# 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.