[MacPorts] #61396: rust @1.47.0: fails to build on Big Sur

[MacPorts]

#61396: rust @1.47.0: fails to build on Big Sur
-------------------------+--------------------
  Reporter:  5nefarious  |      Owner:  (none)
      Type:  defect      |     Status:  closed
  Priority:  Normal      |  Milestone:
 Component:  ports       |    Version:  2.6.99
Resolution:  invalid     |   Keywords:  bigsur
      Port:  rust        |
-------------------------+--------------------

Comment (by 5nefarious):

 Replying to [comment:5 ryandesign]:
 > The port that provides /opt/local/libexec/llvm-9.0/lib/libLLVM.dylib
 (llvm-9.0) needed to have had its revision increased after the port that
 provided /opt/local/lib/libffi.6.dylib (libffi) was updated to a version
 that instead provided libffi.7.dylib. And that did happen 2 months ago in
 [bd5d6800828a3dcda1b65f3999fa748a365b168e/macports-ports]. When you run
 `sudo port sync` and `port outdated`, you should see that llvm-9.0 is
 outdated; you should then upgrade it. Or if that does not happen, then
 when you run `sudo port rev-upgrade` (and rev-upgrade also automatically
 runs after every port installation) it should tell you llvm-9.0 is broken
 and should rebuild it, which will also fix this problem.

 Thanks, Ryan. I'm currently unable to run `port upgrade outdated`, as
 `qt5-qtbase` is failing to build. It seems like the macOS 11 SDK is not
 being detected, as discussed in #61103. I guess I'll look into fixing that
 first.

-- 
Ticket URL: <https://trac.macports.org/ticket/61396#comment:6>
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