Turbopack: Annotate ReadVcFuture as must_use instead of annotating functions that return it by bgw · Pull Request #90839 · vercel/next.js

bgw · 2026-03-03T22:40:38Z

It's a little less error-prone if it's in one place (on the type) than in many (on the functions). I also added it to ReadRawVcFuture.

https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-must_use-attribute

Are these equivalent? Yes.
The Future trait already has this annotation, why do we need it on the type? The annotation on the trait only applies if the function returns impl Future or dyn Future. Our functions return the named type.

bgw · 2026-03-03T22:40:54Z

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codspeed-hq · 2026-03-03T23:01:32Z

Merging this PR will not alter performance

✅ 17 untouched benchmarks
⏩ 3 skipped benchmarks¹

_{Comparing bgw/read-vc-future-must-use (cf29870) with canary (3beb466)²}

3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩
No successful run was found on canary (73049d6) during the generation of this report, so 3beb466 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

nextjs-bot · 2026-03-03T23:02:51Z

Stats from current PR

✅ No significant changes detected

📊 All Metrics

📖 Metrics Glossary

Dev Server Metrics:

Listen = TCP port starts accepting connections
First Request = HTTP server returns successful response
Cold = Fresh build (no cache)
Warm = With cached build artifacts

Build Metrics:

Fresh = Clean build (no .next directory)
Cached = With existing .next directory

Change Thresholds:

Time: Changes < 50ms AND < 10%, OR < 2% are insignificant
Size: Changes < 1KB AND < 1% are insignificant
All other changes are flagged to catch regressions

⚡ Dev Server

Metric	Canary	PR	Change	Trend
Cold (Listen)	456ms	506ms	✓	▁▇▇▁▁
Cold (Ready in log)	459ms	462ms	✓	▂▇▇▂▁
Cold (First Request)	926ms	903ms	✓	▃▇▇▄▂
Warm (Listen)	457ms	506ms	✓	▁▇▇▁▁
Warm (Ready in log)	460ms	461ms	✓	▁▆▆▁▁
Warm (First Request)	385ms	355ms	✓	▁▆▆▂▂

📦 Dev Server (Webpack) (Legacy)

📦 Dev Server (Webpack)

Metric	Canary	PR	Change	Trend
Cold (Listen)	455ms	455ms	✓	▁▁▁▁█
Cold (Ready in log)	437ms	438ms	✓	▅▂▅▆█
Cold (First Request)	1.883s	1.850s	✓	▄▁▄▄█
Warm (Listen)	456ms	456ms	✓	▁▁▁▁█
Warm (Ready in log)	437ms	438ms	✓	▅▂▄▅█
Warm (First Request)	1.887s	1.876s	✓	▄▁▄▄█

⚡ Production Builds

Metric	Canary	PR	Change	Trend
Fresh Build	4.110s	4.093s	✓	▁▆▆▁▃
Cached Build	4.084s	4.082s	✓	▁▆▆▁▃

📦 Production Builds (Webpack) (Legacy)

📦 Production Builds (Webpack)

Metric	Canary	PR	Change	Trend
Fresh Build	13.975s	13.995s	✓	▁▁▂▂█
Cached Build	14.210s	14.240s	✓	▁▁▁▂█
node_modules Size	476 MB	476 MB	✓	▁▁▁▁▁

📦 Bundle Sizes

Bundle Sizes

⚡ Turbopack

Client

Main Bundles: **401 kB** → **401 kB** ✅ -14 B

80 files with content-based hashes (individual files not comparable between builds)

Server

Middleware

	Canary	PR	Change
middleware-b..fest.js gzip	767 B	764 B	✓
Total	767 B	764 B	✅ -3 B

Build Details

Build Manifests

	Canary	PR	Change
_buildManifest.js gzip	450 B	452 B	✓
Total	450 B	452 B	⚠️ +2 B

📦 Webpack

Client

Main Bundles

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5528-HASH.js gzip	5.54 kB	N/A	-
6280-HASH.js gzip	59.4 kB	N/A	-
6335.HASH.js gzip	169 B	N/A	-
912-HASH.js gzip	4.59 kB	N/A	-
e8aec2e4-HASH.js gzip	62.6 kB	N/A	-
framework-HASH.js gzip	59.7 kB	59.7 kB	✓
main-app-HASH.js gzip	255 B	254 B	✓
main-HASH.js gzip	39.1 kB	39.1 kB	✓
webpack-HASH.js gzip	1.68 kB	1.68 kB	✓
262-HASH.js gzip	N/A	4.59 kB	-
2889.HASH.js gzip	N/A	169 B	-
5602-HASH.js gzip	N/A	5.55 kB	-
6948ada0-HASH.js gzip	N/A	62.6 kB	-
9544-HASH.js gzip	N/A	60.2 kB	-
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Polyfills

	Canary	PR	Change
polyfills-HASH.js gzip	39.4 kB	39.4 kB	✓
Total	39.4 kB	39.4 kB	✓

Pages

	Canary	PR	Change
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_error-HASH.js gzip	183 B	180 B	🟢 3 B (-2%)
css-HASH.js gzip	331 B	330 B	✓
dynamic-HASH.js gzip	1.81 kB	1.81 kB	✓
edge-ssr-HASH.js gzip	256 B	256 B	✓
head-HASH.js gzip	351 B	352 B	✓
hooks-HASH.js gzip	384 B	383 B	✓
image-HASH.js gzip	580 B	581 B	✓
index-HASH.js gzip	260 B	260 B	✓
link-HASH.js gzip	2.51 kB	2.51 kB	✓
routerDirect..HASH.js gzip	320 B	319 B	✓
script-HASH.js gzip	386 B	386 B	✓
withRouter-HASH.js gzip	315 B	315 B	✓
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
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Server

Edge SSR

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edge-ssr.js gzip	125 kB	125 kB	✓
page.js gzip	254 kB	254 kB	✓
Total	378 kB	379 kB	⚠️ +513 B

Middleware

	Canary	PR	Change
middleware-b..fest.js gzip	616 B	615 B	✓
middleware-r..fest.js gzip	156 B	155 B	✓
middleware.js gzip	43.2 kB	43.7 kB	✓
edge-runtime..pack.js gzip	842 B	842 B	✓
Total	44.9 kB	45.3 kB	⚠️ +419 B

Build Details

Build Manifests

	Canary	PR	Change
_buildManifest.js gzip	715 B	718 B	✓
Total	715 B	718 B	⚠️ +3 B

Build Cache

	Canary	PR	Change
0.pack gzip	4.04 MB	4.04 MB	🔴 +7.17 kB (+0%)
index.pack gzip	103 kB	103 kB	✓
index.pack.old gzip	102 kB	103 kB	✓
Total	4.24 MB	4.25 MB	⚠️ +8.07 kB

🔄 Shared (bundler-independent)

Runtimes

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app-page-exp...dev.js gzip	321 kB	321 kB	✓
app-page-exp..prod.js gzip	170 kB	170 kB	✓
app-page-tur...dev.js gzip	321 kB	321 kB	✓
app-page-tur..prod.js gzip	170 kB	170 kB	✓
app-page-tur...dev.js gzip	318 kB	318 kB	✓
app-page-tur..prod.js gzip	168 kB	168 kB	✓
app-page.run...dev.js gzip	318 kB	318 kB	✓
app-page.run..prod.js gzip	168 kB	168 kB	✓
app-route-ex...dev.js gzip	70.3 kB	70.3 kB	✓
app-route-ex..prod.js gzip	48.6 kB	48.6 kB	✓
app-route-tu...dev.js gzip	70.4 kB	70.4 kB	✓
app-route-tu..prod.js gzip	48.7 kB	48.7 kB	✓
app-route-tu...dev.js gzip	69.9 kB	69.9 kB	✓
app-route-tu..prod.js gzip	48.4 kB	48.4 kB	✓
app-route.ru...dev.js gzip	69.9 kB	69.9 kB	✓
app-route.ru..prod.js gzip	48.4 kB	48.4 kB	✓
dist_client_...dev.js gzip	324 B	324 B	✓
dist_client_...dev.js gzip	326 B	326 B	✓
dist_client_...dev.js gzip	318 B	318 B	✓
dist_client_...dev.js gzip	317 B	317 B	✓
pages-api-tu...dev.js gzip	43.2 kB	43.2 kB	✓
pages-api-tu..prod.js gzip	32.9 kB	32.9 kB	✓
pages-api.ru...dev.js gzip	43.2 kB	43.2 kB	✓
pages-api.ru..prod.js gzip	32.9 kB	32.9 kB	✓
pages-turbo....dev.js gzip	52.6 kB	52.6 kB	✓
pages-turbo...prod.js gzip	38.5 kB	38.5 kB	✓
pages.runtim...dev.js gzip	52.6 kB	52.6 kB	✓
pages.runtim..prod.js gzip	38.5 kB	38.5 kB	✓
server.runti..prod.js gzip	61.8 kB	61.8 kB	✓
Total	2.83 MB	2.83 MB	⚠️ +1 B

📎 Tarball URL

https://vercel-packages.vercel.app/next/commits/cf2987099cf8725caaf2987f47adc6fb95e43bd3/next

…nctions that return it

bgw · 2026-03-05T19:51:32Z

Merge activity

Mar 5, 7:51 PM UTC: @bgw merged this pull request with Graphite.

…nctions that return it (#90839) It's a little less error-prone if it's in one place (on the type) than in many (on the functions). I also added it to `ReadRawVcFuture`. https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-must_use-attribute - **Are these equivalent?** Yes. - **The** **`Future`** **trait already has this annotation, why do we need it on the type?** The annotation on the trait only applies if the function returns `impl Future` or `dyn Future`. Our functions return the named type.

nextjs-bot added created-by: Turbopack team PRs by the Turbopack team. Turbopack Related to Turbopack with Next.js. labels Mar 3, 2026

bgw mentioned this pull request Mar 3, 2026

Turbopack: Fix some eventually consistent reads at the top level in dev-server and snapshot tests #90792

Merged

bgw requested a review from a team March 3, 2026 22:42

bgw marked this pull request as ready for review March 3, 2026 22:42

bgw requested a review from mmastrac March 3, 2026 22:43

bgw mentioned this pull request Mar 3, 2026

Turbopack: Make ReadVcFuture::strongly_consistent private #90843

Merged

lukesandberg approved these changes Mar 4, 2026

View reviewed changes

bgw changed the base branch from bgw/more-eventual-consistency-fixes to graphite-base/90839 March 5, 2026 19:16

bgw force-pushed the bgw/read-vc-future-must-use branch from df4467c to ecb4b7c Compare March 5, 2026 19:17

bgw force-pushed the graphite-base/90839 branch from 38f8947 to 73049d6 Compare March 5, 2026 19:17

graphite-app bot changed the base branch from graphite-base/90839 to canary March 5, 2026 19:17

Turbopack: Annotate ReadVcFuture as must_use instead of annotating fu…

cf29870

…nctions that return it

bgw force-pushed the bgw/read-vc-future-must-use branch from ecb4b7c to cf29870 Compare March 5, 2026 19:17

bgw merged commit 9d0fbf1 into canary Mar 5, 2026
161 of 162 checks passed

bgw deleted the bgw/read-vc-future-must-use branch March 5, 2026 19:51

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Turbopack: Annotate ReadVcFuture as must_use instead of annotating functions that return it#90839

Turbopack: Annotate ReadVcFuture as must_use instead of annotating functions that return it#90839
bgw merged 1 commit intocanaryfrom
bgw/read-vc-future-must-use

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