ci: use setup-cpp to install the compilers

[aminya]

This uses setup-cpp to install the C++ tools
https://github.com/aminya/setup-cpp/

https://github.com/aminya/trompeloeil/actions/runs/1551038387

[rollbear]

Apologies for being a bit silent, but I will get back to you in a couple of days. I much appreciate the work you're doing. Thanks.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.77%. Comparing base (c9c0df9) to head (f083f90).
⚠️ Report is 247 commits behind head on main.

❗ There is a different number of reports uploaded between BASE (c9c0df9) and HEAD (f083f90). Click for more details.

HEAD has 43 uploads less than BASE

Flag	BASE (c9c0df9)	HEAD (f083f90)
	104	61

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #266       +/-   ##
===========================================
- Coverage   97.75%   75.77%   -21.99%     
===========================================
  Files           1        1               
  Lines         890      875       -15     
===========================================
- Hits          870      663      -207     
- Misses         20      212      +192     

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[rollbear]

On the libc++ build/install-script. It's only there because not all versions have readily available downloads (as .deb packages.) If setup-cpp provides the right libc++ versions already, that step can be removed.

[aminya]

Apologies for being a bit silent, but I will get back to you in a couple of days. I much appreciate the work you're doing. Thanks.

You're welcome!

On the libc++ build/install-script. It's only there because not all versions have readily available downloads (as .deb packages.) If setup-cpp provides the right libc++ versions already, that step can be removed.

setup-cpp downloads the original llvm releases, which usually include the libcxx. It does not use apt for this. So, I think we can try removing it. If there is a separate installation step required for libcxx, we can add it to setup-cpp

[aminya]

The libcxx issue is fixed. It required using the correct LLVM_PATH and also passing the CPPFLAGS and LDFLAGS to cmake.

[aminya]

Yay! Everything is fixed now. 🎉

[aminya]

The failures are due to missing coverage reports on some versions, which I think is unrelated to this PR. Right?

[rollbear]

I'm not so sure that it is unrelated to the PR. If you look at the "Collect Coverage" step for gcc 4.8, it says:

kcov: error while loading shared libraries: libopcodes-2.34-system.so: cannot open shared object file: No such file or directory

Why is that library missing here?

[aminya]

I updated kcov to v39 because it does not need to be built from the source this way. It might rely on some shared libraries that are missing in the old GCC installer. I need to try install missing packages and see if the issue is fixed.

[rollbear]

Sorry for not paying much attention, but the push to finish things before Christmas was a bit intense.

I've looked into the current state, and tried to figure out how to move forward, but I haven't been that successful.

All builds that use ubuntu-18.04 fail because kcov needs binutils-2.34, but the one installed is 2.30. I then tried to use ubuntu-20.04 also for the older compilers, but that failed for completely different reasons. Now C++ standard headers cannot be found, so it looks like libstdc++ and libc++ are not available, or in paths that the compiler cannot find. I had hoped to reach a state where it all builds, but perhaps with some missing functionality, but unfortunately I have failed.

[rollbear]

Of course, a different route forward, that may be easier, is to scrap kcov (it's not like I'm married to it) and use normal coverage builds instead. I have to read up on how to use it with the CI codecov-action, but I presume it's a normal enough use to be reasonably straight forward.