[MacPorts] #71942: Make legacy-support library work properly on later OS than build target

[MacPorts]

#71942: Make legacy-support library work properly on later OS than build target
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  Reporter:  fhgwright       |      Owner:  fhgwright
      Type:  enhancement     |     Status:  assigned
  Priority:  Normal          |  Milestone:
 Component:  ports           |    Version:
Resolution:                  |   Keywords:
      Port:  legacy-support  |
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Comment (by kencu):

 No, the problem I outlined in the initial ticket for this occurs when you
 are building something on a newer system with an older deployment target.
 The legacysupport library on the newer system does not have the
 replacement symbols needed for the older deployment target.

 If I were re-designing legacysupport today with the knowledge I've gained
 over the last 10 years since I first designed and implemented it nearly a
 decade ago, I would exactly implement it as one monolithic library and
 then show/hide the needed symbols dynamically using the {{{$ld$}}}
 mechanism, depending on the deployment target.

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Ticket URL: <https://trac.macports.org/ticket/71942#comment:4>
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