Error code E0552

A unrecognized representation attribute was used.

Erroneous code example:

#![allow(unused)] fn main() { #[repr(D)] // error: unrecognized representation hint struct MyStruct { my_field: usize } }

You can use a repr attribute to tell the compiler how you want a struct or enum to be laid out in memory.

Make sure you're using one of the supported options:

#![allow(unused)] fn main() { #[repr(C)] // ok! struct MyStruct { my_field: usize } }

For more information about specifying representations, see the "Alternative Representations" section of the Rustonomicon.