Rust errors / Types and traits
Rust compiler error · checked with rustc 1.99.0
Rust error E0403: the name `T` is already used for a generic parameter in this item's generic parameters
What it meansSome type parameters have the same name.
What rustc prints
error[E0403]: the name `T` is already used for a generic parameter in this item's generic parameters
--> main.rs:1:9
|
1 | fn f<T, T>(s: T, u: T) {} // error: the name `T` is already used for a generic
| - ^ already used
| |
| first use of `T`Real 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.
E0403Types and traits
Activein rustc 1.99.0
8related errors linked below
The compiler team's explanation
Some type parameters have the same name.
Erroneous code example:
fn f<T, T>(s: T, u: T) {} // error: the name `T` is already used for a generic
// parameter in this item's generic parametersPlease verify that none of the type parameters are misspelled, and rename any clashing parameters. Example:
fn f<T, Y>(s: T, u: Y) {} // ok!Type parameters in an associated item also cannot shadow parameters from the containing item:
trait Foo<T> {
fn do_something(&self) -> T;
fn do_something_else<T: Clone>(&self, bar: T);
}From rustc --explain E0403 (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
- E0393the type parameter `T` must be explicitly specified
- E0401can't use generic parameters from outer item
- E0404expected trait, found struct `Foo`
- E0405cannot find trait `SomeTrait` in this scope
Up next
Often hit nextE0308: mismatched typesA related error from the same family.Read it next →Did this answer your question?