Constify Drop and Destruct

library/core/src/marker.rs

@@ -957,6 +957,7 @@ marker_impls! {
 #[lang = "destruct"]
 #[rustc_on_unimplemented(message = "can't drop `{Self}`", append_const_msg)]
 #[rustc_deny_explicit_impl(implement_via_object = false)]
+#[cfg_attr(not(bootstrap), const_trait)]
 pub trait Destruct {}
 
 /// A marker for tuple types.

library/core/src/ops/drop.rs

@@ -203,7 +203,7 @@
 /// [nomicon]: ../../nomicon/phantom-data.html#an-exception-the-special-case-of-the-standard-library-and-its-unstable-may_dangle
 #[lang = "drop"]
 #[stable(feature = "rust1", since = "1.0.0")]
-// FIXME(const_trait_impl) #[const_trait]
+#[cfg_attr(not(bootstrap), const_trait)]
 pub trait Drop {
     /// Executes the destructor for this type.
     ///