Add `#[rustc_dump_generics]` attribute by addiesh · Pull Request #157384 · rust-lang/rust

addiesh · 2026-06-03T14:59:09Z

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Added a rustc attribute to dump the generic parameters of a given item to the compiler output.

rustbot · 2026-06-03T14:59:13Z

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann, @JonathanBrouwer

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

cc @jdonszelmann, @JonathanBrouwer

Some changes occurred in compiler/rustc_hir/src/attrs

cc @jdonszelmann, @JonathanBrouwer

The rustc-dev-guide subtree was changed. If this PR only touches the dev guide consider submitting a PR directly to rust-lang/rustc-dev-guide otherwise thank you for updating the dev guide with your changes.

cc @BoxyUwU, @tshepang

rustbot · 2026-06-03T14:59:17Z

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @oli-obk (or someone else) some time within the next two weeks.

Please see the contribution instructions for more information. Namely, in order to ensure the minimum review times lag, PR authors and assigned reviewers should ensure that the review label (S-waiting-on-review and S-waiting-on-author) stays updated, invoking these commands when appropriate:

@rustbot author: the review is finished, PR author should check the comments and take action accordingly
@rustbot review: the author is ready for a review, this PR will be queued again in the reviewer's queue

jdonszelmann · 2026-06-04T07:44:41Z

I can review the attrs part!

jdonszelmann · 2026-06-04T07:52:36Z

+        Allow(Target::Struct),
+        Allow(Target::Enum),
+        Allow(Target::Union),
+        Allow(Target::Trait),


You'll probably want a test using it on a trait some day, because I imagine the interaction can be a bit more involved for that. Im not quite sure how far along this is from proof of concept to done. You might want to initially not support traits if that test gives you trouble?

View changes since the review

Just added a test for a trait, but it's definitely not exhaustive. Let me know your thoughts.

oli-obk · 2026-06-10T15:01:53Z

@bors r+ rollup

rust-bors · 2026-06-10T15:10:41Z

📌 Commit 7f0f6e0 has been approved by oli-obk

It is now in the queue for this repository.

rustbot · 2026-06-11T03:28:13Z

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.

mejrs · 2026-06-11T09:17:11Z

@bors try jobs=i686-gnu-nopt-1

Add `#[rustc_dump_generics]` attribute try-job: i686-gnu-nopt-1

rust-bors · 2026-06-11T11:00:35Z

💔 Test for 87945f8 failed: CI. Failed job:

try - i686-gnu-nopt-1 (web logs, enhanced plaintext logs)

addiesh · 2026-06-11T14:45:57Z

That's frustrating. Why does it fail specifically on that target triple?

fmease · 2026-06-11T14:58:56Z

The specific target doesn't matter. You're printing a FxHashMap (param_def_id_to_index) whose entries don't have a "stable ordering" due to the hashing (it happens to be stable across compilations & re-runs but the behavior may differ by target; i686-gnu-nopt-1 differs most likely because it's a 32-bit arch).

You need to add another compiletest normalization rule to make the mapping stable by "normalizing away" the concrete indices.

addiesh · 2026-06-11T15:01:06Z

The specific target doesn't matter. You're printing a FxHashMap (param_def_id_to_index) whose entries don't have a "stable ordering" due to the hashing (it happens to be stable across compilations & re-runs but the behavior may differ by target; i686-gnu-nopt-1 differs most likely because it's a 32-bit arch).

You somehow need to compiletest-normalize away this mapping in the output.

Ah, I see. That makes sense. I'll try my best to do that.

jdonszelmann · 2026-06-15T15:03:44Z

@bors try jobs=i686-gnu-nopt-1

Add `#[rustc_dump_generics]` attribute try-job: i686-gnu-nopt-1

rust-bors · 2026-06-15T17:42:14Z

☀️ Try build successful (CI)
Build commit: 6d5e939 (6d5e9394265d10fa066c6c9497c5e5aab0c7befa, parent: 5ff740e85e8569289a93573ad25f1295dfae0323)

addiesh · 2026-06-19T01:01:48Z

bump; this should be ready to merge

addiesh · 2026-06-19T01:19:55Z

@bors r+ rollup

rust-bors · 2026-06-19T01:19:58Z

@addiesh: 🔑 Insufficient privileges: not in review users

WaffleLapkin · 2026-06-19T01:28:10Z

@bors r=oli-obk
(per #157384 (comment) and #157384 (comment))

rust-bors · 2026-06-19T01:28:13Z

📌 Commit fa0e9bd has been approved by oli-obk

It is now in the queue for this repository.

rust-bors · 2026-06-19T05:10:40Z

☀️ Test successful - CI
Approved by: oli-obk
Duration: 3h 9m 6s
Pushing 8e15021 to main...

github-actions · 2026-06-19T05:13:38Z

What is this?

This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.

Comparing 8c3f167 (parent) -> 8e15021 (this PR)

Test differences

Show 3 test diffs

Stage 1

[ui] tests/ui/attributes/dump_generics.rs: [missing] -> pass (J0)
[ui (polonius)] tests/ui/attributes/dump_generics.rs: [missing] -> pass (J2)

Stage 2

[ui] tests/ui/attributes/dump_generics.rs: [missing] -> pass (J1)

Job group index

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 8e150217bafcaaaa0c45bf685c55fd56cec48598 --output-dir test-dashboard

And then open test-dashboard/index.html in your browser to see an overview of all executed tests.

Job duration changes

x86_64-gnu-gcc-core-tests: 7m 37s -> 14m 20s (+88.1%)
x86_64-gnu-pre-stabilization: 25m 38s -> 37m 9s (+45.0%)
x86_64-gnu-debug: 1h 55m -> 1h 16m (-33.5%)
dist-powerpc64-linux-gnu: 1h 13m -> 1h 35m (+29.5%)
x86_64-msvc-2: 1h 50m -> 2h 20m (+27.2%)
dist-ohos-armv7: 1h 10m -> 51m 35s (-26.5%)
dist-powerpc64le-linux-musl: 1h 36m -> 1h 14m (-22.6%)
dist-powerpc64le-linux-gnu: 1h 37m -> 1h 15m (-22.2%)
pr-check-2: 37m 8s -> 44m 53s (+20.8%)
i686-gnu-nopt-1: 1h 58m -> 2h 22m (+20.3%)

How to interpret the job duration changes?

Job durations can vary a lot, based on the actual runner instance
that executed the job, system noise, invalidated caches, etc. The table above is provided
mostly for t-infra members, for simpler debugging of potential CI slow-downs.

rust-timer · 2026-06-19T05:52:01Z

Finished benchmarking commit (8e15021): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

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

Max RSS (memory usage)

Results (primary -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)	-1.0%	[-1.0%, -1.0%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-1.0%	[-1.0%, -1.0%]	1

Cycles

Results (primary 1.9%, secondary -4.4%)

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

	mean	range	count
Regressions ❌ (primary)	1.9%	[1.9%, 1.9%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-4.4%	[-5.8%, -2.9%]	2
All ❌✅ (primary)	1.9%	[1.9%, 1.9%]	1

Binary size

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

Bootstrap: 480.598s -> 481.812s (0.25%)
Artifact size: 390.74 MiB -> 390.71 MiB (-0.01%)

rustbot assigned oli-obk Jun 3, 2026

addiesh commented Jun 3, 2026

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Comment thread compiler/rustc_attr_parsing/src/attributes/rustc_dump.rs

addiesh commented Jun 3, 2026

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Comment thread compiler/rustc_hir_analysis/src/collect/dump.rs Outdated

addiesh force-pushed the turbofisherwoman branch from c240b2b to 08cf89c Compare June 3, 2026 15:27

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jdonszelmann self-assigned this Jun 4, 2026

jdonszelmann reviewed Jun 4, 2026

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mejrs reviewed Jun 4, 2026

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Comment thread compiler/rustc_hir_analysis/src/collect/dump.rs Outdated

fmease reviewed Jun 4, 2026

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Comment thread compiler/rustc_attr_parsing/src/attributes/rustc_dump.rs

Comment thread compiler/rustc_hir_analysis/src/collect/dump.rs Outdated

fmease approved these changes Jun 5, 2026

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Comment thread compiler/rustc_hir_analysis/src/collect/dump.rs Outdated

Comment thread compiler/rustc_hir_analysis/src/collect/dump.rs Outdated

cjgillot reviewed Jun 5, 2026

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Comment thread compiler/rustc_hir_analysis/src/collect/dump.rs Outdated

Comment thread library/backtrace

addiesh marked this pull request as draft June 8, 2026 16:27

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 8, 2026

addiesh force-pushed the turbofisherwoman branch from 2bae2d2 to 7f0f6e0 Compare June 10, 2026 14:50

addiesh marked this pull request as ready for review June 10, 2026 14:58

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 10, 2026

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rust-bors Bot pushed a commit that referenced this pull request Jun 11, 2026

Auto merge of #157384 - addiesh:turbofisherwoman, r=<try>

87945f8

Add `#[rustc_dump_generics]` attribute try-job: i686-gnu-nopt-1

rust-bors Bot added the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Jun 11, 2026

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fix(?) hashmap instability

fa0e9bd

rust-bors Bot pushed a commit that referenced this pull request Jun 15, 2026

Auto merge of #157384 - addiesh:turbofisherwoman, r=<try>

6d5e939

Add `#[rustc_dump_generics]` attribute try-job: i686-gnu-nopt-1

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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 Jun 19, 2026

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rust-bors Bot added merged-by-bors This PR was explicitly merged by bors. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jun 19, 2026

rust-bors Bot merged commit 8e15021 into rust-lang:main Jun 19, 2026
15 checks passed

rustbot added this to the 1.98.0 milestone Jun 19, 2026

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github-actions Bot commented Jun 19, 2026

Test differences

Stage 1

Stage 2

Job duration changes

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rust-timer commented Jun 19, 2026

Overall result: no relevant changes - no action needed

Instruction count

Max RSS (memory usage)

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