Warning: trimming empty <span>

[dfalbel]

With new CRAN checks for the HTML manual we are seeing warnings similar to those below when using katex::katex_html:

math_to_rd.html:81:795: Warning: trimming empty <span>
math_to_rd.html:81:1030: Warning: trimming empty <span>
math_to_rd.html:81:1116: Warning: trimming empty <span>

It seems that katex adds extra empty spans as they don't seem to be generated by something in the R package.

Further investigation:
katex generates spans like this that are used for vertical alignment but html tidy
seems to think they are useless and should be removed.

<span class="strut" style="height: 0.6833em"></span>

We could perhaps argue that HTML Tidy should be used with the option --drop-empty-elements set to no.

[jeroen]

Yes I am aware, and reported this in tidy-html: htacg/tidy-html5#1046
I think r-base now defaults to --drop-empty-elements=no so the problem probably disappears: wch/r-source@f26715f

[dfalbel]

Oh awesome! That's great!