Implement UnwindSafe by never returning on panic

postgres/src/lib.rs

@@ -154,6 +154,8 @@ impl managed::Manager for Manager {
     }
 }
 
+impl std::panic::UnwindSafe for Manager {}
+
 #[async_trait]
 trait Connect: Sync + Send {
     async fn connect(&self, pg_config: &PgConfig) -> Result<(PgClient, JoinHandle<()>), Error>;

src/managed/mod.rs

@@ -71,6 +71,7 @@ use std::{
     future::Future,
     marker::PhantomData,
     ops::{Deref, DerefMut},
+    panic::{RefUnwindSafe, UnwindSafe},
     sync::{
         atomic::{AtomicUsize, Ordering},
         Arc, Mutex, Weak,
@@ -615,6 +616,18 @@ impl<M: Manager, W: From<Object<M>>> Pool<M, W> {
     }
 }
 
+impl<M: Manager, W: From<Object<M>>> UnwindSafe for Pool<M, W>
+where
+    M: UnwindSafe,
+{
+}
+
+impl<M: Manager, W: From<Object<M>>> RefUnwindSafe for Pool<M, W>
+where
+    M: UnwindSafe,
+{
+}
+
 struct PoolInner<M: Manager> {
     manager: M,
     slots: Mutex<Slots<ObjectInner<M>>>,

src/unmanaged/mod.rs

@@ -78,6 +78,13 @@ impl<T> Object<T> {
 
 impl<T> Drop for Object<T> {
     fn drop(&mut self) {
+        // If we're panicking, there is no way to determine whether the object
+        // we are dropping is the source of the panic. Therefore, always discard
+        // the object on a panic, and do not return it to the pool.
+        if std::thread::panicking() {
+            return;
+        }
+
         if let Some(obj) = self.obj.take() {
             if let Some(pool) = self.pool.upgrade() {
                 {