[MacPorts] #58442: gcc9 (and other gccN) fails to install on Mojave, Xcode-10.2.1

[MacPorts]

#58442: gcc9 (and other gccN) fails to install on Mojave, Xcode-10.2.1
-------------------------+--------------------
  Reporter:  mouse07410  |      Owner:  (none)
      Type:  defect      |     Status:  new
  Priority:  Normal      |  Milestone:
 Component:  ports       |    Version:
Resolution:              |   Keywords:
      Port:  gcc9        |
-------------------------+--------------------

Comment (by kencu):

 We can see the gcc output is going directly into macports-clang-7.0 or
 macports-clang-8.0 to assemble, so nothing is going astray in the
 environment there (ie there is no indication that it is a port select
 issue (port select is not involved here), an ld64 issue, or a cctools
 issue).

 llvm is then crashing on the piped-in assembly.

 But if nobody else can reproduce it, it is probably the specific way mouse
 has built llvm.

 I have triaged many such random crashes in llvm -- you'd be surprised how
 touchy it can be.

-- 
Ticket URL: <https://trac.macports.org/ticket/58442#comment:34>
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