Empty <p> tag inside <figure> markup

[henry.wright]

<figure>
<img src="image.png" alt="">
<figcaption>Caption</figcaption>
</figure>

Using the above markup in the form at Posts > Add New results in an empty <p> tag being output. For example:

<figure>
<img src="image.png" alt=""><p></p>
<figcaption>Caption</figcaption>
</figure>

Interesting, if I remove all whitespace from the markup I enter in the post form:

<figure><img src="image.png" alt=""><figcaption>Caption</figcaption></figure>

... I get a <br> tag instead of the <p></p>:

<figure><img src="image.png" alt=""><br>
<figcaption>Caption</figcaption>
</figure>

I believe the empty <p> is a bug with wpautop().

[lukecavanagh]

@henry.wright

So what happens if you disable the wpautop filter?

​https://codex.wordpress.org/Function_Reference/wpautop

[henry.wright]

Replying to lukecavanagh:

So what happens if you disable the wpautop filter?

The problem doesn't happen when the filter is disabled.

[lukecavanagh]

@henry.wright

Okay, well that helps find the exact cause then.

[ocean90]

The output is actually

<figure>
<img src="image.png" alt=""></p>
<figcaption>Caption</figcaption>
</figure>

The <p> gets added by the browser. This is already mentioned in #15918.

The second issue with the <br> tag is tracked in #27559.

[henry.wright]

@ocean90 no wonder my string replace tinkering didn't work for <p></p> 😃