cmake HAVE_SWIFT_ASYNC_CALL examples

swiftlang/swift Runtimes/Core/cmake/modules/CompilerSettings.cmake :39 

check_source_compiles(CXX
"#if !(__has_attribute(swiftasynccall) && \
  __has_attribute(swift_async_context))
#error CXX compiler must support Swift async calling conventions
#endif
int main(void) { return 0; }"
HAVE_SWIFT_ASYNC_CALL)

swiftlang/swift Runtimes/Supplemental/cmake/modules/SwiftCallingConventions.cmake :18 

check_source_compiles(CXX
"#if !(__has_attribute(swiftasynccall) && \
  __has_attribute(swift_async_context))
#error CXX compiler must support Swift async calling conventions
#endif
int main(void) { return 0; }"
HAVE_SWIFT_ASYNC_CALL)