Print regions in `type_name`. #145284

nnethercote · 2025-08-12T02:26:29Z

Currently they are skipped, which is a bit weird, and it sometimes causes malformed output like Foo<> and dyn Bar<, A = u32>.

Most regions are erased by the time type_name does its work. So all regions are now printed as '_ in non-optional places. Not perfect, but better than the status quo.

c_name is updated to trim lifetimes from MIR pass names, so that the PASS_NAMES sanity check still works. It is also renamed as simplify_pass_type_name and made non-const, because it doesn't need to be const and the non-const implementation is much shorter.

The commit also renames should_print_region as should_print_optional_region, which makes it clearer that it only applies to some regions.

Fixes #145168.

r? @lcnr

rustbot · 2025-08-12T02:26:35Z

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

compiler/rustc_const_eval/src/util/type_name.rs

tests/ui/type/type-name-basic.rs

rustbot · 2025-08-12T11:40:20Z

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

nnethercote · 2025-08-12T11:40:46Z

@lcnr: new code is up. Quite a bit has changed.

@rustbot ready

compiler/rustc_const_eval/src/util/type_name.rs

compiler/rustc_mir_transform/src/pass_manager.rs

nnethercote · 2025-08-12T21:48:36Z

I updated again. c_name is now non-const, which is much nicer, and renamed as simplify_pass_type_name.

@rustbot ready

lcnr · 2025-08-13T07:05:45Z

I updated again. c_name is now non-const, which is much nicer, and renamed as simplify_pass_type_name.

@rustbot ready

i would expect that we've done it in a const block for 👻 perf 👻 reasons? 🤔

@bors2 try @rust-timer queue

Print regions in `type_name`.

rust-bors · 2025-08-13T09:18:16Z

☀️ Try build successful (CI)
Build commit: fc05a4f (fc05a4f44af11286e3ae4b0ab02b85685f709d2b, parent: 1553adfe6884a8f6c28f5a673d3e605535ee0113)

rust-timer · 2025-08-13T10:29:52Z

Finished benchmarking commit (fc05a4f): comparison URL.

Overall result: ❌✅ regressions and improvements - please read the text below

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please do so in sufficient writing along with @rustbot label: +perf-regression-triaged. If not, please fix the regressions and do another perf run. If its results are neutral or positive, the label will be automatically removed.

@bors rollup=never
@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)	1.0%	[0.2%, 4.3%]	70
Regressions ❌ (secondary)	1.2%	[0.1%, 5.3%]	57
Improvements ✅ (primary)	-1.4%	[-1.4%, -1.4%]	1
Improvements ✅ (secondary)	-0.5%	[-1.4%, -0.0%]	3
All ❌✅ (primary)	0.9%	[-1.4%, 4.3%]	71

Max RSS (memory usage)

Results (secondary 4.2%)

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)	4.2%	[1.7%, 5.6%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary 3.0%)

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)	4.0%	[3.0%, 6.0%]	9
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-5.8%	[-5.8%, -5.8%]	1
All ❌✅ (primary)	-	-	0

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 464.093s -> 466.402s (0.50%)
Artifact size: 377.76 MiB -> 377.46 MiB (-0.08%)

bors · 2025-08-14T00:05:47Z

☔ The latest upstream changes (presumably #145366) made this pull request unmergeable. Please resolve the merge conflicts.

Currently they are skipped, which is a bit weird, and it sometimes causes malformed output like `Foo<>` and `dyn Bar<, A = u32>`. Most regions are erased by the time `type_name` does its work. So all regions are now printed as `'_` in non-optional places. Not perfect, but better than the status quo. `c_name` is updated to trim lifetimes from MIR pass names, so that the `PASS_NAMES` sanity check still works. It is also renamed as `simplify_pass_type_name` and made non-const, because it doesn't need to be const and the non-const implementation is much shorter. The commit also renames `should_print_region` as `should_print_optional_region`, which makes it clearer that it only applies to some regions. Fixes rust-lang#145168.

rustbot · 2025-08-14T11:13:20Z

⚠️ Warning ⚠️

There are issue links (such as #123) in the commit messages of the following commits.
Please move them to the PR description, to avoid spamming the issues with references to the commit, and so this bot can automatically canonicalize them to avoid issues with subtree.
- 8296ad0

nnethercote · 2025-08-14T11:14:01Z

I fixed the submodules. Maybe this time it'll be ok? :)

@bors r=lcnr

bors · 2025-08-14T11:14:03Z

📌 Commit 8296ad0 has been approved by lcnr

It is now in the queue for this repository.

Print regions in `type_name`. Currently they are skipped, which is a bit weird, and it sometimes causes malformed output like `Foo<>` and `dyn Bar<, A = u32>`. Most regions are erased by the time `type_name` does its work. So all regions are now printed as `'_` in non-optional places. Not perfect, but better than the status quo. `c_name` is updated to trim lifetimes from MIR pass names, so that the `PASS_NAMES` sanity check still works. It is also renamed as `simplify_pass_type_name` and made non-const, because it doesn't need to be const and the non-const implementation is much shorter. The commit also renames `should_print_region` as `should_print_optional_region`, which makes it clearer that it only applies to some regions. Fixes #145168. r? `@lcnr`

bors · 2025-08-16T08:49:44Z

⌛ Testing commit 8296ad0 with merge 019bbe7...

rust-log-analyzer · 2025-08-16T10:14:05Z

The job x86_64-gnu-llvm-20-1 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

    get(
    ~~~^
        download_info.base_download_url,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ...<3 lines>...
        verbose=download_info.verbose,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/checkout/src/bootstrap/bootstrap.py", line 82, in get
    raise RuntimeError("failed verification")
---
    get(
    ~~~^
        download_info.base_download_url,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ...<3 lines>...
        verbose=download_info.verbose,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/checkout/src/bootstrap/bootstrap.py", line 82, in get
    raise RuntimeError("failed verification")
---
    get(
    ~~~^
        download_info.base_download_url,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ...<3 lines>...
        verbose=download_info.verbose,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/checkout/src/bootstrap/bootstrap.py", line 82, in get
    raise RuntimeError("failed verification")
---
    get(
    ~~~^
        download_info.base_download_url,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ...<3 lines>...
        verbose=download_info.verbose,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/checkout/src/bootstrap/bootstrap.py", line 82, in get
    raise RuntimeError("failed verification")
---
    get(
    ~~~^
        download_info.base_download_url,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ...<3 lines>...
        verbose=download_info.verbose,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/checkout/src/bootstrap/bootstrap.py", line 82, in get
    raise RuntimeError("failed verification")

bors · 2025-08-16T10:14:38Z

💔 Test failed - checks-actions

Zalathar · 2025-08-16T10:50:49Z

@bors retry (flaky download failure?)

Zalathar · 2025-08-17T04:59:12Z

Scheduling: Prefer an arbitrary rollup=never PR over #144476 if rollup #145519 fails.

@bors p=1

bors · 2025-08-17T10:24:24Z

⌛ Testing commit 8296ad0 with merge 425a9c0...

bors · 2025-08-17T14:00:20Z

☀️ Test successful - checks-actions
Approved by: lcnr
Pushing 425a9c0 to master...

github-actions · 2025-08-17T14:03:20Z

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 99ba556 (parent) -> 425a9c0 (this PR)

Test differences

Show 2 test diffs

2 doctest diffs were found. These are ignored, as they are noisy.

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 425a9c0a0e365c0b8c6cfd00c2ded83a73bed9a0 --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

dist-aarch64-linux: 5921.0s -> 8494.0s (43.5%)
x86_64-apple-1: 9511.8s -> 12205.0s (28.3%)
x86_64-apple-2: 6816.9s -> 5661.5s (-16.9%)
dist-armv7-linux: 5002.0s -> 5815.7s (16.3%)
dist-ohos-armv7: 4028.1s -> 4544.4s (12.8%)
dist-aarch64-msvc: 5457.2s -> 5939.9s (8.8%)
aarch64-gnu: 6746.0s -> 7226.4s (7.1%)
aarch64-apple: 5131.7s -> 5459.0s (6.4%)
dist-x86_64-apple: 10285.1s -> 9642.5s (-6.2%)
aarch64-gnu-debug: 4521.9s -> 4798.6s (6.1%)

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 · 2025-08-17T15:11:28Z

Finished benchmarking commit (425a9c0): comparison URL.

Overall result: ❌ regressions - please read the text below

Our benchmarks found a performance regression caused by this PR.
This might be an actual regression, but it can also be just noise.

Next Steps:

If the regression was expected or you think it can be justified,
please write a comment with sufficient written justification, and add
@rustbot label: +perf-regression-triaged to it, to mark the regression as triaged.
If you think that you know of a way to resolve the regression, try to create
a new PR with a fix for the regression.
If you do not understand the regression or you think that it is just noise,
you can ask the @rust-lang/wg-compiler-performance working group for help (members of this group
were already notified of this PR).

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

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)	0.8%	[0.8%, 0.8%]	1
Regressions ❌ (secondary)	0.5%	[0.1%, 2.0%]	8
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.8%	[0.8%, 0.8%]	1

Max RSS (memory usage)

Results (primary 0.9%, secondary -3.9%)

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

	mean	range	count
Regressions ❌ (primary)	0.9%	[0.9%, 0.9%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.9%	[-3.9%, -3.9%]	1
All ❌✅ (primary)	0.9%	[0.9%, 0.9%]	1

Cycles

Results (secondary 10.8%)

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)	14.0%	[2.3%, 21.7%]	5
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-4.9%	[-4.9%, -4.9%]	1
All ❌✅ (primary)	-	-	0

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 469.684s -> 470.373s (0.15%)
Artifact size: 377.58 MiB -> 377.75 MiB (0.05%)

nnethercote · 2025-08-17T22:30:48Z

I think the regressions are just noise. unused-warnings has been bimodal recently.

@rustbot label: +perf-regression-triaged

… r=lcnr Print regions in `type_name`. Currently they are skipped, which is a bit weird, and it sometimes causes malformed output like `Foo<>` and `dyn Bar<, A = u32>`. Most regions are erased by the time `type_name` does its work. So all regions are now printed as `'_` in non-optional places. Not perfect, but better than the status quo. `c_name` is updated to trim lifetimes from MIR pass names, so that the `PASS_NAMES` sanity check still works. It is also renamed as `simplify_pass_type_name` and made non-const, because it doesn't need to be const and the non-const implementation is much shorter. The commit also renames `should_print_region` as `should_print_optional_region`, which makes it clearer that it only applies to some regions. Fixes rust-lang#145168. r? `@lcnr`

rustbot assigned lcnr Aug 12, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Aug 12, 2025

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nnethercote mentioned this pull request Aug 12, 2025

Butchered std::any::type_name output for trait object types with lifetime params #145168

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nnethercote force-pushed the type_name-print-regions branch from 6779af2 to 36f25a0 Compare August 12, 2025 11:40

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nnethercote force-pushed the type_name-print-regions branch from 36f25a0 to 3720e1a Compare August 12, 2025 21:47

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rust-bors bot added a commit that referenced this pull request Aug 13, 2025

Auto merge of #145284 - nnethercote:type_name-print-regions, r=<try>

fc05a4f

Print regions in `type_name`.

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Aug 13, 2025

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rustbot added perf-regression Performance regression. and removed S-waiting-on-perf Status: Waiting on a perf run to be completed. labels Aug 13, 2025

nnethercote force-pushed the type_name-print-regions branch from 3720e1a to 75552ef Compare August 14, 2025 03:52

nnethercote force-pushed the type_name-print-regions branch from 00492e3 to 8296ad0 Compare August 14, 2025 11:13

bors 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 Aug 14, 2025

bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Aug 16, 2025

bors 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-review Status: Awaiting review from the assignee but also interested parties. labels Aug 16, 2025

bors added the merged-by-bors This PR was explicitly merged by bors. label Aug 17, 2025

bors merged commit 425a9c0 into rust-lang:master Aug 17, 2025
11 checks passed

rustbot added this to the 1.91.0 milestone Aug 17, 2025

rustbot added the perf-regression-triaged The performance regression has been triaged. label Aug 17, 2025

nnethercote deleted the type_name-print-regions branch August 17, 2025 22:30

Mark-Simulacrum removed perf-regression Performance regression. perf-regression-triaged The performance regression has been triaged. labels Aug 19, 2025

Print regions in type_name. #145284

Print regions in type_name. #145284

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Overall result: ❌✅ regressions and improvements - please read the text below

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Test differences

Job duration changes

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Overall result: ❌ regressions - please read the text below

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Print regions in `type_name`. #145284

Print regions in `type_name`. #145284

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