fix(loader_tree): propagate metadata to corresponding layout

[kwonoj]

What?

• fixes test

  next.js/test/e2e/app-dir/metadata/metadata.test.ts

  Line 487 in 17553c5

  it('should pick up opengraph-image and twitter-image as static metadata files', async () => {

The way next.js collects static metadata is read static metadata, and then read layout metadata to merge multiple metadatas into a single layout path (

next.js/packages/next/src/lib/metadata/resolve-metadata.ts

Lines 347 to 352 in 17553c5

	const staticFilesMetadata = await resolveStaticMetadata(tree[2], props)
	const metadataExport = mod
	? await getDefinedMetadata(mod, props, { route })
	: null
	metadataItems.push([metadataExport, staticFilesMetadata])

)

When turbopack creates LoaderTree for the corresponding directory tree, it extracts page but skips metadata in result there are orphan components that have a metadata doesn't have layout metadata, as well as a component have a layout doesn't have metadata. Latter is being rendered as a page (since it have correct layout), which eventually falls back to the default metadata instead.

PR trickles down the metadata when extracting page (creating a new component with page) to consolidates those.

Also PR expands Metadata to have base_page property to capture where it has been originally exists, as we clone down metadata then do fillMetadataSegment against the current page where LoaderTree is being created it creates a wrong relative path. For example, currently

/icon.svg
 - opengragph/
      - static -> path being `/opengraph/.../icon.svg` instead of `/icon.svg`

When recursively traverse directory tree, capture each components with corresponding base_page to calculate instead.

Unfortunately this doesn't make pass all of the metadata tests; there are lot to dig more. Would like to scope PR in a reasonable size.

Closes WEB-1795

[ijjk]

Stats from current PR

Default Build

General

	vercel/next.js canary	vercel/next.js app-dir-metadata	Change
buildDuration	10.4s	10.4s	N/A
buildDurationCached	6.1s	6.1s	N/A
nodeModulesSize	174 MB	174 MB	✓
nextStartRea..uration (ms)	520ms	518ms	N/A

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js app-dir-metadata	Change
199-HASH.js gzip	27.6 kB	27.6 kB	✓
3f784ff6-HASH.js gzip	53.3 kB	53.3 kB	✓
99.HASH.js gzip	182 B	182 B	✓
framework-HASH.js gzip	45.3 kB	45.3 kB	✓
main-app-HASH.js gzip	254 B	252 B	N/A
main-HASH.js gzip	32.9 kB	32.9 kB	N/A
webpack-HASH.js gzip	1.75 kB	1.75 kB	N/A
Overall change	126 kB	126 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js app-dir-metadata	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js app-dir-metadata	Change
_app-HASH.js gzip	206 B	205 B	N/A
_error-HASH.js gzip	182 B	180 B	N/A
amp-HASH.js gzip	506 B	505 B	N/A
css-HASH.js gzip	322 B	323 B	N/A
dynamic-HASH.js gzip	2.57 kB	2.57 kB	N/A
edge-ssr-HASH.js gzip	260 B	259 B	N/A
head-HASH.js gzip	350 B	350 B	✓
hooks-HASH.js gzip	369 B	369 B	✓
image-HASH.js gzip	4.36 kB	4.36 kB	N/A
index-HASH.js gzip	256 B	256 B	✓
link-HASH.js gzip	2.64 kB	2.63 kB	N/A
routerDirect..HASH.js gzip	312 B	311 B	N/A
script-HASH.js gzip	385 B	384 B	N/A
withRouter-HASH.js gzip	307 B	308 B	N/A
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Overall change	1.08 kB	1.08 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js app-dir-metadata	Change
_buildManifest.js gzip	484 B	482 B	N/A
Overall change	0 B	0 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js app-dir-metadata	Change
index.html gzip	528 B	529 B	N/A
link.html gzip	541 B	542 B	N/A
withRouter.html gzip	523 B	524 B	N/A
Overall change	0 B	0 B	✓

Edge SSR bundle Size

	vercel/next.js canary	vercel/next.js app-dir-metadata	Change
edge-ssr.js gzip	93.8 kB	93.8 kB	N/A
page.js gzip	155 kB	155 kB	N/A
Overall change	0 B	0 B	✓

Middleware size

	vercel/next.js canary	vercel/next.js app-dir-metadata	Change
middleware-b..fest.js gzip	625 B	622 B	N/A
middleware-r..fest.js gzip	150 B	151 B	N/A
middleware.js gzip	22.9 kB	22.9 kB	N/A
edge-runtime..pack.js gzip	1.92 kB	1.92 kB	✓
Overall change	1.92 kB	1.92 kB	✓

Commit: ed91e66

[ijjk]

Tests Passed

[huozhi]

what will the full url of /favicon.ico? we expect /favicon.ico is the fixed one for backcompatible

[kwonoj]

Turbopack currently puts a querystring after favicon.ico with its hashes. So if file's the same url would be probably remain as-is.

[sokra]

Suggested change

	let components = if components.metadata.base_page.is_some() {
	components
	} else {
	(Components {
	metadata: Metadata {
	base_page: Some(app_page.clone()),
	..components.metadata.clone()
	},
	..*components
	})
	.cell()
	.await?
	};
	let components = if components.metadata.base_page.is_some() {
	Cow::Borrowed(&components)
	} else {
	Cow::Owned(Components {
	metadata: Metadata {
	base_page: Some(app_page.clone()),
	..components.metadata.clone()
	},
	..*components
	})
	};

No need to cell and read it