Auto merge of #43459 - ids1024:asrawfd, r=alexcrichton

Implement AsRawFd for Stdin, Stdout, and Stderr

https://github.com/rust-lang/rfcs/issues/2074

src/libstd/sys/redox/ext/io.rs

@@ -15,6 +15,7 @@
 use fs;
 use net;
 use sys;
+use io;
 use sys_common::{self, AsInner, FromInner, IntoInner};
 
 /// Raw file descriptors.
@@ -109,6 +110,21 @@ fn as_raw_fd(&self) -> RawFd {
     }
 }
 
+#[stable(feature = "asraw_stdio", since = "1.21.0")]
+impl AsRawFd for io::Stdin {
+    fn as_raw_fd(&self) -> RawFd { 0 }
+}
+
+#[stable(feature = "asraw_stdio", since = "1.21.0")]
+impl AsRawFd for io::Stdout {
+    fn as_raw_fd(&self) -> RawFd { 1 }
+}
+
+#[stable(feature = "asraw_stdio", since = "1.21.0")]
+impl AsRawFd for io::Stderr {
+    fn as_raw_fd(&self) -> RawFd { 2 }
+}
+
 #[stable(feature = "from_raw_os", since = "1.1.0")]
 impl FromRawFd for net::TcpStream {
     unsafe fn from_raw_fd(fd: RawFd) -> net::TcpStream {

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

@@ -16,7 +16,9 @@
 use net;
 use os::raw;
 use sys;
+use io;
 use sys_common::{self, AsInner, FromInner, IntoInner};
+use libc;
 
 /// Raw file descriptors.
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -104,6 +106,21 @@ impl AsRawFd for net::UdpSocket {
     fn as_raw_fd(&self) -> RawFd { *self.as_inner().socket().as_inner() }
 }
 
+#[stable(feature = "asraw_stdio", since = "1.21.0")]
+impl AsRawFd for io::Stdin {
+    fn as_raw_fd(&self) -> RawFd { libc::STDIN_FILENO }
+}
+
+#[stable(feature = "asraw_stdio", since = "1.21.0")]
+impl AsRawFd for io::Stdout {
+    fn as_raw_fd(&self) -> RawFd { libc::STDOUT_FILENO }
+}
+
+#[stable(feature = "asraw_stdio", since = "1.21.0")]
+impl AsRawFd for io::Stderr {
+    fn as_raw_fd(&self) -> RawFd { libc::STDERR_FILENO }
+}
+
 #[stable(feature = "from_raw_os", since = "1.1.0")]
 impl FromRawFd for net::TcpStream {
     unsafe fn from_raw_fd(fd: RawFd) -> net::TcpStream {

src/libstd/sys/windows/ext/io.rs

@@ -15,6 +15,7 @@
 use net;
 use sys_common::{self, AsInner, FromInner, IntoInner};
 use sys;
+use io;
 use sys::c;
 
 /// Raw HANDLEs.
@@ -71,6 +72,27 @@ fn as_raw_handle(&self) -> RawHandle {
     }
 }
 
+#[stable(feature = "asraw_stdio", since = "1.21.0")]
+impl AsRawHandle for io::Stdin {
+    fn as_raw_handle(&self) -> RawHandle {
+        unsafe { c::GetStdHandle(c::STD_INPUT_HANDLE) as RawHandle }
+    }
+}
+
+#[stable(feature = "asraw_stdio", since = "1.21.0")]
+impl AsRawHandle for io::Stdout {
+    fn as_raw_handle(&self) -> RawHandle {
+        unsafe { c::GetStdHandle(c::STD_OUTPUT_HANDLE) as RawHandle }
+    }
+}
+
+#[stable(feature = "asraw_stdio", since = "1.21.0")]
+impl AsRawHandle for io::Stderr {
+    fn as_raw_handle(&self) -> RawHandle {
+        unsafe { c::GetStdHandle(c::STD_ERROR_HANDLE) as RawHandle }
+    }
+}
+
 #[stable(feature = "from_raw_os", since = "1.1.0")]
 impl FromRawHandle for fs::File {
     unsafe fn from_raw_handle(handle: RawHandle) -> fs::File {