Support "Type aware" linting for gts files

[vstefanovic97]

I'm not really a pro at Eslint nor Typescript Compiler, but I did notice this strange behaviour
To me it seems that "type aware" linting isn't really fully working.

For example if we import something from a gts file, whatever we imported, the @typescript-eslint/parser won't be aware of it's types

Here is a link to a fork where I setup a test with reproduction:
vstefanovic97@70235ac

This is my theory on why this is happening (though I might be wrong):

Right now we rely on @typescript-eslint/parser to do everything and we just forward options to it, but if we just rely on it, it will generate a Typescript Program w/o including any of our gts files. It seems like we need to create our own typescript Program with a custom CompilerHost that will know how to read gts files.

For context, terminology like Program and CompilerHost are from https://github.com/microsoft/TypeScript/wiki/Using-the-Compiler-API, and typescript-eslint supports us providing it a program in it's options so that seems like the way to go to me at least

[bmish]

@patricklx @NullVoxPopuli

[patricklx]

@NullVoxPopuli i remember you tried something with glint ts program? Maybe that would work for this?

[NullVoxPopuli]

well, to use type-are lints, you may not use @typescript-eslint/parser on gts files, you must use the parser provided by eslint-plugin-ember

@patricklx for the glint ts program thing, I don't recall if that was for linting or not

[vstefanovic97]

@NullVoxPopuli in my reproduction, I am using gjs-gts-parser for the gts files, see here.

But still there is the issue, unless I am missing something

[patricklx]

The issue is when gts is imported, not linted directly. But for typed linting the parser also needs to load the imported files. Internally that is done by typescript-eslint parser

eslint-plugin-ember/lib/parsers/gjs-gts-parser.js

Line 541 in 90d1fc4

? typescriptParser.parseForESLint(jsCode, { ...options, ranges: true })

[patricklx]

Maybe we need a small ts plugin for this? Like for vue
https://github.com/sandersn/vue-ts-plugin/blob/master/lib/index.ts

[vstefanovic97]

@patricklx, @NullVoxPopuli seems like the only reason why even direct linting of a gts file works, is because typescript-eslint internally overrides the readFile method of it's CompilerHost to use the code we provide as the first argument to its parseForEslint method, instead of the actual file on disk.

See https://github.com/typescript-eslint/typescript-eslint/blob/main/packages/typescript-estree/src/create-program/getWatchProgramsForProjects.ts#L273

But unfortunatelly this means it will only treat that one file like that, and for the rest it will read from disk, which means it will try to import gts files which it doesn't know how to read.

Maybe asking typescript-eslint repo for a feature to provide an option as an argument where we could provide our own readFile implementation will be enough?

[vstefanovic97]

@patricklx, @NullVoxPopuli seems like the only reason why even direct linting of a gts file works, is because typescript-eslint internally overrides the readFile method of it's CompilerHost to use the code we provide as the first argument to its parseForEslint method, instead of the actual file on disk.

See https://github.com/typescript-eslint/typescript-eslint/blob/main/packages/typescript-estree/src/create-program/getWatchProgramsForProjects.ts#L273

But unfortunatelly this means it will only treat that one file like that, and for the rest it will read from disk, which means it will try to import gts files which it doesn't know how to read.

Maybe asking typescript-eslint repo for a feature to provide an option as an argument where we could provide our own readFile implementation will be enough?

Such feature might be beneficial not only to us, but seems like vue has same issue right now
vuejs/vue-eslint-parser#104

[NullVoxPopuli]

If we could tell it to use glint instead of tsc of 'the program', i think that could help, as it also has its own read file ...

If it weren't for this

internally overrides the readFile method of it's CompilerHost

🙈

[vstefanovic97]

If we could tell it to use glint instead of tsc of 'the program', i think that could help, as it also has its own read file ...

If it weren't for this

internally overrides the readFile method of it's CompilerHost

🙈

@NullVoxPopuli well if we pass it glints TS program, then it won't override anything it just uses the program as it's given

[vstefanovic97]

Glint just maybe seems a bit overkill for this, if we could just override readFile that typescript-eslint is using by asking them to provide a new option for it, we can the just use transformForEslint method as the override, it would solve the problem I think and not have us depend on glint.

But it is just a theory, I can test it out tomorrow and if it works I can raise a feature request to typescript-eslint. Wdyt?
But in case they won't be willing to let us override it we probably will need to use glint or something

[patricklx]

Maybe we can use this?
https://github.com/typescript-eslint/typescript-eslint/blob/fadc7940b456f1903a282a4b5085daf1b8367b16/packages/parser/src/index.ts#L7
Patch it and pass it as program parser option? but it would be better to transform directly with content tag,

[vstefanovic97]

Glint just maybe seems a bit overkill for this, if we could just override readFile that typescript-eslint is using by asking them to provide a new option for it, we can the just use transformForEslint method as the override, it would solve the problem I think and not have us depend on glint.

But it is just a theory, I can test it out tomorrow and if it works I can raise a feature request to typescript-eslint. Wdyt? But in case they won't be willing to let us override it we probably will need to use glint or something

I tried a few things, but for now I just can't seem to get it to work :(, I'll keep trying next couple of days, but maybe someone else will have more luck with this