[Apple] Preserve Norwegian locale names in hybrid globalization

[matouskozak]

Summary

• preserve the requested no culture name and ISO language codes when Foundation canonicalizes it to nb
• preserve no-NO parent fallback to no for resource lookup
• centralize Apple locale language-code resolution and add cross-platform Norwegian regression coverage

Fixes #112249

Testing

• CoreCLR iOS Simulator native/runtime-pack build
• Norwegian culture regression theory: 2 passed, 0 failed
• CultureInfo constructor matrix: 348 passed, 0 failed
• GetCultureInfo canonicalization matrix: 22 passed, 0 failed

Note

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Pull request overview

This PR adjusts Apple hybrid globalization locale canonicalization so that requests for Norwegian (no / no-NO) preserve the requested culture name and ISO language codes (instead of being canonicalized to nb), and adds regression coverage in System.Globalization tests.

Changes:

• Add Apple-hybrid helpers to resolve locale language code / identifier while preserving no when Foundation canonicalizes to nb.
• Use the preserved language code for ISO639 2- and 3-letter language name queries and for parent-culture computation.
• Add a regression theory verifying CultureInfo("no") and CultureInfo("no-NO") language-code/name/parent expectations.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/native/libs/System.Globalization.Native/pal_locale.m	Centralizes Apple-hybrid language-code / locale-identifier handling and uses it for locale name, ISO codes, and ParentName.
src/libraries/System.Runtime/tests/System.Globalization.Tests/CultureInfo/CultureInfoCtor.cs	Adds Norwegian regression assertions for culture name, ISO language codes, and parent culture.

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Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

[tarekgh]

LGTM

[matouskozak]

/azp run runtime-extra-platforms,runtime

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[github-actions]

Holistic Review

Motivation: Justified. This fixes a confirmed .NET 9 regression (#112249) where Apple hybrid globalization returns nb for the no culture because Foundation canonicalizes no→nb, unlike ICU/Windows/Android which preserve no. The result broke Norwegian resource lookup on iOS, a real, user-reported break with a clear repro.

Approach: Sound and appropriately narrow. The fix centralizes Apple locale language-code resolution into GetLocaleLanguageCode/GetLocaleIdentifier helpers and only overrides Foundation's canonicalization for the specific no→nb case, leaving all other locales untouched. Name, ISO 639-1/639-2, and parent-name paths all flow through the same helpers, keeping the culture name, two/three-letter codes, and no-NO→no parent fallback consistent.

Summary: ✅ LGTM. The special-case is tightly guarded (case-insensitive no subtag match plus exact nb canonical match), the identifier rewrite is defensively bounded (nil checks, equal-code short-circuit, and a length guard before the substring splice), and regression coverage is added as an ICU-gated theory plus the no entry restored to the general ctor matrix. No blocking concerns found.

---

Detailed Findings

✅ Correctness — Narrow, well-guarded override

GetLocaleLanguageCode only substitutes no when the original subtag is no (case-insensitive) AND Foundation canonicalized it to nb, so nb/nn inputs are unaffected. GetLocaleIdentifier rewrites the identifier prefix only when languageCode != canonicalLanguageCode, which today only fires for the no case; the localeIdentifier.length < canonicalLanguageCode.length guard prevents an out-of-range substringFromIndex:. Because no and nb are both length 2 and Foundation's identifier begins with the language code, the splice (no + suffix of nb_...) is safe. Empty-string handling in GetLocaleNameNative is preserved.

✅ Test quality — Appropriate gating and placement

The new Ctor_String_NorwegianLanguageNames theory asserting Name, TwoLetterISOLanguageName, ThreeLetterISOLanguageName, and Parent.Name is correctly gated to IsIcuGlobalization (per the commit message, NLS/invariant may not support no-NO), and uses [Theory]/[InlineData] per conventions. Moving no out of the IsNotHybridGlobalizationOnApplePlatform-only block into the general Ctor_String matrix now exercises the fixed Apple hybrid path directly.

💡 Observation — Generality of the identifier rewrite

The helper naming (GetLocaleIdentifier) reads as general-purpose, but its rewrite branch is effectively no-specific today. If future locales need similar alias handling, the length/prefix assumptions (language code is a leading prefix of the identifier and same length as the alias) would need re-validation. Non-blocking; the current guards make it safe for the only case that triggers it.

Note

This review was generated by this repository's Holistic Review agentic workflow to complement the built-in Copilot review.

Generated by Holistic Review · 71.2 AIC · ⌖ 10.5 AIC · ⊞ 10K

[matouskozak]

/ba-g failures are not related to changes in this PR