bug#59691: Html-like constructs fail in typescript

[Theodor Thornhill via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

On 30 November 2022 13:59:20 CET, "Jostein Kjønigsen" <jostein@secure.kjonigsen.net> wrote:
>On 29.11.2022 23:20, Jostein Kjønigsen wrote:
>> 
>>> On 29 Nov 2022, at 22:48, Theodor Thornhill<theo@thornhill.no>  wrote:
>>> 
>>> 
>>> 
>>>> On 29 November 2022 22:37:25 CET, "Jostein Kjønigsen"<jostein@secure.kjonigsen.net>  wrote:
>>>> Nice!
>>>> 
>>>> Should we until further notice assume that js-ts-mode suffers from the same issues, and that a jsx-ts-mode might be needed too? To me it at least sounds plausible.
>>> No, because there are no ambiguities in the grammar with types and jsx.
>>> 
>> Note this behaviour was triggered even when a HTML-tag was contained inside a plain string.
>> 
>> Even without hard typescript casts, there are places where I suspect the same issues can bleed into js-ts-mode.
>> 
>> I’ll try to do more testing tomorrow.
>
>First of all - good news!
>
>Contrary to my expectations, I've tested and I cannot reproduce this issue in js-ts-mode.
>

Yeah, that's what I've seen as well.

>Even more good news:
>
>Looking deeper into this using treesit-explorer-mode (an extremely helpful tool, Yuan!), I found I may have misinterpreted the state of the parse-tree in previous report.
>
>Based on that, I would like to revise this bug report:
>
> * HTML-like constructs inside strings are --/not/-- treated at
>   jsx_opening_elements,

That's correct!

> * only angle-bracket "hard" casts (which isn't present in Javascript)
>   is causing issues for fontification.
>
>Also, reading up, from what I can tell "hard casts" using angle-brackets are no longer encouraged as the default way to cast:
>
>    const service = <IService>object;
>
>This is because the above code will cause a compiler error if used in TSX-files (as opposed to TS-files). Instead "as" expressions are preferred, because they work equally well for both TS & TSX-files:
>
>    const service = object as IService;
>
>That means that writing idiomatic TypeScript with typescrip-ts-mode should produce the expected behaviour, while one may encounter issues with older code.
>
>I'm not sure introducing a new major-mode for this 1 aspect of TypeScript development is worth it?
>
>Does anyone else have an opinion on this?
>
>--
>Jostein

I think that because this is an actual feature it makes sense to have two modes. But defaulting to tsx as the language of choice until now is ok too.

Theo