diff options
Diffstat (limited to 'src/test/ui/closures/issue-42463.rs')
-rw-r--r-- | src/test/ui/closures/issue-42463.rs | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/src/test/ui/closures/issue-42463.rs b/src/test/ui/closures/issue-42463.rs new file mode 100644 index 000000000..51d6ea3f7 --- /dev/null +++ b/src/test/ui/closures/issue-42463.rs @@ -0,0 +1,32 @@ +// run-pass +use std::ops::{Deref, DerefMut}; + +struct CheckedDeref<T, F> { + value: T, + check: F +} + +impl<F: Fn(&T) -> bool, T> Deref for CheckedDeref<T, F> { + type Target = T; + fn deref(&self) -> &T { + assert!((self.check)(&self.value)); + &self.value + } +} + +impl<F: Fn(&T) -> bool, T> DerefMut for CheckedDeref<T, F> { + fn deref_mut(&mut self) -> &mut T { + assert!((self.check)(&self.value)); + &mut self.value + } +} + + +fn main() { + let mut v = CheckedDeref { + value: vec![0], + check: |v: &Vec<_>| !v.is_empty() + }; + v.push(1); + assert_eq!(*v, vec![0, 1]); +} |