[Qt-creator] Requiring Qt 6 for building Qt Creator 9 and later

[Eike Ziller]

Hi all,

we would like to require Qt 6.2 or later for building Qt Creator itself going forward in master branch, which is Qt Creator 9 and later.

We’ll have released 3 versions of Qt Creator based on Qt 6 then (starting with Qt Creator 6) by then, Qt 6 has matured and has its first LTS version with Qt 6.2. It starts to happen that fixes are done in Qt 6 that are no longer backported to Qt 5, and removing support for Qt 5 will allow us to remove hacks and glue code that enabled us to compile against both Qt 5 and Qt 6.

This by extension means that the required compilers increase to GCC 9 and MSVC 2019 (from GCC 7 and MSVC 2017).
And the supported platforms increase to Ubuntu 20.04, RHEL/CentOS 8, and macOS 10.14, which they already are for our prebuilt binary packages, since these are already Qt 6 based.

The corresponding patch is on Gerrit for comments: https://codereview.qt-project.org/c/qt-creator/qt-creator/+/420047

The Qt versions that we support for developing your own applications with, are of course not affected by this change.

Br, Eike

-- 
Eike Ziller
Principal Software Engineer

The Qt Company GmbH
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eike.ziller at qt.io
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