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

[Randy Taylor]

On Thursday, February 9th, 2023 at 16:19, Dmitry Gutov <dgutov@yandex.ru> wrote:
>On 09/02/2023 05:38, Randy Taylor wrote:
>
>>> What if it looked like this:
>>>
>>>    let date = DateTime::<chrono::utc>::from_utc(date, chrono::utc);
>>>
>>> If we decide purely based on capitalization, then I guess the rule
>>> should be present in both lists (with capitalized? regexp in one, and
>>> !capitalized? regexp in another), and a few more rules should be
>>> duplicated as well.
>>
>> In both cases, utc is still a type even if it's not capitalized.
>> My patch addresses this.
>
>So the end of a scoping chain must also be either a type or a method
>call? We might be able to use that, somehow.

I believe so (with the exception of use declarations as you note).
Not familiar enough with Rust to say for sure :).

>
>Though the 'use' declarations might be exceptions, e.g.
>
>   use crate::foo::baz::foobaz;crate
>
>or
>
>   use std::{fmt, fs, usize};
>
>(fmt and fs are modules, not types).
>
>>> This becomes a little more painful semantically, given that the first
>>> 'utc' in the example above is parsed into a (type_identifier) node, not
>>> just (identifier).
>>>
>>>>> 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.
>>>
>>> So 'usize' in the above is definitely a "type", not a "module"?
>>
>> I think so. You can see on usize's documentation page 
>> (https://doc.rust-lang.org/std/primitive.usize.html)
>> that it provides that function, amongst many others.
>
>I was thinking that it might also be referring to (apparently
>deprecated) https://doc.rust-lang.org/std/usize/index.html.

That module only provides the constants listed on that page.
The usize type itself provides a bunch of constants and functions (same for the 
rest of the primitives).

I'm curious how other editors/IDEs highlight this stuff, but I don't have any 
on hand ATM.

>
>Sorry, I'm not really familiar with Rust. E.g. in Ruby every class can
>also serve as a "module" in the scoping sense. As a result we highlight
>both classes and modules with font-lock-type-face. This could also be an
>option here, if everything else fails.
>
>But we could also highlight based on a "role" (constant if it's used as
>a scope, and type if it's used as a type).
>
>Although one could say that 'Path' in
>
>   Some(Path::new("./foo"))
>
>is being used as a type as well, and 'Some' too. So it might not be the
>best fit.
>
>Speaking of 'usize' again, what if some lib or the app defines an
>'usize' module for its custom functions acting on it? E.g.
>'my::app::usize'. A simple regexp matcher will probably highlight it as
>a type as well.

I don't think we should worry about those cases IMO.

>
>>>>> 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).
>>>
>>> If they're modules here, I suppose they should be highlighted the same in
>>>
>>>    let row = usize::from_str_radix(...)
>>>
>>> as well. The bright side is that will make a more complex regexp
>>> (enumerating the lowercase named types) unnecessary.
>>
>> Yes, except for the primitives.
>>
>> I have attached a patch which I think addresses most of the concerns 
>> (although I've been at it for a few hours and my brain is mush now).
>>
>> The patch does the following:
>> - Separates import-related stuff and module use by leveraging the 
>> use_declaration query (simplifying things greatly IMO).
>> - Highlights primitive types used in scoped_identifiers.
>> - Properly highlights types belonging to a module no matter how deep it is 
>> (or your money back guaranteed!).
>> - Maybe some other stuff I forgot. I'm too tried now :).
>
>Thank you, I can sympathize -- this stuff gets complicated.
>
>Some problems from my testing:
>
>1. If I keep treesit-font-lock-level at its default value (3), some
>stuff gets misfontified:

Sorry, I have only been testing with level 4.
This is also why I want type and module combined into one so we don't have to 
deal with this headache.

>
>   use std::collections::hash_map::{self, HashMap};
>
>'hash_map' is highlighted as a type. 'HashMap' is not highlighted at all.
>
>   use std::{fmt, fs, usize};
>
>Only 'use' is highlighted here.

This is because of how things are broken out into the module feature.
That some highlighting for those occurs is by overlap of queries in the type 
feature.
Which again is why I think module should be part of type.

>
>   test::test1();
>
>'test1' is highlighted as a type (we discussed this problem with
>highlighting types by default -- it becomes necessary to filter out
>function calls, either with more complex queries, or with custom
>highlighter functions).

Right, I added a query to filter that out now.

>
>2. If I switch to treesit-font-lock-level 4:
>
>   let boxed_i32 = Box::new(5_i32);
>
>'Box' is highlighted with font-lock-constant-face. I think it's a type,
>though.

Oops, I accidentally removed the rule for that. Added it back.

>
>Also here's a pre-existing problem mentioned above:
>
>   use std::{fmt, fs, usize};
>
>'fmt' and 'fs' are not types. But they are highlighted with
>font-lock-type-face.

This is really weird, I can reproduce it with emacs -Q but not with my normal 
config...
Also with emacs -Q this:
let date = DateTime::<chrono::hey::there::Utc>::from_utc(date, 
chrono::cool::this::Utc);

highlights incorrectly, where "there" is font-lock-variable-name-face. But with 
my normal config everything is fine.

I'll look into it tomorrow. Not really sure what in my config could cause 
this...

>
>> A few questions:
>> - Should module be moved to level 3 to be with type?
>> - Do we still want the module feature, or should this stuff be put into type?
>
>I suppose we should iron some kinds out first to get a better understanding.

Attached a new patch hopefully addressing most of the problems you ran into 
(minus the level 3 use declaration highlights).
Especially after the problems you ran into at level 3, I strongly think the 
module queries should get thrown into type (and they make sense there anyway 
IMO). Then all those issues go away.

0001-Fix-rust-ts-mode-type-and-module-highlighting.patch
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