Markdown not being parsed correctly with classifier gem

[ivantsepp]

Noticed this weird html at http://jekyllrb.com/docs/configuration/#redcarpet:

I traced it back to this commit: 4cc6a0f. And I eventually figured out that require "classifier" was the problem. The simplest temporary fix is to remove this line. But anyways, I think the issue is some conflict between the classifier gem and kramdown.

[1] pry(main)> require 'kramdown'
=> true
[2] pry(main)> puts Kramdown::Document.new("- a\n\n    paragraph\n\n        # ...ruby code\n\n    paragraph\n- b\n").to_html
<ul>
  <li>
    <p>a</p>

    <p>paragraph</p>

    <pre><code>  # ...ruby code
</code></pre>

    <p>paragraph</p>
  </li>
  <li>
    <p>b</p>
  </li>
</ul>
=> nil

That works as normal. But when we include classifier:

[1] pry(main)> require 'kramdown'
=> true
[2] pry(main)> require 'classifier'
Notice: for 10x faster LSI support, please install http://rb-gsl.rubyforge.org/
=> true
[3] pry(main)> puts Kramdown::Document.new("- a\n\n    paragraph\n\n        # ...ruby code\n\n    paragraph\n- b\n").to_html
<ul>
  <li>a</li>
</ul>

<pre><code>paragraph

    # ...ruby code

paragraph - b
</code></pre>
=> nil

[troyswanson]

Thanks for the detective work on this! 🔎

Ref #2662 and #2661

[alfredxing]

Ref #2677.

[parkr]

Will release the new version of Jekyll and hopefully GHP will review and merge it quickly.

[alfredxing]

Doing a little digging here, and seems like mathn is the problem. In @ivantsepp's example above, if you just include mathn instead of classifier, it causes this Kramdown interference. mathn is required in classifier/extensions/vector.rb.

[parkr]

What about mathn does this? It seems totally benign: http://ruby-doc.org/stdlib-2.1.2/libdoc/mathn/rdoc/index.html

[alfredxing]

@parkr It replaces core math behaviour within Ruby:

• http://ruby-doc.org/stdlib-2.1.2/libdoc/mathn/rdoc/Math.html
• http://ruby-doc.org/stdlib-2.1.2/libdoc/mathn/rdoc/Numeric.html
• http://ruby-doc.org/stdlib-2.1.2/libdoc/mathn/rdoc/Rational.html

I'm guessing parts of Kramdown rely on the standard behaviour.