Forget temporary in iter_inner

Author: wmstack

library/core/src/array/iter/iter_inner.rs

@@ -176,13 +176,16 @@ impl<T> PolymorphicIter<[MaybeUninit<T>]> {
     }
 
     #[inline]
-    pub(super) fn peek_with<U>(&mut self, func: impl for<'b> FnOnce(Option<&'b T>) -> U) -> U {
+    pub(super) fn peek_with<U>(&self, func: impl for<'b> FnOnce(Option<&'b T>) -> U) -> U {
         let tmp = self.alive.clone().next().map(|idx| {
             // SAFETY: `idx` is in self.alive range
             unsafe { self.data.get_unchecked(idx).assume_init_read() }
         });
 
-        func(tmp.as_ref())
+        let out = func(tmp.as_ref());
+        // Avoid dropping before the item is consumed
+        crate::mem::forget(tmp);
+        out
     }
 
     #[inline]