Support both <coroutine> and <experimental/coroutine>

Starting with GCC 10.1, GCC/libstdc++ supports coroutines, but includes
them in their final location in <coroutine>.

This commit generalizes the location of the header, and the name of the
types (either in the std or std::experimental namespace), so that both
the current Clang/MSVC and the GCC approach can be supported.

This should also guarantee that both current and later Clang/MSVC
releases will be supported by the library.

include/cppcoro/async_auto_reset_event.hpp

@@ -5,7 +5,7 @@
 #ifndef CPPCORO_ASYNC_AUTO_RESET_EVENT_HPP_INCLUDED
 #define CPPCORO_ASYNC_AUTO_RESET_EVENT_HPP_INCLUDED
 
-#include <experimental/coroutine>
+#include <cppcoro/coroutine.hpp>
 #include <atomic>
 #include <cstdint>
 
@@ -80,7 +80,7 @@ namespace cppcoro
 		async_auto_reset_event_operation(const async_auto_reset_event_operation& other) noexcept;
 
 		bool await_ready() const noexcept { return m_event == nullptr; }
-		bool await_suspend(std::experimental::coroutine_handle<> awaiter) noexcept;
+		bool await_suspend(cppcoro::coroutine_handle<> awaiter) noexcept;
 		void await_resume() const noexcept {}
 
 	private:
@@ -89,7 +89,7 @@ namespace cppcoro
 
 		const async_auto_reset_event* m_event;
 		async_auto_reset_event_operation* m_next;
-		std::experimental::coroutine_handle<> m_awaiter;
+		cppcoro::coroutine_handle<> m_awaiter;
 		std::atomic<std::uint32_t> m_refCount;
 
 	};

include/cppcoro/async_generator.hpp

@@ -12,7 +12,7 @@
 #include <atomic>
 #include <iterator>
 #include <type_traits>
-#include <experimental/coroutine>
+#include <cppcoro/coroutine.hpp>
 #include <functional>
 #include <cassert>
 
@@ -45,7 +45,7 @@ namespace cppcoro
 			async_generator_promise_base(const async_generator_promise_base& other) = delete;
 			async_generator_promise_base& operator=(const async_generator_promise_base& other) = delete;
 
-			std::experimental::suspend_always initial_suspend() const noexcept
+			cppcoro::suspend_always initial_suspend() const noexcept
 			{
 				return {};
 			}
@@ -89,7 +89,7 @@ namespace cppcoro
 
 			std::exception_ptr m_exception;
 
-			std::experimental::coroutine_handle<> m_consumerCoroutine;
+			cppcoro::coroutine_handle<> m_consumerCoroutine;
 
 		protected:
 
@@ -100,7 +100,7 @@ namespace cppcoro
 		{
 		public:
 
-			async_generator_yield_operation(std::experimental::coroutine_handle<> consumer) noexcept
+			async_generator_yield_operation(cppcoro::coroutine_handle<> consumer) noexcept
 				: m_consumer(consumer)
 			{}
 
@@ -109,8 +109,8 @@ namespace cppcoro
 				return false;
 			}
 
-			std::experimental::coroutine_handle<>
-			await_suspend([[maybe_unused]] std::experimental::coroutine_handle<> producer) noexcept
+			cppcoro::coroutine_handle<>
+			await_suspend([[maybe_unused]] cppcoro::coroutine_handle<> producer) noexcept
 			{
 				return m_consumer;
 			}
@@ -119,7 +119,7 @@ namespace cppcoro
 
 		private:
 
-			std::experimental::coroutine_handle<> m_consumer;
+			cppcoro::coroutine_handle<> m_consumer;
 
 		};
 
@@ -145,7 +145,7 @@ namespace cppcoro
 
 			async_generator_advance_operation(
 				async_generator_promise_base& promise,
-				std::experimental::coroutine_handle<> producerCoroutine) noexcept
+				cppcoro::coroutine_handle<> producerCoroutine) noexcept
 				: m_promise(std::addressof(promise))
 				, m_producerCoroutine(producerCoroutine)
 			{
@@ -155,8 +155,8 @@ namespace cppcoro
 
 			bool await_ready() const noexcept { return false; }
 
-			std::experimental::coroutine_handle<>
-				await_suspend(std::experimental::coroutine_handle<> consumerCoroutine) noexcept
+			cppcoro::coroutine_handle<>
+				await_suspend(cppcoro::coroutine_handle<> consumerCoroutine) noexcept
 			{
 				m_promise->m_consumerCoroutine = consumerCoroutine;
 				return m_producerCoroutine;
@@ -165,7 +165,7 @@ namespace cppcoro
 		protected:
 
 			async_generator_promise_base* m_promise;
-			std::experimental::coroutine_handle<> m_producerCoroutine;
+			cppcoro::coroutine_handle<> m_producerCoroutine;
 
 		};
 
@@ -242,7 +242,7 @@ namespace cppcoro
 		class async_generator_iterator final
 		{
 			using promise_type = async_generator_promise<T>;
-			using handle_type = std::experimental::coroutine_handle<promise_type>;
+			using handle_type = cppcoro::coroutine_handle<promise_type>;
 
 		public:
 
@@ -307,7 +307,7 @@ namespace cppcoro
 		class async_generator_begin_operation final : public async_generator_advance_operation
 		{
 			using promise_type = async_generator_promise<T>;
-			using handle_type = std::experimental::coroutine_handle<promise_type>;
+			using handle_type = cppcoro::coroutine_handle<promise_type>;
 
 		public:
 
@@ -358,7 +358,7 @@ namespace cppcoro
 		{}
 
 		explicit async_generator(promise_type& promise) noexcept
-			: m_coroutine(std::experimental::coroutine_handle<promise_type>::from_promise(promise))
+			: m_coroutine(cppcoro::coroutine_handle<promise_type>::from_promise(promise))
 		{}
 
 		async_generator(async_generator&& other) noexcept
@@ -408,7 +408,7 @@ namespace cppcoro
 
 	private:
 
-		std::experimental::coroutine_handle<promise_type> m_coroutine;
+		cppcoro::coroutine_handle<promise_type> m_coroutine;
 
 	};
 
@@ -451,7 +451,7 @@ namespace cppcoro
 			async_generator_promise_base(const async_generator_promise_base& other) = delete;
 			async_generator_promise_base& operator=(const async_generator_promise_base& other) = delete;
 
-			std::experimental::suspend_always initial_suspend() const noexcept
+			cppcoro::suspend_always initial_suspend() const noexcept
 			{
 				return {};
 			}
@@ -556,7 +556,7 @@ namespace cppcoro
 
 			std::exception_ptr m_exception;
 
-			std::experimental::coroutine_handle<> m_consumerCoroutine;
+			cppcoro::coroutine_handle<> m_consumerCoroutine;
 
 		protected:
 
@@ -579,7 +579,7 @@ namespace cppcoro
 				return m_initialState == state::value_not_ready_consumer_suspended;
 			}
 
-			bool await_suspend(std::experimental::coroutine_handle<> producer) noexcept;
+			bool await_suspend(cppcoro::coroutine_handle<> producer) noexcept;
 
 			void await_resume() noexcept {}
 
@@ -625,7 +625,7 @@ namespace cppcoro
 		}
 
 		inline bool async_generator_yield_operation::await_suspend(
-			std::experimental::coroutine_handle<> producer) noexcept
+			cppcoro::coroutine_handle<> producer) noexcept
 		{
 			state currentState = m_initialState;
 			if (currentState == state::value_not_ready_consumer_active)
@@ -711,7 +711,7 @@ namespace cppcoro
 
 			async_generator_advance_operation(
 				async_generator_promise_base& promise,
-				std::experimental::coroutine_handle<> producerCoroutine) noexcept
+				cppcoro::coroutine_handle<> producerCoroutine) noexcept
 				: m_promise(std::addressof(promise))
 				, m_producerCoroutine(producerCoroutine)
 			{
@@ -740,7 +740,7 @@ namespace cppcoro
 				return m_initialState == state::value_ready_producer_suspended;
 			}
 
-			bool await_suspend(std::experimental::coroutine_handle<> consumerCoroutine) noexcept
+			bool await_suspend(cppcoro::coroutine_handle<> consumerCoroutine) noexcept
 			{
 				m_promise->m_consumerCoroutine = consumerCoroutine;
 
@@ -791,7 +791,7 @@ namespace cppcoro
 		protected:
 
 			async_generator_promise_base* m_promise;
-			std::experimental::coroutine_handle<> m_producerCoroutine;
+			cppcoro::coroutine_handle<> m_producerCoroutine;
 
 		private:
 
@@ -872,7 +872,7 @@ namespace cppcoro
 		class async_generator_iterator final
 		{
 			using promise_type = async_generator_promise<T>;
-			using handle_type = std::experimental::coroutine_handle<promise_type>;
+			using handle_type = cppcoro::coroutine_handle<promise_type>;
 
 		public:
 
@@ -937,7 +937,7 @@ namespace cppcoro
 		class async_generator_begin_operation final : public async_generator_advance_operation
 		{
 			using promise_type = async_generator_promise<T>;
-			using handle_type = std::experimental::coroutine_handle<promise_type>;
+			using handle_type = cppcoro::coroutine_handle<promise_type>;
 
 		public:
 
@@ -988,7 +988,7 @@ namespace cppcoro
 		{}
 
 		explicit async_generator(promise_type& promise) noexcept
-			: m_coroutine(std::experimental::coroutine_handle<promise_type>::from_promise(promise))
+			: m_coroutine(cppcoro::coroutine_handle<promise_type>::from_promise(promise))
 		{}
 
 		async_generator(async_generator&& other) noexcept
@@ -1041,7 +1041,7 @@ namespace cppcoro
 
 	private:
 
-		std::experimental::coroutine_handle<promise_type> m_coroutine;
+		cppcoro::coroutine_handle<promise_type> m_coroutine;
 
 	};
 

include/cppcoro/async_manual_reset_event.hpp

@@ -5,7 +5,7 @@
 #ifndef CPPCORO_ASYNC_MANUAL_RESET_EVENT_HPP_INCLUDED
 #define CPPCORO_ASYNC_MANUAL_RESET_EVENT_HPP_INCLUDED
 
-#include <experimental/coroutine>
+#include <cppcoro/coroutine.hpp>
 #include <atomic>
 #include <cstdint>
 
@@ -87,7 +87,7 @@ namespace cppcoro
 		explicit async_manual_reset_event_operation(const async_manual_reset_event& event) noexcept;
 
 		bool await_ready() const noexcept;
-		bool await_suspend(std::experimental::coroutine_handle<> awaiter) noexcept;
+		bool await_suspend(cppcoro::coroutine_handle<> awaiter) noexcept;
 		void await_resume() const noexcept {}
 
 	private:
@@ -96,7 +96,7 @@ namespace cppcoro
 
 		const async_manual_reset_event& m_event;
 		async_manual_reset_event_operation* m_next;
-		std::experimental::coroutine_handle<> m_awaiter;
+		cppcoro::coroutine_handle<> m_awaiter;
 
 	};
 }

include/cppcoro/async_mutex.hpp

@@ -5,7 +5,7 @@
 #ifndef CPPCORO_ASYNC_MUTEX_HPP_INCLUDED
 #define CPPCORO_ASYNC_MUTEX_HPP_INCLUDED
 
-#include <experimental/coroutine>
+#include <cppcoro/coroutine.hpp>
 #include <atomic>
 #include <cstdint>
 #include <mutex> // for std::adopt_lock_t
@@ -166,7 +166,7 @@ namespace cppcoro
 		{}
 
 		bool await_ready() const noexcept { return false; }
-		bool await_suspend(std::experimental::coroutine_handle<> awaiter) noexcept;
+		bool await_suspend(cppcoro::coroutine_handle<> awaiter) noexcept;
 		void await_resume() const noexcept {}
 
 	protected:
@@ -178,7 +178,7 @@ namespace cppcoro
 	private:
 
 		async_mutex_lock_operation* m_next;
-		std::experimental::coroutine_handle<> m_awaiter;
+		cppcoro::coroutine_handle<> m_awaiter;
 
 	};
 

include/cppcoro/async_scope.hpp

@@ -8,7 +8,7 @@
 #include <cppcoro/on_scope_exit.hpp>
 
 #include <atomic>
-#include <experimental/coroutine>
+#include <cppcoro/coroutine.hpp>
 #include <type_traits>
 #include <cassert>
 
@@ -52,7 +52,7 @@ namespace cppcoro
 					return m_scope->m_count.load(std::memory_order_acquire) == 0;
 				}
 
-				bool await_suspend(std::experimental::coroutine_handle<> continuation) noexcept
+				bool await_suspend(cppcoro::coroutine_handle<> continuation) noexcept
 				{
 					m_scope->m_continuation = continuation;
 					return m_scope->m_count.fetch_sub(1u, std::memory_order_acq_rel) > 1u;
@@ -85,16 +85,16 @@ namespace cppcoro
 		{
 			struct promise_type
 			{
-				std::experimental::suspend_never initial_suspend() { return {}; }
-				std::experimental::suspend_never final_suspend() { return {}; }
+				cppcoro::suspend_never initial_suspend() { return {}; }
+				cppcoro::suspend_never final_suspend() { return {}; }
 				void unhandled_exception() { std::terminate(); }
 				oneway_task get_return_object() { return {}; }
 				void return_void() {}
 			};
 		};
 
 		std::atomic<size_t> m_count;
-		std::experimental::coroutine_handle<> m_continuation;
+		cppcoro::coroutine_handle<> m_continuation;
 
 	};
 }

include/cppcoro/coroutine.hpp

@@ -0,0 +1,32 @@
+#ifndef CPPCORO_COROUTINE_HPP_INCLUDED
+#define CPPCORO_COROUTINE_HPP_INCLUDED
+
+#if __has_include(<coroutine>)
+
+#include <coroutine>
+
+namespace cppcoro {
+  template<typename Promise=void>
+  using coroutine_handle = std::coroutine_handle<Promise>;
+
+  using suspend_always = std::suspend_always;
+  using suspend_never = std::suspend_never;
+}
+
+#elif __has_include(<experimental/coroutine>)
+
+#include <experimental/coroutine>
+
+namespace cppcoro {
+  template<typename Promise=void>
+  using coroutine_handle = std::experimental::coroutine_handle<Promise>;
+
+  using suspend_always = std::experimental::suspend_always;
+  using suspend_never = std::experimental::suspend_never;
+}
+
+#else
+#error Cppcoro requires a C++20 compiler with coroutine support
+#endif
+
+#endif