linter: `eslint/no-loop-func` flags safe let-scoped callbacks

[jeanne-cai]

What version of Oxlint are you using?

1.67.0

What command did you run?

yarn oxlint -c oxlint.config.mjs

What does your .oxlintrc.json (or oxlint.config.ts) config file look like?

import { defineConfig } from 'oxlint';

export default defineConfig({
    categories: {
        correctness: 'off',
    },
    rules: {
        'eslint/no-loop-func': 'error',
    },
});

What happened?

Oxlint reports eslint(no-loop-func) for functions inside loops, even when loop variables use let, incorrectly flagging safe closures.

To reproduce:

const callbacks = [];
for (let row = 0; row < 5; row++) {
    for (let col = 0; col < 5; col++) {
        // flag
        callbacks.push(function () {
            return row + col;
        });
    }
}

let factor = 0;
if (factor < 5) {
    factor++;
} else {
    for (let index = 0; index < 5; index++) {
        // flag
        const compute = (value, index) => factor * value + index;
    }
}

let isOn = false;
if (isOn) {
    isOn = true;
}

for (let imageId = 0; imageId < 5; imageId++) {
    // flag
    image.onload = () => (isOn ? 'enabled' : 'disabled');
}

Output:

  × eslint(no-loop-func): Function declared in a loop contains unsafe references to variable(s)
   ╭─[test.ts:5:24]
 4 │             // flag
 5 │ ╭─▶         callbacks.push(function () {
 6 │ │               return row + col;
 7 │ ╰─▶         });
 8 │         }
   ╰────
  help: Variables declared with 'var' are function-scoped, not block-scoped. Consider using 'let' or 'const' for block-scoped variables, or move the function outside the loop.

  × eslint(no-loop-func): Function declared in a loop contains unsafe references to variable(s)
    ╭─[test.ts:17:25]
 16 │         // flag
 17 │         const compute = (value, index) => factor * value + index;
    ·                         ────────────────────────────────────────
 18 │     }
    ╰────
  help: Variables declared with 'var' are function-scoped, not block-scoped. Consider using 'let' or 'const' for block-scoped variables, or move the function outside the loop.

  × eslint(no-loop-func): Function declared in a loop contains unsafe references to variable(s)
    ╭─[test.ts:28:20]
 27 │     // flag
 28 │     image.onload = () => (isOn ? 'enabled' : 'disabled');
    ·                    ─────────────────────────────────────
 29 │ }
    ╰────
  help: Variables declared with 'var' are function-scoped, not block-scoped. Consider using 'let' or 'const' for block-scoped variables, or move the function outside the loop.