add main fn to test

diff --git a/src/test/run-pass/issue-28871.rs b/src/test/run-pass/issue-28871.rs
index 8e9bd5b104252a6b96f64b3dc478704cd5944d36..92ba98f506257f3a6af713a8767e699186ca3f60 100644 (file)
--- a/src/test/run-pass/issue-28871.rs
+++ b/src/test/run-pass/issue-28871.rs
@@ -29,3 +29,5 @@ impl T for S {
 trait T2 {
     type T: Iterator<Item=<S as T>::T>;
 }
+
+fn main() { }