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// check-pass
#![warn(dropping_copy_types)]
use std::mem::drop;
use std::vec::Vec;
#[derive(Copy, Clone)]
struct SomeStruct;
struct AnotherStruct {
x: u8,
y: u8,
z: Vec<u8>,
}
impl Clone for AnotherStruct {
fn clone(&self) -> AnotherStruct {
AnotherStruct {
x: self.x,
y: self.y,
z: self.z.clone(),
}
}
}
fn main() {
let s1 = SomeStruct {};
let s2 = s1;
let s3 = &s1;
let mut s4 = s1;
let ref s5 = s1;
drop(s1); //~ WARN calls to `std::mem::drop`
drop(s2); //~ WARN calls to `std::mem::drop`
drop(s3); //~ WARN calls to `std::mem::drop`
drop(s4); //~ WARN calls to `std::mem::drop`
drop(s5); //~ WARN calls to `std::mem::drop`
let a1 = AnotherStruct {
x: 255,
y: 0,
z: vec![1, 2, 3],
};
let a2 = &a1;
let mut a3 = a1.clone();
let ref a4 = a1;
let a5 = a1.clone();
drop(a2); //~ WARN calls to `std::mem::drop`
drop(a3);
drop(a4); //~ WARN calls to `std::mem::drop`
drop(a5);
}
#[allow(unused)]
#[allow(clippy::unit_cmp)]
fn issue9482(x: u8) {
fn println_and<T>(t: T) -> T {
println!("foo");
t
}
match x {
// Don't lint (copy type), we only care about side-effects
0 => drop(println_and(12)),
// Don't lint (no copy type), we only care about side-effects
1 => drop(println_and(String::new())),
2 => {
// Lint, even if we only care about the side-effect, it's already in a block
drop(println_and(13)); //~ WARN calls to `std::mem::drop`
},
// Lint, idiomatic use is only in body of `Arm`
3 if drop(println_and(14)) == () => (), //~ WARN calls to `std::mem::drop`
// Lint, not a fn/method call
4 => drop(2),//~ WARN calls to `std::mem::drop`
_ => (),
}
}
fn issue112653() {
fn foo() -> Result<u8, ()> {
println!("doing foo");
Ok(0) // result is not always useful, the side-effect matters
}
fn bar() {
println!("doing bar");
}
fn stuff() -> Result<(), ()> {
match 42 {
0 => drop(foo()?), // drop is needed because we only care about side-effects
1 => bar(),
_ => (), // doing nothing (no side-effects needed here)
}
Ok(())
}
}
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