Improve NumBufferTrait associated items

[GuillaumeGomez]

It allows for NumBuffer::buf size to depend on the integer instead of being the same for all integers.

The idea was suggested by @Amanieu (thanks a lot!).

r? @Amanieu

[rustbot]

Some changes occurred in integer formatting

cc @tgross35

[Amanieu]

@bors r+

[rust-bors]

📌 Commit c558f6b has been approved by Amanieu

It is now in the queue for this repository.

[rust-bors]

⌛ Testing commit c558f6b with merge 22398ff...

Workflow: https://github.com/rust-lang/rust/actions/runs/27855057977

[jhpratt]

yielding to rollup

@bors yield

[rust-bors]

Auto build was cancelled. Cancelled workflows:

• https://github.com/rust-lang/rust/actions/runs/27855057977

The next pull request likely to be tested is #158162.

[jhpratt]

@rust-timer build 94ec748

[rust-timer]

Finished benchmarking commit (94ec748): comparison URL.

Overall result: ❌ regressions - please read:

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

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

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	0.4%	[0.2%, 0.8%]	7
Regressions ❌ (secondary)	0.6%	[0.1%, 1.1%]	21
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.4%	[0.2%, 0.8%]	7

Max RSS (memory usage)

Results (primary 2.8%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.8%	[2.8%, 2.8%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.8%	[2.8%, 2.8%]	1

Cycles

Results (secondary 3.9%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	3.9%	[3.1%, 4.6%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 489.308s -> 480.969s (-1.70%)
Artifact size: 390.69 MiB -> 390.68 MiB (-0.00%)

[GuillaumeGomez]

I'm surprised: is any of these using NumBuffer? O.o