Rust errors / Types and traits
Rust compiler error · checked with rustc 1.99.0
Rust error E0642: patterns aren't allowed in functions without bodies
What it meansTrait methods currently cannot take patterns as arguments.
What rustc prints
error[E0642]: patterns aren't allowed in functions without bodies
--> main.rs:2:12
|
2 | fn foo((x, y): (i32, i32)); // error: patterns aren't allowed
| ^^^^^^ pattern not allowed in function without bodyReal 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.
E0642Types and traits
Activein rustc 1.99.0
8related errors linked below
The compiler team's explanation
Trait methods currently cannot take patterns as arguments.
Erroneous code example:
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:
trait Foo {
fn foo(x_and_y: (i32, i32)); // ok!
}From rustc --explain E0642 (1.99.0), part of the Rust project, MIT or Apache-2.0. Official page.
Related errors
- E0308mismatched types
- E0277the trait bound is not satisfied
- E0599no method named X found in the current scope
- E0433failed to resolve
- E0631type mismatch in closure arguments
- E0634type has conflicting packed representation hints
- E0643method `foo` has incompatible signature for trait
- E0644closure/coroutine type that references itself
Up next
Often hit nextE0308: mismatched typesA related error from the same family.Read it next →Did this answer your question?