CMake Supporting Qt 5.0 and Qt6

[VRonin]

Hi All,
I'm migrating on of my projects to Qt6 but I want to keep backwards compatibility with Qt 5.0.2
The suggested workflow in the docs works well for new-ish versions of Qt but when I try with 5.0.2 I get:

CMake Error at src/CMakeLists.txt:4 (find_package):
  Could not find a package configuration file provided by "QT" with any of the following names:
    Qt6Config.cmake
    qt6-config.cmake
    Qt5Config.cmake
    qt5-config.cmake

What's the minimum supported version of Qt5? Is there any workaround you can think of to make it backwards-compatible with 5.0.2?

---

System Info:

• Ubuntu 12.04
• CMake 3.2.3
• g++ 6.2
• Qt 5.0.2

[VRonin]

Partially answer my own question: Qt 5.1.1 works. Now any smart Idea on how to support 5.0?

[SGaist]

Hi,

The quick and dirty that comes to mind would be to copy/modify the cmake files from a close Qt version and drop them into your 5.0.2 installation.

[VRonin]

@SGaist Agreed but not viable. It's a library so hacking the Qt installation of the end user is not possible

[SGaist]

I thought so...

Will it be system Qt or custom installed ?

[VRonin]

System. I use this ppa for my CI machine

[kshegunov]

@VRonin said in CMake Supporting Qt 5.0 and Qt6:

@SGaist Agreed but not viable. It's a library so i hacking the Qt installation of the end user is not possible

Should a symlink into the binary's build/cmake directory work (I honestly don't know)?

[VRonin]

@kshegunov said in CMake Supporting Qt 5.0 and Qt6:

Should a symlink into the binary's build/cmake directory work (I honestly don't know)?

Nah, the problem is that the folder lib/cmake/Qt5 doesn't exist in Qt 5.0 so the necessary root config files are missing

[kshegunov]

@VRonin said in CMake Supporting Qt 5.0 and Qt6:

Nah, the problem is that the folder lib/cmake/Qt5 doesn't exist in Qt 5.0 so the necessary root config files are missing

I see, it was a long shot anyway. I'm completely out of my element here.

[SGaist]

Didn't KDE's ecm module provide a find script for Qt 5 at that time ?