diff --git a/src/liballoc/borrow.rs b/src/liballoc/borrow.rs
index ee1799fad8e15..d5e15b3719c2e 100644
--- a/src/liballoc/borrow.rs
+++ b/src/liballoc/borrow.rs
@@ -32,6 +32,7 @@ impl<'a, B: ?Sized> Borrow<B> for Cow<'a, B>
 /// from any borrow of a given type.
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait ToOwned {
+    /// The resulting type after obtaining ownership.
     #[stable(feature = "rust1", since = "1.0.0")]
     type Owned: Borrow<Self>;
 
diff --git a/src/liballoc/boxed.rs b/src/liballoc/boxed.rs
index 6a6a9146e2432..8a3950718d7d2 100644
--- a/src/liballoc/boxed.rs
+++ b/src/liballoc/boxed.rs
@@ -760,6 +760,7 @@ impl<A, F: Fn<A> + ?Sized> Fn<A> for Box<F> {
 #[unstable(feature = "fnbox",
            reason = "will be deprecated if and when `Box<FnOnce>` becomes usable", issue = "28796")]
 pub trait FnBox<A>: FnOnce<A> {
+    /// Performs the call operation.
     fn call_box(self: Box<Self>, args: A) -> Self::Output;
 }
 
diff --git a/src/liballoc/lib.rs b/src/liballoc/lib.rs
index 7f3acc933d413..63b3fbbdaefe1 100644
--- a/src/liballoc/lib.rs
+++ b/src/liballoc/lib.rs
@@ -58,12 +58,13 @@
 #![no_std]
 #![needs_allocator]
 
-#![deny(rust_2018_idioms)]
-#![allow(explicit_outlives_requirements)]
-
 #![warn(deprecated_in_future)]
-#![warn(intra_doc_link_resolution_failure)]
+#![warn(missing_docs)]
 #![warn(missing_debug_implementations)]
+#![deny(intra_doc_link_resolution_failure)] // rustdoc is run without -D warnings
+
+#![deny(rust_2018_idioms)]
+#![allow(explicit_outlives_requirements)]
 
 #![cfg_attr(not(test), feature(generator_trait))]
 #![cfg_attr(test, feature(test))]
diff --git a/src/liballoc/slice.rs b/src/liballoc/slice.rs
index f4b2d463778a9..6eac848740106 100644
--- a/src/liballoc/slice.rs
+++ b/src/liballoc/slice.rs
@@ -570,6 +570,16 @@ pub trait SliceConcatExt<T: ?Sized> {
     #[stable(feature = "rename_connect_to_join", since = "1.3.0")]
     fn join(&self, sep: &T) -> Self::Output;
 
+    /// Flattens a slice of `T` into a single value `Self::Output`, placing a
+    /// given separator between each.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #![allow(deprecated)]
+    /// assert_eq!(["hello", "world"].connect(" "), "hello world");
+    /// assert_eq!([[1, 2], [3, 4]].connect(&0), [1, 2, 0, 3, 4]);
+    /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_deprecated(since = "1.3.0", reason = "renamed to join")]
     fn connect(&self, sep: &T) -> Self::Output;
diff --git a/src/libcore/lib.rs b/src/libcore/lib.rs
index 63688e70c45cb..615549f47bbd6 100644
--- a/src/libcore/lib.rs
+++ b/src/libcore/lib.rs
@@ -60,8 +60,8 @@
 
 #![warn(deprecated_in_future)]
 #![warn(missing_docs)]
-#![warn(intra_doc_link_resolution_failure)]
 #![warn(missing_debug_implementations)]
+#![deny(intra_doc_link_resolution_failure)] // rustdoc is run without -D warnings
 
 #![feature(allow_internal_unstable)]
 #![feature(arbitrary_self_types)]
diff --git a/src/libstd/lib.rs b/src/libstd/lib.rs
index ee6ba3f438f15..62bc1991cc93c 100644
--- a/src/libstd/lib.rs
+++ b/src/libstd/lib.rs
@@ -205,9 +205,10 @@
 // Don't link to std. We are std.
 #![no_std]
 
-#![deny(missing_docs)]
-#![deny(intra_doc_link_resolution_failure)]
-#![deny(missing_debug_implementations)]
+//#![warn(deprecated_in_future)] // FIXME: std still has quite a few uses of `mem::uninitialized`
+#![warn(missing_docs)]
+#![warn(missing_debug_implementations)]
+#![deny(intra_doc_link_resolution_failure)] // rustdoc is run without -D warnings
 
 #![deny(rust_2018_idioms)]
 #![allow(explicit_outlives_requirements)]
diff --git a/src/stdsimd b/src/stdsimd
index 2792b45c97588..2323a858f060a 160000
--- a/src/stdsimd
+++ b/src/stdsimd
@@ -1 +1 @@
-Subproject commit 2792b45c975880038240d477adb0d66f760ac048
+Subproject commit 2323a858f060a0d2a39786a619885608017d538f