#Configuration

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

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

#description: 'Disallow variable declarations from shadowing variables declared in the outer scope.'

#@typescript-eslint/no-shadow

Extends the ESLint core no-shadow rule with TypeScript-aware behavior.

#Rule Details

Shadowing occurs when a local variable shares the same name as a variable in its containing scope. The TypeScript variant additionally understands type-only declarations and the related typeof interplay between values and types.

Examples of incorrect code for this rule:

type Foo = number;
function b() {
  type Foo = string;
}

Examples of correct code for this rule:

type Foo = number;
function b() {
  type Bar = string;
}

#Options

This rule accepts the same options as the ESLint core no-shadow rule with these additions and default differences:

#hoist

In addition to the core values ("functions", "all", "never"), this rule supports:

• "types": report shadowing of an outer type or interface that appears later.
• "functions-and-types": report shadowing of outer function or type declarations that appear later.

Default: "functions-and-types" (the core ESLint default is "functions").

#ignoreTypeValueShadow

When true, a value declaration and a type declaration that share a name are not considered shadowing (the two live in different namespaces and a typeof is required to bridge them).

Default: true.

{ "@typescript-eslint/no-shadow": ["error", { "ignoreTypeValueShadow": false }] }

type Foo = number;
function f() {
  const Foo = 1;
}

#ignoreFunctionTypeParameterNameValueShadow

When true, parameters declared inside a function type (for example (x: string) => void) do not report when they shadow an outer value binding.

Default: true.

{ "@typescript-eslint/no-shadow": ["error", { "ignoreFunctionTypeParameterNameValueShadow": false }] }

const test = 1;
type Func = (test: string) => typeof test;

#allow, builtinGlobals, ignoreOnInitialization

Same semantics and defaults as the ESLint core rule.

#Original Documentation

https://typescript-eslint.io/rules/no-shadow