Rust errors / Types and traits
Rust compiler error · checked with rustc 1.99.0
Rust error E0719: the value of the associated type `Item` in trait `Iterator` is already specified
What it meansAn associated item was specified more than once in a trait object.
What rustc prints
error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
--> main.rs:5:37
|
5 | type Foo = dyn Iterator<Item = u32, Item = u32>;
| ---------- ^^^^^^^^^^ re-bound here
| |
| `Item` bound here firstReal output of rustc 1.99.0 compiling the official example below (2021 edition). Your names and line numbers will differ; the first line is the part to match.
E0719Types and traits
Activein rustc 1.99.0
8related errors linked below
The compiler team's explanation
An associated item was specified more than once in a trait object.
Erroneous code example:
trait FooTrait {}
trait BarTrait {}
// error: associated type `Item` in trait `Iterator` is specified twice
type Foo = dyn Iterator<Item = u32, Item = u32>;To fix this, remove the duplicate specifier:
Corrected example:
type Foo = dyn Iterator<Item = u32>; // ok!For more information about associated types, see the book. For more information on associated type bounds, see RFC 2289.
From rustc --explain E0719 (1.99.0), part of the Rust project, MIT or Apache-2.0. Official page.
Related errors
- E0308mismatched types
- E0277the trait bound is not satisfied
- E0599no method named X found in the current scope
- E0433failed to resolve
- E0714marker traits cannot have associated items
- E0715impls for marker traits cannot contain items
- E0720cannot resolve opaque type
- E0735generic parameters cannot use `Self` in their defaults
Up next
Often hit nextE0308: mismatched typesA related error from the same family.Read it next →Did this answer your question?