Add `#[rustc_test_entrypoint_marker]` back ! by N1ark · Pull Request #165879 · rust-lang/rust

N1ark · 2026-11-12T18:01:31Z

Re-add the unstable and internal #[rustc_test_entrypoint_marker] (first sighted in #158854)! This is helpful for tools like Charon to translate test entry points, since once test generation is done there is no simple way of finding these: otherwise one needs to look for statics with #[rustc_test_marker], visit their body, and look for a path to a function inside that body (ugly!)

now that synthetic attributes exist doing this is simple and shouldnt cause any regressions :3 (fingers crossed)

r? jdonszelmann

LLM Disclosure: I used an LLM to research how attributes work and how to best re-add this feature :)

rustbot · 2026-11-12T18:01:36Z

clippy is developed in its own repository. If possible, consider making this change to rust-lang/rust-clippy instead.

cc @rust-lang/clippy

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann, @JonathanBrouwer

Some changes occurred in compiler/rustc_attr_ir

cc @jdonszelmann, @JonathanBrouwer

Some changes occurred in compiler/rustc_passes/src/check_attr.rs

cc @jdonszelmann, @JonathanBrouwer

rustbot · 2026-11-12T18:01:39Z

jdonszelmann is currently at their maximum review capacity.
They may take a while to respond.

JonathanBrouwer · 2026-11-12T18:33:15Z

@bors try @rust-timer queue

Add `#[rustc_test_entrypoint_marker]` back !

rust-bors · 2026-11-12T19:34:11Z

☀️ Try build successful (CI)
Build commit: 7bab611 (7bab6110330e1fe41a554f76213f36f54ab92a9b)
Base parent: 29a5d06 (29a5d066d98b58d948d285ba22390a5f849f5938)

rust-timer · 2026-11-12T20:41:32Z

Finished benchmarking commit (7bab611): comparison URL.

Overall result: ✅ improvements - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.2%	[-0.2%, -0.2%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.2%	[-0.2%, -0.2%]	1

Max RSS (memory usage)

Results (primary -2.7%, secondary -1.0%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.7%	[-4.8%, -1.5%]	3
Improvements ✅ (secondary)	-1.0%	[-1.0%, -1.0%]	1
All ❌✅ (primary)	-2.7%	[-4.8%, -1.5%]	3

Cycles

Results (primary 3.4%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	3.4%	[3.4%, 3.4%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	3.4%	[3.4%, 3.4%]	1

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 484.783s -> 485.111s (0.07%)
Artifact size: 406.09 MiB -> 406.07 MiB (-0.00%)

JonathanBrouwer · 2026-11-12T21:00:10Z

Happy to take a look at this tomorrow :)

mejrs · 2026-11-12T22:19:04Z

This is helpful for tools like Charon to translate test entry points, since once test generation is done there is no simple way of finding these: otherwise one needs to look for statics with #[rustc_test_marker], visit their body, and look for a path to a function inside that body (ugly!)

This is also what clippy does, and it is indeed rather ugly 🤮

mejrs · 2026-11-12T23:34:20Z

+            // Drop the test entrypoint marker -- unclear how that would interact.
+            AttrKind::Synthetic(SyntheticAttr::TestEntrypoint) => {}


uh oh #165894

View changes since the review

oh lmao -- i guess we need to forbid some attrs on EII

Wow a rustc segfault, that is impressive tbh

mejrs · 2026-11-12T23:40:58Z

+    /// This synthetic attribute is added by the `#[test]` and `#[bench]` macros to the annotated
+    /// function, so that tools (e.g. rustc drivers doing analysis) can find test entry points
+    /// without relying on unstable details such test lowering.
+    ///
+    /// The attribute is not used by rustc directly and is instead only provided as a utility for
+    /// out of tree users.
+    TestEntrypoint,


I'm not sure if it's right to have bench and test both emit the same trace attribute. It sounds confusing.

View changes since the review

the thought process was that you can distinguish both from the arguments (none for #[test], &mut Bencher for #[bench]), and we just want to make these items findable (and two synth attribs felt overkill). happy to remove #[bench], personally i have on use for it, idk about clippy & co

I'm happy to keep it for bench for now, the test and bench infra share a lot of internal stuff so it kinda makes sense

rustbot · 2026-11-13T09:42:23Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

JonathanBrouwer

r=me after ci is fixed
@rustbot author

View changes since this review

JonathanBrouwer · 2026-11-13T13:17:00Z

@bors r+ rollup

rust-bors · 2026-11-13T13:17:03Z

📌 Commit 0cfffc4 has been tentatively approved by JonathanBrouwer

It will be put into the queue for this repository once PR CI succeeds.

rust-bors · 2026-11-13T13:54:18Z

❌ Commit 0cfffc4 has been unapproved due to PR CI failure. Reapprove it with @bors r+ force if you want to ignore the failure.

View changes since this unapproval

N1ark · 2026-11-13T14:02:35Z

heh this was in fact not correct

JonathanBrouwer · 2026-11-13T14:52:16Z

@bors r+ rollup
Thanks!

rust-bors · 2026-11-13T14:52:19Z

📌 Commit 395e81a has been tentatively approved by JonathanBrouwer

It will be put into the queue for this repository once PR CI succeeds.

…=JonathanBrouwer Add `#[rustc_test_entrypoint_marker]` back ! Re-add the unstable and internal `#[rustc_test_entrypoint_marker]` (first sighted in rust-lang#158854)! This is helpful for tools like [Charon](https://github.com/AeneasVerif/charon) to translate test entry points, since once test generation is done there is no simple way of finding these: otherwise one needs to look for statics with `#[rustc_test_marker]`, visit their body, and look for a path to a function inside that body (ugly!) now that synthetic attributes exist doing this is simple and shouldnt cause any regressions :3 (fingers crossed) r? jdonszelmann

rustbot assigned jdonszelmann Nov 12, 2026

N1ark commented Nov 12, 2026

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Comment thread compiler/rustc_ast/src/attr/mod.rs Resolved

N1ark changed the title ~~Add RustcTestEntrypointMarker back !~~ Add #[rustc_test_entrypoint_marker] back ! Nov 12, 2026

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rust-bors Bot pushed a commit that referenced this pull request Nov 12, 2026

Auto merge of #165879 - N1ark:test-entrypoint-synthetic, r=<try>

7bab611

Add `#[rustc_test_entrypoint_marker]` back !

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Nov 12, 2026

JonathanBrouwer assigned JonathanBrouwer and unassigned jdonszelmann Nov 12, 2026

mejrs reviewed Nov 12, 2026

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N1ark force-pushed the test-entrypoint-synthetic branch 2 times, most recently from 7ff15d4 to 6ef674a Compare November 13, 2026 09:42

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JonathanBrouwer approved these changes Nov 13, 2026

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N1ark force-pushed the test-entrypoint-synthetic branch from 6ef674a to 0cfffc4 Compare November 13, 2026 12:53

Add RustcTestEntrypointMarker back !

395e81a

N1ark force-pushed the test-entrypoint-synthetic branch from 0cfffc4 to 395e81a Compare November 13, 2026 14:01

rust-bors Bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Nov 13, 2026

WaffleLapkin mentioned this pull request Nov 13, 2026

Rollup of 7 pull requests #165929

Open

		// Drop the test entrypoint marker -- unclear how that would interact.
		AttrKind::Synthetic(SyntheticAttr::TestEntrypoint) => {}

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Overall result: ✅ improvements - no action needed

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