Static rustc_lint::non_local_def::NON_LOCAL_DEFINITIONS

pub static NON_LOCAL_DEFINITIONS: &Lint

The non_local_definitions lint checks for impl blocks and #[macro_export] macro inside bodies (functions, enum discriminant, …).

Example

#![warn(non_local_definitions)]
trait MyTrait {}
struct MyStruct;

fn foo() {
    impl MyTrait for MyStruct {}
}

{{produces}}

Explanation

Creating non-local definitions go against expectation and can create discrepancies in tooling. It should be avoided. It may become deny-by-default in edition 2024 and higher, see the tracking issue https://github.com/rust-lang/rust/issues/120363.

An impl definition is non-local if it is nested inside an item and neither the type nor the trait are at the same nesting level as the impl block.

All nested bodies (functions, enum discriminant, array length, consts) (expect for const _: Ty = { ... } in top-level module, which is still undecided) are checked.