ruby now requires libyaml

[ken@…]

I still prefer not to build things I don't have any use for. I've been building ruby since I started to build texlive, but only using it to test the 'match_parens' script as part of my acceptance testing.

Until now I've not needed libyaml ('optional' in the book) although there is a very old ticket ​https://bugs.ruby-lang.org/issues/6508 explaining why adding a configure switch for libyaml is problematic.

Just now ruby-3.2.0 failed to build.

The configure script told me that the psych extension could not be installed and to look in ext/psych/mkmf.log for more details: it failed to find YAML-1.0.

However, it did not apparently error and started to run make. That failed quickly at lib/yaml.rb:3:

 warning: It seems your ruby installation is missing psych (for YAML output).
To eliminate this warning, please install libyaml and reinstall your ruby.
uh-oh! RDoc had a problem:
cannot load such file -- psych

There are no references in the configure script to psych, yaml or YAML so it appears that libyaml is now required.

My most recent build of ruby was for 3.1.2 where psych and its then yaml files built ok, so this appears to be a recent change.

[ken@…]

From ​https://www.ruby-lang.org/en/news/2022/12/25/ruby-3-2-0-released/

Stdlib compatibility issues
No longer bundle 3rd party sources

    We no longer bundle 3rd party sources like libyaml, libffi.

        libyaml source has been removed from psych. You may need to install libyaml-dev with Ubuntu/Debian platform. The package name is different for each platform.

[ken@…]

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