Several new per-machine Rust compiler options have been added so that the settings found in a Cargo [profile] section can be expressed natively:
rust_panic (none, unwind, abort): selects the panic strategy (-C panic=). It is ignored for dylib and proc-macro crates, which must always unwind.rust_overflow_checks (true, false): toggles runtime integer overflow checks (-C overflow-checks=).rust_codegen_units (integer, 0 to use the compiler default): number of code generation units to split a crate into (-C codegen-units=).rust_incremental (true, false): enables incremental compilation (-C incremental=).rust_incremental_cache_dir (path): directory used to store the incremental compilation data. When left empty a per-target directory under the build directory is used.The remaining Cargo profile keys map onto existing built-in options: opt-level to optimization, debug to debug, debug-assertions to b_ndebug and lto to b_lto.
The Cargo workspace object will also add these automatically based on the value of another new option, rust_cargo_profile.