[MacPorts] #58229: base: defining the same variant both in a PG and a port discards description

[MacPorts]

#58229: base: defining the same variant both in a PG and a port discards
description
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  Reporter:  Ionic   |      Owner:  (none)
      Type:  defect  |     Status:  new
  Priority:  Low     |  Milestone:
 Component:  base    |    Version:  2.5.99
Resolution:          |   Keywords:
      Port:          |
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Comment (by Ionic):

 Mh, I would have expected this to be a supported use case.

 We have at least one PG that implements a variant - `qmake-1.0`. In such a
 case, merging the contents of the same-named variants (for instance
 because the PG implements the base code of a variant with more specific
 per-port code in the actual `Portfile`) would make sense.

 It's not a new concept either, since you can also have multiple
 implementations for the same phase - which are then essentially merged
 together during execution - already. This is typically done with generic
 unconditional code and specialized one based on the platform or the like.

 On the other hand, the `qmake` PG does look broken concerning this
 behavior, so maybe that's the actual problem. The `qmake5` PG only adds a
 debug variant if it isn't already defined by the port, which probably was
 meant to be done in the `qmake` PG as well, but never carried it out
 correctly.

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Ticket URL: <https://trac.macports.org/ticket/58229#comment:4>
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