port install gmp fails on macOS Big Sur

[JayReynoldsFreeman]

I am running MacOS 11.6.5 (Big Sur) on a 2019 Mac Pro with Intel hardware. I have Xcode 13.2.1 installed, and have installed the associated command-line tools. I downloaded the MacPorts distribution for Big Sur and ran an apparently clean install via the installer. After some searching, I tried: "sudo port install gmp" and got the following:

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sudo port install gmp Password: ---> Cleaning gmp ---> Scanning binaries for linking errors ---> Found 12 broken files, matching files to ports Warning: No port llvm-3.0 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: gcc46 @4.6.3 Continue? [Y/n]: Y ---> Fetching distfiles for gcc46 Error: building gcc46 is not supported with Xcode 9 or greater Error: Failed to fetch gcc46: unsupported platform Error: See /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_gcc46/gcc46/main.log for details. Error: rev-upgrade failed: Error rebuilding gcc46 Error: Follow ​https://guide.macports.org/#project.tickets if you believe there is a bug.

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The log file cited gives a long trace of what happened, but the ultimate error is indeed

:error:fetch building gcc46 is not supported with Xcode 9 or greater :error:fetch Failed to fetch gcc46: unsupported platform

The advice in the first snipped output, to run "port rev-upgrade" isn't very useful:

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sudo port rev-upgrade Password: ---> Scanning binaries for linking errors ---> Found 12 broken files, matching files to ports Warning: No port llvm-3.0 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: gcc46 @4.6.3 Continue? [Y/n]: Y ---> Fetching distfiles for gcc46 Error: building gcc46 is not supported with Xcode 9 or greater Error: Failed to fetch gcc46: unsupported platform Error: See /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_gcc46/gcc46/main.log for details. Error: rev-upgrade failed: Error rebuilding gcc46 Error: Follow ​https://guide.macports.org/#project.tickets if you believe there is a bug.

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I learned a little more about what is actually installed:

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port installed gcc46 The following ports are currently installed:

gcc46 @4.6.3_3 (active)

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I posted on the GMP mailing list about this with no useful response so far.