[MacPorts] #58779: base: ports cannot use SDK inside of Developer dir unless using Xcode build type

[MacPorts]

#58779: base: ports cannot use SDK inside of Developer dir unless using Xcode build
type
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  Reporter:  Ionic   |      Owner:  (none)
      Type:  defect  |     Status:  new
  Priority:  Normal  |  Milestone:
 Component:  base    |    Version:  2.5.99
Resolution:          |   Keywords:  tracemode
      Port:          |
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Comment (by Ionic):

 > If you install both Xcode and the CLT then you won't have
 /Library/Developer/CommandLineTools/usr/bin/make, or at least I don't. If
 there is a case where that exists but the SDK inside Xcode is still used,
 that would be a problem.

 That doesn't seem to hold for 10.9 for instance. It's entirely possible
 that such setups only exist in older systems nowadays, but I have both CLT
 and Xcode installed and the paths all exist.

 > That would match what is done elsewhere. Using the headers in
 /usr/include is safer than using the SDK in Xcode because the latter could
 be for a newer OS version, which causes problems with build-time detection
 of features.

 Yeees, since Apple doesn't necessarily ship the needed SDK versions with
 all supported Xcode versions any longer. But also back then, using the
 provided SDKs was safer pre-SIP.


 Not allowing access to the Developer dir isn't just problematic because of
 the SDKs, though. In #58770 I reported a build failure that I "fixed" by
 setting `use_xcode` to `true` in the port, but that workaround is wrong
 and stupid. Nothing within scons or gpsd actually uses xcrun - the call is
 a side-effect of the shims in /usr/bin (for clang for instance). In
 theory, we'd have to allow access to the Developer dir every time we use
 the system compiler as well.

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Ticket URL: <https://trac.macports.org/ticket/58779#comment:4>
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