in-place collect for Vec. Box<[]> and BinaryHeap IntoIter and some adapters

4 files changed, 44 insertions, 0 deletions

diff --git a/library/alloc/tests/binary_heap.rs b/library/alloc/tests/binary_heap.rs
index 62084ccf53c..ce794a9a4af 100644
--- a/library/alloc/tests/binary_heap.rs
+++ b/library/alloc/tests/binary_heap.rs
@@ -231,6 +231,18 @@ fn test_to_vec() {
 }
 
 #[test]
+fn test_in_place_iterator_specialization() {
+    let src: Vec<usize> = vec![1, 2, 3];
+    let src_ptr = src.as_ptr();
+    let heap: BinaryHeap<_> = src.into_iter().map(std::convert::identity).collect();
+    let heap_ptr = heap.iter().next().unwrap() as *const usize;
+    assert_eq!(src_ptr, heap_ptr);
+    let sink: Vec<_> = heap.into_iter().map(std::convert::identity).collect();
+    let sink_ptr = sink.as_ptr();
+    assert_eq!(heap_ptr, sink_ptr);
+}
+
+#[test]
 fn test_empty_pop() {
     let mut heap = BinaryHeap::<i32>::new();
     assert!(heap.pop().is_none());
diff --git a/library/alloc/tests/lib.rs b/library/alloc/tests/lib.rs
index f2ba1ab6481..e0e146dc427 100644
--- a/library/alloc/tests/lib.rs
+++ b/library/alloc/tests/lib.rs
@@ -14,6 +14,7 @@
 #![feature(slice_ptr_get)]
 #![feature(split_inclusive)]
 #![feature(binary_heap_retain)]
+#![feature(inplace_iteration)]
 
 use std::collections::hash_map::DefaultHasher;
 use std::hash::{Hash, Hasher};
diff --git a/library/alloc/tests/slice.rs b/library/alloc/tests/slice.rs
index 3c7d57f8b32..1f561bebd90 100644
--- a/library/alloc/tests/slice.rs
+++ b/library/alloc/tests/slice.rs
@@ -1460,6 +1460,15 @@ fn test_to_vec() {
 }
 
 #[test]
+fn test_in_place_iterator_specialization() {
+    let src: Box<[usize]> = box [1, 2, 3];
+    let src_ptr = src.as_ptr();
+    let sink: Box<_> = src.into_vec().into_iter().map(std::convert::identity).collect();
+    let sink_ptr = sink.as_ptr();
+    assert_eq!(src_ptr, sink_ptr);
+}
+
+#[test]
 fn test_box_slice_clone() {
     let data = vec![vec![0, 1], vec![0], vec![1]];
     let data2 = data.clone().into_boxed_slice().clone().to_vec();
diff --git a/library/alloc/tests/vec.rs b/library/alloc/tests/vec.rs
index ffff543b07f..271a705cf06 100644
--- a/library/alloc/tests/vec.rs
+++ b/library/alloc/tests/vec.rs
@@ -1,6 +1,7 @@
 use std::borrow::Cow;
 use std::collections::TryReserveError::*;
 use std::fmt::Debug;
+use std::iter::InPlaceIterable;
 use std::mem::size_of;
 use std::panic::{catch_unwind, AssertUnwindSafe};
 use std::vec::{Drain, IntoIter};
@@ -776,6 +777,27 @@ fn test_into_iter_leak() {
 }
 
 #[test]
+fn test_from_iter_specialization() {
+    let src: Vec<usize> = vec![0usize; 1];
+    let srcptr = src.as_ptr();
+    let sink = src.into_iter().collect::<Vec<_>>();
+    let sinkptr = sink.as_ptr();
+    assert_eq!(srcptr, sinkptr);
+}
+
+#[test]
+fn test_from_iter_specialization_with_iterator_adapters() {
+    fn assert_in_place_trait<T: InPlaceIterable>(_: &T) {};
+    let src: Vec<usize> = vec![0usize; 65535];
+    let srcptr = src.as_ptr();
+    let iter = src.into_iter().enumerate().map(|i| i.0 + i.1).peekable().skip(1);
+    assert_in_place_trait(&iter);
+    let sink = iter.collect::<Vec<_>>();
+    let sinkptr = sink.as_ptr();
+    assert_eq!(srcptr, sinkptr);
+}
+
+#[test]
 fn test_cow_from() {
     let borrowed: &[_] = &["borrowed", "(slice)"];
     let owned = vec!["owned", "(vec)"];