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Rslint

    no-unsafe-function-type

    Configuration

    rslint.config.ts
    import { defineConfig, ts } from '@rslint/core';

export default defineConfig([
  ts.configs.recommended,
  {
    rules: {
      '@typescript-eslint/no-unsafe-function-type': 'error',
    },
  },
]);

    Rule Details

    Disallow using the built-in Function type. Function describes any callable value: it accepts any number of arguments, returns any, and includes class declarations, which throw at runtime when invoked without new. A concrete signature — including parameters and return type — should be used instead.

    A local declaration named Function (a type alias, interface, or class) shadows the global one, in which case the reference is no longer the unsafe built-in and is not reported.

    Examples of incorrect code for this rule:

    let value: Function;

let values: Function[];

let valueOrNumber: Function | number;

class Weird implements Function {
  // ...
}

interface AlsoWeird extends Function {
  // ...
}

    Examples of correct code for this rule:

    let value: () => void;

let value: <T>(t: T) => T;

{
  type Function = () => void;
  let value: Function;
}

    Original Documentation