6 files changed, 41 insertions, 26 deletions
diff --git a/library/std/src/f128.rs b/library/std/src/f128.rs
index 506d708d0d2..b436fe9929c 100644
--- a/library/std/src/f128.rs
+++ b/library/std/src/f128.rs
@@ -250,9 +250,14 @@ impl f128 {
     ///
     /// Equal to `self` if the sign of `self` and `sign` are the same, otherwise equal to `-self`.
     /// If `self` is a NaN, then a NaN with the same payload as `self` and the sign bit of `sign` is
-    /// returned. Note, however, that conserving the sign bit on NaN across arithmetical operations
-    /// is not generally guaranteed. See [specification of NaN bit
-    /// patterns](primitive@f32#nan-bit-patterns) for more info.
+    /// returned.
+    ///
+    /// If `sign` is a NaN, then this operation will still carry over its sign into the result. Note
+    /// that IEEE 754 doesn't assign any meaning to the sign bit in case of a NaN, and as Rust
+    /// doesn't guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the
+    /// result of `copysign` with `sign` being a NaN might produce an unexpected or non-portable
+    /// result. See the [specification of NaN bit patterns](primitive@f32#nan-bit-patterns) for more
+    /// info.
     ///
     /// # Examples
     ///
diff --git a/library/std/src/f16.rs b/library/std/src/f16.rs
index 033a3d45009..b2cd5fae9d0 100644
--- a/library/std/src/f16.rs
+++ b/library/std/src/f16.rs
@@ -249,9 +249,14 @@ impl f16 {
     ///
     /// Equal to `self` if the sign of `self` and `sign` are the same, otherwise equal to `-self`.
     /// If `self` is a NaN, then a NaN with the same payload as `self` and the sign bit of `sign` is
-    /// returned. Note, however, that conserving the sign bit on NaN across arithmetical operations
-    /// is not generally guaranteed. See [specification of NaN bit
-    /// patterns](primitive@f32#nan-bit-patterns) for more info.
+    /// returned.
+    ///
+    /// If `sign` is a NaN, then this operation will still carry over its sign into the result. Note
+    /// that IEEE 754 doesn't assign any meaning to the sign bit in case of a NaN, and as Rust
+    /// doesn't guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the
+    /// result of `copysign` with `sign` being a NaN might produce an unexpected or non-portable
+    /// result. See the [specification of NaN bit patterns](primitive@f32#nan-bit-patterns) for more
+    /// info.
     ///
     /// # Examples
     ///
diff --git a/library/std/src/f32.rs b/library/std/src/f32.rs
index 35c2a77b533..cafbe9761da 100644
--- a/library/std/src/f32.rs
+++ b/library/std/src/f32.rs
@@ -228,9 +228,14 @@ impl f32 {
     ///
     /// Equal to `self` if the sign of `self` and `sign` are the same, otherwise equal to `-self`.
     /// If `self` is a NaN, then a NaN with the same payload as `self` and the sign bit of `sign` is
-    /// returned. Note, however, that conserving the sign bit on NaN across arithmetical operations
-    /// is not generally guaranteed. See [specification of NaN bit
-    /// patterns](primitive@f32#nan-bit-patterns) for more info.
+    /// returned.
+    ///
+    /// If `sign` is a NaN, then this operation will still carry over its sign into the result. Note
+    /// that IEEE 754 doesn't assign any meaning to the sign bit in case of a NaN, and as Rust
+    /// doesn't guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the
+    /// result of `copysign` with `sign` being a NaN might produce an unexpected or non-portable
+    /// result. See the [specification of NaN bit patterns](primitive@f32#nan-bit-patterns) for more
+    /// info.
     ///
     /// # Examples
     ///
diff --git a/library/std/src/f64.rs b/library/std/src/f64.rs
index c177f74a97e..fba283e3a44 100644
--- a/library/std/src/f64.rs
+++ b/library/std/src/f64.rs
@@ -228,9 +228,14 @@ impl f64 {
     ///
     /// Equal to `self` if the sign of `self` and `sign` are the same, otherwise equal to `-self`.
     /// If `self` is a NaN, then a NaN with the same payload as `self` and the sign bit of `sign` is
-    /// returned. Note, however, that conserving the sign bit on NaN across arithmetical operations
-    /// is not generally guaranteed. See [specification of NaN bit
-    /// patterns](primitive@f32#nan-bit-patterns) for more info.
+    /// returned.
+    ///
+    /// If `sign` is a NaN, then this operation will still carry over its sign into the result. Note
+    /// that IEEE 754 doesn't assign any meaning to the sign bit in case of a NaN, and as Rust
+    /// doesn't guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the
+    /// result of `copysign` with `sign` being a NaN might produce an unexpected or non-portable
+    /// result. See the [specification of NaN bit patterns](primitive@f32#nan-bit-patterns) for more
+    /// info.
     ///
     /// # Examples
     ///
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index f65e9bc8d8b..bea8eda2619 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -362,7 +362,6 @@
 #![feature(allocator_api)]
 #![feature(get_mut_unchecked)]
 #![feature(map_try_insert)]
-#![feature(new_uninit)]
 #![feature(new_zeroed_alloc)]
 #![feature(slice_concat_trait)]
 #![feature(thin_box)]
diff --git a/library/std/src/sys/pal/windows/c.rs b/library/std/src/sys/pal/windows/c.rs
index 2f5d75dc4bc..b888eb7d95c 100644
--- a/library/std/src/sys/pal/windows/c.rs
+++ b/library/std/src/sys/pal/windows/c.rs
@@ -109,19 +109,15 @@ if #[cfg(not(target_vendor = "uwp"))] {
 }
 
 // Use raw-dylib to import ProcessPrng as we can't rely on there being an import library.
-cfg_if::cfg_if! {
-if #[cfg(not(target_vendor = "win7"))] {
-    #[cfg(target_arch = "x86")]
-    #[link(name = "bcryptprimitives", kind = "raw-dylib", import_name_type = "undecorated")]
-    extern "system" {
-        pub fn ProcessPrng(pbdata: *mut u8, cbdata: usize) -> BOOL;
-    }
-    #[cfg(not(target_arch = "x86"))]
-    #[link(name = "bcryptprimitives", kind = "raw-dylib")]
-    extern "system" {
-        pub fn ProcessPrng(pbdata: *mut u8, cbdata: usize) -> BOOL;
-    }
-}}
+#[cfg(not(target_vendor = "win7"))]
+#[cfg_attr(
+    target_arch = "x86",
+    link(name = "bcryptprimitives", kind = "raw-dylib", import_name_type = "undecorated")
+)]
+#[cfg_attr(not(target_arch = "x86"), link(name = "bcryptprimitives", kind = "raw-dylib"))]
+extern "system" {
+    pub fn ProcessPrng(pbdata: *mut u8, cbdata: usize) -> BOOL;
+}
 
 // Functions that aren't available on every version of Windows that we support,
 // but we still use them and just provide some form of a fallback implementation.