Add missing rexml dependency

[deivid-rodriguez]

The next ruby version won't have rexml as a default gem, so it will need to be explicitly added as a dependency.

See https://bugs.ruby-lang.org/issues/16485#change-83794.

[ashmaroli]

The next ruby version won't have rexml as a default gem

Just curious..

Isn't the next ruby version Ruby 3.0?
In that case wouldn't it be better to have all Ruby 3.0 compatibility changes in one PR..? Or does Ruby 2.7 throw deprecation warnings regarding rexml as well?

[deivid-rodriguez]

I test my library against ruby-head to be able to early address any ruby-core incompatibilities. My build against ruby-head broke because of the mentioned change, since under current ruby-head kramdown can no longer be required unless you manually depend on rexml.

This change should be correct regardless, because rexml is a gem, and kramdown depends on it. That said, I understand if you don't want to fix this this early, and I can easily workaround this by adding rexml to my Gemfile to account for kramdown lacking the dependency untill kramdown catches up.

Just let me know and I'll close the PR accordingly.

[ashmaroli]

@deivid-rodriguez I was just asking out of curiosity. I'm not a maintainer of this project..

[deivid-rodriguez]

Oh, ok, sorry. Well, I hope I answered your question in any case :)

[deivid-rodriguez]

I should probably also add that this change does have an impact. For example, if rexml makes a disastrous release that breaks everything, kramdown would be affected. But on the other hand, if rexml fixes a security vulnerability, kramdown will automatically pick that up :)

[deivid-rodriguez]

Actually, those same things can already happen currently, but the changes only happen accross ruby releases. With this PR, any change in the rexml dependency becomes more "agile" because it only requires a gem release, not a release of the full ruby language.

[gettalong]

@deivid-rodriguez Thank you for your contribution!

[deivid-rodriguez]

Thanks for merging! ❤️

[caser]

I'm still getting this error:

/.rvm/gems/ruby-head/gems/kramdown-1.17.0/lib/kramdown/parser/html.rb:10:in require': cannot load such file -- rexml/parsers/baseparser (LoadError)`

Is this related to above?

[deivid-rodriguez]

I don't think this fix has been released yet, so could be related, yeah. Does it get fixed if you manually install rexml or add it to your Gemfile?

[gettalong]

@caser Please try the latest version of kramdown and see if it works!

[JetForMe]

Any progress on this? I just ran into it, as kramdown is a transitive dependency. I had to explicitly include rexml, which now makes my install a little more fragile.

[ashmaroli]

@JetForMe This change was shipped in kramdown-2.2.0. So, you may have to update your installed version.