HashMap is UnwindSafe

Fixes rust-lang#62301, a regression in 1.36.0 which was caused by hashbrown using `NonZero<T>` where the older hashmap used `Unique<T>`.

src/libstd/collections/hash/map.rs

@@ -2608,6 +2608,12 @@ mod test_map {
     use realstd::collections::CollectionAllocErr::*;
     use realstd::usize;
 
+    // https://github.com/rust-lang/rust/issues/62301
+    fn _assert_hashmap_is_unwind_safe() {
+        fn assert_unwind_safe<T: crate::panic::UnwindSafe>() {}
+        assert_unwind_safe::<HashMap<(), crate::cell::UnsafeCell<()>>>();
+    }
+
     #[test]
     fn test_zero_capacities() {
         type HM = HashMap<i32, i32>;

src/libstd/panic.rs

@@ -4,6 +4,7 @@
 
 use crate::any::Any;
 use crate::cell::UnsafeCell;
+use crate::collections;
 use crate::fmt;
 use crate::future::Future;
 use crate::pin::Pin;
@@ -285,6 +286,11 @@ impl RefUnwindSafe for atomic::AtomicBool {}
 #[stable(feature = "unwind_safe_atomic_refs", since = "1.14.0")]
 impl<T> RefUnwindSafe for atomic::AtomicPtr<T> {}
 
+// https://github.com/rust-lang/rust/issues/62301
+#[stable(feature = "hashbrown", since = "1.36.0")]
+impl<K, V, S> UnwindSafe for collections::HashMap<K, V, S>
+    where K: UnwindSafe, V: UnwindSafe, S: UnwindSafe {}
+
 #[stable(feature = "catch_unwind", since = "1.9.0")]
 impl<T> Deref for AssertUnwindSafe<T> {
     type Target = T;