refactor rustc-hash integration

[llogiq]

I found that rustc-hash is used in multiple compiler crates. Also some types use FxBuildHasher whereas others use BuildHasherDefault<FxHasher> (both do the same thing).

In order to simplify future hashing experiments, I changed every location to use rustc_data_structures::fx::* types instead, and also removed the BuildHasherDefault variant. This will simplify future experiments with hashing (for example trying out a hasher that doesn't implement Default for whatever reason).

[rustbot]

Some changes occurred in exhaustiveness checking

cc @Nadrieril

These commits modify the Cargo.lock file. Unintentional changes to Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

[rustbot]

r? @eholk

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They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

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[llogiq]

Ok, I removed the rustc_data_structures. dependency, leaving only the change of BuildHasherDefault<FxHasher> to FxBuildHasher (because that's one less type to import, and leaves us the option of changing the algorithm in the future to something that doesn't impl Default).

[llogiq]

Ok, this compiles now and passes all tests.

[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.

[llogiq]

ping @eholk I assume you're busy, but this should be really quick to review.

[eholk]

Sorry about the delay! Looks good to me.

@bors r+

[rust-bors]

📌 Commit 8c69712 has been approved by eholk

It is now in the queue for this repository.

[rust-bors]

☀️ Test successful - CI
Approved by: eholk
Duration: 3h 14m 59s
Pushing fb292b7 to main...

[github-actions]

What is this?

This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.

Comparing 873d468 (parent) -> fb292b7 (this PR)

Test differences

Show 2 test diffs

2 doctest diffs were found. These are ignored, as they are noisy.

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard fb292b75fb6c410344f7216ec51b2eaa7cc2bb0c --output-dir test-dashboard

And then open test-dashboard/index.html in your browser to see an overview of all executed tests.

Job duration changes

1. dist-aarch64-linux: 6690.6s -> 8955.6s (+33.9%)
2. dist-aarch64-apple: 7049.7s -> 8394.7s (+19.1%)
3. aarch64-apple: 9601.9s -> 11260.7s (+17.3%)
4. dist-apple-various: 3378.1s -> 3867.3s (+14.5%)
5. aarch64-gnu-llvm-20-1: 3174.9s -> 3469.6s (+9.3%)
6. x86_64-msvc-2: 8670.7s -> 7874.4s (-9.2%)
7. aarch64-gnu: 7797.5s -> 7221.8s (-7.4%)
8. aarch64-msvc-2: 6262.1s -> 5810.8s (-7.2%)
9. dist-x86_64-musl: 7847.3s -> 7303.4s (-6.9%)
10. dist-aarch64-llvm-mingw: 5818.8s -> 6212.6s (+6.8%)

How to interpret the job duration changes?

Job durations can vary a lot, based on the actual runner instance
that executed the job, system noise, invalidated caches, etc. The table above is provided
mostly for t-infra members, for simpler debugging of potential CI slow-downs.

[rust-timer]

Finished benchmarking commit (fb292b7): comparison URL.

Overall result: ❌ regressions - no action needed

@rustbot label: -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)	0.1%	[0.1%, 0.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -3.6%, secondary -6.3%)

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)	-	-	0
Improvements ✅ (primary)	-3.6%	[-3.6%, -3.6%]	1
Improvements ✅ (secondary)	-6.3%	[-6.3%, -6.3%]	1
All ❌✅ (primary)	-3.6%	[-3.6%, -3.6%]	1

Cycles

Results (secondary -2.0%)

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)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.0%	[-2.0%, -2.0%]	1
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 474.052s -> 475.284s (0.26%)
Artifact size: 383.68 MiB -> 383.64 MiB (-0.01%)