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

[MacPorts]

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

Comment (by kencu):

 I wonder what would happen if we built legacy-support with an older
 deployment target, say 10.6, on 10.11... then the legacysupport library
 would have all the needed older system symbols in it.

 Then, when we build software with the legacy support headers, if have the
 deployment target set to the current system, the headers would ask for the
 current symbols from the library, but if we build software with the
 deployment target set older, like compiler-rt does, then the needed
 symbols would be found in the legacy-support library, and (I think) the
 software could actually be deployed on the older system and it would
 (hopefully) work. Especially as in this case, where it's linked
 statically...

-- 
Ticket URL: <https://trac.macports.org/ticket/59135#comment:6>
MacPorts <https://www.macports.org/>
Ports system for macOS