Re: [PATCH] git-compat-util: fix NO_OPENSSL on current macOS

[Eric Sunshine <sunshine@sunshineco.com>]

On Sun, Apr 14, 2024 at 12:47 PM René Scharfe <l.s.r@web.de> wrote:
> b195aa00c1 (git-compat-util: suppress unavoidable Apple-specific
> deprecation warnings, 2014-12-16) started to define
> __AVAILABILITY_MACROS_USES_AVAILABILITY in git-compat-util.h.  On
> current versions it is already defined (e.g. on macOS 14.4.1).  Undefine
> it before redefining it to avoid a compilation error.
>
> Signed-off-by: René Scharfe <l.s.r@web.de>
> ---
> On my system I can remove the whole ifdef __APPLE__ section, as the OS
> doesn't include the deprecated OpenSSL anymore.  I get a current version
> via Homebrew, which doesn't throw any deprecation warnings, of course.
>
> Not sure if this is the right fix, as the no longer needed section still
> undefines __AVAILABILITY_MACROS_USES_AVAILABILITY at the end, which we
> may want to keep instead.  But compilation succeeds and tests pass, so
> perhaps it's fine.

I think I added the final `#undef
__AVAILABILITY_MACROS_USES_AVAILABILITY` in b195aa00c1
(git-compat-util: suppress unavoidable Apple-specific deprecation
warnings, 2014-12-16) just for completeness; since I #define'd it, I
also #undef'd it to ensure a clean state or the C preprocessor.

However, taking this new situation into account, where
__AVAILABILITY_MACROS_USES_AVAILABILITY is now defined by default, it
_probably_ would be more correct to drop that final #undef.

Having said that, though, it doesn't seem that it is likely to matter
one way or the other as the project stands presently, especially since
you report that building and testing succeeds. Moreover, the only
other place in the project where we seem to care about the Apple
version-compatibility macros is in
compat/fsmonitor/fsm-listen-darwin.c, but even that isn't a problem
because it consults a version-compatibility macro before #include'ing
git-compat-util:

    #ifndef AVAILABLE_MAC_OS_X_VERSION_10_13_AND_LATER
    #define kFSEventStreamEventFlagItemCloned 0x00400000
    #endif
    #include "git-compat-util.h"

So, this patch can't possibly have any sort of negative interaction
with that code even if __AVAILABILITY_MACROS_USES_AVAILABILITY somehow
impacted AVAILABLE_MAC_OS_X_VERSION_10_13_AND_LATER.