1 files changed, 18 insertions, 7 deletions
diff --git a/src/libstd/rt/mod.rs b/src/libstd/rt/mod.rs
index a4421f23c50..e877dd5c6aa 100644
--- a/src/libstd/rt/mod.rs
+++ b/src/libstd/rt/mod.rs
@@ -92,7 +92,9 @@ fn lang_start(main: *const u8, argc: int, argv: *const *const u8) -> int {
         // but we just do this to name the main thread and to give it correct
         // info about the stack bounds.
         let thread: Thread = NewThread::new(Some("<main>".to_string()));
-        thread_info::set(sys::thread::guard::main(), thread);
+        thread_info::set((my_stack_bottom, my_stack_top),
+                         sys::thread::guard::main(),
+                         thread);
 
         // By default, some platforms will send a *signal* when a EPIPE error
         // would otherwise be delivered. This runtime doesn't install a SIGPIPE
@@ -131,14 +133,20 @@ fn lang_start(main: *const u8, argc: int, argv: *const *const u8) -> int {
     }
 }
 
-/// Enqueues a procedure to run when the main thread exits.
+/// Enqueues a procedure to run when the runtime is cleaned up
+///
+/// The procedure passed to this function will be executed as part of the
+/// runtime cleanup phase. For normal rust programs, this means that it will run
+/// after all other threads have exited.
+///
+/// The procedure is *not* executed with a local `Thread` available to it, so
+/// primitives like logging, I/O, channels, spawning, etc, are *not* available.
+/// This is meant for "bare bones" usage to clean up runtime details, this is
+/// not meant as a general-purpose "let's clean everything up" function.
 ///
 /// It is forbidden for procedures to register more `at_exit` handlers when they
 /// are running, and doing so will lead to a process abort.
-///
-/// Note that other threads may still be running when `at_exit` routines start
-/// running.
-pub fn at_exit<F: FnOnce() + Send>(f: F) {
+pub fn at_exit<F:FnOnce()+Send>(f: F) {
     at_exit_imp::push(Thunk::new(f));
 }
 
@@ -154,5 +162,8 @@ pub fn at_exit<F: FnOnce() + Send>(f: F) {
 pub unsafe fn cleanup() {
     args::cleanup();
     sys::stack_overflow::cleanup();
-    at_exit_imp::cleanup();
+    // FIXME: (#20012): the resources being cleaned up by at_exit
+    // currently are not prepared for cleanup to happen asynchronously
+    // with detached threads using the resources; for now, we leak.
+    // at_exit_imp::cleanup();
 }