[MacPorts] #59389: Failed to build libgcc7 in Catalina

[MacPorts]

#59389: Failed to build libgcc7 in Catalina
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  Reporter:  mengqiz  |      Owner:  (none)
      Type:  defect   |     Status:  closed
  Priority:  Normal   |  Milestone:
 Component:  ports    |    Version:
Resolution:  wontfix  |   Keywords:
      Port:           |
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Comment (by cjones051073):

 I suggest you start again following the migration instructions at

 https://trac.macports.org/wiki/Migration

 as its not possible you installed gcc7 or gcc8 from scratch on macOS
 10.15, they must be left over from a previous OS, meaning you failed to
 follow the migration instructions.

 Its going to be difficult to help you with your system in this ill defined
 state, so you need to remove all your ports, and install them again from
 scratch.

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Ticket URL: <https://trac.macports.org/ticket/59389#comment:4>
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