Rust errors / Types and traits
Rust compiler error · checked with rustc 1.99.0
Rust error E0580: `main` function has wrong type
What it meansThe main function was incorrectly declared.
What rustc prints
error[E0580]: `main` function has wrong type --> main.rs:1:1 | 1 | fn main(x: i32) { // error: main function has wrong type | ^^^^^^^^^^^^^^^ incorrect number of function parameters | = note: expected signature `fn()` found signature `fn(i32)`
Real 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.
E0580Types and traits
Activein rustc 1.99.0
8related errors linked below
The compiler team's explanation
The main function was incorrectly declared.
Erroneous code example:
fn main(x: i32) { // error: main function has wrong type
println!("{}", x);
}The main function prototype should never take arguments. Example:
fn main() {
// your code
}If you want to get command-line arguments, use std::env::args. To exit with a specified exit code, use std::process::exit.
From rustc --explain E0580 (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
- E0576cannot find associated type `You` in trait `Hello`
- E0579lower bound for range pattern must be less than upper bound
- E0587type has conflicting packed and align representation hints
- E0588packed type cannot transitively contain a `#[repr(align)]` type
Up next
Often hit nextE0308: mismatched typesA related error from the same family.Read it next →Did this answer your question?