[Bug 56399] cmd.exe's %~s modifier (short DOS path) expands to mixed short/long format

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=56399

--- Comment #5 from [e-mail] ---
I wouldn't say in general that cmd %~s should behave like winepath -s.
Wine's cmd %~s should behave like Microsoft's cmd %~s.
That means the existing part of the path is converted to short format and the
non-existing part remains unchanged.
After some playing around I can say that winepath -s seems to do exactly that,
i.e. winepath -s is at least significantly closer to Microsoft's cmd %~s than
Wine's current cmd %~s.
All winepath -s does to achieve this is to call GetShortPathNameW, nothing
else.

The proposed modification therefore simplifies to:

/* 4. Handle 's' : Use short paths (File doesn't have to exist) */
if (wmemchr(firstModifier, 's', modifierLen) != NULL) {
    if (finaloutput[0] != 0x00) lstrcatW(finaloutput, L" ");
    GetShortPathNameW(fullfilename, fullfilename, ARRAY_SIZE(fullfilename));
}

I think this modification can only break batch scripts written exclusively for
Wine that rely on the current cmd %~s behavior.