chore: Strict type imports with ESLint

packages/next-intl/eslint.config.mjs

@@ -21,6 +21,12 @@ export default (await getPresets('typescript', 'react', 'vitest')).concat({
           }
         ]
       }
-    ]
+    ],
+
+    // Strict type imports to avoid side effects
+    '@typescript-eslint/consistent-type-imports': 'error',
+    '@typescript-eslint/consistent-type-exports': 'error',
+    '@typescript-eslint/no-import-type-side-effects': 'error',
+    'import/no-duplicates': ['error', {'prefer-inline': true}]
   }
 });

packages/next-intl/src/middleware/getAlternateLinksHeaderValue.test.tsx

@@ -3,7 +3,7 @@
 import {NextRequest} from 'next/server.js';
 import {afterEach, beforeEach, describe, expect, it} from 'vitest';
 import {receiveRoutingConfig} from '../routing/config.tsx';
-import {Pathnames} from '../routing.tsx';
+import type {Pathnames} from '../routing.tsx';
 import getAlternateLinksHeaderValue from './getAlternateLinksHeaderValue.tsx';
 
 describe.each([{basePath: undefined}, {basePath: '/base'}])(

packages/next-intl/src/middleware/getAlternateLinksHeaderValue.tsx

@@ -1,6 +1,6 @@
-import {NextRequest} from 'next/server.js';
-import {ResolvedRoutingConfig} from '../routing/config.tsx';
-import {
+import type {NextRequest} from 'next/server.js';
+import type {ResolvedRoutingConfig} from '../routing/config.tsx';
+import type {
   DomainsConfig,
   LocalePrefixMode,
   Locales,

packages/next-intl/src/middleware/middleware.test.tsx

@@ -3,9 +3,17 @@
 import {RequestCookies} from 'next/dist/compiled/@edge-runtime/cookies';
 import {NextRequest, NextResponse} from 'next/server.js';
 import {pathToRegexp} from 'path-to-regexp';
-import {Mock, afterEach, beforeEach, describe, expect, it, vi} from 'vitest';
+import {
+  type Mock,
+  afterEach,
+  beforeEach,
+  describe,
+  expect,
+  it,
+  vi
+} from 'vitest';
 import createMiddleware from '../middleware.tsx';
-import {Pathnames, defineRouting} from '../routing.tsx';
+import {type Pathnames, defineRouting} from '../routing.tsx';
 
 const COOKIE_LOCALE_NAME = 'NEXT_LOCALE';
 

packages/next-intl/src/middleware/middleware.tsx

@@ -1,6 +1,6 @@
-import {NextRequest, NextResponse} from 'next/server.js';
-import {RoutingConfig, receiveRoutingConfig} from '../routing/config.tsx';
-import {
+import {type NextRequest, NextResponse} from 'next/server.js';
+import {type RoutingConfig, receiveRoutingConfig} from '../routing/config.tsx';
+import type {
   DomainsConfig,
   LocalePrefixMode,
   Locales,

packages/next-intl/src/middleware/resolveLocale.tsx

@@ -1,9 +1,9 @@
 import {match} from '@formatjs/intl-localematcher';
 import Negotiator from 'negotiator';
-import {RequestCookies} from 'next/dist/server/web/spec-extension/cookies.js';
+import type {RequestCookies} from 'next/dist/server/web/spec-extension/cookies.js';
 import type {Locale} from 'use-intl';
-import {ResolvedRoutingConfig} from '../routing/config.tsx';
-import {
+import type {ResolvedRoutingConfig} from '../routing/config.tsx';
+import type {
   DomainConfig,
   DomainsConfig,
   LocalePrefixMode,

packages/next-intl/src/middleware/syncCookie.tsx

@@ -1,10 +1,10 @@
-import {NextRequest, NextResponse} from 'next/server.js';
+import type {NextRequest, NextResponse} from 'next/server.js';
 import type {Locale} from 'use-intl';
-import {
+import type {
   InitializedLocaleCookieConfig,
   ResolvedRoutingConfig
 } from '../routing/config.tsx';
-import {
+import type {
   DomainConfig,
   DomainsConfig,
   LocalePrefixMode,

packages/next-intl/src/middleware/utils.tsx

@@ -1,5 +1,5 @@
 import type {Locale} from 'use-intl';
-import {
+import type {
   DomainConfig,
   DomainsConfig,
   LocalePrefixConfigVerbose,

packages/next-intl/src/navigation/createNavigation.test.tsx

@@ -5,9 +5,13 @@ import {
   redirect as nextRedirect
 } from 'next/navigation.js';
 import {renderToString} from 'react-dom/server';
-import {Locale, useLocale} from 'use-intl';
+import {type Locale, useLocale} from 'use-intl';
 import {beforeEach, describe, expect, it, vi} from 'vitest';
-import {DomainsConfig, Pathnames, defineRouting} from '../routing.tsx';
+import {
+  type DomainsConfig,
+  type Pathnames,
+  defineRouting
+} from '../routing.tsx';
 import createNavigationClient from './react-client/createNavigation.tsx';
 import createNavigationServer from './react-server/createNavigation.tsx';
 import getServerLocale from './react-server/getServerLocale.tsx';

packages/next-intl/src/navigation/react-client/createNavigation.test.tsx

@@ -3,10 +3,9 @@ import {
   usePathname as useNextPathname,
   useRouter as useNextRouter
 } from 'next/navigation.js';
-import type {Locale} from 'use-intl';
-import {useLocale} from 'use-intl';
+import {type Locale, useLocale} from 'use-intl';
 import {beforeEach, describe, expect, it, vi} from 'vitest';
-import {DomainsConfig, Pathnames} from '../../routing.tsx';
+import type {DomainsConfig, Pathnames} from '../../routing.tsx';
 import createNavigation from './createNavigation.tsx';
 
 vi.mock('next/navigation.js');

packages/next-intl/src/navigation/react-client/createNavigation.tsx

@@ -4,11 +4,11 @@ import {
 } from 'next/navigation.js';
 import {useMemo} from 'react';
 import {type Locale, useLocale} from 'use-intl';
-import {
+import type {
   RoutingConfigLocalizedNavigation,
   RoutingConfigSharedNavigation
 } from '../../routing/config.tsx';
-import {
+import type {
   DomainsConfig,
   LocalePrefixMode,
   Locales,

packages/next-intl/src/navigation/react-client/useBasePathname.tsx

@@ -1,7 +1,7 @@
 import {usePathname as useNextPathname} from 'next/navigation.js';
 import {useMemo} from 'react';
 import {useLocale} from 'use-intl';
-import {
+import type {
   LocalePrefixConfigVerbose,
   LocalePrefixMode,
   Locales

packages/next-intl/src/navigation/react-server/createNavigation.tsx

@@ -1,8 +1,8 @@
-import {
+import type {
   RoutingConfigLocalizedNavigation,
   RoutingConfigSharedNavigation
 } from '../../routing/config.tsx';
-import {
+import type {
   DomainsConfig,
   LocalePrefixMode,
   Locales,

packages/next-intl/src/navigation/shared/BaseLink.tsx

@@ -1,17 +1,17 @@
 'use client';
 
-import NextLink, {LinkProps} from 'next/link.js';
+import NextLink, {type LinkProps} from 'next/link.js';
 import {usePathname} from 'next/navigation.js';
 import {
-  ComponentProps,
-  MouseEvent,
-  Ref,
+  type ComponentProps,
+  type MouseEvent,
+  type Ref,
   forwardRef,
   useEffect,
   useState
 } from 'react';
 import {type Locale, useLocale} from 'use-intl';
-import {InitializedLocaleCookieConfig} from '../../routing/config.tsx';
+import type {InitializedLocaleCookieConfig} from '../../routing/config.tsx';
 import syncLocaleCookie from './syncLocaleCookie.tsx';
 
 type NextLinkProps = Omit<ComponentProps<'a'>, keyof LinkProps> &

packages/next-intl/src/navigation/shared/createSharedNavigationFns.tsx

@@ -2,28 +2,28 @@ import {
   permanentRedirect as nextPermanentRedirect,
   redirect as nextRedirect
 } from 'next/navigation.js';
-import {ComponentProps, forwardRef} from 'react';
+import {type ComponentProps, forwardRef} from 'react';
 import type {Locale} from 'use-intl';
 import {
-  RoutingConfigLocalizedNavigation,
-  RoutingConfigSharedNavigation,
+  type RoutingConfigLocalizedNavigation,
+  type RoutingConfigSharedNavigation,
   receiveRoutingConfig
 } from '../../routing/config.tsx';
-import {
+import type {
   DomainConfig,
   DomainsConfig,
   LocalePrefixMode,
   Locales,
   Pathnames
 } from '../../routing/types.tsx';
-import {ParametersExceptFirst, Prettify} from '../../shared/types.tsx';
+import type {ParametersExceptFirst, Prettify} from '../../shared/types.tsx';
 import use from '../../shared/use.tsx';
 import {isLocalizableHref} from '../../shared/utils.tsx';
 import BaseLink from './BaseLink.tsx';
 import {
-  HrefOrHrefWithParams,
-  HrefOrUrlObjectWithParams,
-  QueryParams,
+  type HrefOrHrefWithParams,
+  type HrefOrUrlObjectWithParams,
+  type QueryParams,
   applyPathnamePrefix,
   compileLocalizedPathname,
   normalizeNameOrNameWithParams,

packages/next-intl/src/navigation/shared/syncLocaleCookie.tsx

@@ -1,5 +1,5 @@
 import type {Locale} from 'use-intl';
-import {InitializedLocaleCookieConfig} from '../../routing/config.tsx';
+import type {InitializedLocaleCookieConfig} from '../../routing/config.tsx';
 import {getBasePath} from './utils.tsx';
 
 /**

packages/next-intl/src/navigation/shared/utils.tsx

@@ -1,8 +1,8 @@
 import type {ParsedUrlQueryInput} from 'node:querystring';
 import type {UrlObject} from 'url';
 import type {Locale} from 'use-intl';
-import {ResolvedRoutingConfig} from '../../routing/config.tsx';
-import {
+import type {ResolvedRoutingConfig} from '../../routing/config.tsx';
+import type {
   DomainsConfig,
   LocalePrefixMode,
   Locales,
@@ -16,7 +16,7 @@ import {
   normalizeTrailingSlash,
   prefixPathname
 } from '../../shared/utils.tsx';
-import StrictParams from './StrictParams.tsx';
+import type StrictParams from './StrictParams.tsx';
 
 type SearchParamValue = ParsedUrlQueryInput[keyof ParsedUrlQueryInput];
 

packages/next-intl/src/plugin/getNextConfig.tsx

@@ -1,7 +1,7 @@
 import fs from 'fs';
 import path from 'path';
-import {NextConfig} from 'next';
-import {PluginConfig} from './types.tsx';
+import type {NextConfig} from 'next';
+import type {PluginConfig} from './types.tsx';
 import {throwError} from './utils.tsx';
 
 function withExtensions(localPath: string) {

packages/next-intl/src/react-server/NextIntlClientProviderServer.tsx

@@ -1,4 +1,4 @@
-import {ComponentProps} from 'react';
+import type {ComponentProps} from 'react';
 import getConfigNow from '../server/react-server/getConfigNow.tsx';
 import getFormats from '../server/react-server/getFormats.tsx';
 import {getLocale, getTimeZone} from '../server.react-server.tsx';

packages/next-intl/src/react-server/testUtils.tsx

@@ -1,8 +1,9 @@
-import {ReactNode, Suspense} from 'react';
-import {ReactDOMServerReadableStream} from 'react-dom/server';
+import {type ReactNode, Suspense} from 'react';
+import type {ReactDOMServerReadableStream} from 'react-dom/server';
 // @ts-expect-error -- Not available in types
 import {renderToReadableStream as _renderToReadableStream} from 'react-dom/server.browser';
 
+// eslint-disable-next-line @typescript-eslint/consistent-type-imports
 const renderToReadableStream: typeof import('react-dom/server').renderToReadableStream =
   _renderToReadableStream;
 

packages/next-intl/src/routing/config.tsx

@@ -1,5 +1,5 @@
 import type {NextResponse} from 'next/server.js';
-import {
+import type {
   DomainsConfig,
   LocalePrefix,
   LocalePrefixConfigVerbose,

packages/next-intl/src/routing/defineRouting.tsx

@@ -1,5 +1,10 @@
-import {RoutingConfig} from './config.tsx';
-import {DomainsConfig, LocalePrefixMode, Locales, Pathnames} from './types.tsx';
+import type {RoutingConfig} from './config.tsx';
+import type {
+  DomainsConfig,
+  LocalePrefixMode,
+  Locales,
+  Pathnames
+} from './types.tsx';
 
 export default function defineRouting<
   const AppLocales extends Locales,

packages/next-intl/src/routing/types.test.tsx

@@ -1,6 +1,6 @@
 /* eslint-disable @typescript-eslint/no-unused-vars */
 import {describe, it} from 'vitest';
-import {DomainConfig, LocalePrefix} from './types.tsx';
+import type {DomainConfig, LocalePrefix} from './types.tsx';
 
 describe('LocalePrefix', () => {
   it('does not require a type param for simple values', () => {

packages/next-intl/src/server/react-server/RequestLocale.tsx

@@ -1,6 +1,6 @@
 import {headers} from 'next/headers.js';
 import {cache} from 'react';
-import {Locale} from 'use-intl';
+import type {Locale} from 'use-intl';
 import {HEADER_LOCALE_NAME} from '../../shared/constants.tsx';
 import {getCachedRequestLocale} from './RequestLocaleCache.tsx';
 

packages/next-intl/src/server/react-server/getConfig.tsx

@@ -1,14 +1,14 @@
 import {cache} from 'react';
 import {
-  IntlConfig,
+  type IntlConfig,
   type Locale,
   _createCache,
   _createIntlFormatters,
   initializeConfig
 } from 'use-intl/core';
 import {getRequestLocale} from './RequestLocale.tsx';
 import createRequestConfig from './createRequestConfig.tsx';
-import {GetRequestConfigParams} from './getRequestConfig.tsx';
+import type {GetRequestConfigParams} from './getRequestConfig.tsx';
 
 // This is automatically inherited by `NextIntlClientProvider` if
 // the component is rendered from a Server Component

packages/next-intl/src/server/react-server/getFormatter.tsx

@@ -1,5 +1,5 @@
 import {cache} from 'react';
-import {type Locale, createFormatter} from 'use-intl/core';
+import type {Locale, createFormatter} from 'use-intl/core';
 import getConfig from './getConfig.tsx';
 import getServerFormatter from './getServerFormatter.tsx';
 

packages/next-intl/src/server/react-server/getLocale.tsx

@@ -1,5 +1,5 @@
 import {cache} from 'react';
-import {Locale} from 'use-intl';
+import type {Locale} from 'use-intl';
 import getConfig from './getConfig.tsx';
 
 async function getLocaleCachedImpl(): Promise<Locale> {

packages/next-intl/src/server/react-server/getServerTranslator.tsx

@@ -1,8 +1,8 @@
 import {cache} from 'react';
 import {
-  Messages,
-  NamespaceKeys,
-  NestedKeyOf,
+  type Messages,
+  type NamespaceKeys,
+  type NestedKeyOf,
   createTranslator
 } from 'use-intl/core';
 

packages/next-intl/src/server/react-server/getTranslations.tsx

@@ -1,5 +1,5 @@
 import {cache} from 'react';
-import {
+import type {
   Locale,
   Messages,
   NamespaceKeys,

packages/next-intl/src/shared/NextIntlClientProvider.tsx

@@ -1,7 +1,7 @@
 'use client';
 
-import {ComponentProps} from 'react';
-import {type Locale} from 'use-intl';
+import type {ComponentProps} from 'react';
+import type {Locale} from 'use-intl';
 import {IntlProvider} from 'use-intl/react';
 
 type Props = Omit<ComponentProps<typeof IntlProvider>, 'locale'> & {

packages/next-intl/src/shared/utils.tsx

@@ -1,5 +1,5 @@
-import {LinkProps} from 'next/link.js';
-import {
+import type {LinkProps} from 'next/link.js';
+import type {
   LocalePrefixConfigVerbose,
   LocalePrefixMode,
   Locales

packages/use-intl/eslint.config.mjs

@@ -6,6 +6,12 @@ export default (await getPresets('typescript', 'react', 'vitest')).concat({
     'react-compiler': reactCompilerPlugin
   },
   rules: {
-    'react-compiler/react-compiler': 'error'
+    'react-compiler/react-compiler': 'error',
+
+    // Strict type imports to avoid side effects
+    '@typescript-eslint/consistent-type-imports': 'error',
+    '@typescript-eslint/consistent-type-exports': 'error',
+    '@typescript-eslint/no-import-type-side-effects': 'error',
+    'import/no-duplicates': ['error', {'prefer-inline': true}]
   }
 });