The win32 API doesn't give us much choice. _Some_ code pages have
support for returning some error if we pass a specific flag, but not
all of them.
Anyway, since the code pages might not support all that UTF-16 provides,
we can't reasonably make it error out on characters that cannot be
converted.
So, the most reasonable thing we can handle is a unpaired high surrogate
at the end of a string, assume that the rest of the string was fine, and
that the low surrogate will be provided in the next call.
Pick-to: 6.6 6.5
Fixes: QTBUG-118185
Task-number: QTBUG-105105
Change-Id: I1f193c9d8e04bec769d885d32440c759d9dff0c2
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
d8d5922f16