[MacPorts] #15712: Add versions to platforms

[MacPorts]

#15712: Add versions to platforms
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  Reporter:  raimue       |      Owner:  larryv
      Type:  enhancement  |     Status:  assigned
  Priority:  Normal       |  Milestone:  MacPorts 2.6.0
 Component:  base         |    Version:
Resolution:               |   Keywords:
      Port:               |
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Comment (by mojca):

 OK, we might not need to merge the lists with dependencies, but we do need
 to make sure that multiple PortGroups included in the same port could
 specify that the port cannot be built on some platforms.

 Building `gnuplot +qt` will certainly have different coverage of supported
 platforms than `gnuplot -qt` or `gnuplot +wxt`.

 Then again ... if we evaluate dependencies separately anyway, if a port
 includes qt5 PG and that one pulls in dependency on qt5 anyway, the PG
 might not actually need to blacklist any platforms since the platform will
 already be blacklisted by qt5 itself.

-- 
Ticket URL: <https://trac.macports.org/ticket/15712#comment:32>
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