fix(metadata): align metadata suffix hash between turbopack

[kwonoj]

What?

Wraps up metadata-dynamic-routes tests fixes for the turbopack. There is 1 remaining failing test due to lacks of supporting import.meta.url which need to be addressed separately.

I spent amount of time why turbopack cannot find the route for the dynamic metadata for a certain route. In the end, found there are mismatching expectations for the route due to different hash for the certain route. We do use the same djb2 hash between next.js and turbopack both, so it was quite confusing why we don't get deterministic hash.

After trying some experiments, found out root cause was how 2 different runtimes handle overflow for given type of numbers. In rust + turbpack we use u32 and do 32-bit hash calculation for given string, while in js we implicitly used number type as is, in result overflow occurs with default 53-bit float.

Originally I tried to adjust hash in turbopack side to preserve js hash as-is, but so far I found it was non trivial to do so as rust there's no out of the box types we can coerce to the js number type. In result, unlike other fixes in turbopack this PR changes how js hash is being generated. I hope this woulndn't be a breaking changes; expect so since this is a metadata specific hash that we do not have written spec for it.

Closes WEB-1890

[ijjk]

Tests Passed

[ijjk]

Stats from current PR

Default Build

General Overall increase ⚠️

	vercel/next.js canary	vercel/next.js metadata-dynamic	Change
buildDuration	10.4s	10.4s	N/A
buildDurationCached	5.9s	6s	N/A
nodeModulesSize	175 MB	175 MB	⚠️ +2.36 kB
nextStartRea..uration (ms)	416ms	422ms	N/A

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js metadata-dynamic	Change
199-HASH.js gzip	30 kB	30 kB	N/A
3f784ff6-HASH.js gzip	53.2 kB	53.2 kB	✓
99.HASH.js gzip	182 B	182 B	✓
framework-HASH.js gzip	45.5 kB	45.5 kB	✓
main-app-HASH.js gzip	254 B	252 B	N/A
main-HASH.js gzip	33.1 kB	33.1 kB	N/A
webpack-HASH.js gzip	1.75 kB	1.75 kB	N/A
Overall change	98.9 kB	98.9 kB	✓

Legacy Client Bundles (polyfills)

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

Client Pages

	vercel/next.js canary	vercel/next.js metadata-dynamic	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	2.59 kB	2.59 kB	✓
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	4.38 kB	4.38 kB	N/A
index-HASH.js gzip	256 B	256 B	✓
link-HASH.js gzip	2.67 kB	2.67 kB	N/A
routerDirect..HASH.js gzip	316 B	318 B	N/A
script-HASH.js gzip	385 B	384 B	N/A
withRouter-HASH.js gzip	319 B	319 B	✓
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Overall change	3.99 kB	3.99 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js metadata-dynamic	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 metadata-dynamic	Change
index.html gzip	527 B	529 B	N/A
link.html gzip	540 B	542 B	N/A
withRouter.html gzip	522 B	523 B	N/A
Overall change	0 B	0 B	✓

Edge SSR bundle Size

	vercel/next.js canary	vercel/next.js metadata-dynamic	Change
edge-ssr.js gzip	96.1 kB	96.1 kB	N/A
page.js gzip	140 kB	140 kB	N/A
Overall change	0 B	0 B	✓

Middleware size

	vercel/next.js canary	vercel/next.js metadata-dynamic	Change
middleware-b..fest.js gzip	625 B	623 B	N/A
middleware-r..fest.js gzip	150 B	151 B	N/A
middleware.js gzip	23 kB	23 kB	N/A
edge-runtime..pack.js gzip	1.92 kB	1.92 kB	✓
Overall change	1.92 kB	1.92 kB	✓

Diff details

Diff for page.js

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Diff for 199-HASH.js

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Commit: e9cc837

[jridgewell]

Nit: I think you can

Suggested change

	result.reverse();
	result[..6].iter().collect()
	result.into_iter().rev().take(6).collect()

[ForsakenHarmony]

was actually looking into this and the rust version that more closely matches the js version would have been

fn djb2_hash(str: &str) -> u64 {
    let mut hash: f64 = 5381.0;
    for char in str.chars() {
        let code = char as u64 as f64;
        let tmp_hash = (hash as i64 as i32) << 5;
        hash = (tmp_hash as f64) + hash + code; 
    }
    hash.abs() as u64
}

but changing the js version is probably better

[ForsakenHarmony]

this should happen in get_metadata_route_suffix below, not in here