Consider return type when giving various method suggestions

[compiler-errors]

1. Fix a bug in method probe where we weren't normalizing xform_ret_ty for non-impl method candidates. This shouldn't affect happy-path code, since we only use xform_ret_ty when probing methods for diagnostics (I think).
2. Pass the return type expectation down to lookup_probe/probe_for_name usages in diagnostics. Added a few UI tests to gate against bad suggestions.
3. Make a FnCtxt::lookup_probe_for_diagnostic which properly passes down IsSuggestion(true). Should help suppress other weird notes in some corner cases.

[rustbot]

r? @oli-obk

(rustbot has picked a reviewer for you, use r? to override)

[compiler-errors]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 1bac9237061cb0a72a3b28afb1a719f548c0bc96 with merge 1d2a326a511b803db2092b2da40e17f0608e3975...

[bors]

☀️ Try build successful - checks-actions
Build commit: 1d2a326a511b803db2092b2da40e17f0608e3975 (1d2a326a511b803db2092b2da40e17f0608e3975)

[bors]

☀️ Try build successful - checks-actions
Build commit: 1d2a326a511b803db2092b2da40e17f0608e3975 (1d2a326a511b803db2092b2da40e17f0608e3975)

[rust-timer]

Finished benchmarking commit (1d2a326a511b803db2092b2da40e17f0608e3975): comparison URL.

Overall result: ❌ regressions - ACTION NEEDED

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

@bors rollup=never
@rustbot label: -S-waiting-on-perf +perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.4%	[0.4%, 0.5%]	2
Regressions ❌ (secondary)	2.0%	[0.7%, 4.4%]	10
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.0%	[-1.0%, -1.0%]	1
All ❌✅ (primary)	0.4%	[0.4%, 0.5%]	2

Max RSS (memory usage)

Results

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

Cycles

Results

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)	2.8%	[0.9%, 3.9%]	5
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

[estebank]

I'm really surprised by the perf results (although they are quite localized).

[compiler-errors]

Tempted to believe that it's 1f92d5cca52572b08556620ba339365f485166bb causing the problem. Gonna try an experiment...

[compiler-errors]

Interestingly, due to 1f92d5c, this code also now compiles successfully:

use std::ops::Deref;

trait Foo {
    fn foo(&self) -> &Self::Target where Self: Deref { &**self }
}

trait Bar {
    fn foo(&self) {}
}

fn test(i: impl Foo + Bar) {
    i.foo();
}

... becuase we now unconditionally normalize the xform_ret_ty, not only for impl candidates, but for trait and param method probe candidates as well.

[compiler-errors]

This should revert that behavior, which is a bit disappointing IMO, but should help with the perf regression..?

@bors try @rust-timer queue

[bors]

⌛ Trying commit d85ba523ed961ce6da31dd1885a9766dc92ee8d2 with merge 9c64170fab1f1e34ba27072f0151d06e2bfe0131...

[bors]

☔ The latest upstream changes (presumably #106616) made this pull request unmergeable. Please resolve the merge conflicts.

[bors]

☀️ Try build successful - checks-actions
Build commit: 9c64170fab1f1e34ba27072f0151d06e2bfe0131 (9c64170fab1f1e34ba27072f0151d06e2bfe0131)

[rust-timer]

Finished benchmarking commit (9c64170fab1f1e34ba27072f0151d06e2bfe0131): comparison URL.

Overall result: ✅ improvements - no action needed

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

@bors rollup=never
@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.5%	[-0.5%, -0.5%]	1
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results

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)	-	-	0
Improvements ✅ (primary)	-1.0%	[-1.2%, -0.9%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-1.0%	[-1.2%, -0.9%]	2

Cycles

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

[oli-obk]

r=me after a rebase.

I recently dug around in this code and am very happy about the new _for_diagnostics function.

[compiler-errors]

@bors r=oli-obk

[bors]

📌 Commit 4f15034 has been approved by oli-obk

It is now in the queue for this repository.

[bors]

⌛ Testing commit 4f15034 with merge 0442fba...

[bors]

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing 0442fba to master...

[bors]

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing 0442fba to master...

[rust-timer]

Finished benchmarking commit (0442fba): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

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

Max RSS (memory usage)

Results

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)	2.5%	[2.5%, 2.5%]	1
Regressions ❌ (secondary)	1.5%	[1.3%, 1.8%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.5%	[2.5%, 2.5%]	1

Cycles

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