rust-clippy/tests/compile-fail/methods.rs

#![feature(plugin)]
#![plugin(clippy)]

#![allow(unused)]
#![deny(clippy, clippy_pedantic)]

use std::ops::Mul;

struct T;

impl T {
    fn add(self, other: T) -> T { self } //~ERROR defining a method called `add`
    fn drop(&mut self) { } //~ERROR defining a method called `drop`

    fn sub(&self, other: T) -> &T { self } // no error, self is a ref
    fn div(self) -> T { self } // no error, different #arguments
    fn rem(self, other: T) { } // no error, wrong return type

    fn into_u32(self) -> u32 { 0 } // fine
    fn into_u16(&self) -> u16 { 0 } //~ERROR methods called `into_*` usually take self by value

    fn to_something(self) -> u32 { 0 } //~ERROR methods called `to_*` usually take self by reference
}

#[derive(Clone,Copy)]
struct U;

impl U {
    fn to_something(self) -> u32 { 0 } // ok because U is Copy
}

impl Mul<T> for T {
    type Output = T;
    fn mul(self, other: T) -> T { self } // no error, obviously
}

fn main() {
    let opt = Some(0);
    let _ = opt.unwrap();  //~ERROR used unwrap() on an Option

    let res: Result<i32, ()> = Ok(0);
    let _ = res.unwrap();  //~ERROR used unwrap() on a Result

    let _ = "str".to_string();  //~ERROR `"str".to_owned()` is faster

    let v = &"str";
    let string = v.to_string();  //~ERROR `(*v).to_owned()` is faster
    let _again = string.to_string();  //~ERROR `String.to_string()` is a no-op
}