rustdoc: Use ThinVec in GenericParamDefKind

[camelid]

This should hopefully reduce memory usage and improve performance since
these vectors are often empty (and GenericParamDefKind is constructed a lot).

[rustbot]

r? @jsha

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

[camelid]

r? @GuillaumeGomez

@bors try @rust-timer queue

[bors]

⌛ Trying commit 0039153 with merge ecf3128...

[camelid]

Oof, forgot size checks aren't run on arm...

[camelid]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 3784adc with merge c2a267c...

[bors]

☀️ Try build successful - checks-actions
Build commit: c2a267c (c2a267ce3ff03a6b1fba8a47d82acaa437b5b6f6)

[rust-timer]

Finished benchmarking commit (c2a267c): comparison URL.

Overall result: no relevant changes - 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 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)	-	-	0
Regressions ❌ (secondary)	2.3%	[2.3%, 2.3%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.8%	[-4.4%, -1.2%]	3
All ❌✅ (primary)	-	-	0

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: 636.381s -> 636.608s (0.04%)
Artifact size: 304.39 MiB -> 304.41 MiB (0.01%)

[GuillaumeGomez]

No significant result apparently. Well, the type size still was decreased so let's merge it. Thanks!

@bors r+ rollup

[bors]

📌 Commit 3784adc has been approved by GuillaumeGomez

It is now in the queue for this repository.