Precedence of link within link

[Knagis]

Example 389 shows what happens when a link is nested within a link - the inner link is rendered. But I can't find the rule describing this - probably a statement similar to the emphasis rule (closed-first and opened last) should be added.

[Knagis]

Furthermore, there is an inconsistency between how links and images are handled:

Example 389:
[foo [bar](/uri)](/uri) ➡️ <p>[foo <a href="/uri">bar</a>](/uri)</p>

Example 436:
![foo ![bar](/url)](/url2) ➡️ <p><img src="/url2" alt="foo bar" /></p>

My opinion is that there should be no difference between nested images and links in these cases.

[jgm]

@Knagis - I don't think this is an inconsistency. There's an important difference between the two cases. Links are not allowed in the link text of a link, but they are allowed in the image description. The difference is obscured a bit by the fact that links are not rendered as links inside an alt attribute, but see the AST output:

% ./cmark -t ast
[foo [bar](/uri)](/uri)
paragraph
  text "["
  text "foo "
  link url="/uri"
    text "bar"
  text "]"
  text "(/uri)"
% ./cmark -t ast
![foo ![bar](/url)](/url2)
paragraph
  image url="/url2"
    text "foo "
    image url="/url"
      text "bar"

[Knagis]

For me it feels that these similar looking cases should act the same in terms of which - inner or outer - link/image takes precedence (but that is just a visual thing by looking at these two cases). And for links the same approach as with images would be used - the contents of the link are parsed as is in the AST but rendered without the nested link. So the output for 389 would be <a href="/uri">foo bar</a>.

The only practical benefit though for this approach (apart from the test cases looking nicer together) is that an application could walk the AST and issue a warning that the link-within-link is not a valid construct. If the parser creates text nodes, this cannot be done.

[Knagis]

If that lone argument did not convince you, this issue can be closed - I will then adjust my parser accordingly.

[Knagis]

Looking at the github commits I just realized a rather good example how links within links could be used if the renderer decides to support it:

[Fixed [#285](/issues/285) in cmark](/commits/12345)

<a href="/commits/12345">Fixed </a><a href="/issues/285">#285</a><a href="/commits/12345"> in cmark</a>

[jgm]

Commit #331 clarifies this in the spec, but I'm leaving this issue open, because I think it still needs rethinking.

[mity]

Also note there is yet another inconsistency: While links cannot be nested in each other, an autolink on the other side is allowed to be nested in the link text.

See [<http://foo>](/url)

[mgeier]

There is some additional discussion in https://talk.commonmark.org/t/why-is-link-text-not-allowed-to-contain-other-links/2434.