{aarch64,x86_64}-pc-windows-gnullvm host tools are missing libunwind.dll

[Alovchin91]

The newly introduced host tools for {aarch64,x86_64}-pc-windows-gnullvm triples are missing the libunwind.dll library next to all the executables:

Steps to reproduce:

1. Download rustup-init.exe (this happens with both native Arm64 and emulated X64 toolchains)
2. Install the latest Nightly {aarch64,x86_64}-pc-windows-gnullvm toolchain
3. Rustup-init tries to run Rustc.exe and fails (see the screenshots), but also running anything like Cargo.exe or Rust-lld.exe (double-clicking in the Explorer) doesn't work

How I fixed it:

Copied over libunwind.dll from LLVM 20.1.8 to the toolchain/bin directory. Didn't try with tools that are not in the bin directory (like Rust-lld).

[mati865]

Right, I tested it with that DLL present in my PATH.

[Alovchin91]

As a suggestion, I've used the Windows Sandbox to get the cleanest possible environment 🙂

[msbroadf]

Ive noticed similar with cross compiling on Linux - libunwind.a (dll) is not statically linked

https://users.rust-lang.org/t/is-there-a-way-to-statically-link-libunwind-on-x86-64-pc-windows-gnullvm/130542/4

[mati865]

As a suggestion, I've used the Windows Sandbox to get the cleanest possible environment 🙂

I tried it last year, and it was unbearably slow (compared to proper VM or native) on my Ryzen 5950X and also would require at least minimal setup. Testing on Linux is just easier and faster 😜
Done that in #144659 (comment) but I don't have a good way to run AArch64 binary. However, I don't expect problems there.