next.js

c201b3d3 - Allow `metadataBase` to be a string URL in addition to `URL` instance (#84297)

Allow `metadataBase` to be a string URL in addition to `URL` instance (#84297) As of #49343, in dev mode only, we accidentally change the `metadataBase` from an `URL` instance to a URL string, when passing it to child layouts or pages via the `parent` argument in `generateMetadata`. This is because we clone the metadata object via `JSON.stringify`/`parse` and then freeze it, to prevent relying on mutating resolved metadata. The replacer/reviver functions we used to clone the metadata didn't properly handle preserving `URL` instances as intended, so they were turned into strings. Because user code already had to handle the case of `metadataBase` potentially being a string at runtime in dev mode, we can just officially reflect that as well in our types, not only for the `ResolvedMetadata` input type, but also for the `Metadata` output type. This also enables `'use cache'` being used in `generateMetadata`, because React currently does not support transporting `URL` instances from one environment to another (e.g. `Server` to `Cache`). Note that all other URL properties in `Metadata` and `ResolvedMetadata` already allowed `string`, so this only affects `metadataBase`. To resolve the ambiguity between dev and prod, we're now always transforming all URL instances to strings, before passing the resolved metadata to `generateMetadata`. This is also reflected in the `ResolvedMetadata` type.