[Qt-creator] Updating requirements for building Qt Creator 4.14 / master

[Eike Ziller]

Now that Qt Creator 4.13 is in feature freeze and the “master” branch is reserved for Qt Creator 4.14, let’s bring the topic of bumping the requirements for Qt Creator 4.14 back.

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Required Qt version —> Qt 5.14
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As discussed in another thread (https://lists.qt-project.org/pipermail/qt-creator/2020-June/008574.html), we’d like to bump the required Qt version for building Qt Creator to Qt 5.14.
This will make porting Qt Creator to Qt 6 much easier, since we want a transition phase where Qt Creator compiles with both Qt 5 and Qt 6. Many replacement APIs for things gone in Qt 6 are only available in Qt 5.14. We’ll see if we even need Qt 5.15, or if we can manage with Qt 5.14.
Ubuntu 20.10 will ship Qt 5.14, Debian sid (unstable) has 5.14 too.

https://codereview.qt-project.org/c/qt-creator/qt-creator/+/306477

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Required GCC version -> GCC 7
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Our current minimum GCC version of 5.3 is pretty old and buggy even with regard to C++11/14.
RHEL/CentOS 7 provides GCC 8 already with devtoolset-7.
Ubuntu 18.04 has GCC 7.
Debian 10 (latest stable) has GCC 8.

So I propose updating the requirement to GCC 7. This also allows us to use most C++17 features, so I include upgrading to C++17 in this proposal as well.

https://codereview.qt-project.org/c/qt-creator/qt-creator/+/306478

Br, Eike

-- 
Eike Ziller
Principal Software Engineer

The Qt Company GmbH
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eike.ziller at qt.io
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