Static rustc_ap_rustc_session::lint::builtin::INDIRECT_STRUCTURAL_MATCH

pub static  INDIRECT_STRUCTURAL_MATCH: &Lint

The indirect_structural_match lint detects a const in a pattern that manually implements PartialEq and Eq.

Example

#![deny(indirect_structural_match)]

struct Plus(i32, i32);
const ONE_PLUS_TWO: &&Plus = &&Plus(1, 2);

impl PartialEq for Plus {
    fn eq(&self, other: &Self) -> bool {
        self.0 + self.1 == other.0 + other.1
    }
}

impl Eq for Plus {}

fn main() {
    if let ONE_PLUS_TWO = &&Plus(3, 0) {
        println!("semantic!");
    } else {
        println!("structural!");
    }
}

{{produces}}

Explanation

The compiler unintentionally accepted this form in the past. This is a future-incompatible lint to transition this to a hard error in the future. See issue #62411 for a complete description of the problem, and some possible solutions.