add a closure_exchange_malloc lang item

this makes the exchange allocation header completely unused, and leaves
it uninitialized

1 files changed, 14 insertions, 0 deletions

diff --git a/src/libstd/rt/global_heap.rs b/src/libstd/rt/global_heap.rs
index 5d4ac37055c..f669dc753d6 100644
--- a/src/libstd/rt/global_heap.rs
+++ b/src/libstd/rt/global_heap.rs
@@ -73,6 +73,20 @@ pub unsafe fn exchange_malloc(td: *c_char, size: uintptr_t) -> *c_char {
     assert!(td.is_not_null());
 
     let total_size = get_box_size(size, (*td).align);
+    malloc_raw(total_size as uint) as *c_char
+}
+
+// FIXME: #7496
+#[cfg(not(test))]
+#[lang="closure_exchange_malloc"]
+#[inline]
+pub unsafe fn closure_exchange_malloc(td: *c_char, size: uintptr_t) -> *c_char {
+    let td = td as *TyDesc;
+    let size = size as uint;
+
+    assert!(td.is_not_null());
+
+    let total_size = get_box_size(size, (*td).align);
     let p = malloc_raw(total_size as uint);
 
     let box: *mut BoxRepr = p as *mut BoxRepr;