rust/tests/ui/useless_asref.rs

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// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
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#![deny(clippy::useless_asref)]
#![allow(clippy::trivially_copy_pass_by_ref)]
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use std::fmt::Debug;
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struct FakeAsRef;
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#[allow(clippy::should_implement_trait)]
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impl FakeAsRef {
fn as_ref(&self) -> &Self { self }
}
struct MoreRef;
impl<'a, 'b, 'c> AsRef<&'a &'b &'c MoreRef> for MoreRef {
fn as_ref(&self) -> &&'a &'b &'c MoreRef {
&&&&MoreRef
}
}
fn foo_rstr(x: &str) { println!("{:?}", x); }
fn foo_rslice(x: &[i32]) { println!("{:?}", x); }
fn foo_mrslice(x: &mut [i32]) { println!("{:?}", x); }
fn foo_rrrrmr(_: &&&&MoreRef) { println!("so many refs"); }
fn not_ok() {
let rstr: &str = "hello";
let mut mrslice: &mut [i32] = &mut [1,2,3];
{
let rslice: &[i32] = &*mrslice;
foo_rstr(rstr.as_ref());
foo_rstr(rstr);
foo_rslice(rslice.as_ref());
foo_rslice(rslice);
}
{
foo_mrslice(mrslice.as_mut());
foo_mrslice(mrslice);
foo_rslice(mrslice.as_ref());
foo_rslice(mrslice);
}
{
let rrrrrstr = &&&&rstr;
let rrrrrslice = &&&&&*mrslice;
foo_rslice(rrrrrslice.as_ref());
foo_rslice(rrrrrslice);
foo_rstr(rrrrrstr.as_ref());
foo_rstr(rrrrrstr);
}
{
let mrrrrrslice = &mut &mut &mut &mut mrslice;
foo_mrslice(mrrrrrslice.as_mut());
foo_mrslice(mrrrrrslice);
foo_rslice(mrrrrrslice.as_ref());
foo_rslice(mrrrrrslice);
}
foo_rrrrmr((&&&&MoreRef).as_ref());
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generic_not_ok(mrslice);
generic_ok(mrslice);
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}
fn ok() {
let string = "hello".to_owned();
let mut arr = [1,2,3];
let mut vec = vec![1,2,3];
{
foo_rstr(string.as_ref());
foo_rslice(arr.as_ref());
foo_rslice(vec.as_ref());
}
{
foo_mrslice(arr.as_mut());
foo_mrslice(vec.as_mut());
}
{
let rrrrstring = &&&&string;
let rrrrarr = &&&&arr;
let rrrrvec = &&&&vec;
foo_rstr(rrrrstring.as_ref());
foo_rslice(rrrrarr.as_ref());
foo_rslice(rrrrvec.as_ref());
}
{
let mrrrrarr = &mut &mut &mut &mut arr;
let mrrrrvec = &mut &mut &mut &mut vec;
foo_mrslice(mrrrrarr.as_mut());
foo_mrslice(mrrrrvec.as_mut());
}
FakeAsRef.as_ref();
foo_rrrrmr(MoreRef.as_ref());
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generic_not_ok(arr.as_mut());
generic_ok(&mut arr);
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}
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fn foo_mrt<T: Debug + ?Sized>(t: &mut T) { println!("{:?}", t); }
fn foo_rt<T: Debug + ?Sized>(t: &T) { println!("{:?}", t); }
fn generic_not_ok<T: AsMut<T> + AsRef<T> + Debug + ?Sized>(mrt: &mut T) {
foo_mrt(mrt.as_mut());
foo_mrt(mrt);
foo_rt(mrt.as_ref());
foo_rt(mrt);
}
fn generic_ok<U: AsMut<T> + AsRef<T> + ?Sized, T: Debug + ?Sized>(mru: &mut U) {
foo_mrt(mru.as_mut());
foo_rt(mru.as_ref());
}
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fn main() {
not_ok();
ok();
}