From 65840ee39c5607498c83988e9234535d49a4a60f Mon Sep 17 00:00:00 2001
From: Billy Robert O'Neal III <bion@microsoft.com>
Date: Mon, 27 Jan 2020 18:04:23 -0800
Subject: [PATCH 1/2] Avoid std::atomic_init deprecated by P0883.

Resolves #139
---
 include/cppcoro/multi_producer_sequencer.hpp |  2 ++
 lib/cancellation_state.cpp                   | 21 ++++++++++----------
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/include/cppcoro/multi_producer_sequencer.hpp b/include/cppcoro/multi_producer_sequencer.hpp
index e13bfe6c..6806070d 100644
--- a/include/cppcoro/multi_producer_sequencer.hpp
+++ b/include/cppcoro/multi_producer_sequencer.hpp
@@ -508,11 +508,13 @@ namespace cppcoro
 		constexpr unsigned_diff_t maxSize = static_cast<unsigned_diff_t>(std::numeric_limits<diff_t>::max());
 		assert(bufferSize <= maxSize);
 
+#ifndef __cpp_lib_atomic_value_initialization
 		SEQUENCE seq = initialSequence - (bufferSize - 1);
 		do
 		{
 			std::atomic_init(&m_published[seq & m_sequenceMask], seq);
 		} while (seq++ != initialSequence);
+#endif // !__cpp_lib_atomic_value_initialization
 	}
 
 	template<typename SEQUENCE, typename TRAITS>
diff --git a/lib/cancellation_state.cpp b/lib/cancellation_state.cpp
index e4118f82..a81123c8 100644
--- a/lib/cancellation_state.cpp
+++ b/lib/cancellation_state.cpp
@@ -79,13 +79,13 @@ cppcoro::detail::cancellation_registration_list_chunk::allocate(std::uint32_t en
 		throw std::bad_alloc{};
 	}
 
-	std::atomic_init(&chunk->m_nextChunk, static_cast<cancellation_registration_list_chunk*>(nullptr));
+	::new (&chunk->m_nextChunk) std::atomic<cancellation_registration_list_chunk*>(nullptr);
 	chunk->m_prevChunk = nullptr;
-	std::atomic_init(&chunk->m_approximateFreeCount, static_cast<std::int32_t>(entryCount - 1));
+	::new (&chunk->m_approximateFreeCount) std::atomic<int32_t>(static_cast<std::int32_t>(entryCount - 1));
 	chunk->m_entryCount = entryCount;
 	for (std::uint32_t i = 0; i < entryCount; ++i)
 	{
-		std::atomic_init(&chunk->m_entries[i], static_cast<cancellation_registration*>(nullptr));
+		::new (&chunk->m_entries[i]) std::atomic<cancellation_registration*>(nullptr);
 	}
 
 	return chunk;
@@ -112,14 +112,15 @@ cppcoro::detail::cancellation_registration_list::allocate()
 		throw std::bad_alloc{};
 	}
 
-	std::atomic_init(&bucket->m_approximateTail, &bucket->m_headChunk);
-	std::atomic_init(&bucket->m_headChunk.m_nextChunk, static_cast<cancellation_registration_list_chunk*>(nullptr));
+	::new (&bucket->m_approximateTail) std::atomic<cancellation_registration_list_chunk*>(&bucket->m_headChunk);
+	::new (&bucket->m_headChunk.m_nextChunk) std::atomic<cancellation_registration_list_chunk*>(nullptr);
 	bucket->m_headChunk.m_prevChunk = nullptr;
-	std::atomic_init(&bucket->m_headChunk.m_approximateFreeCount, static_cast<std::int32_t>(initialChunkSize - 1));
+	::new (&bucket->m_headChunk.m_approximateFreeCount)
+		std::atomic<int32_t>(static_cast<std::int32_t>(initialChunkSize - 1));
 	bucket->m_headChunk.m_entryCount = initialChunkSize;
 	for (std::uint32_t i = 0; i < initialChunkSize; ++i)
 	{
-		std::atomic_init(&bucket->m_headChunk.m_entries[i], static_cast<cancellation_registration*>(nullptr));
+		::new (&bucket->m_headChunk.m_entries[i]) std::atomic<cancellation_registration*>(nullptr);
 	}
 
 	return bucket;
@@ -158,7 +159,7 @@ cppcoro::detail::cancellation_registration_state::allocate()
 	state->m_listCount = listCount;
 	for (std::uint32_t i = 0; i < listCount; ++i)
 	{
-		std::atomic_init(&state->m_lists[i], static_cast<cancellation_registration_list*>(nullptr));
+		::new (&state->m_lists[i]) std::atomic<cancellation_registration_list*>(nullptr);
 	}
 
 	return state;
@@ -187,7 +188,7 @@ cppcoro::detail::cancellation_registration_state::add_registration(
 		// Pre-claim the first slot.
 		registration->m_chunk = &newList->m_headChunk;
 		registration->m_entryIndex = 0;
-		std::atomic_init(&newList->m_headChunk.m_entries[0], registration);
+		::new (&newList->m_headChunk.m_entries[0]) std::atomic<cancellation_registration*>(registration);
 
 		if (listPtr.compare_exchange_strong(
 			list,
@@ -305,7 +306,7 @@ cppcoro::detail::cancellation_registration_state::add_registration(
 		// Pre-allocate first slot.
 		registration->m_chunk = newChunk;
 		registration->m_entryIndex = 0;
-		std::atomic_init(&newChunk->m_entries[0], registration);
+		::new (&newChunk->m_entries[0]) std::atomic<cancellation_registration*>(registration);
 
 		cancellation_registration_list_chunk* oldNext = nullptr;
 		if (lastChunk->m_nextChunk.compare_exchange_strong(

From 6d866f92e3394126ade8d33cb3852e9e2e1cdc7f Mon Sep 17 00:00:00 2001
From: Billy Robert O'Neal III <bion@microsoft.com>
Date: Tue, 28 Jan 2020 12:47:31 -0800
Subject: [PATCH 2/2] Restore initialization of the array in
 multi_producer_sequencer.hpp.

---
 include/cppcoro/multi_producer_sequencer.hpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/cppcoro/multi_producer_sequencer.hpp b/include/cppcoro/multi_producer_sequencer.hpp
index 6806070d..72589c3d 100644
--- a/include/cppcoro/multi_producer_sequencer.hpp
+++ b/include/cppcoro/multi_producer_sequencer.hpp
@@ -508,13 +508,15 @@ namespace cppcoro
 		constexpr unsigned_diff_t maxSize = static_cast<unsigned_diff_t>(std::numeric_limits<diff_t>::max());
 		assert(bufferSize <= maxSize);
 
-#ifndef __cpp_lib_atomic_value_initialization
 		SEQUENCE seq = initialSequence - (bufferSize - 1);
 		do
 		{
+#ifdef __cpp_lib_atomic_value_initialization
+			m_published[seq & m_sequenceMask].store(seq, std::memory_order_relaxed);
+#else // ^^^ __cpp_lib_atomic_value_initialization // !__cpp_lib_atomic_value_initialization vvv
 			std::atomic_init(&m_published[seq & m_sequenceMask], seq);
-		} while (seq++ != initialSequence);
 #endif // !__cpp_lib_atomic_value_initialization
+		} while (seq++ != initialSequence);
 	}
 
 	template<typename SEQUENCE, typename TRAITS>