Address review comments

Author: Jules-Bertholet

library/core/src/iter/adapters/map_windows.rs

@@ -207,10 +207,6 @@ impl<T: Clone, const N: usize> Clone for Buffer<T, N> {
         });
 
         // `clone()` could panic; `ManuallyDrop` guards against that.
-        // (We could instead just construct `self.as_array_ref().clone()`
-        // as a local on the stack before creating the buffer.
-        // That would avoid the leak amplification,
-        // but maybe also make it harder to optimize out the local/temporary?)
         buffer.as_uninit_array_mut().write(self.as_array_ref().clone());
 
         // We initialized the buffer above, so we are good now

library/coretests/tests/iter/adapters/map_windows.rs

@@ -147,15 +147,20 @@ mod drop_checks {
     /// Regression test for #156501
     #[test]
     fn panicking_clone() {
+        static CLONE_COUNTER: AtomicUsize = AtomicUsize::new(0);
         static DROP_COUNTER: AtomicUsize = AtomicUsize::new(0);
 
         struct PanickingClone(u8);
 
         impl Clone for PanickingClone {
             fn clone(&self) -> Self {
-                panic!(
-                    "⚞(· <:::> ·)⚟ aaaaaah its the turbofish monster!!! its gonna eat us all!!!1!"
-                );
+                if CLONE_COUNTER.fetch_add(1, Relaxed) == 3 {
+                    panic!(
+                        "⚞(· <:::> ·)⚟ aaaaaah its the turbofish monster!!! its gonna eat us all!!!1!"
+                    );
+                }
+
+                Self(self.0)
             }
         }
 
@@ -181,8 +186,7 @@ mod drop_checks {
 
         assert!(result.is_err());
 
-        // current impl does leak amplification
-        assert_eq!(DROP_COUNTER.load(Relaxed), 0);
+        assert_eq!(DROP_COUNTER.load(Relaxed), 3);
     }
 }