rustdoc: Negative impls are not notable

[compiler-errors]

In #124097, we add impl !Iterator for [T] for coherence reasons, and since Iterator is a notable trait, this means that all -> &[_] now are tagged with a !Iterator impl as a notable trait.

I "fixed" the failing tests in that PR with 6cbbb8b, where I just blessed the tests, since I didn't want to mix these changes with that PR; however, don't believe negative impls are notable, and this PR aims to prevent these impls from being mentioned.

In the standard library, we use negative impls purely to guide coherence. They're not really a signal of anything useful to the end-user. If there ever is a case that we want negative impls to be mentioned as notable, this really should be an opt-in feature.

[rustbot]

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[fmease]

Not sure if we need the positive test because we have a bunch of them already (rg 'notable-traits-data' test/rustdoc)

[compiler-errors]

Doesn't hurt to show that a negative impl doesn't disqualify the positive impl though

[fmease]

Good point!

[fmease]

Otherwise looks good. I'm surprised too see that we do a bunch of similar logic in notable_traits_{decl,button}. Ideally, you wouldn't've need to update two places. Anyway, I would need to look into that a bit deeper so see if that could be avoided through a refactor.

[fmease]

Thanks! @bors r+ rollup

[bors]

📌 Commit 8994840 has been approved by fmease

It is now in the queue for this repository.

[bors]

⌛ Testing commit 8994840 with merge b21b74b...

[bors]

☀️ Test successful - checks-actions
Approved by: fmease
Pushing b21b74b to master...

[rust-timer]

Finished benchmarking commit (b21b74b): comparison URL.

Overall result: ❌ regressions - no action needed

@rustbot label: -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)	0.3%	[0.3%, 0.3%]	1
Regressions ❌ (secondary)	2.1%	[2.1%, 2.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.3%	[0.3%, 0.3%]	1

Max RSS (memory usage)

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

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: 678.357s -> 680.309s (0.29%)
Artifact size: 316.14 MiB -> 316.05 MiB (-0.03%)

[fmease]

(perf regressions spurious, not in doc profile)