I can't read your mind or guess what those "some extra bits" are. Why can't you mark the failing tests with todo_wine and think later how to make the tests pass?
This function must set only supported codepages bits The supported codepages are: ttp://www.microsoft.com/globaldev/reference/WinCP.mspx
For example, we use a symbol from Latin1 codepage. All codepages are include this symbol. So if we use EnumSystemCodePage() it enumerates codepages from the cptables array. This array include all codepages. So when we use a symbol from Latin1, all bits are set (I've tested it long time ago, so maybe I'm mistaken, maybe 1 bit or 2 are not set). But only the following bits must be set: FS_LATIN1 | FS_LATIN2 | FS_CYRILLIC | FS_GREEK | FS_TURKISH | FS_HEBREW | FS_ARABIC | FS_BALTIC | FS_VIETNAMESE | FS_THAI | FS_JISJAPAN | FS_CHINESESIMP | FS_WANSUNG | FS_CHINESETRAD
So, it's impossible to use EnumSystemCodePage()
If we use codepages from mlang_data[], everything works perfect.
The functions GetCPInfo/MultiByteToWideChar aren't also provide the list of needed codepages.
There is one extra problem: I can't find the size of the dbcs_table->cp2uni array, so It needs to calculate it. This calculation works perfect, but maybe there is more easy way to obtain it?