tree 4d50b330ceb6567abb390fe3320d736b6b28e169
parent ba12ee6f5663a89354b1dc04135cdfc878f56895
author Mark Mentovai <mark@chromium.org> 1598659215 -0400
committer Copybara-Service <copybara-worker@google.com> 1611069238 -0800

mac: Switch from <AvailabilityMacros.h> to <Availability.h>

The macOS 11.0 SDK, as of Xcode 12b6 12A8189n, has not updated
<AvailabilityMacros.h> with a MAC_OS_X_VERSION_11_0 or
MAC_OS_X_VERSION_10_16 constant. However, the <Availability.h> interface
has been updated to provide both __MAC_11_0 and __MAC_10_16.
<AvailabilityMacros.h>’s MAC_OS_X_VERSION_MAX_ALLOWED, which is supposed
to identify the SDK version, is broken in the 11.0 SDK in that whenever
the deployment target is set to 10.15 or earlier, the SDK will be
mis-identified through this interface as 10.15. When using the
<Availability.h> equivalent, __MAC_OS_X_VERSION_MAX_ALLOWED, the 11.0
SDK is identified as 10.16 (arguably it should be internally versioned
as 11.0, but at least this interface allows it to be detected
unambiguously.) It’s clear that the <AvailabilityMacros.h> interface
provides no meaningful support for the macOS 11.0 SDK at all, but
<Availability.h> does.

<Availability.h> was introduced in the Mac OS X 10.5 SDK, so there is no
relevant SDK version compatibility problem with this interface.

Key differences between these interfaces for the purposes used by
Crashpad:
 - <AvailabilityMacros.h> → <Availability.h>
 - MAC_OS_X_VERSION_MIN_REQUIRED (DT) → __MAC_OS_X_VERSION_MIN_REQUIRED
 - MAC_OS_X_VERSION_MAX_ALLOWED (SDK) → __MAC_OS_X_VERSION_MAX_ALLOWED
 - MAC_OS_X_VERSION_x_y → __MAC_x_y
 - <Availability.h> __MAC_OS_X_VERSION_* SDK/DT macros are only
   available when targeting macOS, while <AvailabilityMacros.h>
   MAC_OS_X_VERSION_* SDK/DT macros are available on all Apple platforms,
   which may be a source of confusion. (<Availability.h> __MAC_* macros
   do remain available on all Apple platforms.)

This change was made mostly mechanically by:

sed -i '' -Ee 's/<AvailabilityMacros.h>/<Availability.h>/g' \
    $(git grep -E -l '<AvailabilityMacros.h>' |
          grep -v AvailabilityMacros.h)

sed -i '' -Ee 's/(MAC_OS_X_VERSION_(MIN_REQUIRED|MAX_ALLOWED))/__\1/g' \
    $(git grep -E -l 'MAC_OS_X_VERSION_(MIN_REQUIRED|MAX_ALLOWED)' |
          grep -v AvailabilityMacros.h)

sed -i '' -Ee 's/(MAC_OS_X_VERSION_(10_[0-9]+))/__MAC_\2/g' \
    $(git grep -E -l 'MAC_OS_X_VERSION_(10_[0-9]+)' |
          grep -v AvailabilityMacros.h)

Bug: crashpad:347
Change-Id: Iab2d381a09838cdbc08ab409eea7e96320e28d59
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/2382421
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Mark Mentovai <mark@chromium.org>
GitOrigin-RevId: bdf94713241b2656c01601d3e44858deb8d19fda