Avoid duplicate large_assignments lints

[Enselic]

By checking for overlapping spans.

This PR does the "reduce noisiness" task in #83518.

r? @oli-obk who added E-mentor and E-help-wanted and wrote the initial code.

(The fix itself is in dc82736. The two commits before that are just small refactorings.)

[rustbot]

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[rustbot]

r? @jackh726

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[oli-obk]

@bors r+ rollup

Thanks!

[bors]

📌 Commit dc82736 has been approved by oli-obk

It is now in the queue for this repository.

[bors]

⌛ Testing commit dc82736 with merge c587fd4...

[bors]

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing c587fd4 to master...

[rust-timer]

Finished benchmarking commit (c587fd4): comparison URL.

Overall result: ✅ improvements - no action needed

@rustbot label: -perf-regression

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
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.2%	[-0.2%, -0.2%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.2%	[-0.2%, -0.2%]	2

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)	2.0%	[0.9%, 2.9%]	3
Regressions ❌ (secondary)	3.0%	[3.0%, 3.0%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.0%	[0.9%, 2.9%]	3

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: 630.448s -> 629.54s (-0.14%)
Artifact size: 316.23 MiB -> 316.21 MiB (-0.01%)

[Enselic]

@oli-obk (Asking here to avoid noise in the tracking issue.) For the "stop linting in box/arc initialization" step, do you have some angle of attack in mind? For box it seems pretty straightforward since it is a lang item, so code involving box can relatively easily be special-cased in the compiler. But for arc, I see no clear path forward. As E-mentor, maybe you already have a plan for how this can be solved?

[oli-obk]

In addition to lang items, we also have diagnostics items. So you can mark things as diagnostic items in libstd and then check for it in the lint.