rust/tests/ui/must_use_candidates.rs
Andre Bogus cc622608db new lints around #[must_use] fns
`must_use_unit` lints unit-returning functions with a `#[must_use]`
attribute, suggesting to remove it.

`double_must_use` lints functions with a plain `#[must_use]`
attribute, but which return a type which is already `#[must_use]`,
so the attribute has no benefit.

`must_use_candidate` is a pedantic lint that lints functions and
methods that return some non-unit type that is not already
`#[must_use]` and suggests to add the annotation.
2019-10-14 12:09:04 +02:00

89 lines
1.4 KiB
Rust

// run-rustfix
#![feature(never_type)]
#![allow(unused_mut)]
#![warn(clippy::must_use_candidate)]
use std::rc::Rc;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;
pub struct MyAtomic(AtomicBool);
pub struct MyPure;
pub fn pure(i: u8) -> u8 {
i
}
impl MyPure {
pub fn inherent_pure(&self) -> u8 {
0
}
}
pub trait MyPureTrait {
fn trait_pure(&self, i: u32) -> u32 {
self.trait_impl_pure(i) + 1
}
fn trait_impl_pure(&self, i: u32) -> u32;
}
impl MyPureTrait for MyPure {
fn trait_impl_pure(&self, i: u32) -> u32 {
i
}
}
pub fn without_result() {
// OK
}
pub fn impure_primitive(i: &mut u8) -> u8 {
*i
}
pub fn with_callback<F: Fn(u32) -> bool>(f: &F) -> bool {
f(0)
}
pub fn with_marker(_d: std::marker::PhantomData<&mut u32>) -> bool {
true
}
pub fn quoth_the_raven(_more: !) -> u32 {
unimplemented!();
}
pub fn atomics(b: &AtomicBool) -> bool {
b.load(Ordering::SeqCst)
}
pub fn rcd(_x: Rc<u32>) -> bool {
true
}
pub fn rcmut(_x: Rc<&mut u32>) -> bool {
true
}
pub fn arcd(_x: Arc<u32>) -> bool {
false
}
pub fn inner_types(_m: &MyAtomic) -> bool {
true
}
static mut COUNTER: usize = 0;
/// # Safety
///
/// Don't ever call this from multiple threads
pub unsafe fn mutates_static() -> usize {
COUNTER += 1;
COUNTER
}
fn main() {
assert_eq!(1, pure(1));
}