On 12/9/21 04:28, Ryan Schmidt wrote:
(They used __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ instead of MAC_OS_X_VERSION_MIN_REQUIRED; the distinction is not clear to me. It might be that __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ is defined even if AvailabilityMacros.h is not included.)
I think you're right that __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ is predefined; see <https://opensource.apple.com/source/CarbonHeaders/CarbonHeaders-18.1/AvailabilityMacros.h.auto.html>.
There's a similar macro __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ for iOS.