feat: report class evaluation TDZ errors in no-use-before-define

[mdjermanovic]

Prerequisites checklist

• I have read the contributing guidelines.

What is the purpose of this pull request? (put an "X" next to an item)

[ ] Documentation update
[x] Bug fix (template)
[ ] New rule (template)
[ ] Changes an existing rule (template)
[ ] Add autofixing to a rule
[ ] Add a CLI option
[ ] Add something to the core
[ ] Other, please explain:

This bug fix produces only more warnings.

Tell us about your environment

• ESLint Version: v8.0.0-rc.0
• Node Version: v12.22.4
• npm Version: v6.14.14

What parser (default, @babel/eslint-parser, @typescript-eslint/parser, etc.) are you using?

default

Please show your full configuration:

Configuration

module.exports = {
    parserOptions: {
        ecmaVersion: 2022
    }
};

What did you do? Please include the actual source code causing the issue.

/* eslint no-use-before-define: error */

class A extends A {} // TDZ error

class B {
    [B]() {} // TDZ error
}

const C = class {
    static foo = C; // TDZ error
}

/* eslint no-use-before-define: ["error", { variables: false }] */

class D {
    static foo = x; // TDZ error
}

const x = 1;

What did you expect to happen?

no-use-before-define to report all references marked as "TDZ error" in the above examples.

What actually happened? Please include the actual, raw output from ESLint.

No errors.

What changes did you make? (Give an overview)

Fixed the no-use-before-define rule for ClassDefinitionEvaluation steps. Class heritage and computed properties are evaluated before initializing the class binding (A and B create classBinding in the class scope; they also create an outer variable but the references from the class definition are to the inner one, and the outer one is initialized even later). Static initializers are run after the class binding is initialized (if it exists), but still before initializing C in const C = class ... and before declarations that appear after the class (const x).

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

Examples that don't require new syntax are reproducible as false negatives in v7.32.0, too (demo link). This is a bug fix regarding extends and computed properties, and a sort of enhancement regarding static field initializers since they're implicit functions. This rule doesn't track function calls, but in this case we can know when they will be called.

[eslint-github-bot]

Hi @mdjermanovic!, thanks for the Pull Request

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[nzakas]

This melted my brain but LGTM