bug#61302: 29.0.60; rust-ts-mode does not show function-invocation on field-properties

[Randy Taylor <dev@rjt.dev>]

On Tuesday, February 7th, 2023 at 13:25, Dmitry Gutov <dgutov@yandex.ru> wrote:
>> rust-ts-mode looks good to me as well except the imports. Stuff like:
>> use std::fmt::{Display, Formatter};
>>
>> is highlighted incorrectly. In the above example, std and fmt are highlighted as variables.
>
>This is a result of 'variable' being implemented as it is now --
>highlighting all (identifier) nodes that no previous rule has matched.
>
>That makes things complicated when we try to support customizable
>highlighting level where the user can mix and match the enabled features.
>
>With imports, there was also another problem which I mentioned here:
>https://debbugs.gnu.org/cgi/bugreport.cgi?bug=61205#68
>
>If we highlight the imports as constants on level 3, when the 'function'
>feature is disabled, the function names will get highlighted with
>font-lock-constant-face as well. That seems undesirable.
>
>But -- and this just occurred to me today -- if we create a separate
>feature to add to level 4, with rules defined below 'function', that
>should satisfy all the constraints.

I think this is a good idea.

>
>> We should give them font-lock-constant-face.
>>
>> I will try to propose a patch later today unless someone beats me to it.
>
>Try the attached patch, please.

Thanks, it looks good to me.

I think the following rule from the type feature:
(scoped_type_identifier path: (identifier) @font-lock-type-face)

Should be changed to font-lock-constant-face and moved to the module feature.

That way, things like the following will be highlighted correctly:
let date = DateTime::<chrono::Utc>::from_utc(date, chrono::Utc);
                      ^^^^^^ this guy

Unless I'm missing something.

>
>On a distantly related note, we have terms like 'usize' which is
>normally a type (and highlighted as such), but can also feature in
>expressions like
>
>   let row = usize::from_str_radix(row, 10).map_err(|_| error())?;
>
>where it is now highlighted with font-lock-constant-face. Should we try
>to do anything about that? If there is a limited number of built-in
>types in that situation (e.g. all of them primitives), we could handle
>that with a regexp.

Right. I think it makes sense to handle the primitives with a regex.
I'm not sure if there's anything else beyond those.
There's a list of them here: https://doc.rust-lang.org/reference/types.html
I think it would only apply to the numerical and textual types.

>
>Or vice versa, in
>
>   use std::{fmt, fs, usize};
>
>should 'fmt', 'fs' and 'usize' be highlighted with
>font-lock-constant-face rather than font-lock-type-face?

They should indeed be highlighted with font-lock-constant-face because they are modules.
We assume the types will be capitalized since that's all we can really do (and it's the convention anyway).