FAIL test/intl402/Locale/prototype/minimize/removing-likely-subtags-first-adds-likely-subtags.js (default) Full Output: Exception: Test262Error: "und".minimize() should be "en" Expected SameValue(«und», «en») to be true FAIL test/intl402/Locale/prototype/minimize/removing-likely-subtags-first-adds-likely-subtags.js (strict mode) Full Output: Exception: Test262Error: "und".minimize() should be "en" Expected SameValue(«und», «en») to be true ECMA spec: https://tc39.es/ecma402/#sec-Intl.Locale.prototype.minimize Unicode spec: http://www.unicode.org/reports/tr35/#Likely_Subtags Upstream test: https://github.com/tc39/test262/blame/main/test/intl402/Locale/prototype/minimize/removing-likely-subtags-first-adds-likely-subtags.js#L1 Using icu4c 67.1 after https://github.com/unicode-org/icu/pull/1140 (commit ec7e29f2b697188e5a667db2b235a3d0db8a5d20): uloc_minimizeSubtags(nullptr) -> "en" uloc_minimizeSubtags("") -> "en" uloc_minimizeSubtags("und") -> "en" uloc_minimizeSubtags("und-Thai") -> "th" Using icu4c before it: uloc_minimizeSubtags(nullptr) -> "en" uloc_minimizeSubtags("und") -> "" uloc_minimizeSubtags("") -> "" uloc_minimizeSubtags("und-Thai") -> "-Thai" As "und" language gets translated to an empty string in IntlObject.cpp, the test fails with the current ICU behavior.