Remove manual WF hack

[compiler-errors]

We do not need this hack anymore since we fixed the candidate selection problems with Sized bounds. We prefer built-in sized bounds now since #138176, which fixes the only regression this hack was intended to fix.

While this theoretically is broken for some code, for example, when there a param-env bound that shadows an impl or built-in trait, we don't see it in practice and IMO it's not worth the burden of having to maintain this wart in compare_method_predicate_entailment.

The code that regresses is, for example:

trait Bar<'a> {}

trait Foo<'a, T> {
    fn method(&self)
    where
        Self: Bar<'a>;
}

struct W<'a, T>(&'a T)
where
    Self: Bar<'a>;

impl<'a, 'b, T> Bar<'a> for W<'b, T> {}

impl<'a, 'b, T> Foo<'a, T> for W<'b, T> {
    fn method(&self) {}
}

Specifically, I don't believe this is really going to be encountered in practice. For this to fail, there must be a where clause in the trait method that would shadow an impl or built-in (non-Sized) candidate in the trait, and this shadowing would need to be encountered when solving a nested WF goal from the impl self type.

See #108544 for the original regression. Crater run is clean!

r? lcnr

[compiler-errors]

@bors try

[bors]

⌛ Trying commit 1b99dca with merge fc545c6...

[bors]

☀️ Try build successful - checks-actions
Build commit: fc545c6 (fc545c6b951a304df08b327c158f92678582f435)

[lcnr]

@craterbot check

[craterbot]

👌 Experiment pr-140557 created and queued.
🤖 Automatically detected try build fc545c6
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🚧 Experiment pr-140557 is now running

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🚨 Report generation of pr-140557 failed: timed out waiting for connection
🛠️ If the error is fixed use the retry-report command.

🆘 Can someone from the infra team check in on this? @rust-lang/infra
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[lcnr]

@craterbot retry-report

[craterbot]

🛠️ Generation of the report for pr-140557 queued again.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🚨 Report generation of pr-140557 failed: timed out waiting for connection
🛠️ If the error is fixed use the retry-report command.

🆘 Can someone from the infra team check in on this? @rust-lang/infra
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[compiler-errors]

@craterbot retry-report

[craterbot]

🛠️ Generation of the report for pr-140557 queued again.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🚨 Report generation of pr-140557 failed: timed out waiting for connection
🛠️ If the error is fixed use the retry-report command.

🆘 Can someone from the infra team check in on this? @rust-lang/infra
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[compiler-errors]

@craterbot retry-report

[craterbot]

🛠️ Generation of the report for pr-140557 queued again.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🎉 Experiment pr-140557 is completed!
📊 4 regressed and 5 fixed (624228 total)
📰 Open the full report.

⚠️ If you notice any spurious failure please add them to the denylist!
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[compiler-errors]

@craterbot check crates=https://gist.githubusercontent.com/compiler-errors/33c51a36d7aaf1d5b389ba0fd34fe3f6/raw/d01a01565c5a82de036882968100d90b0c77dd38/regressed-plus-unknowns.txt

[craterbot]

👌 Experiment pr-140557-1 created and queued.
🤖 Automatically detected try build fc545c6
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🚧 Experiment pr-140557-1 is now running

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[lcnr]

I am in favor of reverting this hack and we can easily revert it if we encounter a new regression. I think maintaining such warts long time is bound to cause issues at some point.

@rfcbot reviewed

[oli-obk]

yay hack gone

[rfcbot]

🔔 This is now entering its final comment period, as per the review above. 🔔

[lcnr]

@bors r+ rollup=

[bors]

📌 Commit df47958 has been approved by lcnr

It is now in the queue for this repository.

[lcnr]

@bors r+ rollup=never

[bors]

💡 This pull request was already approved, no need to approve it again.

• There's another pull request that is currently being tested, blocking this pull request: Add f16 formatting and parsing #127013

[bors]

📌 Commit df47958 has been approved by lcnr

It is now in the queue for this repository.

[bors]

⌛ Testing commit df47958 with merge 7e19eef...

[bors]

☀️ Test successful - checks-actions
Approved by: lcnr
Pushing 7e19eef to master...

[github-actions]

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 6d1875f (parent) -> 7e19eef (this PR)

Test differences

No test diffs found

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 7e19eef048ba58c28c70afbf5f95da4829c15796 --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

1. dist-apple-various: 6099.5s -> 7828.3s (28.3%)
2. x86_64-apple-1: 8788.4s -> 7502.3s (-14.6%)
3. x86_64-apple-2: 4323.2s -> 4845.9s (12.1%)
4. dist-aarch64-apple: 5459.5s -> 6107.6s (11.9%)
5. x86_64-gnu-llvm-19-3: 7086.2s -> 6579.5s (-7.1%)
6. aarch64-apple: 4390.3s -> 4086.0s (-6.9%)
7. x86_64-gnu-debug: 5891.1s -> 6199.7s (5.2%)
8. x86_64-msvc-ext2: 5729.6s -> 6022.1s (5.1%)
9. dist-x86_64-apple: 9167.5s -> 8704.7s (-5.0%)
10. dist-x86_64-freebsd: 4873.6s -> 5091.1s (4.5%)

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]

Finished benchmarking commit (7e19eef): 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

This is the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	0.3%	[0.1%, 0.6%]	34
Regressions ❌ (secondary)	0.2%	[0.1%, 0.2%]	5
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.3%	[0.1%, 0.6%]	34

Max RSS (memory usage)

Results (primary -5.6%, secondary -1.7%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.2%	[2.2%, 2.2%]	1
Improvements ✅ (primary)	-5.6%	[-5.6%, -5.6%]	1
Improvements ✅ (secondary)	-2.7%	[-4.8%, -1.5%]	4
All ❌✅ (primary)	-5.6%	[-5.6%, -5.6%]	1

Cycles

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

Binary size

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

Bootstrap: 772.375s -> 772.011s (-0.05%)
Artifact size: 365.48 MiB -> 365.45 MiB (-0.01%)

[Kobzol]

The regression seems genuine, but it's also quite small and since this was (AFAIK) long-awaited cleanup, I think we don't need to do anything further.

@rustbot label: +perf-regression-triaged