Unable to install rbs on JRuby
It seems rbs is trying to make a native extension on JRuby which is not supported.
For complete log output, see https://github.com/Shopify/ruby-lsp/issues/2292
That results in rbs not being able to be installed in a JRuby environment, gem install rbs will fail in such.
FWIW we (JRuby) very much want to support rbs and I'm sure it is possible to do so. We just don't have a lot of dev resources right now.
The piece in the extension is the C-based parser, which replaced the old racc-based pure-Ruby parser in #788.
While the extension could possibly be ported to Java, it's quite a lot of work. It might be faster to revive the racc parser and try to update it.