alt Hacker NewsApproximately nothing that uses UTF-16 validates it (I can’t think of a single thing that does), so surrogates will work fine. At least until a UTF-8 system touches it, because they normally do validate (Go is an uncommon exception in not validating).
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Dwedit • today at 1:22 AM
I looked it up. The one place where UTF-16 validation takes place is when using WideCharToMultiByte to convert to UTF-8 text. Before Vista, that was not validated.
The thing is that Windows is actually UCS-2, a consequence of the OS predating UTF-16 by a few years, and coming into existence when Unicode originally thought 16 bits was going to be enough.
For backwards compatibility with old file systems, there's no way the OS can start enforcing surrogate codepoints as forbidden from names. You can just so happen to pretend it's UTF-16 until it's not.