stacker / psm: won't build due to build.rs referencing CARGO_CFG_*

[LER0ever]

The stacker project rust-lang/stacker has a dependency psm which requires a build.rs to build, and uses CARGO_CFG_TARGET_ENV to determine the rust linker arguments. Currently bazel and raze don't set those env vars automatically, is there a workaround for this?

Ref: https://github.com/rust-lang/stacker/blob/master/psm/build.rs#L37

Workarounds in related issues (#138, #116, #41) are point solutions that don't apply to stacker.

[UebelAndre]

Maybe #287 ?

edit: Do you think that would provide a workaround for this issue?

[UebelAndre]

Though this might be something to bring up in rules_rust as well. At second glance it seems like this should be something handled by the rules.

[LER0ever]

Do you think that would provide a workaround for this issue?

@UebelAndre That's for passing the environment variables manually. And in stacker's case, it needs env vars generated automatically by Cargo, which is usually different on each platform / toolchain. Sure I could hardcode the platform vars and passing it after #287 was solved, but that's pretty much ad-hoc.

Not sure if rules_rust should handle this one, since they tends to handle the rustc side, and this one is caused after transforming Cargo.toml of stacker into BUILD. Ideally, we should be able to fetch those CARGO_CFG_* variables from cargo and generate into BUILD (at least for the host platform on which raze is called).

[UebelAndre]

Is CARGO_CFG_TARGET_ENV not determined at build time?

[UebelAndre]

Ah, it is not. Still unsure where this should be handled. Leaning toward rules_rust if there is an easy way to detect target_env