libgcc7 fails to build on 10.15

[ffm-fg]

Looking in /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_gcc7/libgcc7/main.log

the last messages are

:info:build ld: unexpected token: !tapi-tbd-v3 file '/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/lib/libc.tbd' for architecture x86_64
:info:build ld: warning: could not create compact unwind for __Unwind_RaiseException: does not use RBP or RSP based frame
:info:build ld: warning: could not create compact unwind for __Unwind_ForcedUnwind: does not use RBP or RSP based frame
:info:build ld: warning: could not create compact unwind for __Unwind_Resume: non-standard register 0 being saved in prolog
:info:build ld: warning: could not create compact unwind for __Unwind_Resume_or_Rethrow: non-standard register 0 being saved in prolog
:info:build collect2: error: ld returned 1 exit status
:info:build make[3]: *** [libgcc_s.dylib] Error 1
:info:build make[3]: Leaving directory `/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-darwin19/libgcc'
:info:build make[2]: *** [all-stage1-target-libgcc] Error 2
:info:build make[2]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_gcc7/libgcc7/work/build'
:info:build make[1]: *** [stage1-bubble] Error 2
:info:build make[1]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_gcc7/libgcc7/work/build'
:info:build make: *** [bootstrap-lean] Error 2
:info:build make: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_gcc7/libgcc7/work/build'
:info:build Command failed:  cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_gcc7/libgcc7/work/build" && /usr/bin/make -j4 -w bootstrap-lean 
:info:build Exit code: 2
:error:build Failed to build libgcc7: command execution failed
:debug:build Error code: CHILDSTATUS 37281 2
:debug:build Backtrace: command execution failed
:debug:build     while executing
:debug:build "system {*}$notty {*}$nice $fullcmdstring"
:debug:build     invoked from within
:debug:build "command_exec build"
:debug:build     (procedure "portbuild::build_main" line 8)
:debug:build     invoked from within
:debug:build "$procedure $targetname"
:error:build See /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_gcc7/libgcc7/main.log for details.

[jmroot (Joshua Root)]

#59948

[kencu (Ken)]

part of your issue is the ld64 installation, I think. You should not be seeing this error:

ld: unexpected token: !tapi-tbd-v3 file

so please try this:

sudo port -f uninstall ld64
sudo port -v install ld64

and that should get you ld64 +ld64_xcode which is what you need on Catalina at present.

Then retry your build, and report back errors.