[MacPorts] #69867: legacy-support headers should work with later SDK versions

[MacPorts]

#69867: legacy-support headers should work with later SDK versions
-----------------------------+-----------------------
  Reporter:  fhgwright       |      Owner:  fhgwright
      Type:  defect          |     Status:  assigned
  Priority:  Low             |  Milestone:
 Component:  ports           |    Version:  2.9.3
Resolution:                  |   Keywords:
      Port:  legacy-support  |
-----------------------------+-----------------------

Comment (by fhgwright):

 In [changeset:"0e7c7718033057d410fbd09bc22297e0a1f69300/macports-legacy-
 support" 0e7c7718033057d410fbd09bc22297e0a1f69300/macports-legacy-support]
 (master):
 {{{
 #!ConfigurableCommitTicketReference repository="macports-legacy-support"
 revision="0e7c7718033057d410fbd09bc22297e0a1f69300"
 Fix 10.6- builds with 14.x+ SDKs.

 Beginning with the 14.x SDK, AvailabilityInternal.h uses the
 __has_builtin() operator.  Although it includes a defined() condition,
 that doesn't actually work because the operator needs to be parseable
 before evaluating the boolean.  So we provide a default (always false)
 definition when the compiler doesn't have it.

 Re: https://trac.macports.org/ticket/69867

 TESTED:
 Tested on 10.4-10.5 ppc, 10.5-10.6 ppc (i386 Rosetta), 10.4-10.6 i386,
 10.5-12.x x86_64, and 11.x-14.x arm64.  Tested against all 10.4-14.x
 SDKs, using the headerinfo manual test (from a subsequent commit).
 All target/SDK combinations where the SDK supports the CPU
 architecture work correctly, including all SDKs on Intel
 architectures.  Only 10.4-10.6 SDKs support ppc, and only 11.x+ SDKs
 support arm64.
 }}}

-- 
Ticket URL: <https://trac.macports.org/ticket/69867#comment:13>
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