Rust errors / Types and traits
Rust compiler error · checked with rustc 1.99.0
Rust error E0751: found both positive and negative implementation of trait `MyTrait` for type `i32`:
What it meansThere are both a positive and negative trait implementation for the same type.
What rustc prints
error[E0751]: found both positive and negative implementation of trait `MyTrait` for type `i32`:
--> main.rs:3:1
|
2 | impl MyTrait for i32 { }
| -------------------- positive implementation here
3 | impl !MyTrait for i32 { } // error!
| ^^^^^^^^^^^^^^^^^^^^^ negative implementation hereReal 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.
E0751Types and traits
Activein rustc 1.99.0
8related errors linked below
The compiler team's explanation
There are both a positive and negative trait implementation for the same type.
Erroneous code example:
trait MyTrait {}
impl MyTrait for i32 { }
impl !MyTrait for i32 { } // error!Negative implementations are a promise that the trait will never be implemented for the given types. Therefore, both cannot exist at the same time.
From rustc --explain E0751 (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
- E0749negative impls cannot have any items
- E0750negative impls cannot be default impls
- E0770the type of const parameters must not depend on other generic parameters
- E0777expected path to a trait, found literal
Up next
Often hit nextE0308: mismatched typesA related error from the same family.Read it next →Did this answer your question?