BL-15882_reopen_to_macrolanguage

[nabalone]

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[andrew-polk]

@andrew-polk reviewed 6 files and all commit messages, and made 1 comment.
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components/language-chooser/common/find-language/searchForLanguage.ts line 105 at r1 (raw file):

  //  handled
  //  by the searchResultModifier
  const correctedCode = code === "zh" ? "cmn" : code;

devin:

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components/language-chooser/common/find-language/searchForLanguage.ts:R105

Case-sensitive zh check breaks case-insensitive contract of getLanguageBySubtag

The new code === "zh" check at searchForLanguage.ts:105 is case-sensitive, but getLanguageBySubtag (and by extension parseLangtagFromLangChooser) is expected to be case-insensitive, as demonstrated by the existing test parseLangtagFromLangChooser("cE-CyRl-rU") succeeding.

Root Cause and Impact

When parseLangtagFromLangChooser("ZH-Hant") is called, splitTag does not normalize case (components/language-chooser/common/find-language/languageTagUtils.ts:241), so languageSubtag is "ZH". Then getLanguageBySubtag("ZH", searchResultModifier) is called. Because "ZH" !== "zh", the correction to "cmn" is skipped, and correctedCode remains "ZH".

Fuse.js (which is case-insensitive by default) then searches for "ZH" and may find the zho macrolanguage entry (which has languageSubtag: "zh") instead of the intended cmn entry.

• Without a modifier: Returns the zho macrolanguage entry instead of the data-rich cmn entry.
• With defaultSearchResultModifier: zho is in EXCLUDED_PROBLEMATIC_LANGUAGE_CODES (searchResultModifiers.ts:246), so it gets filtered out, and the function returns undefined — causing parseLangtagFromLangChooser to fail for a valid Chinese tag.

Impact: Any caller passing an uppercase or mixed-case "zh" language subtag (e.g. "ZH-Hant", "Zh-CN") to parseLangtagFromLangChooser or getLanguageBySubtag will get incorrect results or undefined for Chinese.

[andrew-polk]

@andrew-polk reviewed 2 files and all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @nabalone).

[andrew-polk]

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