installing pdftk it fails to build libgcc7

[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.