Warn about incomplete symbol links ( Link ` )

[d-ronnqvist]

It's easy to make a typo when writing symbol links and close the link with only a single backtick (`). For example,

Some text with a ``Link` followed by some more text.

The example markup above parses as a single text element, making it hard for other tools that use Swift Markdown to diagnose the issue.

Paragraph
└─ Text "Some text with a ``Link` followed by some more text."

---

For comparison, if the same markup was written like ``Link`` or Link then it parses as 3 distinct elements.

Paragraph
├─ Text "Some text with a "
├─ SymbolLink destination: Link
└─ Text " followed by some more text."

or

Paragraph
├─ Text "Some text with a "
├─ InlineCode `Link`
└─ Text " followed by some more text."

[QuietMisdreavus]

It looks like this is down to behavior in swift-cmark; the upstream CommonMark/GitHub-Flavored Markdown spec says that mismatched delimiters are emitted literally:

When a backtick string is not closed by a matching backtick string, we just have literal backticks:

```foo``

<p>```foo``</p>

It might be possible to add an optional flag to swift-cmark that enables some more permissive parsing behavior, but this would break compatibility with CommonMark and GitHub-Flavored Markdown.

[d-ronnqvist]

Does Markdown have a mechanism for emitting warnings? If so, it could continue to emit the parsed content according to the spec but also give callers an indication of potential syntax issues.

[QuietMisdreavus]

It does not; the parsing philosophy in Markdown is to be maximally permissive and always fall back to emitting the text as given. GFM (like CommonMark before it) does not emit any warnings about content whatsoever.