1 files changed, 14 insertions, 5 deletions
diff --git a/library/core/src/borrow.rs b/library/core/src/borrow.rs
index da05f236d2f..6ce7e4656b9 100644
--- a/library/core/src/borrow.rs
+++ b/library/core/src/borrow.rs
@@ -154,6 +154,8 @@
 /// [`String`]: ../../std/string/struct.String.html
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_diagnostic_item = "Borrow"]
+#[const_trait]
+#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
 pub trait Borrow<Borrowed: ?Sized> {
     /// Immutably borrows from an owned value.
     ///
@@ -185,6 +187,8 @@ pub trait Borrow<Borrowed: ?Sized> {
 /// for more information on borrowing as another type.
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_diagnostic_item = "BorrowMut"]
+#[const_trait]
+#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
 pub trait BorrowMut<Borrowed: ?Sized>: Borrow<Borrowed> {
     /// Mutably borrows from an owned value.
     ///
@@ -206,7 +210,8 @@ pub trait BorrowMut<Borrowed: ?Sized>: Borrow<Borrowed> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized> Borrow<T> for T {
+#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
+impl<T: ?Sized> const Borrow<T> for T {
     #[rustc_diagnostic_item = "noop_method_borrow"]
     fn borrow(&self) -> &T {
         self
@@ -214,28 +219,32 @@ impl<T: ?Sized> Borrow<T> for T {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized> BorrowMut<T> for T {
+#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
+impl<T: ?Sized> const BorrowMut<T> for T {
     fn borrow_mut(&mut self) -> &mut T {
         self
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized> Borrow<T> for &T {
+#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
+impl<T: ?Sized> const Borrow<T> for &T {
     fn borrow(&self) -> &T {
         self
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized> Borrow<T> for &mut T {
+#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
+impl<T: ?Sized> const Borrow<T> for &mut T {
     fn borrow(&self) -> &T {
         self
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized> BorrowMut<T> for &mut T {
+#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
+impl<T: ?Sized> const BorrowMut<T> for &mut T {
     fn borrow_mut(&mut self) -> &mut T {
         self
     }