cmake: add CMakePresets with defaults relevant for building CXX-Qt

[ahayzen-kdab]

This allows us to have presets for building with Qt 5, specifying recommended generators, caching tools, and showing output on failure of tests.

• Add preset for vcpkg
• Add preset for sscache (?)
• Add preset for ninja (?)
• Potentially use presets for CI too
• Add RUSTC_WRAPPER to environment for sscache presets
• Should we have all the combinations or just the simplest + "best" ?

[ahayzen-kdab]

Seems Windows might need the --config Release etc at build time ? So might need buildPresets for all the combinations too 😅

[Be-ing]

I don't understand the point of having presets when there's a preset for every combination of options. Why not just specify the CMake options that already exist?

[ahayzen-kdab]

I don't understand the point of having presets when there's a preset for every combination of options. Why not just specify the CMake options that already exist?

Right maybe we don't need all the options but just the main few. But it's still release yes/no, Qt5 yes/no, and vcpkg yes/no, then assume they have ninja and sscache (which removes one set from the matrix).

Note that the CMakePresets are useful for IDEs like vscode as the CMake plugin there uses the presets to decide how to build and setting the options manually is kinda a pain.

And other KDAB projects have various combinations in the CMakePresets https://github.com/KDAB/KDDockWidgets/blob/1.7/CMakePresets.json :-)

And putting some of the options into presets means that developers don't have to hunt around README/CMakeLists.txt finding which options are available, as described in the blog https://www.kdab.com/the-power-of-cmake-presets/

[Be-ing]

vscode... setting the options manually is kinda a pain.

That sounds like a VSCode problem. :)

I don't have any use for these because I build in a shell, so I don't really mind what you do with these. @LeonMatthesKDAB, thoughts?

[ahayzen-kdab]

vscode... setting the options manually is kinda a pain.

That sounds like a VSCode problem. :)

Hehe :-) I can keep them as CMakeUserPresets just didn't know if they were useful upstream. Also CI could use them and when building from the CLI they could be used rather than multiple flags.

Or the matrix could be reduced so there are only some options :-)

[ahayzen-kdab]

If we do use this we likely also want to set the parallel / execution jobs to something larger than 1

"execution": {
    "jobs": 2
},

[ahayzen-kdab]

Going to close this for now as there are too many combinations to push into the repo.