Bug?: type-utils > TypeOrValueSpecifier's file detection is case insensitive

[JoshuaKGoldberg]

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Relevant Package

type-utils

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Description

Following up from https://github.com/typescript-eslint/typescript-eslint/pull/4436/files#r1134626465: in order to get the PR merged, the "is this type declared in one of these files?" logic (typeDeclaredInFile) logic was changed to be case insensitive. It .toLowerCase()s all strings.

That means this config:

{ from: 'file', name: 'MyType', path: './filename' }

...will match ./filename, ./Filename, ./FILENAME, and so on.

This case insensitivity probably won't matter in any projects. But most file systems are in fact case sensitive. So we really should get it to work at some point.

Additional Info

To start on this issue, remove the .toLowerCase() calls in typeDeclaredInFile.

typescript-eslint/packages/type-utils/src/TypeOrValueSpecifier.ts

Line 130 in 346fdbc

function typeDeclaredInFile(

Re-run unit tests for type-utils and eslint-plugin. You'll also want to add unit tests to TypeOrValueSpecifier.test.ts to make sure that case sensitivity is respected.

[marekdedic]

From the linked review, on the machine of @JoshuaKGoldberg:

• relativePath is 'tests/fixtures/file.ts'
• absolutePath is '/Users/josh/repos/typescript-eslint/packages/type-utils/tests/fixtures/file.ts
• declarationFiles[0].fileName is '/users/josh/repos/typescript-eslint/packages/type-utils/tests/fixtures/file.ts'

[bradzacher]

There's a function in typescript-estree called getCannonicalFilename that you can use to make sure it matches TS

[marekdedic]

On my machine:

• realtivePath is tests/fixtures/file.ts
• absolutePath is /home/marekdedic/Documents/git/typescript-eslint/packages/type-utils/tests/fixtures/file.ts
• declarationFiles[0].fileName is /home/marekdedic/Documents/git/typescript-eslint/packages/type-utils/tests/fixtures/file.ts

I'm on Linux and I presume @JoshuaKGoldberg is on a Mac. It seems like declarationFiles[0].fileName is getting lower-cased on Mac and not on Linux...

[JoshuaKGoldberg]

Btw, yes, I'm on a Mac. 👍

[JoshuaKGoldberg]

Fixed in #6781, will be released in v6 🚀. Thanks @marekdedic as always!