"not sure if anyone has tried..." <- I’ve tried many options. Building with `cargo` + `cc` (then linking with `rust-ldd`), I’ve been able to : * Enable LTO for the Rust code and link with C code compiled by `gcc`, `clang` and `armclang` without LTO enabled, * Enable LTO for the Rust code and link with C code compiled by `clang` with the `-flto` flag, and this shows an improvement and xlto works properly. However (and this is expected I assume), passing `-flto` to either `gcc` or `armclang` would lead to a link error, `rust-lld` stating that symbols are not found.