Re: [RFC PATCH v2 2/6] audio/coreaudio: Remove a deprecation warning on macOS 12

[Akihiko Odaki]

On 2022/01/10 22:22, Peter Maydell wrote:
> On Mon, 10 Jan 2022 at 13:14, Christian Schoenebeck
> <qemu_oss@crudebyte.com> wrote:
> > I'd suggest to use:
> >
> > #if !defined(MAC_OS_VERSION_12_0) ||
> >      (MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_VERSION_12_0)
> > #define kAudioObjectPropertyElementMain kAudioObjectPropertyElementMaster
> > #endif
>
> This is also how we do this for existing checks of this sort,
> like the one in osdep.h for qemu_thread_jit_execute().
>
> -- PMM

If I understand correctly, Many macOS-specific codes already no longer 
complies with GCC because they depend on modern features GCC doesn't 
provide. The most problematic construction is block; it is extensively 
used by Apple's ABI and API and you cannot avoid using it even if you try.

Also, note that MAC_OS_X_VERSION_MAX_ALLOWED defines the upper bound of 
the supported version. The lower bound should be preferred here because 
the usage of the new identifier is applied regardless of the version of 
the host system. It is in contrary to the usage of 
MAC_OS_X_VERSION_MAX_ALLOWED in osdep.h where the new interfaces are 
used only for the newer versions. The lower bound is defined as 
MAC_OS_X_VERSION_MIN_REQUIRED. Practically there is no difference of the 
two macros because they have the same value in QEMU and 
kAudioObjectPropertyElementMain is a constant resolved compile-time, but 
it is still nice to have the code semantically correct.

Regards,
Akihiko Odaki