[CI] Update Windows job to LLVM 15

[straight-shoota]

Goes on top of #13207

[HertzDevil]

Since LLVM 15, downloading the LLVM source is not enough, and the CMake archive must also be extracted alongside LLVM (e.g. https://github.com/llvm/llvm-project/releases/download/llvmorg-15.0.7/cmake-15.0.7.src.tar.xz). The directory structure would look like:

cmake
- Modules
  - ...
- README.rst
llvm
- cmake
  - modules
  - platforms
  - ...
- CMakeLists.txt

[straight-shoota]

Yes, I just talked about this with @beta-ziliani and we're planning to do the same changes as in crystal-lang/distribution-scripts#234, that is downloading the entire project and building only a selected part of it.

I guess just downloading cmake in addition to the llvm source could be an alternative solution that's a bit more efficient?

[beta-ziliani]

efficiency is in the eye of the beholder. downloading two things means updating two things in the future :-)

[straight-shoota]

Yeah, but it's two things that sum up to about 50 MB vs. one thing that's 100 MB 😁

[beta-ziliani]

does it make sense to build for aarch64?

[HertzDevil]

We can add AArch64 and WebAssembly to LLVM_TARGETS_TO_BUILD. Native Crystal on an ARM64 host is a different story

[beta-ziliani]

AArch64 is there already, I was questioning its use, but I got it now with your comment. I'll leave adding WebAssembly for now. We need to also add it in the macOS build; I don't know what's the story for linux.

[HertzDevil]

I tested locally and #13218 should fix all the spec failures (including ones in primitives_spec)

[straight-shoota]

@HertzDevil CI is still failing even with #13218
It's different errors now and fewer, so I guess we're making progress 😅

https://github.com/crystal-lang/crystal/actions/runs/4509903796/jobs/7940211383?pr=13208

[HertzDevil]

It's probably because the overflow conditions for 128-bit integers are not as simple as T::MIN <= self <= T::MAX, so the safe conversions have to replicate the overflow checks in #codegen_out_of_range exactly

[straight-shoota]

Let's see if #13222 finally fixes it =)

[straight-shoota]

Yes, CI is green: https://github.com/crystal-lang/crystal/actions/runs/4518906833/jobs/7959071198?pr=13208 👍