Error code E0191

An associated type wasn't specified for a trait object.

Erroneous code example:

#![allow(unused)] fn main() { trait Trait { type Bar; } type Foo = dyn Trait; // error: the value of the associated type `Bar` (from // the trait `Trait`) must be specified }

Trait objects need to have all associated types specified. Please verify that all associated types of the trait were specified and the correct trait was used. Example:

#![allow(unused)] fn main() { trait Trait { type Bar; } type Foo = dyn Trait<Bar=i32>; // ok! }