Looks like it was copied from QUtf16::convertFromUnicode(), but for the
UTF-32 case that is not correct. UTF-16 to UTF-32 conversions can change
the length of the string due to surrogates.
There are unit test tests for creating and parsing UTF-32 headers, and
for detecting content as UTF-32, but there aren't any for UTF-32
conversions. I don't have time to add a full test for that.
Fixes: QTBUG-97122
Pick-to: 6.2 6.1
Change-Id: Ic17a33f599b844d8ab5dfffd16ab2c4cb6b0547d
Reviewed-by: Ievgenii Meshcheriakov <ievgenii.meshcheriakov@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
333b40a12e