[macp2052:~] caux% sudo port install gcc5                                                                            Password:
--->  Computing dependencies for gcc5
--->  Building gcc5
Error: Failed to build gcc5: command execution failed
Error: See /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_gcc5/gcc5/main.log for details.
Error: Follow https://guide.macports.org/#project.tickets to report a bug.
Error: Processing of port gcc5 failed
[macp2052:~] caux% 

in /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_gcc5/gcc5/main.log

after millions of lines, I have :

:info:build 13 warnings and 1 error generated.
:info:build make[3]: *** [auto-profile.o] Error 1
:info:build make[3]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_gcc5/gcc5/work/build/gcc'
:info:build make[2]: *** [all-stage1-gcc] Error 2
:info:build make[2]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_gcc5/gcc5/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_release_tarballs_ports_lang_gcc5/gcc5/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_release_tarballs_ports_lang_gcc5/gcc5/work/build'
:info:build Command failed:  cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_gcc5/gcc5/work/build" && /usr/bin/make -w bootstrap-lean 
:info:build Exit code: 2
:error:build Failed to build gcc5: command execution failed
:debug:build Error code: CHILDSTATUS 73589 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_release_tarballs_ports_lang_gcc5/gcc5/main.log for details.
[macp2052:~] caux%