The associated type used was not defined in the trait.
Erroneous code example:
trait T1 {
type Bar;
}
type Foo = T1<F=i32>; // error: associated type `F` not found for `T1`
// or:
trait T2 {
type Bar;
// error: Baz is used but not declared
fn return_bool(&self, _: &Self::Bar, _: &Self::Baz) -> bool;
}Make sure that you have defined the associated type in the trait body. Also, verify that you used the right trait or you didn’t misspell the associated type name. Example:
trait T1 {
type Bar;
}
type Foo = T1<Bar=i32>; // ok!
// or:
trait T2 {
type Bar;
type Baz; // we declare `Baz` in our trait.
// and now we can use it here:
fn return_bool(&self, _: &Self::Bar, _: &Self::Baz) -> bool;
}