4 files changed, 31 insertions, 17 deletions
diff --git a/library/alloc/src/collections/btree/map.rs b/library/alloc/src/collections/btree/map.rs
index 78b7da9d6b3..5ca32ed741a 100644
--- a/library/alloc/src/collections/btree/map.rs
+++ b/library/alloc/src/collections/btree/map.rs
@@ -1917,14 +1917,13 @@ pub struct ExtractIf<
     V,
     F,
     #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + Clone = Global,
-> where
-    F: 'a + FnMut(&K, &mut V) -> bool,
-{
+> {
     pred: F,
     inner: ExtractIfInner<'a, K, V>,
     /// The BTreeMap will outlive this IntoIter so we don't care about drop order for `alloc`.
     alloc: A,
 }
+
 /// Most of the implementation of ExtractIf are generic over the type
 /// of the predicate, thus also serving for BTreeSet::ExtractIf.
 pub(super) struct ExtractIfInner<'a, K, V> {
@@ -1940,14 +1939,14 @@ pub(super) struct ExtractIfInner<'a, K, V> {
 }
 
 #[unstable(feature = "btree_extract_if", issue = "70530")]
-impl<K, V, F> fmt::Debug for ExtractIf<'_, K, V, F>
+impl<K, V, F, A> fmt::Debug for ExtractIf<'_, K, V, F, A>
 where
     K: fmt::Debug,
     V: fmt::Debug,
-    F: FnMut(&K, &mut V) -> bool,
+    A: Allocator + Clone,
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_tuple("ExtractIf").field(&self.inner.peek()).finish()
+        f.debug_struct("ExtractIf").field("peek", &self.inner.peek()).finish_non_exhaustive()
     }
 }
 
diff --git a/library/alloc/src/collections/btree/set.rs b/library/alloc/src/collections/btree/set.rs
index 7ad9e59dfed..343934680b8 100644
--- a/library/alloc/src/collections/btree/set.rs
+++ b/library/alloc/src/collections/btree/set.rs
@@ -1556,10 +1556,7 @@ pub struct ExtractIf<
     T,
     F,
     #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + Clone = Global,
-> where
-    T: 'a,
-    F: 'a + FnMut(&T) -> bool,
-{
+> {
     pred: F,
     inner: super::map::ExtractIfInner<'a, T, SetValZST>,
     /// The BTreeMap will outlive this IntoIter so we don't care about drop order for `alloc`.
@@ -1567,13 +1564,15 @@ pub struct ExtractIf<
 }
 
 #[unstable(feature = "btree_extract_if", issue = "70530")]
-impl<T, F, A: Allocator + Clone> fmt::Debug for ExtractIf<'_, T, F, A>
+impl<T, F, A> fmt::Debug for ExtractIf<'_, T, F, A>
 where
     T: fmt::Debug,
-    F: FnMut(&T) -> bool,
+    A: Allocator + Clone,
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_tuple("ExtractIf").field(&self.inner.peek().map(|(k, _)| k)).finish()
+        f.debug_struct("ExtractIf")
+            .field("peek", &self.inner.peek().map(|(k, _)| k))
+            .finish_non_exhaustive()
     }
 }
 
diff --git a/library/alloc/src/collections/linked_list.rs b/library/alloc/src/collections/linked_list.rs
index cc42a120e4f..00e2805d11f 100644
--- a/library/alloc/src/collections/linked_list.rs
+++ b/library/alloc/src/collections/linked_list.rs
@@ -1976,9 +1976,14 @@ where
 }
 
 #[stable(feature = "extract_if", since = "1.87.0")]
-impl<T: fmt::Debug, F> fmt::Debug for ExtractIf<'_, T, F> {
+impl<T, F, A> fmt::Debug for ExtractIf<'_, T, F, A>
+where
+    T: fmt::Debug,
+    A: Allocator,
+{
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_tuple("ExtractIf").field(&self.list).finish()
+        let peek = self.it.map(|node| unsafe { &node.as_ref().element });
+        f.debug_struct("ExtractIf").field("peek", &peek).finish_non_exhaustive()
     }
 }
 
diff --git a/library/alloc/src/vec/extract_if.rs b/library/alloc/src/vec/extract_if.rs
index 8a591a87796..a456d3d9e60 100644
--- a/library/alloc/src/vec/extract_if.rs
+++ b/library/alloc/src/vec/extract_if.rs
@@ -1,5 +1,5 @@
 use core::ops::{Range, RangeBounds};
-use core::{ptr, slice};
+use core::{fmt, ptr, slice};
 
 use super::Vec;
 use crate::alloc::{Allocator, Global};
@@ -16,7 +16,6 @@ use crate::alloc::{Allocator, Global};
 /// let iter: std::vec::ExtractIf<'_, _, _> = v.extract_if(.., |x| *x % 2 == 0);
 /// ```
 #[stable(feature = "extract_if", since = "1.87.0")]
-#[derive(Debug)]
 #[must_use = "iterators are lazy and do nothing unless consumed"]
 pub struct ExtractIf<
     'a,
@@ -108,3 +107,15 @@ impl<T, F, A: Allocator> Drop for ExtractIf<'_, T, F, A> {
         }
     }
 }
+
+#[stable(feature = "extract_if", since = "1.87.0")]
+impl<T, F, A> fmt::Debug for ExtractIf<'_, T, F, A>
+where
+    T: fmt::Debug,
+    A: Allocator,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let peek = if self.idx < self.end { self.vec.get(self.idx) } else { None };
+        f.debug_struct("ExtractIf").field("peek", &peek).finish_non_exhaustive()
+    }
+}