Move return type an associated type of the `Fn*` traits. Mostly this involves tweaking things in

the compiler that assumed two input types to assume two ouputs; we also have to teach `project.rs`
to project `Output` from the unboxed closure and fn traits.

1 files changed, 3 insertions, 1 deletions

diff --git a/src/libcollections/btree/set.rs b/src/libcollections/btree/set.rs
index e95087fa846..a090e4f24ce 100644
--- a/src/libcollections/btree/set.rs
+++ b/src/libcollections/btree/set.rs
@@ -758,7 +758,9 @@ mod test {
         expected: &'b [int],
     }
 
-    impl<'a, 'b, 'c> FnMut(&'c int) -> bool for Counter<'a, 'b> {
+    impl<'a, 'b, 'c> FnMut<(&'c int,)> for Counter<'a, 'b> {
+        type Output = bool;
+
         extern "rust-call" fn call_mut(&mut self, (&x,): (&'c int,)) -> bool {
             assert_eq!(x, self.expected[*self.i]);
             *self.i += 1;