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