From f9d7a9121098c1948581b314bb55ed95ead7cc2f Mon Sep 17 00:00:00 2001
From: Miuna <miuna.oshino@gmail.com>
Date: Wed, 26 Jul 2023 14:25:35 -0400
Subject: [PATCH] fix: coroutines: better support for clang, remove
 experimental if unneeded, add missing headers

---
 include/dpp/coro.h     | 27 ++++++++++++++++++++------
 library/CMakeLists.txt | 44 +++++++++++++++++++++++++++++++++++++-----
 2 files changed, 60 insertions(+), 11 deletions(-)

diff --git a/include/dpp/coro.h b/include/dpp/coro.h
index 53ea155b9f..4f912d823d 100644
--- a/include/dpp/coro.h
+++ b/include/dpp/coro.h
@@ -1,11 +1,21 @@
 #ifdef DPP_CORO
 #pragma once
 
-#if !(defined( _MSC_VER ) || defined( _CONSOLE ) || defined( __GNUC__ )) // if libc++
-#  define EXPERIMENTAL_COROUTINE
+#if (defined(_LIBCPP_VERSION) and !defined(__cpp_impl_coroutine)) // if libc++ experimental implementation (LLVM < 14)
+#  define STDCORO_EXPERIMENTAL_HEADER
+#  define STDCORO_EXPERIMENTAL_NAMESPACE
 #endif
 
-#ifdef EXPERIMENTAL_COROUTINE
+#ifdef STDCORO_GLIBCXX_COMPAT
+#  define __cpp_impl_coroutine 1
+namespace std {
+	namespace experimental {
+		using namespace std;
+	}
+}
+#endif
+
+#ifdef STDCORO_EXPERIMENTAL_HEADER
 #  include <experimental/coroutine>
 #else
 #  include <coroutine>
@@ -14,6 +24,11 @@
 #include <memory>
 #include <utility>
 #include <type_traits>
+#include <concepts>
+#include <optional>
+#include <functional>
+#include <mutex>
+#include <exception>
 
 namespace dpp {
 	class cluster;
@@ -33,7 +48,7 @@ namespace dpp {
 		 */
 		namespace std_coroutine {}
 #else
-#  ifdef EXPERIMENTAL_COROUTINE
+#  ifdef STDCORO_EXPERIMENTAL_NAMESPACE
 		namespace std_coroutine = std::experimental;
 #  else
 		namespace std_coroutine = std;
@@ -282,7 +297,7 @@ namespace dpp {
 			 *
 			 * @return <a href="https://en.cppreference.com/w/cpp/coroutine/suspend_never">std::suspend_never</a> Don't suspend, the coroutine starts immediately.
 			 */
-			std::suspend_never initial_suspend() noexcept {
+			std_coroutine::suspend_never initial_suspend() noexcept {
 				return {};
 			}
 
@@ -454,7 +469,7 @@ namespace dpp {
 				 *
 				 * @see <a href="https://en.cppreference.com/w/cpp/coroutine/coroutine_handle">std::coroutine_handle</a>
 				 */
-				std::coroutine_handle<> coro_handle = nullptr;
+				detail::std_coroutine::coroutine_handle<> coro_handle = nullptr;
 			};
 
 			/**
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index 4bf20455bf..e74c4e33bb 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -293,17 +293,51 @@ if(HAVE_PTHREAD_SETNAME_NP)
 endif()
 
 if(DPP_CORO)
-	message("-- ${Yellow}Enabled experimental coroutine support${ColourReset}")
+	message("-- ${Yellow}Enabled experimental coroutine feature${ColourReset}")
 	set(CMAKE_CXX_STANDARD 20)
 	target_compile_features(dpp PUBLIC cxx_std_20)
 	if(WIN32 AND NOT MINGW)
 		set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /await:strict")
 	else()
 		if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-			set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libc++")
-			target_link_libraries(dpp PUBLIC "c++abi")
-		else()
-			set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fcoroutines")
+			if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 14.0.0) # clang >= 14 has native support
+				message("-- ${Yellow}Clang < 14 - attempting to detect if using libc++ or stdc++${ColourReset}")
+				check_cxx_source_compiles("
+					#include <iostream>
+
+					int a =
+					#ifdef __GLIBCXX__
+						1;
+					#else
+						fgsfds;
+					#endif
+
+					int main(int argc, char* argv[])
+					{
+						return 0;
+					}
+					" IS_GLIBCXX)
+				if(IS_GLIBCXX)
+					if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 12.0.0)
+						message(FATAL_ERROR "Clang with stdc++ and coroutines requires version 12.0.0 or above")
+					endif()
+					message("-- ${Yellow}Detected stdc++ - enabling mock std::experimental namespace${ColourReset}")
+					target_compile_definitions(dpp PUBLIC "STDCORO_GLIBCXX_COMPAT")
+				else()
+					message("-- ${Yellow}Detected libc++ - using <experimental/coroutine>")
+					if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 9.0.0)
+						set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fcoroutines-ts")
+					endif()
+				endif()
+				message("-- ${Yellow}Note - coroutines in clang < 14 are experimental, upgrading is recommended")
+			endif()
+		elseif(CMAKE_CXX_COMPILER_ID MATCHES "GNU")
+			if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 10.0)
+				message(FATAL_ERROR "Coroutines with g++ require version 10 or above")
+			elseif(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 11.0)
+				message("-- ${Yellow}Note - coroutines in g++10 are experimental, upgrading to g++11 or above is recommended")
+				set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fcoroutines")
+			endif()
 		endif()
 	endif()
 	target_compile_definitions(dpp PUBLIC DPP_CORO)