support cross-compilation by not using the cfg macro in build.rs

[noonien]

Fixes #14

[noonien]

Opps, missed that.

It's fixed now. Also did a cargo check and cargo test in the workspace to make sure everything compiles, and runs.

There is a SIGSEGV in pqcrypto-classicmceliece, however, the error exists in the old code as well.

[thomwiggers]

There is a SIGSEGV in pqcrypto-classicmceliece, however, the error exists in the old code as well.

Yeah, I think there's some issue in the upstream code but I had a hard time locking it down.

[noonien]

I'm not exactly sure what the disable_avx2 opt-in feature is. Will it be passed using a cfg_attr macro? Because it's not defined in Config.tom. If so, are you sure that is the right place to use it like this? I'm not sure those config attrs will be available in build.rs.

[thomwiggers]

Some good questions :sweat_smile: I think I used it via -C disable_avx2 for testing.

[noonien]

Was that set in RUSTFLAGS?

[thomwiggers]

I think so, yeah

[noonien]

RUSTFLAGS also doesn't work when cross-compiling. I'll add a feature to Cargo.toml.

[thomwiggers]

It's still helpful to have, it allows me to test the non-AVX2 codepaths on an AVX2 machine.

[noonien]

Fixed.

I added a feature in Cargo.toml for packages that support avx2. To run without avx2 support use:

cargo build --no-default-features

[noonien]

Thanks, cheers!

:handshake:

[thomwiggers]

Thanks for the contribution

[noonien]

Any chance to get this change in a release?

[thomwiggers]

I've run the script.

I also should update everything with PQClean changes, but I'm not sure if I'll have time for that anytime soon...