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Diffstat (limited to 'library/alloc/tests/rc.rs')
| -rw-r--r-- | library/alloc/tests/rc.rs | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/library/alloc/tests/rc.rs b/library/alloc/tests/rc.rs new file mode 100644 index 000000000..efb39a609 --- /dev/null +++ b/library/alloc/tests/rc.rs @@ -0,0 +1,208 @@ +use std::any::Any; +use std::cell::RefCell; +use std::cmp::PartialEq; +use std::iter::TrustedLen; +use std::mem; +use std::rc::{Rc, Weak}; + +#[test] +fn uninhabited() { + enum Void {} + let mut a = Weak::<Void>::new(); + a = a.clone(); + assert!(a.upgrade().is_none()); + + let mut a: Weak<dyn Any> = a; // Unsizing + a = a.clone(); + assert!(a.upgrade().is_none()); +} + +#[test] +fn slice() { + let a: Rc<[u32; 3]> = Rc::new([3, 2, 1]); + let a: Rc<[u32]> = a; // Unsizing + let b: Rc<[u32]> = Rc::from(&[3, 2, 1][..]); // Conversion + assert_eq!(a, b); + + // Exercise is_dangling() with a DST + let mut a = Rc::downgrade(&a); + a = a.clone(); + assert!(a.upgrade().is_some()); +} + +#[test] +fn trait_object() { + let a: Rc<u32> = Rc::new(4); + let a: Rc<dyn Any> = a; // Unsizing + + // Exercise is_dangling() with a DST + let mut a = Rc::downgrade(&a); + a = a.clone(); + assert!(a.upgrade().is_some()); + + let mut b = Weak::<u32>::new(); + b = b.clone(); + assert!(b.upgrade().is_none()); + let mut b: Weak<dyn Any> = b; // Unsizing + b = b.clone(); + assert!(b.upgrade().is_none()); +} + +#[test] +fn float_nan_ne() { + let x = Rc::new(f32::NAN); + assert!(x != x); + assert!(!(x == x)); +} + +#[test] +fn partial_eq() { + struct TestPEq(RefCell<usize>); + impl PartialEq for TestPEq { + fn eq(&self, other: &TestPEq) -> bool { + *self.0.borrow_mut() += 1; + *other.0.borrow_mut() += 1; + true + } + } + let x = Rc::new(TestPEq(RefCell::new(0))); + assert!(x == x); + assert!(!(x != x)); + assert_eq!(*x.0.borrow(), 4); +} + +#[test] +fn eq() { + #[derive(Eq)] + struct TestEq(RefCell<usize>); + impl PartialEq for TestEq { + fn eq(&self, other: &TestEq) -> bool { + *self.0.borrow_mut() += 1; + *other.0.borrow_mut() += 1; + true + } + } + let x = Rc::new(TestEq(RefCell::new(0))); + assert!(x == x); + assert!(!(x != x)); + assert_eq!(*x.0.borrow(), 0); +} + +const SHARED_ITER_MAX: u16 = 100; + +fn assert_trusted_len<I: TrustedLen>(_: &I) {} + +#[test] +fn shared_from_iter_normal() { + // Exercise the base implementation for non-`TrustedLen` iterators. + { + // `Filter` is never `TrustedLen` since we don't + // know statically how many elements will be kept: + let iter = (0..SHARED_ITER_MAX).filter(|x| x % 2 == 0).map(Box::new); + + // Collecting into a `Vec<T>` or `Rc<[T]>` should make no difference: + let vec = iter.clone().collect::<Vec<_>>(); + let rc = iter.collect::<Rc<[_]>>(); + assert_eq!(&*vec, &*rc); + + // Clone a bit and let these get dropped. + { + let _rc_2 = rc.clone(); + let _rc_3 = rc.clone(); + let _rc_4 = Rc::downgrade(&_rc_3); + } + } // Drop what hasn't been here. +} + +#[test] +fn shared_from_iter_trustedlen_normal() { + // Exercise the `TrustedLen` implementation under normal circumstances + // where `size_hint()` matches `(_, Some(exact_len))`. + { + let iter = (0..SHARED_ITER_MAX).map(Box::new); + assert_trusted_len(&iter); + + // Collecting into a `Vec<T>` or `Rc<[T]>` should make no difference: + let vec = iter.clone().collect::<Vec<_>>(); + let rc = iter.collect::<Rc<[_]>>(); + assert_eq!(&*vec, &*rc); + assert_eq!(mem::size_of::<Box<u16>>() * SHARED_ITER_MAX as usize, mem::size_of_val(&*rc)); + + // Clone a bit and let these get dropped. + { + let _rc_2 = rc.clone(); + let _rc_3 = rc.clone(); + let _rc_4 = Rc::downgrade(&_rc_3); + } + } // Drop what hasn't been here. + + // Try a ZST to make sure it is handled well. + { + let iter = (0..SHARED_ITER_MAX).map(drop); + let vec = iter.clone().collect::<Vec<_>>(); + let rc = iter.collect::<Rc<[_]>>(); + assert_eq!(&*vec, &*rc); + assert_eq!(0, mem::size_of_val(&*rc)); + { + let _rc_2 = rc.clone(); + let _rc_3 = rc.clone(); + let _rc_4 = Rc::downgrade(&_rc_3); + } + } +} + +#[test] +#[should_panic = "I've almost got 99 problems."] +fn shared_from_iter_trustedlen_panic() { + // Exercise the `TrustedLen` implementation when `size_hint()` matches + // `(_, Some(exact_len))` but where `.next()` drops before the last iteration. + let iter = (0..SHARED_ITER_MAX).map(|val| match val { + 98 => panic!("I've almost got 99 problems."), + _ => Box::new(val), + }); + assert_trusted_len(&iter); + let _ = iter.collect::<Rc<[_]>>(); + + panic!("I am unreachable."); +} + +#[test] +fn shared_from_iter_trustedlen_no_fuse() { + // Exercise the `TrustedLen` implementation when `size_hint()` matches + // `(_, Some(exact_len))` but where the iterator does not behave in a fused manner. + struct Iter(std::vec::IntoIter<Option<Box<u8>>>); + + unsafe impl TrustedLen for Iter {} + + impl Iterator for Iter { + fn size_hint(&self) -> (usize, Option<usize>) { + (2, Some(2)) + } + + type Item = Box<u8>; + + fn next(&mut self) -> Option<Self::Item> { + self.0.next().flatten() + } + } + + let vec = vec![Some(Box::new(42)), Some(Box::new(24)), None, Some(Box::new(12))]; + let iter = Iter(vec.into_iter()); + assert_trusted_len(&iter); + assert_eq!(&[Box::new(42), Box::new(24)], &*iter.collect::<Rc<[_]>>()); +} + +#[test] +fn weak_may_dangle() { + fn hmm<'a>(val: &'a mut Weak<&'a str>) -> Weak<&'a str> { + val.clone() + } + + // Without #[may_dangle] we get: + let mut val = Weak::new(); + hmm(&mut val); + // ~~~~~~~~ borrowed value does not live long enough + // + // `val` dropped here while still borrowed + // borrow might be used here, when `val` is dropped and runs the `Drop` code for type `std::rc::Weak` +} |