Add expansion info to default bounds

[oli-obk]

Relanding part of #158122

The incremental issues are resolved in this PR, but we still need to check perf

r? @ghost

[oli-obk]

@bors try @rust-timer queue

[oli-obk]

@bors try cancel seems stuck

[rust-bors]

Try build cancelled. Cancelled workflows:

• https://github.com/rust-lang/rust/actions/runs/27962724059

[oli-obk]

@bors try

[rust-bors]

☀️ Try build successful (CI)
Build commit: 6c4a2f9 (6c4a2f95b8d82a704b3d651a5a527b432add2ee8)
Base parent: cddcbec (cddcbec198760511240bf0e728193bf4d700acb4)

[rust-timer]

Finished benchmarking commit (6c4a2f9): 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)	0.6%	[0.1%, 3.0%]	80
Regressions ❌ (secondary)	0.6%	[0.0%, 1.8%]	58
Improvements ✅ (primary)	-0.2%	[-0.3%, -0.1%]	3
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.6%	[-0.3%, 3.0%]	83

Max RSS (memory usage)

Results (primary 1.6%, secondary 4.5%)

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

	mean	range	count
Regressions ❌ (primary)	1.8%	[0.5%, 3.2%]	28
Regressions ❌ (secondary)	4.5%	[0.7%, 11.5%]	12
Improvements ✅ (primary)	-2.2%	[-2.3%, -2.1%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.6%	[-2.3%, 3.2%]	30

Cycles

Results (primary 3.1%, secondary 2.2%)

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

	mean	range	count
Regressions ❌ (primary)	3.4%	[2.0%, 5.2%]	15
Regressions ❌ (secondary)	3.0%	[2.1%, 4.3%]	16
Improvements ✅ (primary)	-1.7%	[-1.7%, -1.7%]	1
Improvements ✅ (secondary)	-4.2%	[-5.3%, -3.1%]	2
All ❌✅ (primary)	3.1%	[-1.7%, 5.2%]	16

Binary size

Results (primary 2.3%, secondary 2.3%)

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

	mean	range	count
Regressions ❌ (primary)	2.3%	[0.0%, 11.9%]	78
Regressions ❌ (secondary)	2.3%	[0.0%, 11.4%]	47
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.3%	[0.0%, 11.9%]	78

Bootstrap: 505.379s -> 506.981s (0.32%)
Artifact size: 353.06 MiB -> 353.64 MiB (0.16%)

[rust-bors]

☔ The latest upstream changes (presumably #158268) made this pull request unmergeable. Please resolve the merge conflicts by rebasing.