Test for issue 1896 (which appears to be fixed)

src/test/compile-fail/issue-1896.rs

@@ -0,0 +1,8 @@
+type t<T> = { f: fn() -> T };
+
+fn f<T>(_x: t<T>) {}
+
+fn main() {
+  let x: t<()> = { f: { || () } }; //! ERROR expressions with stack closure
+    f(x);
+}