As with the Rust build itself, when distros build and package binaries of Cargo applications, they want to be able to customize all command lines to all compilers.

In the Cargo case this means at least customizing the rustc command line; it's not clear whether Cargo itself needs to provide facilities for customizing CFLAGS, etc. or if that's the responsibility of build scripts.

This requirement seems to be at odds with design goals of the Cargo developers. Design work is needed.

re https://internals.rust-lang.org/t/perfecting-rust-packaging-the-plan/2767