gnuplot fails to build under Catalina because gcc49 is not supported with Xcode 9 or greater

[cwmccurdy]

After installing Macports for Catalina, gnuplot build failed because it was trying to build gcc49. This happened after an operating system update and having uninstalled and clean the old gnuplot from macports. The error is:

sudo port install gnuplot Password: ---> Computing dependencies for gnuplot ---> Cleaning gnuplot ---> Scanning binaries for linking errors ---> Found 131 broken files, matching files to ports Warning: No port llvm-3.8 found in the index; can't rebuild ---> Found 1 broken port, determining rebuild order You can always run 'port rev-upgrade' again to fix errors. The following ports will be rebuilt: openmpi-default @1.10.3+gcc49 Continue? [Y/n]: y Warning: Your DNS servers incorrectly claim to know the address of nonexistent hosts. This may cause checksum mismatches for some ports. See this page for more information: <​https://trac.macports.org/wiki/MisbehavingServers> ---> Fetching distfiles for gcc49 Error: building gcc49 is not supported with Xcode 9 or greater Error: Failed to fetch gcc49: unsupported platform