Cross language LTO broken for crates with build.rs

[dragostis]

On aarch64-apple-darwin, Rust 1.72 this fails:

cargo new --lib foo && cd foo && echo "fn main() {}" > build.rs && RUSTFLAGS="-Clinker-plugin-lto" cargo build

with ld: unknown option: -plugin-opt=O0.

Building without build.rs works as intended.

[bjorn3]

I would guess this is caused by the combination of -Copt-level=0 and -Clinker-plugin-lto. As workaround try adding --target aarch64-apple-darwin to the cargo invocation. That will cause it to ignore RUSTFLAGS for proc macros and build scripts.