Vscode-ng-language-service: Typeching of context doesn't work with custom directives

[tonivj5]

🐞 bug report

Affected Package

The issue is caused by package @angular/language-service

Is this a regression?

No

Description

Typechecking of context doesn't work. I have copied the ngIf directive and rename it to myIf to test it:

• Code
• with ngIf test is null
• with myIf test is any

🔬 Minimal Reproduction

https://github.com/tonivj5/angular-issues-35424-and-35426

🔥 Exception or Error

None

🌍 Your Environment

Angular Version:

Angular CLI: 9.0.2
Node: 13.7.0
OS: linux x64

Angular: 9.0.1
... animations, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router
Ivy Workspace: Yes

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.900.2
@angular-devkit/build-angular     0.900.2
@angular-devkit/build-optimizer   0.900.2
@angular-devkit/build-webpack     0.900.2
@angular-devkit/core              9.0.2
@angular-devkit/schematics        9.0.2
@angular/cli                      9.0.2
@ngtools/webpack                  9.0.2
@schematics/angular               9.0.2
@schematics/update                0.900.2
rxjs                              6.5.4
typescript                        3.7.5
webpack                           4.41.2

Anything else relevant?

[tonivj5]

I have added a reproduction

[alexzuza]

Looks like Angular language service supports only build-in ngIf and ngFor directives for such kind of cases
https://github.com/angular/angular/blob/a8609ba0ad2e9c1eec3f59f81468c766bc006b56/packages/language-service/src/expression_diagnostics.ts#L136-L186

[tonivj5]

Thanks @alexzuza for the info! Then, is it a feature request or a bug? Reading the docs don't notice about that (is this the purpouse of the strictContextGenerics flag?). And in this PR describe how to implement it

I would like to use this feature in my owns directives! :cowboy_hat_face:

[ayazhafiz]

This is a bug. The language service should read from the directive template context rather than provide the one-off typings for ngFor. We already have the infrastructure for getting the template context of a structural directive, so this shouldn't be too difficult to fix..

[tonivj5]

Thanks @ayazhafiz for the clarification :+1:. I think https://github.com/angular/angular/pull/35561 should fix it, shouldn't?

Related https://github.com/angular/vscode-ng-language-service/issues/649 (relation lost in the transfer :rocket:)

[tonivj5]

Ey @ayazhafiz, I have tryed this feature again with the last release (9.1.0), but it doesn't work :laughing: I don't know if it's a regression of the latest release or never worked (I didn't test it again, I've been very busy until now :sweat_smile:)

I have updated the demo to the latest Angular, and test follow being any. Can this issue be reopen or I should open a new one?

[ayazhafiz]

Weird, this should not be the case... what version of the language service/language server extension are you using?

[tonivj5]

I'm using the latest of both (9.1.0)

[ayazhafiz]

Hmm okay I will take a look soon

---

От: Toni Villena [e-mail]
Отправлено: Friday, March 27, 2020 8:13:23 AM
Кому: angular/vscode-ng-language-service [e-mail]
Копия: hafiz [e-mail]; Mention [e-mail]
Тема: Re: [angular/vscode-ng-language-service] Typeching of context doesn't work with custom directives (#650)

I'm using the latest of both (9.1.0)
[image]https://user-images.githubusercontent.com/7110786/77770593-c944b900-7045-11ea-8519-98cf2035aad4.png

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[tonivj5]

Thanks :+1:

[ayazhafiz]

@tonivj5 I see, it doesn't work with the MyIf directive. This is a known problem that won't be fix until we flip the language service to Ivy. Basically the issue is that today the language service cannot resolve generic type parameters.

For NgIf we have a special case to look up the type of the variable bound to the directive, but we can't do this for every custom directive.

[tonivj5]

So, I will have to wait to use this feature :cry:. I suppose it will happen with Angular 10, won't?

Can this issue hold open meanwhile?

Thanks anyway for the time invested :smile:. I will look forward to this feature :zap:

[ayazhafiz]

@kyliau can give us some more insight. Ivy is scheduled to land with 10, right? Do we have an existing issue keeping track of the generic bindings problem?

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