From a83851bd05393ce0150923fc20899cf1a6ca33a6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Henrik=20S=2E=20Ga=C3=9Fmann?= <henrik.gassmann@adesso.de>
Date: Thu, 21 Jul 2022 10:45:03 +0200
Subject: [PATCH] Simplify the selection for dynamic thread pool impl

- If on window use native OS APIs (libdispatch isn't available anyways).
- If on linux use the superior custom implementation unless the user
  explicitly requests libdispatch (which is incompatible with gcc).
- Otherwise require libdispatch.
---
 CMakeLists.txt                                |  3 +--
 .../detail/impl/dynamic_thread_pool_group.ipp | 24 +++++--------------
 2 files changed, 7 insertions(+), 20 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 25bdc34b6..134156bbb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -349,10 +349,9 @@ else()
       check_have_libdispatch(WITH_LIBDISPATCH dispatch)
       if(LLFIO_HAS_LIBDISPATCH_WITH_LIBDISPATCH)
         all_link_libraries(PUBLIC dispatch)
+        all_compile_definitions(PUBLIC LLFIO_DYNAMIC_THREAD_POOL_GROUP_USING_GCD=1)
       endif()
     endif()
-  else()
-    all_compile_definitions(PUBLIC LLFIO_DYNAMIC_THREAD_POOL_GROUP_USING_GCD=0)
   endif()
   if(NOT LLFIO_HAS_LIBDISPATCH_BUILTIN AND NOT LLFIO_HAS_LIBDISPATCH_WITH_LIBDISPATCH AND (CMAKE_SYSTEM_NAME MATCHES "FreeBSD" OR APPLE))
     indented_message(FATAL_ERROR "FATAL: Grand Central Dispatch as libdispatch was not found on this FreeBSD or Mac OS system. libdispatch is required for LLFIO to build on those systems.")
diff --git a/include/llfio/v2.0/detail/impl/dynamic_thread_pool_group.ipp b/include/llfio/v2.0/detail/impl/dynamic_thread_pool_group.ipp
index 240d59479..71a5096c0 100644
--- a/include/llfio/v2.0/detail/impl/dynamic_thread_pool_group.ipp
+++ b/include/llfio/v2.0/detail/impl/dynamic_thread_pool_group.ipp
@@ -39,31 +39,19 @@ Distributed under the Boost Software License, Version 1.0.
 
 #include <iostream>
 
-#ifndef LLFIO_DYNAMIC_THREAD_POOL_GROUP_USING_GCD
-#if LLFIO_FORCE_USE_LIBDISPATCH
-#include <dispatch/dispatch.h>
-#define LLFIO_DYNAMIC_THREAD_POOL_GROUP_USING_GCD 1
-#else
-#ifdef _WIN32
+#if defined(_WIN32)
 #include "windows/import.hpp"
 #include <threadpoolapiset.h>
-#else
-#if __has_include(<dispatch/dispatch.h>)
-#include <dispatch/dispatch.h>
-#define LLFIO_DYNAMIC_THREAD_POOL_GROUP_USING_GCD 1
-#endif
-#endif
-#endif
-#endif
-#if !LLFIO_DYNAMIC_THREAD_POOL_GROUP_USING_GCD && !defined(_WIN32)
-#if !defined(__linux__)
-#error dynamic_thread_pool_group requires Grand Central Dispatch (libdispatch) on non-Linux POSIX.
-#endif
+#elif defined(__linux__) && !LLFIO_DYNAMIC_THREAD_POOL_GROUP_USING_GCD
 #include <dirent.h> /* Defines DT_* constants */
 #include <sys/syscall.h>
 
 #include <condition_variable>
 #include <thread>
+#elif __has_include(<dispatch/dispatch.h>)
+#include <dispatch/dispatch.h>
+#else
+#error dynamic_thread_pool_group requires Grand Central Dispatch (libdispatch) on non-Linux POSIX.
 #endif
 
 #define LLFIO_DYNAMIC_THREAD_POOL_GROUP_PRINTING 0