int64_t> a{};