fix: remove redundant Comment member from CSSSyntaxElement union

[louis-young-slice]

Prerequisites checklist

• I have read the contributing guidelines.

What is the purpose of this pull request?

To resolve #118.

What changes did you make? (Give an overview)

• Remove Comment from the CSSSyntaxElement union.
  • The CssNodePlain type is a union that includes Comment as a member, making it redundant in the CSSSyntaxElement union. See: https://github.com/eslint/csstree/blob/main/lib/index.d.ts#L971.
• Explicitly specify the lib TypeScript compiler option.
  • Remove the default inherited type definitions from the project by aligning lib with target, making the type environment stricter, and verifying that the previous fix resolves the intended issue by surfacing related errors via the type tests. See: https://www.typescriptlang.org/tsconfig/#lib.

Related Issues

Fixes #118.

Is there anything you'd like reviewers to focus on?

N/A.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: louis-young-slice / name: Louis Young (f7032cf, 0c59bd6, 199a7e1)

[eslint-github-bot]

Hi @louis-young-slice!, thanks for the Pull Request

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[eslint-github-bot]

Hi @louis-young-slice!, thanks for the Pull Request

The pull request title isn't properly formatted. We ask that you update the pull request title to match this format, as we use it to generate changelogs and automate releases.

• The commit message tag wasn't recognized. Did you mean "docs", "fix", or "feat"?
• There should be a space following the initial tag and colon, for example 'feat: Message'.

To Fix: You can fix this problem by clicking 'Edit' next to the pull request title at the top of this page.

Read more about contributing to ESLint here

[nzakas]

Thanks so much for tracking this down. Is there a way to can automate checking this?

We have types.test.ts for our type checking. Is there a way to modify that or the tsconfig in that directory to verify this fixes the problem?

[fasttime]

We could probably exclude the DOM library in tsconfig.json in the project root, since that library is not used in this project. That would be adding "lib": ["ES2022"] to the TypeScript compiler options. The type tests (npx run test:types) will then fail if any DOM types are inadvertently used. We have a similar setting in eslint-visitor-keys.

[louis-young-slice]

Thanks so much for tracking this down.

My pleasure. Thank you for creating and maintaining one of the most helpful tools in the ecosystem.

Is there a way to automate checking this? We have types.test.ts for our type checking. Is there a way to modify that or the tsconfig in that directory to verify this fixes the problem?

Absolutely; there's a simple way to update the project's TypeScript configuration to verify that this pull request resolves the issue.

Generally, it's best to expose as few global types as possible. As @fasttime said, updating the lib compiler option to only include type definitions for "ES2022" - matching the target JavaScript language version - will cause this error (and those of the same nature) to surface via the type tests.

Since the project uses a composite TypeScript configuration (multiple configurations extending a shared base configuration), and none of them currently override lib, setting lib in the root tsconfig.json will be sufficient to apply the change project-wide.

[louis-young-slice]

Now that I’m not rushing around at 6pm on a Friday evening, I’ve had another look and realised that CssNodePlain is a union that includes Comment as a member, making it redundant in the CSSSyntaxElement union. To resolve this, I’ve removed Comment from the CSSSyntaxElement union and left it as an alias for CssNodePlain.

[fasttime]

LGTM, thanks! Leaving open for @nzakas to verify before merging.

[nzakas]

Nice work catching that! LGTM. Thanks.