ruby31 3.1.3: fails to build on OS X 10.8 and 10.9

[erikbs]

The build configures as usual, but fails during the build stage. Log extract:

...
:info:build make[1]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_ruby31/ruby31/work/ruby-3.1.3'
:info:build generating makefile exts.mk
:info:build compiling ./enc/trans/emoji_sjis_kddi.c
:info:build compiling ./enc/iso_8859_2.c
:info:build compiling ./enc/iso_8859_3.c
:info:build exts.mk updated
:info:build make[1]: Entering directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_ruby31/ruby31/work/ruby-3.1.3'
:info:build make[2]: Entering directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_ruby31/ruby31/work/ruby-3.1.3/ext/-test-/RUBY_ALIGNOF'
:info:build make[2]: *** No rule to make target `all'.  Stop.
:info:build make[2]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_ruby31/ruby31/work/ruby-3.1.3/ext/-test-/RUBY_ALIGNOF'
:info:build make[1]: *** [ext/-test-/RUBY_ALIGNOF/all] Error 2

The error is not that ext/-test-/RUBY_ALIGNOF/Makefile does not contain a target all, but that the Makefile in this directory does not exist at all. According to a comment on an earlier ticket from a few months ago (​https://trac.macports.org/ticket/65290#comment:1), the generation of this Makefile overwrites the Makefile in the build root directory, and that seems to be the case on my system as well.

I have tried compiling with Clang 14, Clang 15 and GCC 11 – the result is always the same. I also tried using gmake instead of make and to build with use_autoreconf yes in the Portfile (required an additional patch akin to patch-configure.diff for configure.ac). Nothing helped.

If I build Ruby from source outside of Macports (same source tgz), I do not encounter this issue. I noticed that even if I pass all the Portfile configure options, the generated Makefiles are quite different (I will attach both files).