fix(array): route collection reads before array validation

[proggeramlug]

Summary

• route managed-header-tagged, authoritative-registry-confirmed Map/Set indexed reads before clean_arr_ptr's strict array-only validation
• leave fix(gc): install array growth forwarding for low-address arenas #8041's non-array rejection unchanged and assert that Map/Set still fail the array-only funnel
• reuse the pre-clean header tag for ordinary arrays, rereading only when cleaning resolves a forwarded array head

Fixes #8060.

Causal evidence

Exact base: ef6e111a4fb85dcc9fd81f69c30bf57a0bf40a61.

#8041 made clean_arr_ptr reject every tracked non-array, but js_array_get_f64 reached its Map/Set branches only after that rejection. Six pre-existing tests failed individually with NaN instead of collection values. js_array_length was the positive control: it already consulted the managed tag and authoritative registry before cleaning, and returned the correct sizes for the same receivers.

Local validation

Using isolated worktree and target:

• all six formerly failing tests: 20/20 fresh-process runs each
• array collection-tag tests: 6/6
• dynamic-index collection-tag tests: 3/3
• typed-feedback tests: 49/49
• array-subclass strict-cleaning controls: 6/6
• array/forwarding tests: 74/74
• cargo check -p perry-runtime --lib
• cargo fmt --all --check
• git diff --check

One full default-parallel runtime suite after the fix reported 2,313 passed, 1 failed, 4 ignored. The sole failure was promise::keyed_table::tests::settling_many_keys_is_not_quadratic, the independently diagnosed wall-clock assertion replaced by #8059; all six #8060 tests and the shadow-root witness passed.

Summary by CodeRabbit

• Bug Fixes

  • Fixed indexed reads on Map and Set values so they no longer incorrectly return NaN.
  • Out-of-range indexed reads now consistently return undefined.
  • Improved handling of collection-backed and forwarded array-like values during indexed access.

• Tests

  • Added coverage validating correct Map and Set indexing behavior, pointer validation, registry-backed reads, and collection size reporting.

• Documentation

  • Added a changelog entry describing the corrected collection indexing behavior.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 59ffc17d-b535-4152-acd5-a3f1c35632c9

📥 Commits

Reviewing files that changed from the base of the PR and between a2c90a1 and ef62f0d.

📒 Files selected for processing (1)

• crates/perry-runtime/src/array/indexing.rs

🚧 Files skipped from review as they are similar to previous changes (1)

• crates/perry-runtime/src/array/indexing.rs

---

📝 Walkthrough

Walkthrough

js_array_get_f64 now routes registered Map and Set receivers before strict array pointer validation. It preserves array forwarding behavior, returns undefined for out-of-range collection reads, and adds receiver validation tests and changelog coverage.

Changes

Map and Set indexed-read fix

Layer / File(s)	Summary
Collection dispatch and pointer validation crates/perry-runtime/src/array/indexing.rs, crates/perry-runtime/src/array/collection_tag_tests.rs, changelog.d/8061-collection-index-before-array-clean.md	js_array_get_f64 checks registered Map and Set receivers before array pointer cleaning, reads collection entries with bounds checks, preserves forwarded-array tag handling, and adds regression assertions and changelog documentation.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Mergeability Score: ⚪ Minimal · up to ef62f

The change routes Map/Set indexed reads before strict array validation while preserving rejection of non-array inputs through the array-only path; no actionable merge-blocking risk remains after normal checks and review.

Possibly related PRs

• PerryTS/perry#7603: Both changes update clean_arr_ptr and array indexed-read dispatch for collection receivers.
• PerryTS/perry#7765: Both changes modify js_array_get_f64 and collection-tag tests for Map and Set handling.
• PerryTS/perry#7880: Both changes update Map and Set registry dispatch before array-pointer validation.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes routing collection reads before strict array validation.
Description check	✅ Passed	The description provides the change summary, implementation details, linked issue, and detailed validation results.
Linked Issues check	✅ Passed	The changes satisfy #8060 by preserving strict non-array rejection and restoring validated Map/Set indexed reads before array cleaning.
Out of Scope Changes check	✅ Passed	The code, regression tests, and changelog entry directly support the linked issue and stated pull request objectives.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/8060-map-set-index

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[proggeramlug]

@coderabbitai review

[coderabbitai]

⚠️ Action not completed

Already reviewed.

Note: CodeRabbit is an incremental review system and does not re-review already reviewed commits. This command is applicable only when automatic reviews are paused.