Clarify "It is an error to..." wording for zero-duration behaviors.

Documentation fix side of #48311.

Author: frewsxcv

src/libstd/net/tcp.rs

@@ -259,8 +259,8 @@ impl TcpStream {
     /// Sets the read timeout to the timeout specified.
     ///
     /// If the value specified is [`None`], then [`read`] calls will block
-    /// indefinitely. It is an error to pass the zero `Duration` to this
-    /// method.
+    /// indefinitely. An [`Err`] is returned if the zero [`Duration`] is
+    /// passed to this method.
     ///
     /// # Platform-specific behavior
     ///
@@ -269,9 +269,11 @@ impl TcpStream {
     /// error of the kind [`WouldBlock`], but Windows may return [`TimedOut`].
     ///
     /// [`None`]: ../../std/option/enum.Option.html#variant.None
+    /// [`Err`]: ../../std/result/enum.Result.html#variant.Err
     /// [`read`]: ../../std/io/trait.Read.html#tymethod.read
     /// [`WouldBlock`]: ../../std/io/enum.ErrorKind.html#variant.WouldBlock
     /// [`TimedOut`]: ../../std/io/enum.ErrorKind.html#variant.TimedOut
+    /// [`Duration`]: ../../std/time/struct.Duration.html
     ///
     /// # Examples
     ///
@@ -282,6 +284,20 @@ impl TcpStream {
     ///                        .expect("Couldn't connect to the server...");
     /// stream.set_read_timeout(None).expect("set_read_timeout call failed");
     /// ```
+    ///
+    /// An [`Err`] is returned if the zero [`Duration`] is passed to this
+    /// method:
+    ///
+    /// ```no_run
+    /// use std::io;
+    /// use std::net::TcpStream;
+    /// use std::time::Duration;
+    ///
+    /// let stream = TcpStream::connect("127.0.0.1:8080").unwrap();
+    /// let result = stream.set_read_timeout(Some(Duration::new(0, 0)));
+    /// let err = result.unwrap_err();
+    /// assert_eq!(err.kind(), io::ErrorKind::InvalidInput)
+    /// ```
     #[stable(feature = "socket_timeout", since = "1.4.0")]
     pub fn set_read_timeout(&self, dur: Option<Duration>) -> io::Result<()> {
         self.0.set_read_timeout(dur)
@@ -290,8 +306,8 @@ impl TcpStream {
     /// Sets the write timeout to the timeout specified.
     ///
     /// If the value specified is [`None`], then [`write`] calls will block
-    /// indefinitely. It is an error to pass the zero [`Duration`] to this
-    /// method.
+    /// indefinitely. An [`Err`] is returned if the zero [`Duration`] is
+    /// passed to this method.
     ///
     /// # Platform-specific behavior
     ///
@@ -300,6 +316,7 @@ impl TcpStream {
     /// an error of the kind [`WouldBlock`], but Windows may return [`TimedOut`].
     ///
     /// [`None`]: ../../std/option/enum.Option.html#variant.None
+    /// [`Err`]: ../../std/result/enum.Result.html#variant.Err
     /// [`write`]: ../../std/io/trait.Write.html#tymethod.write
     /// [`Duration`]: ../../std/time/struct.Duration.html
     /// [`WouldBlock`]: ../../std/io/enum.ErrorKind.html#variant.WouldBlock
@@ -314,6 +331,20 @@ impl TcpStream {
     ///                        .expect("Couldn't connect to the server...");
     /// stream.set_write_timeout(None).expect("set_write_timeout call failed");
     /// ```
+    ///
+    /// An [`Err`] is returned if the zero [`Duration`] is passed to this
+    /// method:
+    ///
+    /// ```no_run
+    /// use std::io;
+    /// use std::net::TcpStream;
+    /// use std::time::Duration;
+    ///
+    /// let stream = TcpStream::connect("127.0.0.1:8080").unwrap();
+    /// let result = stream.set_write_timeout(Some(Duration::new(0, 0)));
+    /// let err = result.unwrap_err();
+    /// assert_eq!(err.kind(), io::ErrorKind::InvalidInput)
+    /// ```
     #[stable(feature = "socket_timeout", since = "1.4.0")]
     pub fn set_write_timeout(&self, dur: Option<Duration>) -> io::Result<()> {
         self.0.set_write_timeout(dur)

src/libstd/net/udp.rs

@@ -228,8 +228,8 @@ impl UdpSocket {
     /// Sets the read timeout to the timeout specified.
     ///
     /// If the value specified is [`None`], then [`read`] calls will block
-    /// indefinitely. It is an error to pass the zero [`Duration`] to this
-    /// method.
+    /// indefinitely. An [`Err`] is returned if the zero [`Duration`] is
+    /// passed to this method.
     ///
     /// # Platform-specific behavior
     ///
@@ -238,6 +238,7 @@ impl UdpSocket {
     /// error of the kind [`WouldBlock`], but Windows may return [`TimedOut`].
     ///
     /// [`None`]: ../../std/option/enum.Option.html#variant.None
+    /// [`Err`]: ../../std/result/enum.Result.html#variant.Err
     /// [`read`]: ../../std/io/trait.Read.html#tymethod.read
     /// [`Duration`]: ../../std/time/struct.Duration.html
     /// [`WouldBlock`]: ../../std/io/enum.ErrorKind.html#variant.WouldBlock
@@ -251,6 +252,20 @@ impl UdpSocket {
     /// let socket = UdpSocket::bind("127.0.0.1:34254").expect("couldn't bind to address");
     /// socket.set_read_timeout(None).expect("set_read_timeout call failed");
     /// ```
+    ///
+    /// An [`Err`] is returned if the zero [`Duration`] is passed to this
+    /// method:
+    ///
+    /// ```no_run
+    /// use std::io;
+    /// use std::net::UdpSocket;
+    /// use std::time::Duration;
+    ///
+    /// let socket = UdpSocket::bind("127.0.0.1:34254").unwrap();
+    /// let result = socket.set_read_timeout(Some(Duration::new(0, 0)));
+    /// let err = result.unwrap_err();
+    /// assert_eq!(err.kind(), io::ErrorKind::InvalidInput)
+    /// ```
     #[stable(feature = "socket_timeout", since = "1.4.0")]
     pub fn set_read_timeout(&self, dur: Option<Duration>) -> io::Result<()> {
         self.0.set_read_timeout(dur)
@@ -259,8 +274,8 @@ impl UdpSocket {
     /// Sets the write timeout to the timeout specified.
     ///
     /// If the value specified is [`None`], then [`write`] calls will block
-    /// indefinitely. It is an error to pass the zero [`Duration`] to this
-    /// method.
+    /// indefinitely. An [`Err`] is returned if the zero [`Duration`] is
+    /// passed to this method.
     ///
     /// # Platform-specific behavior
     ///
@@ -269,6 +284,7 @@ impl UdpSocket {
     /// an error of the kind [`WouldBlock`], but Windows may return [`TimedOut`].
     ///
     /// [`None`]: ../../std/option/enum.Option.html#variant.None
+    /// [`Err`]: ../../std/result/enum.Result.html#variant.Err
     /// [`write`]: ../../std/io/trait.Write.html#tymethod.write
     /// [`Duration`]: ../../std/time/struct.Duration.html
     /// [`WouldBlock`]: ../../std/io/enum.ErrorKind.html#variant.WouldBlock
@@ -282,6 +298,20 @@ impl UdpSocket {
     /// let socket = UdpSocket::bind("127.0.0.1:34254").expect("couldn't bind to address");
     /// socket.set_write_timeout(None).expect("set_write_timeout call failed");
     /// ```
+    ///
+    /// An [`Err`] is returned if the zero [`Duration`] is passed to this
+    /// method:
+    ///
+    /// ```no_run
+    /// use std::io;
+    /// use std::net::UdpSocket;
+    /// use std::time::Duration;
+    ///
+    /// let socket = UdpSocket::bind("127.0.0.1:34254").unwrap();
+    /// let result = socket.set_write_timeout(Some(Duration::new(0, 0)));
+    /// let err = result.unwrap_err();
+    /// assert_eq!(err.kind(), io::ErrorKind::InvalidInput)
+    /// ```
     #[stable(feature = "socket_timeout", since = "1.4.0")]
     pub fn set_write_timeout(&self, dur: Option<Duration>) -> io::Result<()> {
         self.0.set_write_timeout(dur)

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

@@ -387,10 +387,11 @@ impl UnixStream {
     /// Sets the read timeout for the socket.
     ///
     /// If the provided value is [`None`], then [`read`] calls will block
-    /// indefinitely. It is an error to pass the zero [`Duration`] to this
+    /// indefinitely. An [`Err`] is returned if the zero [`Duration`] is passed to this
     /// method.
     ///
     /// [`None`]: ../../../../std/option/enum.Option.html#variant.None
+    /// [`Err`]: ../../../../std/result/enum.Result.html#variant.Err
     /// [`read`]: ../../../../std/io/trait.Read.html#tymethod.read
     /// [`Duration`]: ../../../../std/time/struct.Duration.html
     ///
@@ -403,6 +404,20 @@ impl UnixStream {
     /// let socket = UnixStream::connect("/tmp/sock").unwrap();
     /// socket.set_read_timeout(Some(Duration::new(1, 0))).expect("Couldn't set read timeout");
     /// ```
+    ///
+    /// An [`Err`] is returned if the zero [`Duration`] is passed to this
+    /// method:
+    ///
+    /// ```no_run
+    /// use std::io;
+    /// use std::os::unix::net::UnixStream;
+    /// use std::time::Duration;
+    ///
+    /// let socket = UnixStream::connect("/tmp/sock").unwrap();
+    /// let result = socket.set_read_timeout(Some(Duration::new(0, 0)));
+    /// let err = result.unwrap_err();
+    /// assert_eq!(err.kind(), io::ErrorKind::InvalidInput)
+    /// ```
     #[stable(feature = "unix_socket", since = "1.10.0")]
     pub fn set_read_timeout(&self, timeout: Option<Duration>) -> io::Result<()> {
         self.0.set_timeout(timeout, libc::SO_RCVTIMEO)
@@ -411,10 +426,11 @@ impl UnixStream {
     /// Sets the write timeout for the socket.
     ///
     /// If the provided value is [`None`], then [`write`] calls will block
-    /// indefinitely. It is an error to pass the zero [`Duration`] to this
-    /// method.
+    /// indefinitely. An [`Err`] is returned if the zero [`Duration`] is
+    /// passed to this method.
     ///
     /// [`None`]: ../../../../std/option/enum.Option.html#variant.None
+    /// [`Err`]: ../../../../std/result/enum.Result.html#variant.Err
     /// [`write`]: ../../../../std/io/trait.Write.html#tymethod.write
     /// [`Duration`]: ../../../../std/time/struct.Duration.html
     ///
@@ -427,6 +443,20 @@ impl UnixStream {
     /// let socket = UnixStream::connect("/tmp/sock").unwrap();
     /// socket.set_write_timeout(Some(Duration::new(1, 0))).expect("Couldn't set write timeout");
     /// ```
+    ///
+    /// An [`Err`] is returned if the zero [`Duration`] is passed to this
+    /// method:
+    ///
+    /// ```no_run
+    /// use std::io;
+    /// use std::net::UdpSocket;
+    /// use std::time::Duration;
+    ///
+    /// let socket = UdpSocket::bind("127.0.0.1:34254").unwrap();
+    /// let result = socket.set_write_timeout(Some(Duration::new(0, 0)));
+    /// let err = result.unwrap_err();
+    /// assert_eq!(err.kind(), io::ErrorKind::InvalidInput)
+    /// ```
     #[stable(feature = "unix_socket", since = "1.10.0")]
     pub fn set_write_timeout(&self, timeout: Option<Duration>) -> io::Result<()> {
         self.0.set_timeout(timeout, libc::SO_SNDTIMEO)
@@ -1250,10 +1280,11 @@ impl UnixDatagram {
     /// Sets the read timeout for the socket.
     ///
     /// If the provided value is [`None`], then [`recv`] and [`recv_from`] calls will
-    /// block indefinitely. It is an error to pass the zero [`Duration`] to this
-    /// method.
+    /// block indefinitely. An [`Err`] is returned if the zero [`Duration`]
+    /// is passed to this method.
     ///
     /// [`None`]: ../../../../std/option/enum.Option.html#variant.None
+    /// [`Err`]: ../../../../std/result/enum.Result.html#variant.Err
     /// [`recv`]: #method.recv
     /// [`recv_from`]: #method.recv_from
     /// [`Duration`]: ../../../../std/time/struct.Duration.html
@@ -1267,6 +1298,20 @@ impl UnixDatagram {
     /// let sock = UnixDatagram::unbound().unwrap();
     /// sock.set_read_timeout(Some(Duration::new(1, 0))).expect("set_read_timeout function failed");
     /// ```
+    ///
+    /// An [`Err`] is returned if the zero [`Duration`] is passed to this
+    /// method:
+    ///
+    /// ```no_run
+    /// use std::io;
+    /// use std::os::unix::net::UnixDatagram;
+    /// use std::time::Duration;
+    ///
+    /// let socket = UnixDatagram::unbound().unwrap();
+    /// let result = socket.set_read_timeout(Some(Duration::new(0, 0)));
+    /// let err = result.unwrap_err();
+    /// assert_eq!(err.kind(), io::ErrorKind::InvalidInput)
+    /// ```
     #[stable(feature = "unix_socket", since = "1.10.0")]
     pub fn set_read_timeout(&self, timeout: Option<Duration>) -> io::Result<()> {
         self.0.set_timeout(timeout, libc::SO_RCVTIMEO)
@@ -1275,7 +1320,7 @@ impl UnixDatagram {
     /// Sets the write timeout for the socket.
     ///
     /// If the provided value is [`None`], then [`send`] and [`send_to`] calls will
-    /// block indefinitely. It is an error to pass the zero [`Duration`] to this
+    /// block indefinitely. An [`Err`] is returned if the zero [`Duration`] is passed to this
     /// method.
     ///
     /// [`None`]: ../../../../std/option/enum.Option.html#variant.None
@@ -1293,6 +1338,20 @@ impl UnixDatagram {
     /// sock.set_write_timeout(Some(Duration::new(1, 0)))
     ///     .expect("set_write_timeout function failed");
     /// ```
+    ///
+    /// An [`Err`] is returned if the zero [`Duration`] is passed to this
+    /// method:
+    ///
+    /// ```no_run
+    /// use std::io;
+    /// use std::os::unix::net::UnixDatagram;
+    /// use std::time::Duration;
+    ///
+    /// let socket = UnixDatagram::unbound().unwrap();
+    /// let result = socket.set_write_timeout(Some(Duration::new(0, 0)));
+    /// let err = result.unwrap_err();
+    /// assert_eq!(err.kind(), io::ErrorKind::InvalidInput)
+    /// ```
     #[stable(feature = "unix_socket", since = "1.10.0")]
     pub fn set_write_timeout(&self, timeout: Option<Duration>) -> io::Result<()> {
         self.0.set_timeout(timeout, libc::SO_SNDTIMEO)