[Bug 56175] New: Ntdll RtlUpcaseUnicodeChar support is too good (supports more recent Unicode versions than Windows)

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=56175

Bug ID: 56175
           Summary: Ntdll RtlUpcaseUnicodeChar support is too good
                    (supports more recent Unicode versions than Windows)
           Product: Wine
           Version: 9.0-rc5
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: ntdll
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

I am investigating a failure in a test for the Zig programming language's
support for Windows, when run under Wine.  The test passes on a real Windows
installation, but fails under Wine.  The test is exercising ntdll
RtlUpcaseUnicodeChar and, when run under Wine, it finds about 190 characters
that are unexpectedly upper cased.

From what I can tell, Wine uses up-to-date definitions from Unicode (via
tools/make_unicode), but Windows has not updated its Unicode tables as
recently.  I have not found any documentation from Microsoft about what
specific Unicode version they support.

For a specific example, the Greek Letter Yot (U+3f3, "ϳ", 
https://www.compart.com/en/unicode/U+03f3) is one that Window's
RtlUpcaseUnicodeChar will not upcase. But Wine's RtlUpcaseUnicodeChar will
upcase it to a Greek Capital Letter Yot (U+37f, "Ϳ",
https://www.compart.com/en/unicode/U+037F).

I believe this is a bug in Wine, and it should use the same upper casing rules
(and presumably a lot of other Unicode tables?) as Windows.  I can provide a
Zig test case (probably not that useful!), or I can try building a C test case
if that would be helpful.