[MacPorts] #64316: gcc9 @9.4.0_1 & gcc10 @10.3.0_1: build failure: Undefined symbols for architecture x86_64

[MacPorts]

#64316: gcc9 @9.4.0_1 & gcc10 @10.3.0_1: build failure: Undefined symbols for
architecture x86_64
-------------------------+--------------------
  Reporter:  i0ntempest  |      Owner:  (none)
      Type:  defect      |     Status:  new
  Priority:  Normal      |  Milestone:
 Component:  ports       |    Version:  2.7.1
Resolution:              |   Keywords:
      Port:  gcc9 gcc10  |
-------------------------+--------------------

Comment (by cooljeanius):

 Hi, this bug currently blocks upgrades for mpich-default, openmpi-default,
 and R for me.

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Ticket URL: <https://trac.macports.org/ticket/64316#comment:11>
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