| // run-pass |
| #![allow(unused_mut)] |
| #![allow(unused_variables)] |
| // 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; |
| } |