Different rustflags for build.rs and main.rs

[Volker_Weissmann]

Hello,

I need to generate two builds from my crate:

In the first build, neither build.rs and main.rs should be compiled with target-cpu=znver1.

In the second build, only main.rs should be compiled with target-cpu=znver1.

Any ideas?

I tried export RUSTFLAGS="-C target-cpu=znver1", but this affects both main.rs and build.rs

[Yandros]

@Volker_Weissmann

In the second build, only main.rs should be compiled with target-cpu=znver1 .

Any ideas?

I'd try two approaches:

• cargo rustc -- -C target-cpu=znver1
  

  which, IIRC, ought to only apply those passed rust flags to the compilation of main.rs,

• RUSTFLAGS=-Ctarget-cpu=znver1 \
  cargo build --target <host_triplet>
  

  • e.g.

    RUSTFLAGS=-Ctarget-cpu=znver1 \
    cargo build --target "$(rustc -vV | sed -n 's/^host: //p')"
    

  since the moment --target is passed, Cargo will refuse to pass RUSTFLAGS to host-specific Rust code, such as build.rs scripts and procedural macros.