[MacPorts] #59135: legacy-support: functions properly only if os.version = deployment target

[MacPorts]

#59135: legacy-support: functions properly only if os.version = deployment target
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  Reporter:  kencu                                 |      Owner:  kencu
      Type:  defect                                |     Status:  assigned
  Priority:  Normal                                |  Milestone:
 Component:  ports                                 |    Version:
Resolution:                                        |   Keywords:
      Port:  legacy-support, legacy-support-devel  |
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Comment (by kencu):

 This comes up again now, trying to build clang-devel on 10.11 using
 legacy-support.

 When 10.11 builds legacy-support, the defines are such that function
 wrapping is disabled.

 However, when clang-devel builds compiler-rt on 10.11, it sets the
 deployment target to something lower, and then the defines are such that
 function wrapping is enabled. So legacy-support renames some functions,
 like sysconf, to macports_legacysupport_sysconf, but that function does
 not exist in the library, so there is a link error.

 Fixing this properly is kind of tricky. For now, I will either force
 function wrapping off for the clang-devel build, or reset the deployment
 target for compiler-rt to the current system... (I'm just pondering what,
 if any, deleterious effect that might have on compiler-rt... ).

-- 
Ticket URL: <https://trac.macports.org/ticket/59135#comment:5>
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