Error code E0203

Having multiple relaxed default bounds is unsupported.

Erroneous code example:

#![allow(unused)] fn main() { struct Bad<T: ?Sized + ?Send>{ inner: T } }

Here the type T cannot have a relaxed bound for multiple default traits (Sized and Send). This can be fixed by only using one relaxed bound.

#![allow(unused)] fn main() { struct Good<T: ?Sized>{ inner: T } }