Wrap pid into ProcessId struct

src/libstd/process.rs

@@ -907,7 +907,7 @@ impl Child {
     /// }
     /// ```
     #[stable(feature = "process_id", since = "1.3.0")]
-    pub fn id(&self) -> u32 {
+    pub fn id(&self) -> imp::ProcessId {
         self.handle.id()
     }
 

src/libstd/sys/redox/process.rs

@@ -9,6 +9,7 @@
 // except according to those terms.
 
 use collections::hash_map::HashMap;
+use core::ops::Deref;
 use env;
 use ffi::OsStr;
 use fmt;
@@ -483,15 +484,31 @@ impl fmt::Display for ExitStatus {
     }
 }
 
+/// Represents a process id.
+///
+/// Returned by the [Child::id]() method.
+#[derive(Debug, Clone, Copy, PartialEq, PartialOrd, Hash)]
+#[stable(feature = "rust1", since = "1.21.0")]
+pub struct ProcessId(pub usize);
+
+#[stable(feature = "rust1", since = "1.21.0")]
+impl Deref for ProcessId {
+    type Target = usize;
+
+    fn deref(&self) -> &usize {
+        &self.0
+    }
+}
+
 /// The unique id of the process (this should never be negative).
 pub struct Process {
     pid: usize,
     status: Option<ExitStatus>,
 }
 
 impl Process {
-    pub fn id(&self) -> u32 {
-        self.pid as u32
+    pub fn id(&self) -> ProcessId {
+        ProcessId(self.pid)
     }
 
     pub fn kill(&mut self) -> io::Result<()> {

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

@@ -9,7 +9,7 @@
 // except according to those terms.
 
 pub use self::process_common::{Command, ExitStatus, Stdio, StdioPipes};
-pub use self::process_inner::Process;
+pub use self::process_inner::{Process, ProcessId};
 
 mod process_common;
 #[cfg(not(target_os = "fuchsia"))]

src/libstd/sys/unix/process/process_fuchsia.rs

@@ -13,6 +13,7 @@ use libc;
 use mem;
 use ptr;
 
+use core::ops::Deref;
 use sys::process::magenta::{Handle, mx_handle_t};
 use sys::process::process_common::*;
 
@@ -126,13 +127,29 @@ impl Command {
 // Processes
 ////////////////////////////////////////////////////////////////////////////////
 
+/// Represents a process id.
+///
+/// Returned by the [Child::id]() method.
+#[derive(Debug, Clone, Copy, PartialEq, PartialOrd, Hash)]
+#[stable(feature = "rust1", since = "1.21.0")]
+pub struct ProcessId(pub i32);
+
+#[stable(feature = "rust1", since = "1.21.0")]
+impl Deref for ProcessId {
+    type Target = i32;
+
+    fn deref(&self) -> &i32 {
+        &self.0
+    }
+}
+
 pub struct Process {
     handle: Handle,
 }
 
 impl Process {
-    pub fn id(&self) -> u32 {
-        self.handle.raw() as u32
+    pub fn id(&self) -> ProcessId {
+        ProcessId(self.handle.raw())
     }
 
     pub fn kill(&mut self) -> io::Result<()> {

src/libstd/sys/unix/process/process_unix.rs

@@ -13,6 +13,7 @@ use libc::{self, c_int, gid_t, pid_t, uid_t};
 use mem;
 use ptr;
 
+use core::ops::Deref;
 use sys::cvt;
 use sys::process::process_common::*;
 
@@ -224,15 +225,31 @@ impl Command {
 // Processes
 ////////////////////////////////////////////////////////////////////////////////
 
+/// Represents a process id.
+///
+/// Returned by the [Child::id]() method.
+#[derive(Debug, Clone, Copy, PartialEq, PartialOrd, Hash)]
+#[stable(feature = "rust1", since = "1.21.0")]
+pub struct ProcessId(pub i32);
+
+#[stable(feature = "rust1", since = "1.21.0")]
+impl Deref for ProcessId {
+    type Target = i32;
+
+    fn deref(&self) -> &i32 {
+        &self.0
+    }
+}
+
 /// The unique id of the process (this should never be negative).
 pub struct Process {
     pid: pid_t,
     status: Option<ExitStatus>,
 }
 
 impl Process {
-    pub fn id(&self) -> u32 {
-        self.pid as u32
+    pub fn id(&self) -> ProcessId {
+        ProcessId(self.pid)
     }
 
     pub fn kill(&mut self) -> io::Result<()> {

src/libstd/sys/windows/process.rs

@@ -11,6 +11,7 @@
 use ascii::*;
 use collections::HashMap;
 use collections;
+use core::ops::Deref;
 use env::split_paths;
 use env;
 use ffi::{OsString, OsStr};
@@ -322,6 +323,22 @@ impl From<File> for Stdio {
 // Processes
 ////////////////////////////////////////////////////////////////////////////////
 
+/// Represents a process id.
+///
+/// Returned by the [Child::id]() method.
+#[derive(Debug, Clone, Copy, PartialEq, PartialOrd, Hash)]
+#[stable(feature = "rust1", since = "1.21.0")]
+pub struct ProcessId(pub u32);
+
+#[stable(feature = "rust1", since = "1.21.0")]
+impl Deref for ProcessId {
+    type Target = u32;
+
+    fn deref(&self) -> &u32 {
+        &self.0
+    }
+}
+
 /// A value representing a child process.
 ///
 /// The lifetime of this value is linked to the lifetime of the actual
@@ -339,9 +356,9 @@ impl Process {
         Ok(())
     }
 
-    pub fn id(&self) -> u32 {
+    pub fn id(&self) -> ProcessId {
         unsafe {
-            c::GetProcessId(self.handle.raw()) as u32
+            ProcessId(c::GetProcessId(self.handle.raw()))
         }
     }