Ignore #[doc(hidden)] items when computing trimmed paths for printing

[Zalathar]

The trimmed_def_paths query examines all items in the current crate, and all pub items in immediate-dependency crates (including the standard library), to see which item names are unique and can therefore be printed unambiguously as a bare name without a module path.

Currently that query has no special handling for #[doc(hidden)] items, which has two consequences:

• Hidden names can be considered unique, and will therefore be printed without a path, making it hard to find where that name is defined (since it normally isn't listed in documentation).
• Hidden names can conflict with visible names that would otherwise be considered unique, causing diagnostics to mysteriously become more verbose based on internal details of other crates.

This PR therefore makes the trimmed_def_paths query ignore external-crate items that are #[doc(hidden)], along with their descendants.

As a result, hidden item names are never considered unique for trimming, and no longer interfere with visible item names being considered unique.

---

• Fixes Standard library internal modules are treated as potential name colliders #148387.

[rustbot]

This PR modifies tests/ui/issues/. If this PR is adding new tests to tests/ui/issues/,
please refrain from doing so, and instead add it to more descriptive subdirectories.

[rustbot]

r? @wesleywiser

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[Zalathar]

@rustbot ready

[rustbot]

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[davidtwco]

@bors r+

[rust-bors]

📌 Commit 2df2c72 has been approved by davidtwco

It is now in the queue for this repository.

[Kobzol]

@rust-timer build e83b9d3

Checking for #151381.

[rust-timer]

Finished benchmarking commit (e83b9d3): comparison URL.

Overall result: ❌ regressions - please read the text below

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please do so in sufficient writing along with @rustbot label: +perf-regression-triaged. If not, please fix the regressions and do another perf run. If its results are neutral or positive, the label will be automatically removed.

@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
Regressions ❌ (secondary)	5.1%	[0.5%, 20.2%]	18
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (secondary 0.9%)

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)	3.2%	[2.1%, 4.3%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.8%	[-3.8%, -3.8%]	1
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary 6.7%)

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)	6.7%	[2.9%, 17.6%]	8
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 473.058s -> 474.781s (0.36%)
Artifact size: 383.29 MiB -> 383.31 MiB (0.00%)

[Kobzol]

So, the regressions are only on stress tests, but it still seems a bit suspicious. The is_doc_hidden query is apparently not that cheap 😆