From 2c010b9c56f069efad2b2c10bffaef4ed059736e Mon Sep 17 00:00:00 2001
From: fanquake <fanquake@gmail.com>
Date: Fri, 15 Jan 2021 10:40:29 +0800
Subject: [PATCH 1/2] add std::atomic include to bitcoin-util.cpp

---
 src/bitcoin-util.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/bitcoin-util.cpp b/src/bitcoin-util.cpp
index b702a68bdf..71b2f02041 100644
--- a/src/bitcoin-util.cpp
+++ b/src/bitcoin-util.cpp
@@ -25,6 +25,7 @@
 #include <util/system.h>
 #include <util/translation.h>
 
+#include <atomic>
 #include <functional>
 #include <memory>
 #include <stdio.h>

From 54ce4fac80689621dcbcc76169b2b00b179ee743 Mon Sep 17 00:00:00 2001
From: fanquake <fanquake@gmail.com>
Date: Fri, 15 Jan 2021 10:54:07 +0800
Subject: [PATCH 2/2] build: improve macro for testing -latomic requirement

riscv builds are currently failing because -latomic isn't being linked
against, when it is needed:
```bash
/home/ubuntu/build/bitcoin/distsrc-riscv64-linux-gnu/src/bitcoin-util.cpp:98: undefined reference to `__atomic_exchange_1'
```

This exteneds our macro to ensure that -latomic is linked against when
required.
---
 build-aux/m4/l_atomic.m4 | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/build-aux/m4/l_atomic.m4 b/build-aux/m4/l_atomic.m4
index 75c43f9a92..5201a8cc7c 100644
--- a/build-aux/m4/l_atomic.m4
+++ b/build-aux/m4/l_atomic.m4
@@ -14,6 +14,9 @@ m4_define([_CHECK_ATOMIC_testbody], [[
   #include <cstdint>
 
   int main() {
+    std::atomic<bool> lock{true};
+    std::atomic_exchange(&lock, false);
+
     std::atomic<int64_t> a{};
 
     int64_t v = 5;