HTML Generator: Inconsistent choice of html tags of strikethrough and underline extensions

[znewt99]

Either <u>...</u> & <s>...</s> or <ins>...</ins> & <del>...</del> should be paired together;
like, <i>...</i> & <b>...</b> vs <em>...</em> & <strong>...</strong>
It should not be a mix of both.

[mity]

Can you be clearer? Ideally provide an example input, what output you get, and what output you expect.

[znewt99]

Currently, underline uses the <u> tag and strikethrough uses the <del> tag. It should be that underline uses <ins> & strikethrough uses <del>. For example, italics uses the <em> tag and bold uses the <strong> tag.

4.5.29 Usage summary
4.7 Edits

Pairs of elements:
The ins element and the del element.
The u element and the s element.
The em element and the strong element.
The i element and the b element.

[mity]

(Ohh I see, I thought you have encountered some problem with the Raw HTML spans on the input side. Sorry for the confusion.)

The question however is what to do with this mess now. The current behavior is with us for quite a long time over multiple stable releases. As much as I can accept it's not entirely consistent behavior, I'm also not entirely sure whether this is worth of potential compatibility issue to some users.

I'll keep this issue open for now, so that other people might provide a feedback on this. After some time we might switch <u></u> to <ins></ins> if there's not much opposition (I would for surely vote for keeping the <del>foo</del> for compatibility with Github, which is in my mind the strongest rule-setter beyond the CommonMark specs).

[znewt99]

My suggestion for the initial switch to <ins></ins> is keep the span type as MD_SPAN_U. So, there will not be any compatibility issues for projects that only use the md4c parser. And, only change the md4c-html renderer so it outputs <ins></ins> instead of <u></u>. Then, sometime later switch the span type from MD_SPAN_U to MD_SPAN_INS or just keep it as MD_SPAN_U. But, I think it's best to keep it as <u></u> until after the next one or two stable releases.

[znewt99]

Some Markdown implementations use ++text++ for <ins></ins> instead of _text_. So, --funderline, MD_SPAN_U, and <u></u> can be left alone, and MD_SPAN_INS can be added for <ins></ins> with the ++text++ syntax. Maybe something like --finsert could be the command line option.