Add second batch of feedback from review

Author: yoshuawuyts

library/core/src/mem/drop_guard.rs

@@ -27,7 +27,6 @@ use crate::ptr;
 /// }
 /// ```
 #[unstable(feature = "drop_guard", issue = "none")]
-#[derive(PartialEq, Eq, PartialOrd, Ord, Hash)]
 #[doc(alias = "ScopeGuard")]
 #[doc(alias = "defer")]
 pub struct DropGuard<T, F = fn(T)>

library/coretests/tests/lib.rs

@@ -30,6 +30,7 @@
 #![feature(core_private_diy_float)]
 #![feature(cstr_display)]
 #![feature(dec2flt)]
+#![feature(drop_guard)]
 #![feature(duration_constants)]
 #![feature(duration_constructors)]
 #![feature(duration_constructors_lite)]

library/coretests/tests/mem.rs

@@ -819,3 +819,24 @@ fn drop_guard_into_inner() {
     assert_eq!(dropped.get(), false);
     assert_eq!(*inner, 42);
 }
+
+#[test]
+fn drop_guard_always_drops_value_if_closure_drop_unwinds() {
+    // Create a value with a destructor, which we will validate ran successfully.
+    let mut value_was_dropped = false;
+    let value_with_tracked_destruction = DropGuard::new((), |_| value_was_dropped = true);
+
+    // Create a closure that will begin unwinding when dropped.
+    let drop_bomb = DropGuard::new((), |_| panic!());
+    let closure_that_panics_on_drop = move |_| {
+        let _drop_bomb = drop_bomb;
+    };
+
+    // This will run the closure, which will panic when dropped. This should
+    // run the destructor of the value we passed, which we validate.
+    let _ = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
+        let guard = DropGuard::new(value_with_tracked_destruction, closure_that_panics_on_drop);
+        DropGuard::into_inner(guard);
+    }));
+    assert!(value_was_dropped);
+}