From 5313fb77fd8d89c99ac4147ae68a12fc45a31794 Mon Sep 17 00:00:00 2001
From: Christopher James Halse Rogers <christopher.halse.rogers@canonical.com>
Date: Fri, 5 Apr 2024 16:53:51 +1100
Subject: [PATCH 1/2] ThreadPoolExecutor: Drop std::binary_semaphore polyfill.

All targets we compile for should now support enough C++20 stdlib features
to remove the need for us to provide a fallback.
---
 src/common/thread_pool_executor.cpp | 56 -----------------------------
 1 file changed, 56 deletions(-)

diff --git a/src/common/thread_pool_executor.cpp b/src/common/thread_pool_executor.cpp
index f73d963ebc1..d3aea60d3f7 100644
--- a/src/common/thread_pool_executor.cpp
+++ b/src/common/thread_pool_executor.cpp
@@ -24,62 +24,6 @@
 #include <list>
 #include <future>
 
-#include <version>
-
-#ifdef __cpp_lib_semaphore
-#include <semaphore>
-#else
-// Hello, there! This version of libstdc++ doesn't support the C++20 feature std::binary_semaphore
-// We shall, instead, open-code the simplest possible implementation of what we use here.
-namespace std
-{
-class binary_semaphore
-{
-public:
-    binary_semaphore(int initial)
-        : raised{initial == 1}
-    {
-    }
-
-    void release()
-    {
-        {
-            std::lock_guard lock{mutex};
-            raised = true;
-        }
-        cv.notify_all();
-    }
-
-    void acquire()
-    {
-        std::unique_lock lock{mutex};
-        if (raised)
-        {
-            raised = false;
-            return;
-        }
-        cv.wait(lock, [this]() { return raised; });
-        raised = false;
-    }
-
-    bool try_acquire()
-    {
-        std::lock_guard lock{mutex};
-        if (raised)
-        {
-            raised = false;
-            return true;
-        }
-        return false;
-    }
-private:
-    std::mutex mutex;
-    std::condition_variable cv;
-    bool raised;
-};
-}
-#endif
-
 namespace
 {
 constexpr int const min_threadpool_threads = 4;

From d36c200742072a48cd84782a97ea99a3a95cbdcb Mon Sep 17 00:00:00 2001
From: Christopher James Halse Rogers <christopher.halse.rogers@canonical.com>
Date: Mon, 8 Apr 2024 11:49:18 +1000
Subject: [PATCH 2/2] ThreadPoolExecutor: Oops, actually `#include <semaphore>`

It's tranitively included from somewhere else, but we explicitly
use it so we should explicitly `#include` it.
---
 src/common/thread_pool_executor.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/common/thread_pool_executor.cpp b/src/common/thread_pool_executor.cpp
index d3aea60d3f7..ed41274da90 100644
--- a/src/common/thread_pool_executor.cpp
+++ b/src/common/thread_pool_executor.cpp
@@ -23,6 +23,7 @@
 #include <atomic>
 #include <list>
 #include <future>
+#include <semaphore>
 
 namespace
 {