Add aarch64 to ubuntu release

[hn8]

Would you please consider adding aarch64 binary release for linux VM running on Apple Silicon without rosetta2? Thanks

[bolinfest]

If you build DotSlash from source on that Linux VM right now, does it work?

But yes, we should be able to provide ARM Ubuntu release builds pretty easily.

[bolinfest]

Hmm, this is going to be a bit harder than I thought since GitHub does not seem to provide these runners by default yet:

https://github.com/actions/runner-images/issues/2536

On my Ubuntu 20.04 machine, I tried updating Cargo.toml to include:

[target.aarch64-unknown-linux-gnu]
linker = "aarch64-linux-gnu-gcc"

and did:

sudo apt install -y gcc-aarch64-linux-gnu g++-aarch64-linux-gnu libc6-dev-arm64-cross

but the build fails with:

          /usr/bin/ld: /home/mbolin/src/dotslash/target/aarch64-unknown-linux-gnu/debug/deps/dotslash-1106e55710a63aa1.11827l57e7qgx8lz.rcgu.o: error adding symbols: file in wrong format

Based on the articles I've found, my best guess is that something in the transitive deps of DotSlash has some build step that is outside of Cargo (so a build.rs) that is likely producing x86_64 artifacts instead of ARM64 ones, which don't link.

@dtolnay any suggestions?

[bolinfest]

Incidentally, this does not match anything:

find target/aarch64-unknown-linux-gnu/ -name \*.o | xargs -I {} file {} | grep -v ARM

[dtolnay]

This builds successfully for me from Ubuntu: CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER=aarch64-linux-gnu-gcc cargo build --target aarch64-unknown-linux-gnu --release

[bolinfest]

Hmm, that works for me as well. I saw a comment somewhere that maybe I needed to update .cargo/config.toml instead of Cargo.toml?