[MacPorts] #65987: libgcc9 fails to upgrade on BigSur 11.7

[MacPorts]

#65987: libgcc9 fails to upgrade on BigSur 11.7
--------------------------+--------------------
  Reporter:  bradman1972  |      Owner:  (none)
      Type:  defect       |     Status:  new
  Priority:  Normal       |  Milestone:
 Component:  ports        |    Version:  2.7.2
Resolution:               |   Keywords:
      Port:  libgcc9      |
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Comment (by cjones051073):

 That will not really help in this case, and it isn't really how the gccX
 port works, they don't replace each other but exist along side (where they
 can).

 The issue is the (lib)gcc9 dep usually come from the compilers PG, that
 picks a variant for ports to use. Once a user installs a port with a
 certain variant, even if its just because its the default, if that default
 changes in the future that user is not automatically migrated to the new
 (default) variant, so stay with the old one. I am not aware of a way to
 handle this, other than the user having to reinstall any ports that have a
 (lib)gcc9 dep, using the more recent defaults. if you know a way to do
 this please let me know.

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Ticket URL: <https://trac.macports.org/ticket/65987#comment:2>
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