[MacPorts] #57356: libgcc8 @8.2.0.1 fails to build on Mojave with "C compiler cannot create executables"

[MacPorts]

#57356: libgcc8 @8.2.0.1 fails to build on Mojave with "C compiler cannot create
executables"
--------------------+---------------------
 Reporter:  p-vitt  |      Owner:  (none)
     Type:  defect  |     Status:  new
 Priority:  Normal  |  Milestone:
Component:  ports   |    Version:  2.5.4
 Keywords:  mojave  |       Port:  libgcc8
--------------------+---------------------
 I just updated my OS to 10.14 Mojave and followed the Migration process
 described in the wiki. Three Mac Minis succeeded, but the first MacBook
 somehow failed:


 {{{
 Error: Failed to build libgcc8: command execution failed
 Error: See
 /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_gcc8/libgcc8/main.log
 for details.
 }}}

 In main.log it says:

 {{{
 :info:build checking for C compiler default output file name...-
 :info:build configure: error: in
 `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_gcc8/libgcc8/work/build/x86_64
 -apple-darwin18/libgomp':
 :info:build configure: error: C compiler cannot create executables
 :info:build See `config.log' for more details.
 :info:build make[2]: *** [configure-stage1-target-libgomp] Error 77
 }}}

 In libgomp's config.log, it says {{{error: unrecognized command line
 option '-V'}}} or {{{error: unrecognized command line option '-qversion';
 did you mean '--version'}}} or {{{error: C compiler cannot create
 executables}}}.

 I reinstalled XCode, accepted the license, checked the Command Line Tools,
 everything is fine. I also tried a binary install, without success.
 {{{port install -b libgcc8}}} fails with 404 on all probed sources.

 Then I tried to install gcc7, but this also depends on libgcc8.
 [https://trac.macports.org/ticket/57198 Uninstalling libunwind] doesn't
 help. I also had a look at some [https://trac.macports.org/ticket/33041
 older] [https://trac.macports.org/ticket/41217 tickets], without success.

 Right now, I have no clue how to proceed. Any help appreciated.

-- 
Ticket URL: <https://trac.macports.org/ticket/57356>
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