Rust errors / Types and traits
Rust compiler error · checked with rustc 1.99.0
Rust error E0200: the trait `Bar` requires an `unsafe impl` declaration
What it meansAn unsafe trait was implemented without an unsafe implementation.
What rustc prints
error[E0200]: the trait `Bar` requires an `unsafe impl` declaration --> main.rs:5:1 | 5 | impl Bar for Foo { } // error! | ^^^^^^^^^^^^^^^^ | = note: the trait `Bar` enforces invariants that the compiler can't check. Review the trait documentation and make sure this implementation upholds those invariants before adding the `unsafe` keyword help: add `unsafe` to this trait implementation | 5 | unsafe impl Bar for Foo { } // error! | ++++++
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.
E0200Types and traits
Activein rustc 1.99.0
8related errors linked below
The compiler team's explanation
An unsafe trait was implemented without an unsafe implementation.
Erroneous code example:
struct Foo;
unsafe trait Bar { }
impl Bar for Foo { } // error!Unsafe traits must have unsafe implementations. This error occurs when an implementation for an unsafe trait isn't marked as unsafe. This may be resolved by marking the unsafe implementation as unsafe.
struct Foo;
unsafe trait Bar { }
unsafe impl Bar for Foo { } // ok!From rustc --explain E0200 (1.99.0), part of the Rust project, MIT or Apache-2.0. Official page.
Related errors
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