Rollup merge of rust-lang#94145 - ssomers:binary_heap_tests, r=jyn514

Test leaking of BinaryHeap Drain iterators

Add test cases about forgetting the `BinaryHeap::Drain` iterator, and slightly fortifies some other test cases.

Consists of separate commits that I don't think are relevant on their own (but I'll happily turn these into more PRs if desired).

library/alloc/src/collections/binary_heap/tests.rs

@@ -1,8 +1,8 @@
 use super::*;
 use crate::boxed::Box;
+use crate::testing::crash_test::{CrashTestDummy, Panic};
 use std::iter::TrustedLen;
 use std::panic::{catch_unwind, AssertUnwindSafe};
-use std::sync::atomic::{AtomicU32, Ordering};
 
 #[test]
 fn test_iterator() {
@@ -291,33 +291,83 @@ fn test_drain_sorted() {
 
 #[test]
 fn test_drain_sorted_leak() {
-    static DROPS: AtomicU32 = AtomicU32::new(0);
-
-    #[derive(Clone, PartialEq, Eq, PartialOrd, Ord)]
-    struct D(u32, bool);
-
-    impl Drop for D {
-        fn drop(&mut self) {
-            DROPS.fetch_add(1, Ordering::SeqCst);
-
-            if self.1 {
-                panic!("panic in `drop`");
-            }
-        }
-    }
-
+    let d0 = CrashTestDummy::new(0);
+    let d1 = CrashTestDummy::new(1);
+    let d2 = CrashTestDummy::new(2);
+    let d3 = CrashTestDummy::new(3);
+    let d4 = CrashTestDummy::new(4);
+    let d5 = CrashTestDummy::new(5);
     let mut q = BinaryHeap::from(vec![
-        D(0, false),
-        D(1, false),
-        D(2, false),
-        D(3, true),
-        D(4, false),
-        D(5, false),
+        d0.spawn(Panic::Never),
+        d1.spawn(Panic::Never),
+        d2.spawn(Panic::Never),
+        d3.spawn(Panic::InDrop),
+        d4.spawn(Panic::Never),
+        d5.spawn(Panic::Never),
     ]);
 
-    catch_unwind(AssertUnwindSafe(|| drop(q.drain_sorted()))).ok();
+    catch_unwind(AssertUnwindSafe(|| drop(q.drain_sorted()))).unwrap_err();
+
+    assert_eq!(d0.dropped(), 1);
+    assert_eq!(d1.dropped(), 1);
+    assert_eq!(d2.dropped(), 1);
+    assert_eq!(d3.dropped(), 1);
+    assert_eq!(d4.dropped(), 1);
+    assert_eq!(d5.dropped(), 1);
+    assert!(q.is_empty());
+}
 
-    assert_eq!(DROPS.load(Ordering::SeqCst), 6);
+#[test]
+fn test_drain_forget() {
+    let a = CrashTestDummy::new(0);
+    let b = CrashTestDummy::new(1);
+    let c = CrashTestDummy::new(2);
+    let mut q =
+        BinaryHeap::from(vec![a.spawn(Panic::Never), b.spawn(Panic::Never), c.spawn(Panic::Never)]);
+
+    catch_unwind(AssertUnwindSafe(|| {
+        let mut it = q.drain();
+        it.next();
+        mem::forget(it);
+    }))
+    .unwrap();
+    // Behaviour after leaking is explicitly unspecified and order is arbitrary,
+    // so it's fine if these start failing, but probably worth knowing.
+    assert!(q.is_empty());
+    assert_eq!(a.dropped() + b.dropped() + c.dropped(), 1);
+    assert_eq!(a.dropped(), 0);
+    assert_eq!(b.dropped(), 0);
+    assert_eq!(c.dropped(), 1);
+    drop(q);
+    assert_eq!(a.dropped(), 0);
+    assert_eq!(b.dropped(), 0);
+    assert_eq!(c.dropped(), 1);
+}
+
+#[test]
+fn test_drain_sorted_forget() {
+    let a = CrashTestDummy::new(0);
+    let b = CrashTestDummy::new(1);
+    let c = CrashTestDummy::new(2);
+    let mut q =
+        BinaryHeap::from(vec![a.spawn(Panic::Never), b.spawn(Panic::Never), c.spawn(Panic::Never)]);
+
+    catch_unwind(AssertUnwindSafe(|| {
+        let mut it = q.drain_sorted();
+        it.next();
+        mem::forget(it);
+    }))
+    .unwrap();
+    // Behaviour after leaking is explicitly unspecified,
+    // so it's fine if these start failing, but probably worth knowing.
+    assert_eq!(q.len(), 2);
+    assert_eq!(a.dropped(), 0);
+    assert_eq!(b.dropped(), 0);
+    assert_eq!(c.dropped(), 1);
+    drop(q);
+    assert_eq!(a.dropped(), 1);
+    assert_eq!(b.dropped(), 1);
+    assert_eq!(c.dropped(), 1);
 }
 
 #[test]

library/alloc/src/collections/btree/map/tests.rs

@@ -1,12 +1,12 @@
-use super::super::testing::crash_test::{CrashTestDummy, Panic};
-use super::super::testing::ord_chaos::{Cyclic3, Governed, Governor};
-use super::super::testing::rng::DeterministicRng;
 use super::Entry::{Occupied, Vacant};
 use super::*;
 use crate::boxed::Box;
 use crate::fmt::Debug;
 use crate::rc::Rc;
 use crate::string::{String, ToString};
+use crate::testing::crash_test::{CrashTestDummy, Panic};
+use crate::testing::ord_chaos::{Cyclic3, Governed, Governor};
+use crate::testing::rng::DeterministicRng;
 use crate::vec::Vec;
 use std::cmp::Ordering;
 use std::convert::TryFrom;

library/alloc/src/collections/btree/mod.rs

@@ -21,6 +21,3 @@ trait Recover<Q: ?Sized> {
     fn take(&mut self, key: &Q) -> Option<Self::Key>;
     fn replace(&mut self, key: Self::Key) -> Option<Self::Key>;
 }
-
-#[cfg(test)]
-mod testing;

library/alloc/src/collections/btree/set/tests.rs

@@ -1,6 +1,6 @@
-use super::super::testing::crash_test::{CrashTestDummy, Panic};
-use super::super::testing::rng::DeterministicRng;
 use super::*;
+use crate::testing::crash_test::{CrashTestDummy, Panic};
+use crate::testing::rng::DeterministicRng;
 use crate::vec::Vec;
 use std::cmp::Ordering;
 use std::hash::{Hash, Hasher};

library/alloc/src/collections/linked_list/tests.rs

@@ -1,4 +1,5 @@
 use super::*;
+use crate::testing::crash_test::{CrashTestDummy, Panic};
 use crate::vec::Vec;
 
 use std::panic::{catch_unwind, AssertUnwindSafe};
@@ -984,35 +985,34 @@ fn drain_filter_complex() {
 
 #[test]
 fn drain_filter_drop_panic_leak() {
-    static mut DROPS: i32 = 0;
-
-    struct D(bool);
-
-    impl Drop for D {
-        fn drop(&mut self) {
-            unsafe {
-                DROPS += 1;
-            }
-
-            if self.0 {
-                panic!("panic in `drop`");
-            }
-        }
-    }
-
+    let d0 = CrashTestDummy::new(0);
+    let d1 = CrashTestDummy::new(1);
+    let d2 = CrashTestDummy::new(2);
+    let d3 = CrashTestDummy::new(3);
+    let d4 = CrashTestDummy::new(4);
+    let d5 = CrashTestDummy::new(5);
+    let d6 = CrashTestDummy::new(6);
+    let d7 = CrashTestDummy::new(7);
     let mut q = LinkedList::new();
-    q.push_back(D(false));
-    q.push_back(D(false));
-    q.push_back(D(false));
-    q.push_back(D(false));
-    q.push_back(D(false));
-    q.push_front(D(false));
-    q.push_front(D(true));
-    q.push_front(D(false));
-
-    catch_unwind(AssertUnwindSafe(|| drop(q.drain_filter(|_| true)))).ok();
-
-    assert_eq!(unsafe { DROPS }, 8);
+    q.push_back(d3.spawn(Panic::Never));
+    q.push_back(d4.spawn(Panic::Never));
+    q.push_back(d5.spawn(Panic::Never));
+    q.push_back(d6.spawn(Panic::Never));
+    q.push_back(d7.spawn(Panic::Never));
+    q.push_front(d2.spawn(Panic::Never));
+    q.push_front(d1.spawn(Panic::InDrop));
+    q.push_front(d0.spawn(Panic::Never));
+
+    catch_unwind(AssertUnwindSafe(|| drop(q.drain_filter(|_| true)))).unwrap_err();
+
+    assert_eq!(d0.dropped(), 1);
+    assert_eq!(d1.dropped(), 1);
+    assert_eq!(d2.dropped(), 1);
+    assert_eq!(d3.dropped(), 1);
+    assert_eq!(d4.dropped(), 1);
+    assert_eq!(d5.dropped(), 1);
+    assert_eq!(d6.dropped(), 1);
+    assert_eq!(d7.dropped(), 1);
     assert!(q.is_empty());
 }
 

library/alloc/src/lib.rs

@@ -206,6 +206,8 @@
 extern crate std;
 #[cfg(test)]
 extern crate test;
+#[cfg(test)]
+mod testing;
 
 // Module with internal macros used by other modules (needs to be included before other modules).
 #[macro_use]