[MacPorts] #57196: libgcc7 fails to compile/install on macOS Mojave

[MacPorts]

#57196: libgcc7 fails to compile/install on macOS Mojave
------------------------------+--------------------
  Reporter:  ProgrammingPoet  |      Owner:  (none)
      Type:  defect           |     Status:  new
  Priority:  Normal           |  Milestone:
 Component:  ports            |    Version:  2.5.3
Resolution:                   |   Keywords:  mojave
      Port:  libgcc7          |
------------------------------+--------------------

Comment (by kencu):

 I broke down the failing command:
 {{{
 :info:build /bin/sh ../../libtool --tag CXX --tag disable-shared
 --mode=compile
 /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_gcc7/libgcc7/work/build/./gcc/xgcc
 -shared-libgcc
 -B/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_gcc7/libgcc7/work/build/./gcc
 -nostdinc++
 -L/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_gcc7/libgcc7/work/build/x86_64
 -apple-darwin18/libstdc++-v3/src
 -L/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_gcc7/libgcc7/work/build/x86_64
 -apple-darwin18/libstdc++-v3/src/.libs
 -L/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_gcc7/libgcc7/work/build/x86_64
 -apple-darwin18/libstdc++-v3/libsupc++/.libs
 -B/opt/local/x86_64-apple-darwin18/bin/
 -B/opt/local/x86_64-apple-darwin18/lib/
 -isystem /opt/local/x86_64-apple-darwin18/include
 -isystem /opt/local/x86_64-apple-darwin18/sys-include
 -I/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_gcc7/libgcc7/work/gcc-7.3.0/libstdc++-v3/../libgcc
 -I/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_gcc7/libgcc7/work/build/x86_64
 -apple-darwin18/libstdc++-v3/include/x86_64-apple-darwin18
 -I/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_gcc7/libgcc7/work/build/x86_64
 -apple-darwin18/libstdc++-v3/include
 -I/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_gcc7/libgcc7/work/gcc-7.3.0/libstdc++-v3/libsupc++
 -prefer-pic -D_GLIBCXX_SHARED -std=gnu++14 -Wall -Wextra -Wwrite-strings
 -Wcast-qual -Wabi  -fdiagnostics-show-location=once  -fvisibility-inlines-
 hidden -ffunction-sections -fdata-sections  -frandom-seed=cow-ops.lo -g
 -O2 -pipe -Os
 -isysroot/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk
 -c -o cow-ops.lo
 /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_gcc7/libgcc7/work/gcc-7.3.0/libstdc++-v3/src/filesystem
 /cow-ops.cc


 :info:build  #include <experimental/bits/lfts_config.h>
 :info:build           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 }}}

 that file is here:
 {{{
 $ locate lfts_config.h
 /opt/local/include/gcc/c++/experimental/bits/lfts_config.h
 /opt/local/include/gcc5/c++/experimental/lfts_config.h
 /opt/local/include/gcc6/c++/experimental/bits/lfts_config.h
 /opt/local/include/gcc7/c++/experimental/bits/lfts_config.h

 $ port provides /opt/local/include/gcc/c++/experimental/bits/lfts_config.h
 /opt/local/include/gcc/c++/experimental/bits/lfts_config.h is provided by:
 libgcc8
 }}}
 none of which are on a search path that I can see.

 There is probably another copy of that file in the headers of the libgcc
 that is being built.

 I'm not quite sure why it's not being found.

 Are we messing with the build by overriding the CPP and forcing it to use
 clang?
 {{{
 # the generated compiler doesn't accept -arch
 configure.env-append \
     CPP="${configure.cc} -E" \
     CXXCPP="${configure.cxx} -E"
 build.env-append \
     CPP="${configure.cc} -E" \
     CXXCPP="${configure.cxx} -E"
 }}}

-- 
Ticket URL: <https://trac.macports.org/ticket/57196#comment:4>
MacPorts <https://www.macports.org/>
Ports system for macOS