Hard Line Breaks and Link Reference Definitions

Spec
#1

Just to be clear with anyone that is seeing me post “how about this Markdown” posts. I am writing a Markdown linter and getting around to most of my corner cases. While 99.5% of the scenarios that I come up with parse fine, the ones I ask about here are ones that I am trying to figure out the “right” thing to do.

So, going through and validating another round of tests, and came across this pair of tests.

[  
foo]: /uri

[  
foo]

(note the two space characters after the open and before the newline) which parses to:

<p><a href="/uri"><br />
foo</a></p>

However, if instead of the two spaces I use a single backslash:

[\
foo]: /uri

[\
foo]

I get:

<p>[<br />
foo]: /uri</p>
<p>[<br />
foo]</p>

Now, based on conversations in this topic, I believe it would be correct to say that reference parser tries to handle this as the first part of a paragraph. It’s just a guess, but I would think that it has an issue with a single backslash and aborts the Link Reference Definition?

Curious as to what causes this behavior.

#2

You get with what implementation? I cannot reproduce. (Tried with cmark and MD4C.)

I don’t think so: Even if its first parsed as a paragraph, its beginning (in this case all of it) has to be tested whether it satisfies all the rules for the reference definition. I believe it does. Nothing forbids a backslash in the link. ref. def. label. So, it’s ripped from the paragraph and treated as a link ref. def. (before the rest of it is even passed to an inline processing).

#3

This appears to be a bug in commonmark.js. cmark and
the other implementations I tried got it right. You can
submit a bug report on GitHub.

#4

Sorry about that… posted later in the evening and forgot to include references.

BabelMark is what I was using to verify the behavior.

I do see MD4C 0.2.7 (both modes) giving:

<p><a href="/uri"><br>
foo</a></p>

which backs up what you see. I see the following parsers returning the information that I quoted:

  • commonmark.js 0.29.2
  • cheapskate 0.1.0.5
  • league/commonmark 1.5.7
  • markdig 0.22.0.0

Sorry about that! Let me know if you need any more information.

#5

@jgm based on the answers I am getting from BabelMark, which projects should I file a bug report to?

#6

@jgm based on the answers I am getting from BabelMark, which projects should I file a bug report to?

As I said before, commonmark.js. Some of the others you mentioned aren’t even trying to target commonmark (e.g. cheapskate, which is also unmaintained).

1 Like
#7

Really busy couple of weeks, but just added as
issue 211