wrong target_os?

[ibigbug]

Checklist

• I've looked through the issues and pull requests for similar reports

Describe your issue

have a build.rs in an empty crate

fn main(){
#[cfg(target_os="linux")]
println!("cargo:warning=linux");
#[cfg(target_os = "freebsd")]
println!("cargo:warning=freebsd");
}

and run cross build --target x86_64-unknown-freebsd

it should print "freebsd"

What target(s) are you cross-compiling for?

No response

Which operating system is the host (e.g computer cross is on) running?

• macOS
• Windows
• Linux / BSD
• other OS (specify in description)

What architecture is the host?

• x86_64 / AMD64
• arm32
• arm64 (including Mac M1)

What container engine is cross using?

• docker
• podman
• other container engine (specify in description)

cross version

cross 0.2.5 (107433f 2025-02-06) [cross] note: Falling back to cargo on the host. cargo 1.83.0 (5ffbef321 2024-10-29)

Example

No response

Additional information / notes

No response

[Emilgardis]

why would a cross build run the executable?

Is this a buildscript? buildscripts are ran as the host, so when a buildscript is ran target_os=host_os

[ibigbug]

sorry i wasn't clear it was a build script(updated desc)

buildscripts are ran as the host, so when a buildscript is ran target_os=host_os

I see. that makes so much sense.

I was trying to build this https://github.com/LeoBorai/network-interface/blob/main/build.rs#L5

do you think it's possible to cross it ? given the build script was created that way

[ibigbug]

buildscripts are ran as the host

so this is actually the cargo behaviour?

[ibigbug]

rust-lang/cargo#13277 found it

[Emilgardis]

yes it's possible, they are doing a big mistake in the buildscript, it should be gated by runtime env args, not cfg.

See https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-build-scripts

[Emilgardis]

closing this issue as it's nothing we can resolve. The build script needs to be fixed