[MacPorts] #54900: libgcc @7.2.0: fatal error: bits/regex_scanner.tcc: No such file or directory

[MacPorts]

#54900: libgcc @7.2.0: fatal error: bits/regex_scanner.tcc: No such file or
directory
---------------------------+------------------------
  Reporter:  cjones051073  |      Owner:
      Type:  defect        |     Status:  new
  Priority:  Normal        |  Milestone:
 Component:  ports         |    Version:  2.4.1
Resolution:                |   Keywords:  highsierra
      Port:  libgcc        |
---------------------------+------------------------

Comment (by cjones051073):

 There appears to be a non-reproducible nature to the failure. I have run
 the build a few times now and each time the exact error is slightly
 different. Its in roughly the same place, and relates to an "bits/XYZ"
 include, but not exactly the same include each time. For instance

 {{{
 :info:build
 /opt/local/var/macports/build/_Users_chris_Projects_MacPorts_ports_lang_gcc7/libgcc/work/build/x86_64
 -apple-darwin17/libstdc++-v3/include/string:41:10: fatal error:
 bits/allocator.h: No such file or directory
 :info:build  #include <bits/allocator.h>
 :info:build           ^~~~~~~~~~~~~~~~~~
 }}}

 Could this be an APFS issue (the machine I am using was updated to the new
 filesystem). I ran checks with the betas version prior to the release, in
 a VM, and the only difference I can think of is that VM was not using APFS
 but the old file system...

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Ticket URL: <https://trac.macports.org/ticket/54900#comment:4>
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