Test crc-fast 1.4 to verify canary catches dependency issues

[vcjana]

Purpose

This PR demonstrates the canary dependency resolution bug.

What this PR does

• Pins crc-fast = "1.4" in aws-smithy-checksums/Cargo.toml
• Updates Cargo.lock to use crc-fast 1.4.0
• Does NOT include the Cargo.lock deletion fix

Expected behavior

Canary should FAIL because crc-fast 1.4.0 causes SIGILL on ARM (awesomized/crc-fast-rust#14)

Actual behavior (bug)

Canary will PASS because it uses stale Cargo.lock files with crc-fast 1.6.0

Proof of bug

1. This PR has crc-fast 1.4.0 in Cargo.lock
2. Canary will use existing workspace Cargo.lock files
3. Those files still have crc-fast 1.6.0 (not updated by PR)
4. Canary tests pass with 1.6.0, missing the 1.4.0 issue

The fix

See commit 8ef68d5 on the crc-fast branch:

• Deletes workspace Cargo.lock files before canary build
• Forces cargo to regenerate from Cargo.toml
• Canary now tests actual PR dependencies

Related

• Original issue: SIGILL on 1.4 with machine that doesn't support avx512 awesomized/crc-fast-rust#14
• Architecture testing PR: Add runtime architecture testing for x86_64 and ARM #4428

[github-actions]

A new generated diff is ready to view.

• AWS SDK (ignoring whitespace)
• Client Test (ignoring whitespace)
• No codegen difference in the Server Test
• No codegen difference in the Server Test Python
• No codegen difference in the Server Test Typescript

A new doc preview is ready to view.

[vcjana]

Update: Applied Cargo.lock deletion fix

All CIs passed in the previous run, proving the canary bug exists.

Now applied commit 330601c which deletes workspace Cargo.lock files before canary runs.

Expected result: Canary should now FAIL on ARM architectures because it will use crc-fast 1.4.0 from this PR (which causes SIGILL on ARM).

This will prove the fix works.

[github-actions]

A new generated diff is ready to view.

• AWS SDK (ignoring whitespace)
• Client Test (ignoring whitespace)
• No codegen difference in the Server Test
• No codegen difference in the Server Test Python
• No codegen difference in the Server Test Typescript

A new doc preview is ready to view.

[vcjana]

Closing this - turns out we can't actually reproduce the crc-fast 1.4 issue in CI.

The problem is that crc-fast 1.4 only crashes on x86_64 CPUs that don't have AVX-512. GitHub Actions runners have AVX-512, and QEMU emulates it, so our tests pass even with the broken version.

That said, the Cargo.lock deletion fix (330601c) is still valid. It makes sure the canary actually tests the dependency versions from the PR instead of whatever's in the committed lock files. aws-sdk-rust's canary caught the crc-fast issue because they run on real AWS instances, some of which don't have AVX-512.

We just can't prove it would catch this specific bug in our CI environment. But the fix is still worth having to prevent similar issues.