typescript-eslint · StyleShit · Feb 12, 2024 · Feb 12, 2024 · Feb 12, 2024 · Feb 13, 2024
diff --git a/packages/eslint-plugin/docs/rules/require-types-exports.mdx b/packages/eslint-plugin/docs/rules/require-types-exports.mdx
@@ -0,0 +1,80 @@
+---
+description: 'Require exporting types that are used in exported entities.'
+---
+
+import Tabs from '@theme/Tabs';
+import TabItem from '@theme/TabItem';
+
+> 🛑 This file is source code, not the primary documentation location! 🛑
+>
+> See **https://typescript-eslint.io/rules/require-types-exports** for documentation.
+
+When exporting entities from a module, it is recommended to export also all the
+types that are used in their declarations. This is useful for consumers of the
+module, as it allows them to use the types in their own code without having to
+use utility types like [`Parameters`](https://www.typescriptlang.org/docs/handbook/utility-types.html#parameterstype)
+or [`ReturnType`](https://www.typescriptlang.org/docs/handbook/utility-types.html#returntypetype)
+in order to extract the types from your code.
+
+## Examples
+
+<Tabs>
+<TabItem value="❌ Incorrect">
+
+```ts
+type Arg = string;
+type Result = number;
+
+export function strLength(arg: Arg): Result {
+  return arg.length;
+}
+
+interface Fruit {
+  name: string;
+  color: string;
+}
+
+export const getFruitName = (fruit: Fruit) => fruit.name;
+
+enum Color {
+  Red = 'red',
+  Green = 'green',
+  Blue = 'blue',
+}
+
+export declare function getRandomColor(): Color;
+```
+
+</TabItem>
+<TabItem value="✅ Correct">
+
+```ts
+export type Arg = string;
+export type Result = number;
+
+export function strLength(arg: Arg): Result {
+  return arg.length;
+}
+
+export interface Fruit {
+  name: string;
+  color: string;
+}
+
+export const getFruitName = (fruit: Fruit) => fruit.name;
+
+export enum Color {
+  Red = 'red',
+  Green = 'green',
+  Blue = 'blue',
+}
+
+export declare function getRandomColor(): Color;
+```
+
+</TabItem>
+</Tabs>
+
+## When Not To Use It
+
+When you don't want to enforce exporting types that are used in exported functions declarations.
diff --git a/packages/eslint-plugin/src/configs/all.ts b/packages/eslint-plugin/src/configs/all.ts
@@ -146,6 +146,7 @@ export = {
     '@typescript-eslint/require-array-sort-compare': 'error',
     'require-await': 'off',
     '@typescript-eslint/require-await': 'error',
+    '@typescript-eslint/require-types-exports': 'error',
     '@typescript-eslint/restrict-plus-operands': 'error',
     '@typescript-eslint/restrict-template-expressions': 'error',
     'no-return-await': 'off',

diff --git a/packages/eslint-plugin/src/configs/strict-type-checked.ts b/packages/eslint-plugin/src/configs/strict-type-checked.ts
@@ -73,6 +73,7 @@ export = {
     '@typescript-eslint/prefer-return-this-type': 'error',
     'require-await': 'off',
     '@typescript-eslint/require-await': 'error',
+    '@typescript-eslint/require-types-exports': 'error',
     '@typescript-eslint/restrict-plus-operands': [
       'error',
       {

diff --git a/packages/eslint-plugin/src/configs/strict.ts b/packages/eslint-plugin/src/configs/strict.ts
@@ -40,6 +40,7 @@ export = {
     '@typescript-eslint/no-var-requires': 'error',
     '@typescript-eslint/prefer-as-const': 'error',
     '@typescript-eslint/prefer-literal-enum-member': 'error',
+    '@typescript-eslint/require-types-exports': 'error',
     '@typescript-eslint/triple-slash-reference': 'error',
     '@typescript-eslint/unified-signatures': 'error',
   },

diff --git a/packages/eslint-plugin/src/rules/array-type.ts b/packages/eslint-plugin/src/rules/array-type.ts
@@ -72,13 +72,13 @@ function typeNeedsParentheses(node: TSESTree.Node): boolean {
 }
 
 export type OptionString = 'array-simple' | 'array' | 'generic';
-type Options = [
+export type Options = [
   {
     default: OptionString;
     readonly?: OptionString;
   },
 ];
-type MessageIds =
+export type MessageIds =
   | 'errorStringArray'
   | 'errorStringArraySimple'
   | 'errorStringGeneric'

diff --git a/packages/eslint-plugin/src/rules/ban-ts-comment.ts b/packages/eslint-plugin/src/rules/ban-ts-comment.ts
@@ -3,12 +3,12 @@ import { AST_TOKEN_TYPES } from '@typescript-eslint/utils';
 
 import { createRule, getStringLength, nullThrows } from '../util';
 
-type DirectiveConfig =
+export type DirectiveConfig =
   | boolean
   | 'allow-with-description'
   | { descriptionFormat: string };
 
-interface Options {
+export interface Options {
   'ts-expect-error'?: DirectiveConfig;
   'ts-ignore'?: DirectiveConfig;
   'ts-nocheck'?: DirectiveConfig;
@@ -18,7 +18,7 @@ interface Options {
 
 const defaultMinimumDescriptionLength = 3;
 
-type MessageIds =
+export type MessageIds =
   | 'tsDirectiveComment'
   | 'tsIgnoreInsteadOfExpectError'
   | 'tsDirectiveCommentDescriptionNotMatchPattern'

diff --git a/packages/eslint-plugin/src/rules/class-literal-property-style.ts b/packages/eslint-plugin/src/rules/class-literal-property-style.ts
@@ -9,8 +9,8 @@ import {
   nullThrows,
 } from '../util';
 
-type Options = ['fields' | 'getters'];
-type MessageIds =
+export type Options = ['fields' | 'getters'];
+export type MessageIds =
   | 'preferFieldStyle'
   | 'preferFieldStyleSuggestion'
   | 'preferGetterStyle'

diff --git a/packages/eslint-plugin/src/rules/class-methods-use-this.ts b/packages/eslint-plugin/src/rules/class-methods-use-this.ts
@@ -8,15 +8,15 @@ import {
   getStaticStringValue,
 } from '../util';
 
-type Options = [
+export type Options = [
   {
     exceptMethods?: string[];
     enforceForClassFields?: boolean;
     ignoreOverrideMethods?: boolean;
     ignoreClassesThatImplementAnInterface?: boolean | 'public-fields';
   },
 ];
-type MessageIds = 'missingThis';
+export type MessageIds = 'missingThis';
 
 export default createRule<Options, MessageIds>({
   name: 'class-methods-use-this',

diff --git a/packages/eslint-plugin/src/rules/comma-spacing.ts b/packages/eslint-plugin/src/rules/comma-spacing.ts
@@ -10,13 +10,13 @@ import {
   isTokenOnSameLine,
 } from '../util';
 
-type Options = [
+export type Options = [
   {
     before: boolean;
     after: boolean;
   },
 ];
-type MessageIds = 'missing' | 'unexpected';
+export type MessageIds = 'missing' | 'unexpected';
 
 export default createRule<Options, MessageIds>({
   name: 'comma-spacing',

diff --git a/packages/eslint-plugin/src/rules/consistent-generic-constructors.ts b/packages/eslint-plugin/src/rules/consistent-generic-constructors.ts
@@ -3,8 +3,8 @@ import { AST_NODE_TYPES } from '@typescript-eslint/utils';
 
 import { createRule, nullThrows, NullThrowsReasons } from '../util';
 
-type MessageIds = 'preferConstructor' | 'preferTypeAnnotation';
-type Options = ['constructor' | 'type-annotation'];
+export type MessageIds = 'preferConstructor' | 'preferTypeAnnotation';
+export type Options = ['constructor' | 'type-annotation'];
 
 export default createRule<Options, MessageIds>({
   name: 'consistent-generic-constructors',

diff --git a/packages/eslint-plugin/src/rules/consistent-indexed-object-style.ts b/packages/eslint-plugin/src/rules/consistent-indexed-object-style.ts
@@ -3,8 +3,8 @@ import { AST_NODE_TYPES, ASTUtils } from '@typescript-eslint/utils';
 
 import { createRule } from '../util';
 
-type MessageIds = 'preferIndexSignature' | 'preferRecord';
-type Options = ['index-signature' | 'record'];
+export type MessageIds = 'preferIndexSignature' | 'preferRecord';
+export type Options = ['index-signature' | 'record'];
 
 export default createRule<Options, MessageIds>({
   name: 'consistent-indexed-object-style',

diff --git a/packages/eslint-plugin/src/rules/consistent-return.ts b/packages/eslint-plugin/src/rules/consistent-return.ts
@@ -11,10 +11,10 @@ import { getESLintCoreRule } from '../util/getESLintCoreRule';
 
 const baseRule = getESLintCoreRule('consistent-return');
 
-type Options = InferOptionsTypeFromRule<typeof baseRule>;
-type MessageIds = InferMessageIdsTypeFromRule<typeof baseRule>;
+export type Options = InferOptionsTypeFromRule<typeof baseRule>;
+export type MessageIds = InferMessageIdsTypeFromRule<typeof baseRule>;
 
-type FunctionNode =
+export type FunctionNode =
   | TSESTree.FunctionDeclaration
   | TSESTree.FunctionExpression
   | TSESTree.ArrowFunctionExpression;

diff --git a/packages/eslint-plugin/src/rules/consistent-type-exports.ts b/packages/eslint-plugin/src/rules/consistent-type-exports.ts
@@ -12,7 +12,7 @@ import {
   NullThrowsReasons,
 } from '../util';
 
-type Options = [
+export type Options = [
   {
     fixMixedExportsWithInlineTypeSpecifier: boolean;
   },
@@ -32,7 +32,7 @@ interface ReportValueExport {
   inlineTypeSpecifiers: TSESTree.ExportSpecifier[];
 }
 
-type MessageIds =
+export type MessageIds =
   | 'multipleExportsAreTypes'
   | 'singleExportIsType'
   | 'typeOverValue';

diff --git a/packages/eslint-plugin/src/rules/consistent-type-imports.ts b/packages/eslint-plugin/src/rules/consistent-type-imports.ts
@@ -15,10 +15,10 @@ import {
   NullThrowsReasons,
 } from '../util';
 
-type Prefer = 'no-type-imports' | 'type-imports';
-type FixStyle = 'inline-type-imports' | 'separate-type-imports';
+export type Prefer = 'no-type-imports' | 'type-imports';
+export type FixStyle = 'inline-type-imports' | 'separate-type-imports';
 
-type Options = [
+export type Options = [
   {
     prefer?: Prefer;
     disallowTypeAnnotations?: boolean;
@@ -44,7 +44,7 @@ interface ReportValueImport {
   inlineTypeSpecifiers: TSESTree.ImportSpecifier[];
 }
 
-type MessageIds =
+export type MessageIds =
   | 'typeOverValue'
   | 'someImportsAreOnlyTypes'
   | 'avoidImportType'

diff --git a/packages/eslint-plugin/src/rules/explicit-function-return-type.ts b/packages/eslint-plugin/src/rules/explicit-function-return-type.ts
@@ -9,7 +9,7 @@ import {
   isValidFunctionExpressionReturnType,
 } from '../util/explicitReturnTypeUtils';
 
-type Options = [
+export type Options = [
   {
     allowExpressions?: boolean;
     allowTypedFunctionExpressions?: boolean;
@@ -21,7 +21,7 @@ type Options = [
     allowIIFEs?: boolean;
   },
 ];
-type MessageIds = 'missingReturnType';
+export type MessageIds = 'missingReturnType';
 
 type FunctionNode =
   | TSESTree.ArrowFunctionExpression

diff --git a/packages/eslint-plugin/src/rules/explicit-member-accessibility.ts b/packages/eslint-plugin/src/rules/explicit-member-accessibility.ts
@@ -12,12 +12,12 @@ import {
   getParameterPropertyHeadLoc,
 } from '../util/getMemberHeadLoc';
 
-type AccessibilityLevel =
+export type AccessibilityLevel =
   | 'explicit' // require an accessor (including public)
   | 'no-public' // don't require public
   | 'off'; // don't check
 
-interface Config {
+export interface Config {
   accessibility?: AccessibilityLevel;
   ignoredMethodNames?: string[];
   overrides?: {
@@ -29,9 +29,9 @@ interface Config {
   };
 }
 
-type Options = [Config];
+export type Options = [Config];
 
-type MessageIds =
+export type MessageIds =
   | 'addExplicitAccessibility'
   | 'missingAccessibility'
   | 'unwantedPublicAccessibility';

diff --git a/packages/eslint-plugin/src/rules/explicit-module-boundary-types.ts b/packages/eslint-plugin/src/rules/explicit-module-boundary-types.ts
@@ -16,7 +16,7 @@ import {
   isTypedFunctionExpression,
 } from '../util/explicitReturnTypeUtils';
 
-type Options = [
+export type Options = [
   {
     allowArgumentsExplicitlyTypedAsAny?: boolean;
     allowDirectConstAssertionInArrowFunctions?: boolean;
@@ -25,7 +25,7 @@ type Options = [
     allowTypedFunctionExpressions?: boolean;
   },
 ];
-type MessageIds =
+export type MessageIds =
   | 'anyTypedArg'
   | 'anyTypedArgUnnamed'
   | 'missingArgType'

diff --git a/packages/eslint-plugin/src/rules/indent.ts b/packages/eslint-plugin/src/rules/indent.ts
@@ -17,8 +17,8 @@ import { getESLintCoreRule } from '../util/getESLintCoreRule';
 
 const baseRule = getESLintCoreRule('indent');
 
-type Options = InferOptionsTypeFromRule<typeof baseRule>;
-type MessageIds = InferMessageIdsTypeFromRule<typeof baseRule>;
+export type Options = InferOptionsTypeFromRule<typeof baseRule>;
+export type MessageIds = InferMessageIdsTypeFromRule<typeof baseRule>;
 
 const KNOWN_NODES = new Set([
   // Class properties aren't yet supported by eslint...

diff --git a/packages/eslint-plugin/src/rules/index.ts b/packages/eslint-plugin/src/rules/index.ts
@@ -131,6 +131,7 @@ import promiseFunctionAsync from './promise-function-async';
 import quotes from './quotes';
 import requireArraySortCompare from './require-array-sort-compare';
 import requireAwait from './require-await';
+import requireTypesExports from './require-types-exports';
 import restrictPlusOperands from './restrict-plus-operands';
 import restrictTemplateExpressions from './restrict-template-expressions';
 import returnAwait from './return-await';
@@ -281,6 +282,7 @@ export default {
   quotes: quotes,
   'require-array-sort-compare': requireArraySortCompare,
   'require-await': requireAwait,
+  'require-types-exports': requireTypesExports,
   'restrict-plus-operands': restrictPlusOperands,
   'restrict-template-expressions': restrictTemplateExpressions,
   'return-await': returnAwait,

diff --git a/packages/eslint-plugin/src/rules/lines-between-class-members.ts b/packages/eslint-plugin/src/rules/lines-between-class-members.ts
@@ -11,8 +11,8 @@ import { getESLintCoreRule } from '../util/getESLintCoreRule';
 
 const baseRule = getESLintCoreRule('lines-between-class-members');
 
-type Options = InferOptionsTypeFromRule<typeof baseRule>;
-type MessageIds = InferMessageIdsTypeFromRule<typeof baseRule>;
+export type Options = InferOptionsTypeFromRule<typeof baseRule>;
+export type MessageIds = InferMessageIdsTypeFromRule<typeof baseRule>;
 
 const schema = Object.values(
   deepMerge(