Clean up and harden various methods around trait substs

[oli-obk]

r? @lcnr

[rustbot]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @lcnr (or someone else) soon.

Please see the contribution instructions for more information.

[rustbot]

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

[bors]

☔ The latest upstream changes (presumably #104555) made this pull request unmergeable. Please resolve the merge conflicts.

[bors]

☔ The latest upstream changes (presumably #98914) made this pull request unmergeable. Please resolve the merge conflicts.

[oli-obk]

@rustbot ready

cc @lcnr

[oli-obk]

@bors r=lcnr

[bors]

📌 Commit 6b9312897d94b04b9b8f52df51aa952e288d33c5 has been approved by lcnr

It is now in the queue for this repository.

[bors]

☔ The latest upstream changes (presumably #104673) made this pull request unmergeable. Please resolve the merge conflicts.

[oli-obk]

@bors r=lcnr p=1 bitrotty

[bors]

📌 Commit c2ecd8f has been approved by lcnr

It is now in the queue for this repository.

[bors]

⌛ Testing commit c2ecd8f with merge 28a53cd...

[bors]

☀️ Test successful - checks-actions
Approved by: lcnr
Pushing 28a53cd to master...

[rust-timer]

Finished benchmarking commit (28a53cd): comparison URL.

Overall result: ❌ regressions - ACTION NEEDED

Next Steps: If you can justify the regressions found in this perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please open an issue or create a new PR that fixes the regressions, add a comment linking to the newly created issue or PR, and then add the perf-regression-triaged label to this PR.

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.3%	[0.2%, 0.5%]	11
Regressions ❌ (secondary)	0.6%	[0.2%, 0.9%]	27
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.3%	[-0.3%, -0.3%]	1
All ❌✅ (primary)	0.3%	[0.2%, 0.5%]	11

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)	2.4%	[1.6%, 3.1%]	5
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.5%	[-5.0%, -2.1%]	2
All ❌✅ (primary)	-	-	0

Cycles

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