Static rustc_lint_defs::builtin::RUST_2021_PRELUDE_COLLISIONS

pub static RUST_2021_PRELUDE_COLLISIONS: &Lint

The rust_2021_prelude_collisions lint detects the usage of trait methods which are ambiguous with traits added to the prelude in future editions.

Example

#![deny(rust_2021_prelude_collisions)]

trait Foo {
    fn try_into(self) -> Result<String, !>;
}

impl Foo for &str {
    fn try_into(self) -> Result<String, !> {
        Ok(String::from(self))
    }
}

fn main() {
    let x: String = "3".try_into().unwrap();
    //                  ^^^^^^^^
    // This call to try_into matches both Foo::try_into and TryInto::try_into as
    // `TryInto` has been added to the Rust prelude in 2021 edition.
    println!("{x}");
}

{{produces}}

Explanation

In Rust 2021, one of the important introductions is the prelude changes, which add TryFrom, TryInto, and FromIterator into the standard library’s prelude. Since this results in an ambiguity as to which method/function to call when an existing try_into method is called via dot-call syntax or a try_from/from_iter associated function is called directly on a type.