Implement RFC 3624 supertrait_item_shadowing (v2)

[compiler-errors]

Implements RFC 3624 and the associated lint in the RFC.

Implements:

• Shadowing algorithm
• Lint for call-site shadowing (allow by default, gated)
• Lint for definition-site shadowing (allow by default, gated)

Tracking:

• Tracking Issue for RFC: Supertrait Item Shadowing #89151

cc @Amanieu and rust-lang/rfcs#3624 and #89151

[bors]

☔ The latest upstream changes (presumably #125443) made this pull request unmergeable. Please resolve the merge conflicts.

[compiler-errors]

OK, this is ready pending RFC approval.

[compiler-errors]

The RFC is now in FCP, so this could probably get reviewed preliminarily but should probably not land until the RFC is merged.

r? compiler

[bors]

☔ The latest upstream changes (presumably #124895) made this pull request unmergeable. Please resolve the merge conflicts.

[teor2345]

I think there’s a few missing words in the lint comments, and maybe some places that say “method” should say “item”?

[compiler-errors]

@rustbot ready

This PR is ready for review since the corresponding RFC has landed.

[bors]

☔ The latest upstream changes (presumably #136954) made this pull request unmergeable. Please resolve the merge conflicts.

[compiler-errors]

@bors r=BoxyUwU

[bors]

📌 Commit 1824221 has been approved by BoxyUwU

It is now in the queue for this repository.

[compiler-errors]

@bors r=BoxyUwU

[bors]

📌 Commit 72b4df3 has been approved by BoxyUwU

It is now in the queue for this repository.

[bors]

⌛ Testing commit 72b4df3 with merge 3cb0272...

[bors]

☀️ Test successful - checks-actions
Approved by: BoxyUwU
Pushing 3cb0272 to master...

[rust-timer]

Finished benchmarking commit (3cb0272): comparison URL.

Overall result: ❌ regressions - 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)	0.2%	[0.2%, 0.3%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -1.3%, secondary -1.0%)

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)	1.1%	[1.1%, 1.1%]	1
Improvements ✅ (primary)	-1.3%	[-1.3%, -1.3%]	1
Improvements ✅ (secondary)	-3.0%	[-3.0%, -3.0%]	1
All ❌✅ (primary)	-1.3%	[-1.3%, -1.3%]	1

Cycles

Results (primary -2.6%, secondary 2.5%)

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)	2.5%	[2.5%, 2.5%]	1
Improvements ✅ (primary)	-2.6%	[-2.6%, -2.6%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.6%	[-2.6%, -2.6%]	1

Binary size

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

Bootstrap: 788.303s -> 789.524s (0.15%)
Artifact size: 347.81 MiB -> 347.86 MiB (0.01%)