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119 lines
2.7 KiB
Rust
119 lines
2.7 KiB
Rust
#![deny(useless_asref)]
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use std::fmt::Debug;
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struct FakeAsRef;
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#[allow(should_implement_trait)]
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impl FakeAsRef {
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fn as_ref(&self) -> &Self { self }
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}
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struct MoreRef;
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impl<'a, 'b, 'c> AsRef<&'a &'b &'c MoreRef> for MoreRef {
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fn as_ref(&self) -> &&'a &'b &'c MoreRef {
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&&&&MoreRef
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}
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}
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fn foo_rstr(x: &str) { println!("{:?}", x); }
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fn foo_rslice(x: &[i32]) { println!("{:?}", x); }
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fn foo_mrslice(x: &mut [i32]) { println!("{:?}", x); }
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fn foo_rrrrmr(_: &&&&MoreRef) { println!("so many refs"); }
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fn not_ok() {
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let rstr: &str = "hello";
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let mut mrslice: &mut [i32] = &mut [1,2,3];
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{
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let rslice: &[i32] = &*mrslice;
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foo_rstr(rstr.as_ref());
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foo_rstr(rstr);
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foo_rslice(rslice.as_ref());
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foo_rslice(rslice);
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}
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{
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foo_mrslice(mrslice.as_mut());
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foo_mrslice(mrslice);
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foo_rslice(mrslice.as_ref());
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foo_rslice(mrslice);
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}
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{
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let rrrrrstr = &&&&rstr;
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let rrrrrslice = &&&&&*mrslice;
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foo_rslice(rrrrrslice.as_ref());
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foo_rslice(rrrrrslice);
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foo_rstr(rrrrrstr.as_ref());
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foo_rstr(rrrrrstr);
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}
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{
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let mrrrrrslice = &mut &mut &mut &mut mrslice;
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foo_mrslice(mrrrrrslice.as_mut());
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foo_mrslice(mrrrrrslice);
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foo_rslice(mrrrrrslice.as_ref());
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foo_rslice(mrrrrrslice);
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}
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foo_rrrrmr((&&&&MoreRef).as_ref());
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generic_not_ok(mrslice);
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generic_ok(mrslice);
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}
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fn ok() {
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let string = "hello".to_owned();
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let mut arr = [1,2,3];
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let mut vec = vec![1,2,3];
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{
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foo_rstr(string.as_ref());
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foo_rslice(arr.as_ref());
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foo_rslice(vec.as_ref());
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}
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{
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foo_mrslice(arr.as_mut());
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foo_mrslice(vec.as_mut());
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}
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{
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let rrrrstring = &&&&string;
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let rrrrarr = &&&&arr;
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let rrrrvec = &&&&vec;
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foo_rstr(rrrrstring.as_ref());
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foo_rslice(rrrrarr.as_ref());
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foo_rslice(rrrrvec.as_ref());
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}
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{
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let mrrrrarr = &mut &mut &mut &mut arr;
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let mrrrrvec = &mut &mut &mut &mut vec;
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foo_mrslice(mrrrrarr.as_mut());
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foo_mrslice(mrrrrvec.as_mut());
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}
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FakeAsRef.as_ref();
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foo_rrrrmr(MoreRef.as_ref());
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generic_not_ok(arr.as_mut());
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generic_ok(&mut arr);
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}
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fn foo_mrt<T: Debug + ?Sized>(t: &mut T) { println!("{:?}", t); }
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fn foo_rt<T: Debug + ?Sized>(t: &T) { println!("{:?}", t); }
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fn generic_not_ok<T: AsMut<T> + AsRef<T> + Debug + ?Sized>(mrt: &mut T) {
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foo_mrt(mrt.as_mut());
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foo_mrt(mrt);
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foo_rt(mrt.as_ref());
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foo_rt(mrt);
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}
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fn generic_ok<U: AsMut<T> + AsRef<T> + ?Sized, T: Debug + ?Sized>(mru: &mut U) {
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foo_mrt(mru.as_mut());
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foo_rt(mru.as_ref());
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}
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fn main() {
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not_ok();
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ok();
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}
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