Huh? Both have LTO. There are linker optimizations available to Rust and not to C and C++. They all use the same God damn linker.

A few years ago I pulled a rust library into a swift app on ios via static linking & C FFI. And I had a tiny bit of C code bridge the languages together.

When I compiled the final binary, I ran llvm LTO across all 3 languages. That was incredibly cool.