Replace &Vec<_>s with &[_]s

[WaffleLapkin]

It's generally preferable to use &[_] since it's one less indirection and it can be created from types other that Vec.

I've left &Vec in some locals where it doesn't really matter, in cases where TypeFoldable is expected (TypeFoldable: Clone so slice can't implement it) and in cases where it's &TypeAliasThatIsActiallyVec. Nothing important, really, I was just a little annoyed by visit_generic_param_vec :D

r? @compiler-errors

[compiler-errors]

I don't expect this to show anything but noise but worth a shot

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

[bors]

⌛ Trying commit afaa985 with merge c2567afd60370409f05b8c2d8e0baf9f45f6764c...

[bors]

☀️ Try build successful - checks-actions
Build commit: c2567afd60370409f05b8c2d8e0baf9f45f6764c (c2567afd60370409f05b8c2d8e0baf9f45f6764c)

[rust-timer]

Queued c2567afd60370409f05b8c2d8e0baf9f45f6764c with parent e40d5e8, future comparison URL.

[rust-timer]

Finished benchmarking commit (c2567afd60370409f05b8c2d8e0baf9f45f6764c): comparison url.

Instruction count

• Primary benchmarks: 🎉 relevant improvement found
• Secondary benchmarks: 🎉 relevant improvements found

	mean1	max	count2
Regressions 😿 (primary)	N/A	N/A	0
Regressions 😿 (secondary)	N/A	N/A	0
Improvements 🎉 (primary)	-0.3%	-0.3%	1
Improvements 🎉 (secondary)	-0.7%	-0.8%	6
All 😿🎉 (primary)	-0.3%	-0.3%	1

Max RSS (memory usage)

Results

• Primary benchmarks: 🎉 relevant improvement found
• Secondary benchmarks: 🎉 relevant improvement found

	mean1	max	count2
Regressions 😿 (primary)	N/A	N/A	0
Regressions 😿 (secondary)	N/A	N/A	0
Improvements 🎉 (primary)	-3.0%	-3.0%	1
Improvements 🎉 (secondary)	-2.4%	-2.4%	1
All 😿🎉 (primary)	-3.0%	-3.0%	1

Cycles

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

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

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-review -S-waiting-on-perf -perf-regression

Footnotes

1. the arithmetic mean of the percent change ↩ ↩²

2. number of relevant changes ↩ ↩²

[compiler-errors]

Cool. @WaffleLapkin, r=me with those comments addressed above.

@bors delegate+

[bors]

✌️ @WaffleLapkin can now approve this pull request

[WaffleLapkin]

@bors r+

[bors]

📌 Commit cae3c78 has been approved by WaffleLapkin

[bors]

⌛ Testing commit cae3c78 with merge 4322a78...

[bors]

☀️ Test successful - checks-actions
Approved by: WaffleLapkin
Pushing 4322a78 to master...

[rust-timer]

Finished benchmarking commit (4322a78): comparison url.

Instruction count

• Primary benchmarks: 🎉 relevant improvement found
• Secondary benchmarks: no relevant changes found

	mean1	max	count2
Regressions 😿 (primary)	N/A	N/A	0
Regressions 😿 (secondary)	N/A	N/A	0
Improvements 🎉 (primary)	-0.6%	-0.6%	1
Improvements 🎉 (secondary)	N/A	N/A	0
All 😿🎉 (primary)	-0.6%	-0.6%	1

Max RSS (memory usage)

Results

• Primary benchmarks: no relevant changes found
• Secondary benchmarks: mixed results

	mean1	max	count2
Regressions 😿 (primary)	N/A	N/A	0
Regressions 😿 (secondary)	2.3%	2.6%	2
Improvements 🎉 (primary)	N/A	N/A	0
Improvements 🎉 (secondary)	-4.6%	-4.6%	1
All 😿🎉 (primary)	N/A	N/A	0

Cycles

Results

• Primary benchmarks: 😿 relevant regression found
• Secondary benchmarks: no relevant changes found

	mean1	max	count2
Regressions 😿 (primary)	2.6%	2.6%	1
Regressions 😿 (secondary)	N/A	N/A	0
Improvements 🎉 (primary)	N/A	N/A	0
Improvements 🎉 (secondary)	N/A	N/A	0
All 😿🎉 (primary)	2.6%	2.6%	1

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

@rustbot label: -perf-regression

Footnotes

1. the arithmetic mean of the percent change ↩ ↩² ↩³

2. number of relevant changes ↩ ↩² ↩³

[compiler-errors]

not a big deal, but next time @WaffleLapkin write r=compiler-errors instead of r+ so the merge commit says that i approved it.

it's just the merge commit title, though, so not a problem.

[WaffleLapkin]

Ah, ok