Build ID: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; ja-JP-mac; rv:1.9.2a1pre) Gecko/20090110 Minefield/3.2a1pre Steps to reproduce: run the following JavaScript var dts = Components.classes["@mozilla.org/intl/scriptabledateformat;1"] .getService(Components.interfaces.nsIScriptableDateFormat); var s = dts.FormatDate("da", dts.dateFormatLong, 2009, 1, 10); alert(s); Actual Result: Sat, Jan 10, 2009 Expected Result(I'm not sure, I guess): lør 10. jan 2009 I suspect the cause is that |*regionCode| is not set at http://hg.mozilla.org/mozilla-central/annotate/1c4fdd5a9b17/intl/locale/src/mac/nsMacLocale.cpp#l266

It seems like http://mxr.mozilla.org/mozilla-central/source/intl/locale/src/mac/nsDateTimeFormatMac.cpp#386 only uses the script code and region code, whereas the language code is the primary identifier in the Mozilla locale code.

Bug 470837 seems to be a friend of this one, from glancing at it. It's about day names being cumbersome on OSX, when no locale code is specified, like in the cookies dialog.

Fixed by bug 360018

Covered by the test for bug 22310

Verified on trunk and 1.9.1 with: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.2a1pre) Gecko/20090421 Minefield/3.6a1pre ID:20090421032809 Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.1b4pre) Gecko/20090421 Shiretoko/3.5b4pre ID:20090421030848