[00200200]

Fixes #995.

The size-hint test helpers multiply before dividing to compute binomial coefficients. The intermediate product can overflow usize even when the result fits: C(27, 7) on 32-bit and C(21, 19) on 64-bit.

Both integration-test helpers now reuse checked_binomial through a #[doc(hidden)] re-export, as requested in review. Regression coverage protects the overflow cases; genuinely unrepresentable results still fail the tests.

A separate small maintenance commit replaces four equivalent early-return matches with ? in the product iterator, MultiPeek, and the two folding helpers. This resolves the current Clippy question_mark failures without suppressing the lint or changing iterator behavior.

Validation on the updated head:

• All four CI Clippy configurations passed with RUSTFLAGS="--deny warnings": default, no-default-features, use_alloc, and all-targets/all-features.
• test_std: 94 passed; quick: 158 passed; folding documentation examples: 5 passed.
• cargo fmt --all --check and git diff --check passed.

32-bit execution, the Rust 1.63 MSRV, and Miri were not run locally. The previously reported semver check concerns the existing EitherOrBoth Copy implementation; this PR does not modify that type.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.77%. Comparing base (6814180) to head (7ed4bbf).
⚠️ Report is 226 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1131      +/-   ##
==========================================
- Coverage   94.38%   93.77%   -0.61%     
==========================================
  Files          48       52       +4     
  Lines        6665     6478     -187     
==========================================
- Hits         6291     6075     -216     
- Misses        374      403      +29     

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[phimuemue]

If it's the same algorithm, can't we just call checked_binomial?

[00200200]

Because checked_binomial is pub(crate) inside the private adaptors module, it isn't visible to the integration test crates in tests/.

If you'd prefer to share the implementation across tests rather than keeping the local helper, I can expose it with #[doc(hidden)] pub use crate::adaptors::checked_binomial; in lib.rs and call it here as itertools::checked_binomial(n, k).unwrap_or(0). Would you like me to do that?

[phimuemue]

If it's really supposed to be the same code. I very much prefer this.

Or, alternatively, move the tests to src. I do not even know if we have a good reason to keep them under a separate directory, especially if we have [test] within src already.

@jswrenn opinions on this?

[00200200]

Addressed in e6fce47: both integration-test helpers now reuse checked_binomial through a #[doc(hidden)] re-export. All 656 integration/doc tests passed, along with the helper unit test, no_std checks, docs, and formatting. Strict Clippy reports the same four pre-existing question_mark warnings as the previous PR head.

[00200200]

Rebased on current master and addressed the four question_mark Clippy diagnostics in a separate small maintenance commit, without lint suppressions. The early-return behavior of Product, MultiPeek, fold_ok, and fold_options is preserved.

On 7ed4bbf, all four CI Clippy feature configurations pass with RUSTFLAGS="--deny warnings". The standard integration suite passes 94 tests, quickcheck passes 158, and the folding documentation examples pass 5; formatting and diff checks pass. The PR description now reflects this validation.

The new CI and coverage runs require maintainer approval: https://github.com/rust-itertools/itertools/actions/runs/42362308297 and https://github.com/rust-itertools/itertools/actions/runs/42362308294 . Could these be approved? The current-head semver and coverage checks have not run yet.

[phimuemue]

Thanks.

[phimuemue]

I took this so that we can move forward. However, I still think we should probably simplify our tests so that they are inline.

Moreover, this commit revealed some for element in it - didn't we at some point change all these to it.for_each(...)?