ruby30: won't install on Mac OS X 10.12.6

[simon-dedeo]

with MacPorts version 2.6.4

simon$ sudo port install ruby30
--->  Computing dependencies for ruby30
--->  Fetching archive for ruby30
--->  Attempting to fetch ruby30-3.0.0_0.darwin_16.x86_64.tbz2 from https://ywg.ca.packages.macports.org/mirror/macports/packages/ruby30
--->  Attempting to fetch ruby30-3.0.0_0.darwin_16.x86_64.tbz2 from https://mse.uk.packages.macports.org/ruby30
--->  Attempting to fetch ruby30-3.0.0_0.darwin_16.x86_64.tbz2 from https://lil.fr.packages.macports.org/ruby30
--->  Fetching distfiles for ruby30
--->  Verifying checksums for ruby30
--->  Extracting ruby30
--->  Configuring ruby30
--->  Building ruby30
Error: Failed to build ruby30: command execution failed
Error: See /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_ruby30/ruby30/main.log for details.
Error: Follow https://guide.macports.org/#project.tickets to report a bug.
Error: Processing of port ruby30 failed

The logfile is attached.

Oddly, my particular version of Mac OS X (10.12) is flagged as bad at ​https://ports.macports.org/port/ruby30/summary

Thank you for any help -- keen to get our code up and running on the new system.

UPDATE: FIXED

After some more playing around, I noticed that there was a version incompatability between the clang residing in /usr/bin/clang, and the one in /Library/Developer/CommandLineTools/usr/bin/:

simon$ /usr/bin/clang --version
Apple LLVM version 8.1.0 (clang-802.0.42)
Target: x86_64-apple-darwin16.7.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

simon$ /Library/Developer/CommandLineTools/usr/bin/clang --version
Apple LLVM version 9.0.0 (clang-900.0.39.2)
Target: x86_64-apple-darwin16.7.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

simon$ /opt/local/bin/clang --version
clang version 9.0.1 
Target: x86_64-apple-darwin16.7.0
Thread model: posix
InstalledDir: /opt/local/libexec/llvm-9.0/bin

For some reason, making a soft link from /Library/Developer/CommandLineTools/usr/bin/clang to /opt/local/clang seemed to trigger the right behavior. Amusingly, one reason I noticed this is that I had an older ticket here about my adventures in clang version land.

I don't know if the earlier failure to compile was triggered by running things with clang 8.1, or if it had something to do with mixing clang 8.1 and 9.0 at different stages.

I've attached the new, successful log file in case people are curious.

[simon-dedeo]

logfile output from ports ("Error: See /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_lang_ruby30/ruby30/main.log for details")

[simon-dedeo]

(partial version of) a successful log file for the install