rollup merge of #23907: alexcrichton/impl-exit

This commit is an implementation of [RFC #1011][rfc] which adds an `exit`
function to the standard library for immediately terminating the current process
with a specified exit code.

[rfc]: https://github.com/rust-lang/rfcs/pull/1011

Closes #23914

4 files changed, 25 insertions, 0 deletions

diff --git a/src/libstd/process.rs b/src/libstd/process.rs
index ece0aa8f064..63023855514 100644
--- a/src/libstd/process.rs
+++ b/src/libstd/process.rs
@@ -522,6 +522,22 @@ impl Child {
     }
 }
 
+/// Terminates the current process with the specified exit code.
+///
+/// This function will never return and will immediately terminate the current
+/// process. The exit code is passed through to the underlying OS and will be
+/// available for consumption by another process.
+///
+/// Note that because this function never returns, and that it terminates the
+/// process, no destructors on the current stack or any other thread's stack
+/// will be run. If a clean shutdown is needed it is recommended to only call
+/// this function at a known point where there are no more destructors left
+/// to run.
+#[stable(feature = "rust1", since = "1.0.0")]
+pub fn exit(code: i32) -> ! {
+    ::sys::os::exit(code)
+}
+
 #[cfg(test)]
 mod tests {
     use prelude::v1::*;
diff --git a/src/libstd/sys/unix/os.rs b/src/libstd/sys/unix/os.rs
index af5b40af938..7b13e951b9b 100644
--- a/src/libstd/sys/unix/os.rs
+++ b/src/libstd/sys/unix/os.rs
@@ -506,3 +506,7 @@ pub fn home_dir() -> Option<PathBuf> {
         }
     }
 }
+
+pub fn exit(code: i32) -> ! {
+    unsafe { libc::exit(code as c_int) }
+}
diff --git a/src/libstd/sys/windows/c.rs b/src/libstd/sys/windows/c.rs
index b9be4eb6bf5..b930e35c064 100644
--- a/src/libstd/sys/windows/c.rs
+++ b/src/libstd/sys/windows/c.rs
@@ -433,6 +433,7 @@ extern "system" {
                             TokenHandle: *mut libc::HANDLE) -> libc::BOOL;
     pub fn GetCurrentProcess() -> libc::HANDLE;
     pub fn GetStdHandle(which: libc::DWORD) -> libc::HANDLE;
+    pub fn ExitProcess(uExitCode: libc::UINT) -> !;
 }
 
 #[link(name = "userenv")]
diff --git a/src/libstd/sys/windows/os.rs b/src/libstd/sys/windows/os.rs
index ef153c7e845..f98c39cfad0 100644
--- a/src/libstd/sys/windows/os.rs
+++ b/src/libstd/sys/windows/os.rs
@@ -380,3 +380,7 @@ pub fn home_dir() -> Option<PathBuf> {
         }, super::os2path).ok()
     })
 }
+
+pub fn exit(code: i32) -> ! {
+    unsafe { libc::ExitProcess(code as libc::UINT) }
+}