Hyperlinks do not work if they are inside square brackets

Question

I can imagine situations when somebody might include a bare URL in post. And the link might even be between [ and ] - if it is a part of some explanatory remark.

It seems that in such cases the link is not actually rendered as a link - see the links which I posted below as a test. (They are not "clickable" in the post - although they are displayed as links in the preview.)

Of course, this can be easily avoided - one can simply use [text](URL) syntax. So it can be considered a very minor bug - but I though that it was still worth reporting.

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Here is a test - the links are displayed just as text:

In Stack Exchange posts we often use hyperlinks. [Still, we should keep in mind that the post should make sense even if the links stops working: https://en.wikipedia.org/wiki/Main_Page. As an example, I chose a link to the Wikipedia: https://en.wikipedia.org/wiki/Main_Page.]

(The same text works if I do not use square brackets: Still, we should keep in mind that the post should make sense even if the links stops working: https://en.wikipedia.org/wiki/Main_Page. As an example, chose a link to the Wikipedia: https://en.wikipedia.org/wiki/Main_Page.)

[Does it work with escaped brackets? Yes it does: Still, we should keep in mind that the post should make sense even if the links stops working: https://en.wikipedia.org/wiki/Main_Page. As an example, I chose a link to the Wikipedia: https://en.wikipedia.org/wiki/Main_Page.\]

Interestingly, the behavior changes a bit if there is [text](URL) at some place between the brackets. [Still, we should keep in mind that the post should make sense even if the links stops working: https://en.wikipedia.org/wiki/Main_Page. As an example, I chose a link to the Wikipedia: https://en.wikipedia.org/wiki/Main_Page.]

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This is what I see after posting:

This is what I see in the preview (while posting/editing):

Answer 1

This is not a bug; the behaviour you're pointing out is in accordance with the CommonMark Specification.

The text inside the square brackets [] is refered to as link text (emphasis mine):

6 Inlines

6.3 Links

A link text consists of a sequence of zero or more inline elements enclosed by square brackets ([ and ]). The following rules apply:

• Links may not contain other links, at any level of nesting. If multiple otherwise valid link definitions appear nested inside each other, the inner-most definition is used.

So what happens is the bare URL https://en.wikipedia.org/wiki/Main_Page will not render as an HTML <a href></a> if it's nested inside a link text.

Your example that isn't nested or escapes the enclosing square brackets of the link text renders as (source indented for readability):

<p>[Does it work with escaped brackets? Yes it does:
    Still, we should keep in mind that the post should make sense even if the links stops working:
    <a href="https://en.wikipedia.org/wiki/Main_Page" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Main_Page</a>.
    As an example, I chose a link to the Wikipedia:
    <a href="https://en.wikipedia.org/wiki/Main_Page.%5C%5D" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Main_Page.\]</a>
</p>

While in the nested example no <a href></a> is rendered.

<p> (...) [Still, we should keep in mind that the post should make sense even if the links stops working: https://en.wikipedia.org/wiki/Main_Page. As an example, I chose a link to the Wikipedia: https://en.wikipedia.org/wiki/Main_Page.]
</p>