Error code E0229
An associated item constraint was written in an unexpected context.
Erroneous code example:
#![allow(unused)] fn main() { pub trait Foo { type A; fn boo(&self) -> <Self as Foo>::A; } struct Bar; impl Foo for isize { type A = usize; fn boo(&self) -> usize { 42 } } fn baz<I>(x: &<I as Foo<A = Bar>>::A) {} // error: associated item constraint are not allowed here }
To solve this error, please move the associated item constraints to the type parameter declaration:
#![allow(unused)] fn main() { struct Bar; trait Foo { type A; } fn baz<I: Foo<A=Bar>>(x: &<I as Foo>::A) {} // ok! }
Or into the where-clause:
#![allow(unused)] fn main() { struct Bar; trait Foo { type A; } fn baz<I>(x: &<I as Foo>::A) where I: Foo<A=Bar> {} }