WIP: examples: create a multi project to test multiple crates

[ahayzen-kdab]

No description provided.

[Be-ing]

Blocked on rust-lang/rust#108081

[Be-ing]

Upstream PR to make this work: rust-lang/rust#113301

[Be-ing]

The upstream PR has been merged and will be released in stable Rust 1.74, which is scheduled for 16 November 2023. I suggest to leave this as a draft until then.

[ahayzen-kdab]

@Be-ing Awesome news, thanks! :-)

[Be-ing]

Rust 1.74 has been released so this now builds with stable Rust! 🥳

[ahayzen-kdab]

@Be-ing sweet! Great work on getting that stabilised into Rust 💪 We look at getting this landed and the reshuffle internally in the next cycle I think as 0.6 is imminent with a deadline we need to reach.

[ahayzen-kdab]

Seems to be getting a linking issue with double resources, need to investigate. Wonder if it's the QML module changes.

[Be-ing]

Seems to be getting a linking issue with double resources, need to investigate. Wonder if it's the QML module changes.

Fixed in #755

[ahayzen-kdab]

Locally this builds now, but it fails to run as it can't find the sub QML QObjects, needs some further investigation or maybe a clean build.

[Be-ing]

I can reproduce that. nm -C build/examples/meta_project/example_meta_project|grep cxx_qt_demo_sub1 shows that the symbols for registering the QML type do end up in the executable... so why aren't they working? 🤔

[Be-ing]

I opened a PR for your fork to get this working: ahayzen-kdab#4 The errors were simply from missing #[qml_element] attributes :)

[ahayzen-kdab]

I opened a PR for your fork to get this working: ahayzen-kdab#4 The errors were simply from missing #[qml_element] attributes :)

Aha! great spot thanks!

[ahayzen-kdab]

Seems macOS works, Windows has had a wobble with file locking / mapped stuff, Linux explodes using ld.gold.

Is this one of those, only lld works situations ?

[Be-ing]

Seems we're continuing the CXX-Qt tradition of stumbling over the weirdest edge cases of toolchains 😅

Somehow Cargo does specify linking the same qt-static-initializers library twice with --whole-archive, so it makes sense why gold fails... but why does Cargo do that? And only does that for cargo test?? Perhaps a Cargo bug?

As for the Windows Qt5 build error:

 error: failed to write file '\\?\C:\cxx-qt\build\cargo\build\x86_64-pc-windows-msvc\release\deps\libsub1-ef2617c41816f8ec.rlib': The requested operation cannot be performed on a file with a user-mapped section open. (os error 1224)

I don't know. Another cargo/rustc bug? A Windows bug? I don't see this error code anywhere in any rust-lang GitHub repositories.

A quick hack around both of these problems would be replacing the --all-targets CLI option to cargo test in the root CMakeLists.txt with --workspace --exclude qml-meta-project. The qml-meta-project crate doesn't even have Cargo tests, so there's not much point building it in that context.

[ahayzen-kdab]

Seems we're continuing the CXX-Qt tradition of stumbling over the weirdest edge cases of toolchains 😅

😅

Yeah, a switch around to ensure it builds (and maybe runs) would be useful, I'll probably look into this next month as I'm tight on time.

[Be-ing]

I don't think it's worth deep diving into the root causes of these errors right now considering that qml-meta-project doesn't even have Cargo tests. So I think switching to --workspace --exclude qml-meta-project would be sufficient for finally merging this PR.

[Be-ing]

Hopefully this will be enough to merge finally: ahayzen-kdab#5

[ahayzen-kdab]

Split only running cachegen when there are QML files in #811

[ahayzen-kdab]

Wonder if it's the Rust side that needs to not be parallel rather than the C++/CMake side, but still shouldn't happen.

[ahayzen-kdab]

This will need further work and changes for the way QML modules are now passed around and as part of the 0.8 cycle improvements where a single crate could become a QML module.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (7d57542) to head (0530e1a).
Report is 1 commits behind head on main.

Additional details and impacted files

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##              main      #598   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files           71        71           
  Lines        11953     11953           
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  Hits         11953     11953           

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