DocBook change: use a stack of fonts

[Richard Kimberly Heck]

On 12/26/22 20:13, Thibaut Cuvelier wrote:
> Dear list,
>
> To solve https://www.lyx.org/trac/ticket/12585, I wrote the attached 
> patch. Basically, LyX now considers the order of font tags when 
> closing them, otherwise you get strange results like in the ticket. 
> The bug is quite serious, actually, even though I don't believe many 
> users will hit it.

I struggled with that when writing the original XHTML code. It's hard to 
get right. I know it sometimes would fail. Is this same code also used 
with XHTML now? Or would it need to be adapted for that case?

I'm no good with tests, but I can review the code. Generally speaking, 
it makes sense to me.

Is [[nodiscard]] something we support now? I've never seen that before.

> +    DocBookFontOperation endTransaction() {
> +        return {.fontsToClose = fontsToClose_, .fontsToOpen = 
> fontsToOpen_};
> +    }
> +
What is ".fontsToClose"? What's the dot doing? Is the "=" right? This 
code just confuses me.

Riki