t from getTranslations({locale, namespace}) can`t receive any arguments when not using typed messages

[SergGen]

Description

When calling t from getTranslations with correct argument, the IDE shows on t argument this TypeScript error: TS2345: An argument of type string is not assigned to a parameter of type never. This error appears also when is building.
This error appears in next-intl starting from version 3.0.0-rc.10. In version 3.0.1, this error is also present.
IDE show this type of t:

const t: <>(key: never, values?: (TranslationValues | undefined), formats?: (Partial<Formats> | undefined)) => string

Sample code with this error:

export async function generateMetadata({ params: { locale } }: { params: { locale: 'en' | 'de' } }) {
      const t = await getTranslations({ locale, namespace: 'pages.metadata' });
      return { title: t('title'), description: t('description')};
}

I am using IDE Webstorm 2023.2.5. TypeScript version 5.2.2. Next.js version 14.0.2.

CodeSandbox reproduction do not show this error. This error is in IDE with TypeScript and building.

Expected behaviour

I want there to be no TypeScript error: TS2345: An argument of type string is not assigned to a parameter of type never.

[amannn]

To be able to look into this, a reproduction would be required. Maybe your IDE uses another version of TypeScript that reports a false positive (instead of the local one)?

This repo also uses typescript@^5.2.2 and the getTranslations API is working.

What I did notice so far is that getTranslations({locale, namespace: ''}) for some reason doesn't display autocomplete in VSCode, while getTranslations('') does. However, both validate correctly and will show errors if an invalid string is provided. Not sure if a fix is required on the TypeScript side or next-intl.

[SergGen]

I cloned your example and compared the package versions with my project. It's all the same.
Your example works and builds correctly.

I don't understand why this error occurs in my project...

An IDE should not affect the build process. Build error still appear in terminal.

Type error: Argument of type 'string' is not assignable to parameter of type 'never'.

When next-intl version set to 3.0.0-rc.9, there are no any error.

[tianyingchun]

i have update to 3.0.1 face this issue too

export async function generateMetadata({ params: { locale } }: PageProps) {
  const t = await getTranslations({ locale, namespace: 'IndexPage' });
  return {
    title: t('title'),
  };
}

namespace: 'IndexPage' can not show typings auto promoting, but it can verify if IndexPage correct.

useTranslations() works fine.

[amannn]

Ah, I think I found the error!

The error happens when you don't use the TypeScript integration of next-intl.

As a temporary workaround, you can define this in a file like ./global.d.ts:

// Temporary workaround for https://github.com/amannn/next-intl/issues/625
type Messages = any
declare interface IntlMessages extends Messages {}

getTranslations(namespace) doesn't seem to be affected.

I'll look into a proper fix. Thanks for the report!

[tianyingchun]

// Use type safe message keys with `next-intl`
type Messages = typeof import('./messages/en.json');
declare interface IntlMessages extends Messages {}

3.0.2 also has this issue.
@amannn

[tianyingchun]

[email protected]

Nothing prompting here it should give tips `

[amannn]

Yep, I noticed too that somehow TypeScript doesn't provide autocomplete for this case. However, errors are correctly detected. Note that this only affects the object form, not when calling getTranslations(namespace?).

If some TypeScript wizard would like to have a look, I'd really appreciate it!

[tianyingchun]

haha, Expect ts experts to help :) have no idea

[CreativeArtDesign]

I trying to do this.

but it does not find my string and my string is right.
import {getTranslations} from 'next-intl/server';

const local = "sv" // MANUALLY SPECIFIED LOCALE
const t = await getTranslations({
locale: local, // OR "en" BASED ON THE DESIRED LOCALE
namespaces: ["Notifications"],
})

error:

IntlError: MISSING_MESSAGE: Could not resolve ResetYourPassword in messages for locale sv.

I use
version 3.7.0