XQuartz 2.7.9 (xorg-server 1.17.4), Xcode 7.3.1, command line tools, “sudo port -v self update”, “port upgrade outdated” were all OK. When I tried “sudo port install xorg-server demeter”, it showed:
---> Computing dependencies for xorg-server
---> Cleaning xorg-server
---> Computing dependencies for demeter
---> Dependencies to be installed: ifeffit libgcc cctools llvm-3.8 libcxx libffi llvm_select gmp isl ld64 ld64-latest libmpc mpfr pgplot gcc5 ... (a long list)
Then after many attempts to fetch libcxx-3.7.1_0.darwin_15.x86_64.tbz2 from various websites, it showed:
Error: org.macports.archivefetch for port libcxx returned: archivefetch failed for libcxx @3.7.1_0
Error: Failed to install libcxx
Please see the log file for port libcxx for details:
/opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_libcxx/libcxx/main.log