impl OsString::leak & PathBuf::leak

2 files changed, 26 insertions, 0 deletions

diff --git a/library/std/src/ffi/os_str.rs b/library/std/src/ffi/os_str.rs
index 9dd3d7d3fa1..f6b9de26c1c 100644
--- a/library/std/src/ffi/os_str.rs
+++ b/library/std/src/ffi/os_str.rs
@@ -533,6 +533,25 @@ impl OsString {
         unsafe { Box::from_raw(rw) }
     }
 
+    /// Consumes and leaks the `OsString`, returning a mutable reference to the contents,
+    /// `&'a mut OsStr`.
+    ///
+    /// The caller has free choice over the returned lifetime, including 'static.
+    /// Indeed, this function is ideally used for data that lives for the remainder of
+    /// the program’s life, as dropping the returned reference will cause a memory leak.
+    ///
+    /// It does not reallocate or shrink the `OsString`, so the leaked allocation may include
+    /// unused capacity that is not part of the returned slice. If you want to discard excess
+    /// capacity, call [`into_boxed_os_str`], and then [`Box::leak`] instead.
+    /// However, keep in mind that trimming the capacity may result in a reallocation and copy.
+    ///
+    /// [`into_boxed_os_str`]: Self::into_boxed_os_str
+    #[unstable(feature = "os_string_pathbuf_leak", issue = "125965")]
+    #[inline]
+    pub fn leak<'a>(self) -> &'a mut OsStr {
+        OsStr::from_inner_mut(self.inner.leak())
+    }
+
     /// Part of a hack to make PathBuf::push/pop more efficient.
     #[inline]
     pub(crate) fn as_mut_vec_for_path_buf(&mut self) -> &mut Vec<u8> {
diff --git a/library/std/src/ffi/os_str/tests.rs b/library/std/src/ffi/os_str/tests.rs
index b020e05eaab..2379f0ba489 100644
--- a/library/std/src/ffi/os_str/tests.rs
+++ b/library/std/src/ffi/os_str/tests.rs
@@ -24,6 +24,13 @@ fn test_os_string_clear() {
 }
 
 #[test]
+fn test_os_string_leak() {
+    let os_string = OsString::from("have a cake");
+    let leaked = os_string.leak();
+    assert_eq!(leaked.as_encoded_bytes(), b"have a cake");
+}
+
+#[test]
 fn test_os_string_capacity() {
     let os_string = OsString::with_capacity(0);
     assert_eq!(0, os_string.capacity());