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
}
}