mirror of https://github.com/rust-lang/rust
119 lines
3.4 KiB
Rust
119 lines
3.4 KiB
Rust
//@ check-pass
|
|
|
|
#![warn(dropping_references)]
|
|
|
|
struct SomeStruct;
|
|
|
|
fn main() {
|
|
drop(&SomeStruct); //~ WARN calls to `std::mem::drop`
|
|
|
|
let mut owned1 = SomeStruct;
|
|
drop(&owned1); //~ WARN calls to `std::mem::drop`
|
|
drop(&&owned1); //~ WARN calls to `std::mem::drop`
|
|
drop(&mut owned1); //~ WARN calls to `std::mem::drop`
|
|
drop(owned1);
|
|
|
|
let reference1 = &SomeStruct;
|
|
drop(reference1); //~ WARN calls to `std::mem::drop`
|
|
|
|
let reference2 = &mut SomeStruct;
|
|
drop(reference2); //~ WARN calls to `std::mem::drop`
|
|
|
|
let ref reference3 = SomeStruct;
|
|
drop(reference3); //~ WARN calls to `std::mem::drop`
|
|
}
|
|
|
|
#[allow(dead_code)]
|
|
fn test_generic_fn_drop<T>(val: T) {
|
|
drop(&val); //~ WARN calls to `std::mem::drop`
|
|
drop(val);
|
|
}
|
|
|
|
#[allow(dead_code)]
|
|
fn test_similarly_named_function() {
|
|
fn drop<T>(_val: T) {}
|
|
drop(&SomeStruct); //OK; call to unrelated function which happens to have the same name
|
|
std::mem::drop(&SomeStruct); //~ WARN calls to `std::mem::drop`
|
|
}
|
|
|
|
#[derive(Copy, Clone)]
|
|
pub struct Error;
|
|
fn produce_half_owl_error() -> Result<(), Error> {
|
|
Ok(())
|
|
}
|
|
|
|
fn produce_half_owl_ok() -> Result<bool, ()> {
|
|
Ok(true)
|
|
}
|
|
|
|
#[allow(dead_code)]
|
|
fn test_owl_result() -> Result<(), ()> {
|
|
produce_half_owl_error().map_err(|_| ())?;
|
|
produce_half_owl_ok().map(|_| ())?;
|
|
// the following should not be linted,
|
|
// we should not force users to use toilet closures
|
|
// to produce owl results when drop is more convenient
|
|
produce_half_owl_error().map_err(drop)?;
|
|
produce_half_owl_ok().map_err(drop)?;
|
|
Ok(())
|
|
}
|
|
|
|
#[allow(dead_code)]
|
|
fn test_owl_result_2() -> Result<u8, ()> {
|
|
produce_half_owl_error().map_err(|_| ())?;
|
|
produce_half_owl_ok().map(|_| ())?;
|
|
// the following should not be linted,
|
|
// we should not force users to use toilet closures
|
|
// to produce owl results when drop is more convenient
|
|
produce_half_owl_error().map_err(drop)?;
|
|
produce_half_owl_ok().map(drop)?;
|
|
Ok(1)
|
|
}
|
|
|
|
#[allow(unused)]
|
|
#[allow(clippy::unit_cmp)]
|
|
fn issue10122(x: u8) {
|
|
// This is a function which returns a reference and has a side-effect, which means
|
|
// that calling drop() on the function is considered an idiomatic way of achieving
|
|
// the side-effect in a match arm.
|
|
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<&'static 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(())
|
|
}
|
|
}
|