Auto merge of #45674 - kennytm:rollup, r=kennytm

Rollup of 14 pull requests

- Successful merges: #45450, #45579, #45602, #45619, #45624, #45644, #45646, #45648, #45649, #45650, #45652, #45660, #45664, #45671
- Failed merges:

src/libstd/io/mod.rs

@@ -736,10 +736,10 @@ pub trait Read {
 
     /// Transforms this `Read` instance to an [`Iterator`] over its bytes.
     ///
-    /// The returned type implements [`Iterator`] where the `Item` is [`Result`]`<`[`u8`]`,
-    /// R::Err>`. The yielded item is [`Ok`] if a byte was successfully read and
-    /// [`Err`] otherwise for I/O errors. EOF is mapped to returning [`None`] from
-    /// this iterator.
+    /// The returned type implements [`Iterator`] where the `Item` is
+    /// [`Result`]`<`[`u8`]`, `[`io::Error`]>`.
+    /// The yielded item is [`Ok`] if a byte was successfully read and [`Err`]
+    /// otherwise. EOF is mapped to returning [`None`] from this iterator.
     ///
     /// # Examples
     ///
@@ -748,6 +748,7 @@ pub trait Read {
     /// [file]: ../fs/struct.File.html
     /// [`Iterator`]: ../../std/iter/trait.Iterator.html
     /// [`Result`]: ../../std/result/enum.Result.html
+    /// [`io::Error``]: ../../std/io/struct.Error.html
     /// [`u8`]: ../../std/primitive.u8.html
     /// [`Ok`]: ../../std/result/enum.Result.html#variant.Ok
     /// [`Err`]: ../../std/result/enum.Result.html#variant.Err
@@ -1410,6 +1411,8 @@ pub trait BufRead: Read {
     ///
     /// If successful, this function will return the total number of bytes read.
     ///
+    /// An empty buffer returned indicates that the stream has reached EOF.
+    ///
     /// # Errors
     ///
     /// This function will ignore all instances of [`ErrorKind::Interrupted`] and
@@ -1470,6 +1473,8 @@ pub trait BufRead: Read {
     ///
     /// If successful, this function will return the total number of bytes read.
     ///
+    /// An empty buffer returned indicates that the stream has reached EOF.
+    ///
     /// # Errors
     ///
     /// This function has the same error semantics as [`read_until`] and will

src/libstd/sys/unix/ext/mod.rs

@@ -10,8 +10,14 @@
 
 //! Experimental extensions to `std` for Unix platforms.
 //!
-//! For now, this module is limited to extracting file descriptors,
-//! but its functionality will grow over time.
+//! Provides access to platform-level information on Unix platforms, and
+//! exposes Unix-specific functions that would otherwise be inappropriate as
+//! part of the core `std` library.
+//!
+//! It exposes more ways to deal with platform-specific strings (`OsStr`,
+//! `OsString`), allows to set permissions more granularly, extract low-level
+//! file descriptors from files and sockets, and has platform-specific helpers
+//! for spawning processes.
 //!
 //! # Examples
 //!

src/libstd/sys/unix/rand.rs

@@ -49,7 +49,9 @@ mod imp {
                   target_arch = "powerpc64",
                   target_arch = "s390x")))]
     fn getrandom(buf: &mut [u8]) -> libc::c_long {
-        #[cfg(target_arch = "x86_64")]
+        #[cfg(all(target_arch = "x86_64", target_pointer_width = "32"))]
+        const NR_GETRANDOM: libc::c_long = 0x40000000 + 318;
+        #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
         const NR_GETRANDOM: libc::c_long = 318;
         #[cfg(target_arch = "x86")]
         const NR_GETRANDOM: libc::c_long = 355;