Error code E0138

More than one function was declared with the #[start] attribute.

Erroneous code example:

#![allow(unused)]
#![feature(start)]

fn main() {
#[start]
fn foo(argc: isize, argv: *const *const u8) -> isize {}

#[start]
fn f(argc: isize, argv: *const *const u8) -> isize {}
// error: multiple 'start' functions
}

This error indicates that the compiler found multiple functions with the #[start] attribute. This is an error because there must be a unique entry point into a Rust program. Example:

#![allow(unused)]
#![feature(start)]

fn main() {
#[start]
fn foo(argc: isize, argv: *const *const u8) -> isize { 0 } // ok!
}