rustdoc: use ThinVec for generic arg parts

[notriddle]

This reduces the size of both these args, and of path segments, so should measurably help with memory use.

[rustbot]

r? @GuillaumeGomez

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[compiler-errors]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 3814ec5 with merge 39e809d...

[bors]

☀️ Try build successful - checks-actions
Build commit: 39e809d (39e809d66cdc2761c224c082c361c06112189a8c)

[rust-timer]

Finished benchmarking commit (39e809d): 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 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
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.3%	[-0.5%, -0.1%]	20
Improvements ✅ (secondary)	-0.4%	[-0.6%, -0.2%]	17
All ❌✅ (primary)	-0.3%	[-0.5%, -0.1%]	20

Max RSS (memory usage)

Results (primary -2.8%, secondary 3.0%)

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)	3.0%	[2.2%, 3.8%]	2
Improvements ✅ (primary)	-2.8%	[-3.6%, -2.0%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.8%	[-3.6%, -2.0%]	2

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: 777.289s -> 776.243s (-0.13%)
Artifact size: 328.44 MiB -> 328.47 MiB (0.01%)

[fmease]

Lovely, thanks!

r? fmease @bors r+

[bors]

📌 Commit 3814ec5 has been approved by fmease

It is now in the queue for this repository.

[bors]

⌛ Testing commit 3814ec5 with merge a3fd735...

[bors]

💔 Test failed - checks-actions

[rust-log-analyzer]

A job failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[fmease]

spurious @bors retry

[bors]

⌛ Testing commit 3814ec5 with merge 3086510...

[bors]

☀️ Test successful - checks-actions
Approved by: fmease
Pushing 3086510 to master...

[rust-timer]

Finished benchmarking commit (3086510): comparison URL.

Overall result: ✅ improvements - no action needed

@rustbot label: -perf-regression

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
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.3%	[-0.5%, -0.2%]	20
Improvements ✅ (secondary)	-0.4%	[-0.6%, -0.1%]	18
All ❌✅ (primary)	-0.3%	[-0.5%, -0.2%]	20

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: 777.594s -> 778.16s (0.07%)
Artifact size: 329.01 MiB -> 329.00 MiB (-0.00%)