Update docs and examples for async params in Next.js 15

[ChristianIvicevic]

Link to page

https://next-intl-docs.vercel.app/docs/getting-started/app-router/with-i18n-routing#layout

Describe the problem

The change required is pretty simple as it's just the following:

export default async function LocaleLayout({
  children,
- params: {locale},
+ params,
}: {
  children: React.ReactNode;
- params: {locale: string};
+ params: Promise<{locale: string}>;
}) {
+ const locale = (await params).locale;
// ...

The issue is that the docs wouldn't be correct for Next 14 if this diff was to be applied. As such I didn't want to open a PR straight away and wanted to start a conversation how to proceed here from a UX-perspective.

• Should two tabs be introduced like in this example to distinguish Next 14 and 15? https://next-intl-docs.vercel.app/docs/getting-started/app-router/without-i18n-routing#next-config
• Should a separate page for v15 be introduced?
• Should a short paragraph be added that explains this particular required diff?

[amannn]

I've created a PR for Next.js to address the issue with alternate links: vercel/next.js#73431. Once that is merged, I'd like to finally suggest updating to Next.js 15 in the docs & examples (see #1089). I saw many users run into this bug so far and I can't really recommend Next.js 15 for setups with i18n routing at this point since it's too easy to miss :-/.