Rollup merge of #48618 - scottmcm:elaborate-exitcode, r=alexcrichton

Better docs and associated SUCCESS/FAILURE for process::ExitCode

Follow-up to https://github.com/rust-lang/rust/pull/48497#discussion_r170676525, since that PR was the minimal thing to unblock https://github.com/rust-lang/rust/issues/48453#issuecomment-368155082.

r? @nikomatsakis

1 files changed, 13 insertions, 0 deletions

diff --git a/src/libstd/sys/redox/process.rs b/src/libstd/sys/redox/process.rs
index 3fd54973896..d0b94e14f54 100644
--- a/src/libstd/sys/redox/process.rs
+++ b/src/libstd/sys/redox/process.rs
@@ -13,6 +13,7 @@ use ffi::OsStr;
 use os::unix::ffi::OsStrExt;
 use fmt;
 use io::{self, Error, ErrorKind};
+use libc::{EXIT_SUCCESS, EXIT_FAILURE};
 use path::{Path, PathBuf};
 use sys::fd::FileDesc;
 use sys::fs::{File, OpenOptions};
@@ -480,6 +481,18 @@ impl fmt::Display for ExitStatus {
     }
 }
 
+#[derive(PartialEq, Eq, Clone, Copy, Debug)]
+pub struct ExitCode(u8);
+
+impl ExitCode {
+    pub const SUCCESS: ExitCode = ExitCode(EXIT_SUCCESS as _);
+    pub const FAILURE: ExitCode = ExitCode(EXIT_FAILURE as _);
+
+    pub fn as_i32(&self) -> i32 {
+        self.0 as i32
+    }
+}
+
 /// The unique id of the process (this should never be negative).
 pub struct Process {
     pid: usize,