Remove dependency on QTextCodec for qt6

[geustache]

Remove dependency on QTextCodec for qt6 with QStringConvert
3 cases
Qt5 -> Use QTextCodec
QT6 + Core5Compat -> Use QTextCodec (more encoding available)
QT6 without Core5Compat -> Use QStringConvert (less encoding available but probably enought for new projects)

[geustache]

I don't know git very well yet, so I had to delete my previous pull request to put in a clean one.
Sorry about that

[cen1]

Should we even bother with QT6 + Core5Compat -> Use QTextCodec? I don't see a good reason to keep it.

[geustache]

Hello @cen1
I understand your comment but there's a good reason for it
Qt6 with QTextCodec requires Core5Compat but allows you to manage more encodings.

QStringConverter only handles the following codecs (see Qt doc for more details):

QStringConverter::Utf8
QStringConverter::Utf16
QStringConverter::Utf16
QStringConverter::Utf16LE
QStringConverter::Utf32
QStringConverter::Utf32BE
QStringConverter::Utf32LE
QStringConverter::Latin1

In practice, for new projects, I think Utf8 will be used

[cen1]

After a quick review:

1. The code does not seem to compile. As a result, tests are failing: https://github.com/cen1/quazip/actions/runs/11243129081/job/31258319130
2. Please rebase to include latest tests
3. Overall the code seems ok, I'll just need to do a deeper dive into the .cpp portion to understand how things work, haven't been dealing with codecs so far.
4. Unfortunately this breaks ABI but I don't see a more elegant way to do this. So I'll probably make a release without this patch first and then it will go into the next one.
5. As you mentioned in your last comment, the new method handles less codecs. There are already a few encoding unit tests, can you add one that specifically looks for a failure (e.g. using an encoding that was supported by QUAZIP_CAN_USE_QTEXTCODEC, then specifically checking for a failure when compat is missing )

We will also need to add Core5Compat into the CI matrix so we test both build scenarios for at least some tests but that's on me.

[geustache]

I commit fix about compilation issue !
As soon as I have a bit of time, I could look into refining the test scripts to take into account codecs that are not present with qt6 (without core5compat).

[oetken]

You should also use
target_compile_definitions(${QUAZIP_LIB_TARGET_NAME} PUBLIC QUAZIP_CAN_USE_QTEXTCODEC)
instead of
add_compile_definitions(QUAZIP_CAN_USE_QTEXTCODEC)
otherwise including quazip.h will not work as quazip_textcodec.h will still include even if Qt5 is used.
Probably u must move this to quazip/CMakeLists.txt