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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// 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.
// Test that we choose Deref or DerefMut appropriately based on mutability of ref bindings (#15609).
use std::ops::{Deref, DerefMut};
struct DerefOk<T>(T);
struct DerefMutOk<T>(T);
impl<T> Deref for DerefOk<T> {
type Target = T;
fn deref(&self) -> &Self::Target {
&self.0
}
}
impl<T> DerefMut for DerefOk<T> {
fn deref_mut(&mut self) -> &mut Self::Target {
panic!()
}
}
impl<T> Deref for DerefMutOk<T> {
type Target = T;
fn deref(&self) -> &Self::Target {
panic!()
}
}
impl<T> DerefMut for DerefMutOk<T> {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.0
}
}
fn main() {
// Check that mutable ref binding in match picks DerefMut
let mut b = DerefMutOk(0);
match *b {
ref mut n => n,
};
// Check that mutable ref binding in let picks DerefMut
let mut y = DerefMutOk(1);
let ref mut z = *y;
// Check that immutable ref binding in match picks Deref
let mut b = DerefOk(2);
match *b {
ref n => n,
};
// Check that immutable ref binding in let picks Deref
let mut y = DerefOk(3);
let ref z = *y;
// Check that mixed mutable/immutable ref binding in match picks DerefMut
let mut b = DerefMutOk((0, 9));
match *b {
(ref mut n, ref m) => (n, m),
};
let mut b = DerefMutOk((0, 9));
match *b {
(ref n, ref mut m) => (n, m),
};
// Check that mixed mutable/immutable ref binding in let picks DerefMut
let mut y = DerefMutOk((1, 8));
let (ref mut z, ref a) = *y;
let mut y = DerefMutOk((1, 8));
let (ref z, ref mut a) = *y;
// Check that multiple immutable ref bindings in match picks Deref
let mut b = DerefOk((2, 7));
match *b {
(ref n, ref m) => (n, m),
};
// Check that multiple immutable ref bindings in let picks Deref
let mut y = DerefOk((3, 6));
let (ref z, ref a) = *y;
// Check that multiple mutable ref bindings in match picks DerefMut
let mut b = DerefMutOk((4, 5));
match *b {
(ref mut n, ref mut m) => (n, m),
};
// Check that multiple mutable ref bindings in let picks DerefMut
let mut y = DerefMutOk((5, 4));
let (ref mut z, ref mut a) = *y;
}
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