Implement StableHash for BitSet and BitMatrix via Hash

[tmiasko]

This fixes an issue where bit sets / bit matrices the same word
content but a different domain size would receive the same hash.

[rust-highfive]

r? @jackh726

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[jackh726]

Is there a specific test/issue that this fixes?

[tmiasko]

Added tests that used to fail in a previous implementation.

I added test cases to the stable hasher since it strictly requires the hash to include all information that affects PartialEq comparison.

[jackh726]

@bors r+

[bors]

📌 Commit d0281bc has been approved by jackh726

[matthiaskrgr]

@bors rollup=never just in case..

[bors]

⌛ Testing commit d0281bc with merge e64e21a81265ec2f9388dad1ace1e1833ba0904c...

[bors]

💔 Test failed - checks-actions

[rust-log-analyzer]

A job failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

Attempting with retry: docker build --rm -t rust-ci -f /gha/_work/rust/rust/src/ci/docker/host-aarch64/aarch64-gnu/Dockerfile /gha/_work/rust/rust/src/ci/docker
Sending build context to Docker daemon  506.4kB

Step 1/6 : FROM ubuntu:20.04
Head https://registry-1.docker.io/v2/library/ubuntu/manifests/20.04: received unexpected HTTP status: 503 Service Unavailable
Sending build context to Docker daemon  506.4kB

Step 1/6 : FROM ubuntu:20.04
Step 1/6 : FROM ubuntu:20.04
Head https://registry-1.docker.io/v2/library/ubuntu/manifests/20.04: received unexpected HTTP status: 503 Service Unavailable
Sending build context to Docker daemon  506.4kB

Step 1/6 : FROM ubuntu:20.04
Step 1/6 : FROM ubuntu:20.04
Head https://registry-1.docker.io/v2/library/ubuntu/manifests/20.04: received unexpected HTTP status: 503 Service Unavailable
Sending build context to Docker daemon  506.4kB

Step 1/6 : FROM ubuntu:20.04
Step 1/6 : FROM ubuntu:20.04
Head https://registry-1.docker.io/v2/library/ubuntu/manifests/20.04: received unexpected HTTP status: 503 Service Unavailable
Sending build context to Docker daemon  506.4kB

Step 1/6 : FROM ubuntu:20.04
Step 1/6 : FROM ubuntu:20.04
Head https://registry-1.docker.io/v2/library/ubuntu/manifests/20.04: received unexpected HTTP status: 503 Service Unavailable
##[error]Process completed with exit code 1.
Post job cleanup.

[matthiaskrgr]

@bors retry docker.io 503

[bors]

⌛ Testing commit d0281bc with merge 87e8639...

[bors]

☀️ Test successful - checks-actions
Approved by: jackh726
Pushing 87e8639 to master...

[rust-timer]

Finished benchmarking commit (87e8639): comparison url.

Summary: This benchmark run did not return any relevant changes.

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

@rustbot label: -perf-regression