rubygem-xmlparser-0.7.2.1-37.fc38.x86_64 does not load because the C sources call the ENC_TO_ENCINDEX function, which is not defined: $ ruby -e 'require "xmlparser"' <internal:/usr/share/rubygems/rubygems/core_ext/kernel_require.rb>:159:in `require': /usr/lib64/gems/ruby/xmlparser-0.7.2.1/xmlparser.so: undefined symbol: ENC_TO_ENCINDEX - /usr/lib64/gems/ruby/xmlparser-0.7.2.1/xmlparser.so (LoadError) from <internal:/usr/share/rubygems/rubygems/core_ext/kernel_require.rb>:159:in `rescue in require' from <internal:/usr/share/rubygems/rubygems/core_ext/kernel_require.rb>:39:in `require' from -e:1:in `<main>' <internal:/usr/share/rubygems/rubygems/core_ext/kernel_require.rb>:85:in `require': cannot load such file -- xmlparser (LoadError) from <internal:/usr/share/rubygems/rubygems/core_ext/kernel_require.rb>:85:in `require' from -e:1:in `<main>'
Looking at the upstream there does not seem to be an update (yet?). The missing symbol is defined in https://github.com/ruby/ruby/blob/master/encoding.c it seems.
This bug appears to have been reported against 'rawhide' during the Fedora Linux 39 development cycle. Changing version to 39.