Merge pull request #23 from andreasbuhr/fix_msvc_cpp17

Fix msvc cpp17

Author: andreasbuhr

cmake/FindCoroutines.cmake

@@ -150,10 +150,19 @@ endif()
 
 if(find_final)
     check_include_file_cxx("coroutine" _CXX_COROUTINES_HAVE_HEADER)
+    if(_CXX_COROUTINES_HAVE_HEADER)
+        check_cxx_source_compiles("#include <coroutine> \n typedef std::suspend_never blub; \nint main() {} " _CXX_COROUTINES_FINAL_HEADER_COMPILES)
+        set(_CXX_COROUTINES_HAVE_HEADER ${}_CXX_COROUTINES_FINAL_HEADER_COMPILES})
+    endif()
+
     if(NOT _CXX_COROUTINES_HAVE_HEADER)
         cmake_push_check_state()
         set(CMAKE_REQUIRED_FLAGS "${_CXX_COROUTINES_EXTRA_FLAGS}")
         check_include_file_cxx("coroutine" _CXX_COROUTINES_HAVE_HEADER_WITH_FLAG)
+        if(_CXX_COROUTINES_HAVE_HEADER_WITH_FLAG)
+            check_cxx_source_compiles("#include <coroutine> \n typedef std::suspend_never blub; \nint main() {} " _CXX_COROUTINES_FINAL_HEADER_COMPILES_WITH_FLAG)
+            set(_CXX_COROUTINES_HAVE_HEADER_WITH_FLAG ${_CXX_COROUTINES_FINAL_HEADER_COMPILES_WITH_FLAG})
+        endif()
         set(_CXX_COROUTINES_HAVE_HEADER ${_CXX_COROUTINES_HAVE_HEADER_WITH_FLAG})
         cmake_pop_check_state()
     endif()

include/cppcoro/config.hpp

@@ -150,4 +150,17 @@
 # define CPPCORO_CPU_CACHE_LINE 64
 #endif
 
+#if CPPCORO_COMPILER_MSVC
+    #if __has_include(<coroutine>)
+    #include <yvals_core.h>
+    #ifdef __cpp_lib_coroutine
+    #define CPPCORO_COROHEADER_FOUND_AND_USABLE
+    #endif
+    #endif
+#else
+    #if __has_include(<coroutine>)
+    #define CPPCORO_COROHEADER_FOUND_AND_USABLE
+    #endif
+#endif
+
 #endif

include/cppcoro/coroutine.hpp

@@ -1,7 +1,9 @@
 #ifndef CPPCORO_COROUTINE_HPP_INCLUDED
 #define CPPCORO_COROUTINE_HPP_INCLUDED
 
-#if __has_include(<coroutine>)
+#include <cppcoro/config.hpp>
+
+#ifdef CPPCORO_COROHEADER_FOUND_AND_USABLE
 
 #include <coroutine>