From bc646d01c501f2566fd78057e23c283cfedc0eb0 Mon Sep 17 00:00:00 2001
From: Graydon Hoare <graydon@mozilla.com>
Date: Mon, 13 Sep 2010 13:37:24 -0700
Subject: [PATCH] Fix leaking arg slots on tail calls. Closes #160.

---
 src/Makefile                            |  1 +
 src/boot/me/trans.ml                    |  2 ++
 src/test/run-pass/tail-call-arg-leak.rs | 11 +++++++++++
 3 files changed, 14 insertions(+)
 create mode 100644 src/test/run-pass/tail-call-arg-leak.rs

diff --git a/src/Makefile b/src/Makefile
index 56fe9b98b38..8400e7a10f8 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -533,6 +533,7 @@ TEST_XFAILS_LLVM := $(TASK_XFAILS) \
                       str-concat.rs \
                       str-idx.rs \
                       tag.rs \
+                      tail-call-arg-leak.rs \
                       tail-cps.rs \
                       tail-direct.rs \
                       task-comm.rs \
diff --git a/src/boot/me/trans.ml b/src/boot/me/trans.ml
index ad0d6445d70..dd1dd46da43 100644
--- a/src/boot/me/trans.ml
+++ b/src/boot/me/trans.ml
@@ -4219,6 +4219,8 @@ let trans_visitor
                (Printf.sprintf "copy args for tail call to %s" (logname ())));
       copy_fn_args true true CLONE_none call;
       drop_slots_at_curr_stmt();
+      iflog (fun _ -> annotate "drop args");
+      iter_arg_slots cx (current_fn()) callee_drop_slot;
       abi.Abi.abi_emit_fn_tail_call (emitter())
         (force_sz (current_fn_callsz()))
         caller_argsz callee_code callee_argsz;
diff --git a/src/test/run-pass/tail-call-arg-leak.rs b/src/test/run-pass/tail-call-arg-leak.rs
new file mode 100644
index 00000000000..d99ceaec03b
--- /dev/null
+++ b/src/test/run-pass/tail-call-arg-leak.rs
@@ -0,0 +1,11 @@
+// use of tail calls causes arg slot leaks, issue #160.
+
+fn inner(str dummy, bool b) {
+  if (b) {
+    be inner(dummy, false);
+  }
+}
+
+fn main() {
+  inner("hi", true);
+}