Fix/i32 min rem overflow (minor)

[Jayesh-Dev21]

This Pull Request fixes/closes #5481.

It changes the following:

Fixes a panic when computing (-2147483648 | 0) % (-1 | 0). The fast-path integer remainder operations (rem and rem_fast) used bare x % y on i32 values, which panics on signed integer overflow when x = i32::MIN and y = -1.
Changes

• core/engine/src/value/operations.rs: Replaced bare x % y with x.checked_rem(y) in both rem() and rem_fast(). On overflow (None), falls back to f64 arithmetic — the same pattern already used by add, sub, mul, and div in the same file.
• core/engine/src/value/tests.rs: Added regression test rem_i32_min_by_neg_one asserting the result is -0.0.

Verification

• (-2147483648 | 0) % (-1 | 0) now returns -0 instead of panicking (matches Node.js behaviour)

• Existing rem_by_zero test still passes
• Clippy clean (both --all-features and --no-default-features)

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	53,578	53,578	0
Passed	51,426	51,426	0
Ignored	1,648	1,648	0
Failed	504	504	0
Panics	0	0	0
Conformance	95.98%	95.98%	0.00%

Tested main commit: 665f03924a54e5162be227e7e909612e36f6e35a
Tested PR commit: b9ff062884403585e8bfcfac558269dbd3890524
Compare commits: 665f039...b9ff062

[codecov]

Codecov Report

❌ Patch coverage is 62.50000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 62.81%. Comparing base (6ddc2b4) to head (b9ff062).
⚠️ Report is 1050 commits behind head on main.

Files with missing lines	Patch %	Lines
core/engine/src/value/operations.rs	62.50%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #5501       +/-   ##
===========================================
+ Coverage   47.24%   62.81%   +15.57%     
===========================================
  Files         476      536       +60     
  Lines       46892    60288    +13396     
===========================================
+ Hits        22154    37871    +15717     
+ Misses      24738    22417     -2321     

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[nekevss]

Feel free to mark this as ready for review whenever you're ready for a maintainer to take a look

[Jayesh-Dev21]

@nekevss Marked this Pr as ready for review. Let me know if there's anything you'd like me to change.
Thanks!

[Copilot]

🟡 Changes recommended

The new rem_i32_min_by_neg_one test uses assert_eq which treats +0 and -0 as equal, so it doesn’t actually validate the negative-zero behavior.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Fixes an i32 signed-overflow panic in the % fast paths by switching to checked remainder and falling back to f64 arithmetic on overflow, aligning behavior with JavaScript (e.g., producing -0 instead of panicking).

Changes:

• Replace x % y with x.checked_rem(y) in rem() and rem_fast(), with f64 fallback on overflow.
• Add regression tests covering i32::MIN % -1 behavior for both the interpreter path and rem_fast().

File summaries

File	Description
core/engine/src/value/operations.rs	Prevents % overflow panic for i32::MIN % -1 by using checked_rem with f64 fallback and correct -0 sign handling.
core/engine/src/value/tests.rs	Adds regression tests for i32::MIN % -1, including a rem_fast() sign-of-zero assertion.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 1
• Review effort level: Lite

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[jedel1043]

Need to address Copilot's review first; either reject with a reasoning or include the review

[Jayesh-Dev21]

@jedel1043 I have addressed the Copilot review and now switched rem_i32_min_by_neg_one to use assert_with_op with is_sign_negative(), so it properly validates the negative (-) zero sign bit, not just the value. Both rem_i32_min_by_neg_one and rem_fast_i32_min_by_neg_one now use the same approach.

Ready for another look.