nco +gcc6 failing to build with missing symbols from antlr

[gnurser (George Nurser)]

Mac OS 10.12.3, Xcode 8.2.1 with gcc6 @6.3.0_2, openmpi-gcc6

nco build fails at linking stage with missing antlr symbols. First error:

:info:build libtool: link: /opt/local/bin/g++-mp-6 -pipe -Os -Wl,-headerpad_max_install_names -o ncap2 Invoke.o ncap2.o ncap2_utl.o ncap2_att.o sdo_utl.o sym_cls.o fmc_cls.o fmc_all_cls.o fmc_gsl_cls.o prs_cls.o NcapVar.o NcapVarVector.o ncoLexer.o ncoParser.o ncoTree.o nco_gsl.o  -L../nco 
/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_science_nco/nco/work/nco-4.6.4/src/nco/.libs/libnco.a -L/opt/local/lib -lantlr -lhdf5_hl -lhdf5 -ldl -lz -lxerces-c -lvecLibFort -lexpat -lresolv -lintl -lm -lnetcdf -lcurl -lgsl -lgslcblas -ludunits2 -fopenmp
:info:build Undefined symbols for architecture x86_64:
:info:build   "antlr::ASTFactory::create(int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)", referenced from:
:info:build       ncoParser::dmn_list_p()      in ncoParser.o

[gnurser (George Nurser)]

main.log

[ryandesign (Ryan Carsten Schmidt)]

This looks similar to #59674, only the other way around.

nco uses antlr's static library which has been built with the default compiler (clang) and linked with the default c++ standard library. On your macOS 10.12 system, that's libc++. But now you're building nco with g++, and g++ doesn't use libc++; it uses its own c++ standard library called libstdc++, which is not compatible with libc++. I don't see how using g++ here could ever work. (It could have worked back on OS X 10.8 and earlier, back when the default c++ standard library was libstdc++.) I don't know why the port gives you the option of attempting a build that will never work. It seems like the gcc variants should be removed from the port.

[tenomoto (Takeshi Enomoto)]

In 542b27150e6255a82b7e95bfc1f0bdecc03583b7/macports-ports (master):

nco: update to 4.9.1 and exclude gcc after Lion

Closes: #53839

[tenomoto (Takeshi Enomoto)]

In 542b27150e6255a82b7e95bfc1f0bdecc03583b7/macports-ports (dar, master, py38-reproject, revert-6945-rust-1.43.0, wireshark):

nco: update to 4.9.1 and exclude gcc after Lion

Closes: #53839