That's a special case and sits at the boundaries / bridge of languages. > There is no indirection for these types; all data is stored within the struct, as you

That's a special case and sits at the boundaries / bridge of languages. > There is no indirection for these types; all data is stored within the struct, as you would expect in C. However with the exception of arrays (which are densely packed and in-order), the layout of data is not specified by default. struct A { a: i32, b: u64, } struct B { a: i32, b: u64, } > Rust does guarantee that two instances of A have their data laid out in exactly the same way. However Rust does not currently guarantee that an instance of A has the same field ordering or padding as an instance of B. https://doc.rust-lang.org/nomicon/repr-rust.html https://doc.rust-lang.org/nomicon/repr-rust.html