Error code E0642

Trait methods currently cannot take patterns as arguments.

Erroneous code example:

#![allow(unused)] fn main() { trait Foo { fn foo((x, y): (i32, i32)); // error: patterns aren't allowed // in trait methods } }

You can instead use a single name for the argument:

#![allow(unused)] fn main() { trait Foo { fn foo(x_and_y: (i32, i32)); // ok! } }