qt_apple_check_os_version fails with WatchOS

When for some reason we end up in qt_apple_check_os_version on WatchOS, we end up with an assert saying that iOS version 4.3 is not compatible with Qt that requires an higher version of iOS.

Just try to instantiate a QGuiApplication into a WatchOS app for instance.

This is due to something rather interesting when building Qt for WatchOS.

When adding these line after all includes within qtbase/src/corelib/kernel/qcore_mac_objc.mm:

50 #define STR(X) #X
51 #define DEFER(M,...) M(_VA_ARGS_)
52 #pragma message "env ios min version required is " DEFER(STR,_ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED_)
53 #pragma message "env mac min version required is " DEFER(STR,_ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED_)
54 #pragma message "env watch min version required is " DEFER(STR,_ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED_)
55
56 #pragma message "ios min version required is " DEFER(STR,__IPHONE_OS_VERSION_MIN_REQUIRED)
57 #pragma message "mac min version required is " DEFER(STR,__MAC_OS_X_VERSION_MIN_REQUIRED)
58 #pragma message "watch min version required is " DEFER(STR,__WATCH_OS_VERSION_MIN_REQUIRED)

You have the following output when it is compiled for watchOS:

kernel/qcore_mac_objc.mm:52:9: warning: env ios min version required is _ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED_ -W#pragma-messages
#pragma message "env ios min version required is " DEFER(STR,_ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED_)
^
kernel/qcore_mac_objc.mm:53:9: warning: env mac min version required is _ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED_ -W#pragma-messages
#pragma message "env mac min version required is " DEFER(STR,_ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED_)
^
kernel/qcore_mac_objc.mm:54:9: warning: env watch min version required is 30000 -W#pragma-messages
#pragma message "env watch min version required is " DEFER(STR,_ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED_)
^
kernel/qcore_mac_objc.mm:56:9: warning: ios min version required is 90000 -W#pragma-messages
#pragma message "ios min version required is " DEFER(STR,__IPHONE_OS_VERSION_MIN_REQUIRED)
^
kernel/qcore_mac_objc.mm:57:9: warning: mac min version required is __MAC_OS_X_VERSION_MIN_REQUIRED -W#pragma-messages
#pragma message "mac min version required is " DEFER(STR,__MAC_OS_X_VERSION_MIN_REQUIRED)
^
kernel/qcore_mac_objc.mm:58:9: warning: watch min version required is 30000 -W#pragma-messages
#pragma message "watch min version required is " DEFER(STR,__WATCH_OS_VERSION_MIN_REQUIRED)

You can easily see that _IPHONE_OS_VERSION_MIN_REQUIRED is defined while it should not since __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED_ is not set . Otherwise everything for WATCH_OS is properly set but this messes up the  qt_apple_check_os_version.