warn about deprecated-in-future in most of libstd

src/libstd/lib.rs

@@ -205,7 +205,7 @@
 // Don't link to std. We are std.
 #![no_std]
 
-//#![warn(deprecated_in_future)] // FIXME: std still has quite a few uses of `mem::uninitialized`
+#![warn(deprecated_in_future)]
 #![warn(missing_docs)]
 #![warn(missing_debug_implementations)]
 #![deny(intra_doc_link_resolution_failure)] // rustdoc is run without -D warnings

src/libstd/sync/mod.rs

@@ -163,7 +163,7 @@ pub use self::condvar::{Condvar, WaitTimeoutResult};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::mutex::{Mutex, MutexGuard};
 #[stable(feature = "rust1", since = "1.0.0")]
-#[allow(deprecated)]
+#[allow(deprecated_in_future)]
 pub use self::once::{Once, OnceState, ONCE_INIT};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use crate::sys_common::poison::{PoisonError, TryLockError, TryLockResult, LockResult};

src/libstd/sys/cloudabi/mod.rs

@@ -1,4 +1,4 @@
-#![allow(deprecated)] // mem::uninitialized
+#![allow(deprecated_in_future)] // mem::uninitialized; becomes `deprecated` when nightly is 1.39
 
 use crate::io::ErrorKind;
 use crate::mem;