Cannot build on Arch [BUILD]

[gnolooo]

Commit Hash
10ce5fb, but also many previous versions (I've not managed to build succesfully in months).

Platform
Arch Linux

Summary
Build stops at around ~35%, with a really long output. I can't figure out the issue and I can't build it.
I need to build it because I'm on Wayland with fractional scaling, and AppImage doesn't support Wayland (check #2320).
In my system right now I have an old version, the last one I managed to build successfully, but it no longer opens because it needs older dependencies. If there is a way to get the version of a manually installed binary, please tell me and I will provide you the latest commit that worked for me, so you can track back to what changed after it.

Additional Information / Output
olive.log

[Simran-B]

Most errors appear to originate from breaking changes in Qt 6. Please use Qt 5.15.2, as that is the version the code was written for and also the version used for the CI builds.

Some of the errors could also be caused by the compiler you use, which might be stricter in more recent versions than the one used in CI. Warnings are promoted to errors as well, so newly added warnings can cause problems, too. The "official" compilers are GCC 9.3.1 and Clang 10.0.1.

[gnolooo]

How do I build using Qt 5.15.2 then? Do I need to specify some particular flags while compiling, or some other thing?

[Simran-B]

IIRC, -DQt5_DIR=/path/to/qt when configuring CMake for Olive. It seems that the path needs to point to the folder that contains Qt5Config.cmake but I'm not sure.

[gnolooo]

I tried various options but they didn't work. I found online that setting -DQt5_DIR=/path/to/qt should be correct, but it doesn't seem to work in this case.

[Simran-B]

It does get picked up for me with cmake .. -G Ninja -DQt5_DIR=/root/olive/custom_qt_install/lib/cmake/Qt5.
That folder contains Qt5Config.cmake.

Does it pick a wrong Qt that is installed? It's possible that Qt5_DIR doesn't have the highest precedence, although should come right after checking CMAKE_PREFIX_PATH.

---

A couple of things I had to do in addition: Qt configure with -no-webp because of unresolved symbols (potentially a problem with CentOS 7), change qt_add_translation in app/CMakeLists.txt to qt5_add_translation, and manually point to the X11 Extras module: -DQt5X11Extras_DIR=/root/olive/custom_qt_install/lib/cmake/Qt5X11Extras

[Simran-B]

Huh, I think it actually selected the wrong Qt I installed earlier (5.9). Interestingly, I have to run CMake twice to make it pick up the Qt directory for some reason:

cmake .. -G Ninja -DQt5_DIR=/root/olive/custom_qt_install/lib/cmake/Qt5 -DQt5X11Extras_DIR=/root/olive/custom_qt_install/lib/cmake/Qt5X11Extras
cmake .. -G Ninja -DQT_DIR=/root/olive/custom_qt_install/lib/cmake/Qt5 -DQt5X11Extras_DIR=/root/olive/custom_qt_install/lib/cmake/Qt5X11Extras

The order of these commands doesn't appear to matter but neither works on its own with a new build directory. Odd.

[gnolooo]

It still fails with the following log: olive.log

[Simran-B]

What compiler do you use and what version of arch, the compiler and Qt exactly?

[gnolooo]