1 files changed, 68 insertions, 0 deletions
diff --git a/library/std/src/rt.rs b/library/std/src/rt.rs
new file mode 100644
index 00000000000..fb825ab16eb
--- /dev/null
+++ b/library/std/src/rt.rs
@@ -0,0 +1,68 @@
+//! Runtime services
+//!
+//! The `rt` module provides a narrow set of runtime services,
+//! including the global heap (exported in `heap`) and unwinding and
+//! backtrace support. The APIs in this module are highly unstable,
+//! and should be considered as private implementation details for the
+//! time being.
+
+#![unstable(
+    feature = "rt",
+    reason = "this public module should not exist and is highly likely \
+              to disappear",
+    issue = "none"
+)]
+#![doc(hidden)]
+
+// Re-export some of our utilities which are expected by other crates.
+pub use crate::panicking::{begin_panic, begin_panic_fmt, panic_count};
+
+// To reduce the generated code of the new `lang_start`, this function is doing
+// the real work.
+#[cfg(not(test))]
+fn lang_start_internal(
+    main: &(dyn Fn() -> i32 + Sync + crate::panic::RefUnwindSafe),
+    argc: isize,
+    argv: *const *const u8,
+) -> isize {
+    use crate::panic;
+    use crate::sys;
+    use crate::sys_common;
+    use crate::sys_common::thread_info;
+    use crate::thread::Thread;
+
+    sys::init();
+
+    unsafe {
+        let main_guard = sys::thread::guard::init();
+        sys::stack_overflow::init();
+
+        // Next, set up the current Thread with the guard information we just
+        // created. Note that this isn't necessary in general for new threads,
+        // but we just do this to name the main thread and to give it correct
+        // info about the stack bounds.
+        let thread = Thread::new(Some("main".to_owned()));
+        thread_info::set(main_guard, thread);
+
+        // Store our args if necessary in a squirreled away location
+        sys::args::init(argc, argv);
+
+        // Let's run some code!
+        let exit_code = panic::catch_unwind(|| {
+            sys_common::backtrace::__rust_begin_short_backtrace(move || main())
+        });
+
+        sys_common::cleanup();
+        exit_code.unwrap_or(101) as isize
+    }
+}
+
+#[cfg(not(test))]
+#[lang = "start"]
+fn lang_start<T: crate::process::Termination + 'static>(
+    main: fn() -> T,
+    argc: isize,
+    argv: *const *const u8,
+) -> isize {
+    lang_start_internal(&move || main().report(), argc, argv)
+}