fix(runtime): #5582 — coerce null Intl option values per GetOption (10 test262)

[proggeramlug]

Summary

Addresses part of #5582 (test262 intl402 DateTimeFormat parity). ECMA-402 GetOption treats only undefined as "absent → use the fallback"; every other value — null included — is coerced with ToString and then validated. Perry's get_option_string short-circuited null to None, so a null enum option was silently ignored instead of being rejected.

With this fix null coerces to the string "null", which:

• fails every closed-enum allow-list → RangeError (matching Node), for localeMatcher, formatMatcher, weekday, hourCycle, dateStyle, and the NumberFormat / ListFormat / RelativeTimeFormat enums (style, type, numeric, currencyDisplay, roundingPriority, …); and
• for the Unicode locale-extension keys calendar / numberingSystem, "null" is a well-formed but unsupported type subtag, so ResolveLocale drops it and resolvedOptions reports the locale default (gregory / latn). A small get_locale_extension_option mirrors that observable outcome by treating null as absent rather than echoing "null". It reads the option getter exactly once so the GetOption call-order tests still pass.

Validation

Local test262 sweep (pinned sha 4249661, Node v26.3.0 oracle, scripts/test262_subset.py) across intl402/{DateTimeFormat,NumberFormat,ListFormat,PluralRules,RelativeTimeFormat,Locale}:

+10 pass, 0 regressions (321 → 311 runtime-fails).

Fixed:

DateTimeFormat/test-option-date-time-components.js
DateTimeFormat/test-option-formatMatcher.js
DateTimeFormat/test-option-localeMatcher.js
ListFormat/constructor/constructor/options-style-invalid.js
ListFormat/constructor/constructor/options-type-invalid.js
NumberFormat/test-option-currencyDisplay.js
NumberFormat/test-option-roundingPriority.js
NumberFormat/test-option-style.js
RelativeTimeFormat/constructor/constructor/options-numeric-invalid.js
RelativeTimeFormat/constructor/constructor/options-style-invalid.js

Added gap test test-files/test_gap_intl_datetimeformat_null_option_5582.ts, which is byte-identical against node --experimental-strip-types.

Note: the remaining #5582 failures are largely Temporal/ICU formatting-fidelity gaps — Perry's DateTimeFormat format/formatToParts currently render a fixed M/D/YYYY regardless of component/style/timeZone options. That formatting overhaul is out of scope here.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Improved Intl.DateTimeFormat handling for null option values.
  • null is now treated as absent for calendar and numberingSystem, preventing errors and allowing locale-based fallback.
  • Other format options keep their existing validation behavior, with null still handled consistently.

[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: a714c989-594c-4d13-a505-4f6a8c818eff

📥 Commits

Reviewing files that changed from the base of the PR and between f8c259c and bd71f2b.

📒 Files selected for processing (2)

• crates/perry-runtime/src/intl.rs
• test-files/test_gap_intl_datetimeformat_null_option_5582.ts

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📝 Walkthrough

Walkthrough

Intl option coercion now distinguishes undefined from null, and DateTimeFormat treats calendar and numberingSystem as locale-extension options with null-as-absent behavior. A new test exercises null inputs and the resulting resolvedOptions() values.

Changes

Intl DateTimeFormat null option handling

Layer / File(s)	Summary
Shared option coercion crates/perry-runtime/src/intl.rs	Adds coerce_option_string, rebuilds get_option_string on it, and adds get_locale_extension_option with different null handling for Unicode locale-extension keys.
DateTimeFormat null handling and test crates/perry-runtime/src/intl.rs, test-files/test_gap_intl_datetimeformat_null_option_5582.ts	DateTimeFormat reads calendar and numberingSystem through get_locale_extension_option, and the new test probes null behavior for several option names plus locale-extension resolution.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• PerryTS/perry#5601: Also changes crates/perry-runtime/src/intl.rs Intl.DateTimeFormat option handling around calendar and related locale-extension behavior.
• PerryTS/perry#5649: Also changes Intl.DateTimeFormat option parsing in make_instance, including numberingSystem and null-related semantics.

Poem

A bunny hopped through Intl’s gate,
With null and undef in different state.
calendar blinked, numberingSystem too,
The locale keys knew what to do.
نرم hops and whiskers, all agreed:
absent means absent—just what we need. 🐰

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description covers summary and validation, but it omits required template sections like Changes, Related issue, Test plan, and Checklist.	Add the missing template sections: concrete Changes bullets, Related issue, explicit Test plan commands, optional screenshots/output, and the checklist items.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is concise and accurately summarizes the main runtime change around coercing null Intl option values.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ 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 worktree-fix-5582-datetimeformat

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