typescript-eslint · JoshuaKGoldberg · Feb 12, 2024 · Feb 12, 2024 · Feb 12, 2024 · Feb 13, 2024
diff --git a/packages/ast-spec/src/declaration/ExportAndImportKind.ts b/packages/ast-spec/src/declaration/ExportAndImportKind.ts
@@ -1,4 +1,4 @@
-type ExportAndImportKind = 'type' | 'value';
+export type ExportAndImportKind = 'type' | 'value';
 
 export type ExportKind = ExportAndImportKind;
 export type ImportKind = ExportAndImportKind;
diff --git a/packages/ast-spec/tests/util/parsers/parser-types.ts b/packages/ast-spec/tests/util/parsers/parser-types.ts
@@ -1,6 +1,6 @@
-type SnapshotPathFn = (i: number) => string;
+export type SnapshotPathFn = (i: number) => string;
 
-interface SuccessSnapshotPaths {
+export interface SuccessSnapshotPaths {
   readonly ast: SnapshotPathFn;
   readonly tokens: SnapshotPathFn;
 }

diff --git a/packages/eslint-plugin-internal/src/rules/plugin-test-formatting.ts b/packages/eslint-plugin-internal/src/rules/plugin-test-formatting.ts
@@ -87,14 +87,14 @@ function escapeTemplateString(code: string): string {
   return fixed;
 }
 
-type Options = [
+export type Options = [
   {
     // This option exists so that rules like type-annotation-spacing can exist without every test needing a prettier-ignore
     formatWithPrettier?: boolean;
   },
 ];
 
-type MessageIds =
+export type MessageIds =
   | 'invalidFormatting'
   | 'invalidFormattingErrorTest'
   | 'noUnnecessaryNoFormat'

diff --git a/packages/eslint-plugin/docs/rules/require-types-exports.mdx b/packages/eslint-plugin/docs/rules/require-types-exports.mdx
@@ -0,0 +1,87 @@
+---
+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 file, it is often useful to export also all the types that are used in their declarations.
+Doing so ensures consumers of the file can directly import and use those types when using those entities.
+
+Otherwise, consumers may have 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 the entities.
+
+## Examples
+
+<Tabs>
+<TabItem value="❌ Incorrect">
+
+```ts
+interface Fruit {
+  name: string;
+  color: string;
+}
+
+export const getFruitName = (fruit: Fruit) => fruit.name;
+```
+
+```ts
+const fruits = {
+  apple: '🍏',
+  banana: '🍌',
+};
+
+export const getFruit = (key: keyof typeof fruits) => fruits[key];
+```
+
+```ts
+enum Color {
+  Red = 'red',
+  Green = 'green',
+  Blue = 'blue',
+}
+
+export declare function getRandomColor(): Color;
+```
+
+</TabItem>
+<TabItem value="✅ Correct">
+
+```ts
+export interface Fruit {
+  name: string;
+  color: string;
+}
+
+export const getFruitName = (fruit: Fruit) => fruit.name;
+```
+
+```ts
+export const fruits = {
+  apple: '🍏',
+  banana: '🍌',
+};
+
+export const getFruit = (key: keyof typeof fruits) => fruits[key];
+```
+
+```ts
+export enum Color {
+  Red = 'red',
+  Green = 'green',
+  Blue = 'blue',
+}
+
+export declare function getRandomColor(): Color;
+```
+
+</TabItem>
+</Tabs>
+
+## When Not To Use It
+
+If your files utilize many complex self-referential types that you don't want external consumers to reference, you may want to avoid this rule for those cases.
+You might consider using [ESLint disable comments](https://eslint.org/docs/latest/use/configure/rules#using-configuration-comments-1) for those specific situations instead of completely disabling this rule.
diff --git a/packages/eslint-plugin/src/configs/all.ts b/packages/eslint-plugin/src/configs/all.ts
@@ -147,6 +147,7 @@ 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/disable-type-checked.ts b/packages/eslint-plugin/src/configs/disable-type-checked.ts
@@ -8,7 +8,7 @@
 import type { ClassicConfig } from '@typescript-eslint/utils/ts-eslint';
 
 export = {
-  parserOptions: { project: false, program: null, projectService: false },
+  parserOptions: { program: null, project: false, projectService: false },
   rules: {
     '@typescript-eslint/await-thenable': 'off',
     '@typescript-eslint/consistent-return': 'off',

diff --git a/packages/eslint-plugin/src/configs/strict-type-checked-only.ts b/packages/eslint-plugin/src/configs/strict-type-checked-only.ts
@@ -61,10 +61,10 @@ export = {
       {
         allowAny: false,
         allowBoolean: false,
+        allowNever: false,
         allowNullish: false,
         allowNumber: false,
         allowRegExp: false,
-        allowNever: false,
       },
     ],
     '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
@@ -79,6 +79,7 @@ export = {
     '@typescript-eslint/related-getter-setter-pairs': '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
@@ -43,6 +43,7 @@ export = {
     '@typescript-eslint/prefer-as-const': 'error',
     '@typescript-eslint/prefer-literal-enum-member': 'error',
     '@typescript-eslint/prefer-namespace-keyword': '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
@@ -73,13 +73,13 @@ function typeNeedsParentheses(node: TSESTree.Node): boolean {
 }
 
 export type OptionString = 'array' | 'array-simple' | 'generic';
-type Options = [
+export type Options = [
   {
     default: OptionString;
     readonly?: OptionString;
   },
 ];
-type MessageIds =
+export type MessageIds =
   | 'errorStringArray'
   | 'errorStringArrayReadonly'
   | 'errorStringArraySimple'

diff --git a/packages/eslint-plugin/src/rules/await-thenable.ts b/packages/eslint-plugin/src/rules/await-thenable.ts
@@ -15,7 +15,7 @@ import {
 } from '../util';
 import { getForStatementHeadLoc } from '../util/getForStatementHeadLoc';
 
-type MessageId =
+export type MessageId =
   | 'await'
   | 'awaitUsingOfNonAsyncDisposable'
   | 'convertToOrdinaryFor'

diff --git a/packages/eslint-plugin/src/rules/ban-ts-comment.ts b/packages/eslint-plugin/src/rules/ban-ts-comment.ts
@@ -4,12 +4,12 @@ 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 {
   minimumDescriptionLength?: number;
   'ts-check'?: DirectiveConfig;
   'ts-expect-error'?: DirectiveConfig;
@@ -19,7 +19,7 @@ interface Options {
 
 const defaultMinimumDescriptionLength = 3;
 
-type MessageIds =
+export type MessageIds =
   | 'replaceTsIgnoreWithTsExpectError'
   | 'tsDirectiveComment'
   | '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
@@ -11,8 +11,8 @@ 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
@@ -9,15 +9,15 @@ import {
   getStaticMemberAccessValue,
 } from '../util';
 
-type Options = [
+export type Options = [
   {
     enforceForClassFields?: boolean;
     exceptMethods?: string[];
     ignoreClassesThatImplementAnInterface?: boolean | 'public-fields';
     ignoreOverrideMethods?: boolean;
   },
 ];
-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/consistent-generic-constructors.ts b/packages/eslint-plugin/src/rules/consistent-generic-constructors.ts
@@ -4,8 +4,8 @@ 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
@@ -10,11 +10,11 @@ import {
   nullThrows,
 } from '../util';
 
-type MessageIds =
+export type MessageIds =
   | 'preferIndexSignature'
   | 'preferIndexSignatureSuggestion'
   | 'preferRecord';
-type Options = ['index-signature' | 'record'];
+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
@@ -13,10 +13,10 @@ 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.ArrowFunctionExpression
   | TSESTree.FunctionDeclaration
   | TSESTree.FunctionExpression;

diff --git a/packages/eslint-plugin/src/rules/consistent-type-assertions.ts b/packages/eslint-plugin/src/rules/consistent-type-assertions.ts
@@ -21,7 +21,7 @@ export type MessageIds =
   | 'replaceObjectTypeAssertionWithAnnotation'
   | 'replaceObjectTypeAssertionWithSatisfies'
   | 'unexpectedObjectTypeAssertion';
-type OptUnion =
+export type OptUnion =
   | {
       assertionStyle: 'angle-bracket' | 'as';
       objectLiteralTypeAssertions?: 'allow' | 'allow-as-parameter' | 'never';

diff --git a/packages/eslint-plugin/src/rules/consistent-type-exports.ts b/packages/eslint-plugin/src/rules/consistent-type-exports.ts
@@ -14,7 +14,7 @@ import {
   NullThrowsReasons,
 } from '../util';
 
-type Options = [
+export type Options = [
   {
     fixMixedExportsWithInlineTypeSpecifier: boolean;
   },
@@ -34,7 +34,7 @@ interface ReportValueExport {
   valueSpecifiers: 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
@@ -16,10 +16,10 @@ 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 = [
   {
     disallowTypeAnnotations?: boolean;
     fixStyle?: FixStyle;
@@ -45,7 +45,7 @@ interface ReportValueImport {
   valueSpecifiers: TSESTree.ImportClause[];
 }
 
-type MessageIds =
+export type MessageIds =
   | 'avoidImportType'
   | 'noImportTypeAnnotations'
   | 'someImportsAreOnlyTypes'

diff --git a/packages/eslint-plugin/src/rules/explicit-function-return-type.ts b/packages/eslint-plugin/src/rules/explicit-function-return-type.ts
@@ -11,7 +11,7 @@ import {
   isValidFunctionExpressionReturnType,
 } from '../util/explicitReturnTypeUtils';
 
-type Options = [
+export type Options = [
   {
     allowConciseArrowFunctionExpressionsStartingWithVoid?: boolean;
     allowDirectConstAssertionInArrowFunctions?: boolean;
@@ -23,7 +23,7 @@ type Options = [
     allowTypedFunctionExpressions?: 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
@@ -14,12 +14,12 @@ import {
 } from '../util/getMemberHeadLoc';
 import { rangeToLoc } from '../util/rangeToLoc';
 
-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?: {
@@ -31,9 +31,9 @@ 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
@@ -18,7 +18,7 @@ import {
   isTypedFunctionExpression,
 } from '../util/explicitReturnTypeUtils';
 
-type Options = [
+export type Options = [
   {
     allowArgumentsExplicitlyTypedAsAny?: boolean;
     allowDirectConstAssertionInArrowFunctions?: boolean;
@@ -27,7 +27,7 @@ type Options = [
     allowTypedFunctionExpressions?: boolean;
   },
 ];
-type MessageIds =
+export type MessageIds =
   | 'anyTypedArg'
   | 'anyTypedArgUnnamed'
   | 'missingArgType'