1 files changed, 22 insertions, 0 deletions
diff --git a/src/test/ui/unboxed-closures/issue-30906.rs b/src/test/ui/unboxed-closures/issue-30906.rs
new file mode 100644
index 000000000..e2d219e47
--- /dev/null
+++ b/src/test/ui/unboxed-closures/issue-30906.rs
@@ -0,0 +1,22 @@
+#![feature(fn_traits, unboxed_closures)]
+
+fn test<F: for<'x> FnOnce<(&'x str,)>>(_: F) {}
+
+struct Compose<F, G>(F, G);
+impl<T, F, G> FnOnce<(T,)> for Compose<F, G>
+where
+    F: FnOnce<(T,)>,
+    G: FnOnce<(F::Output,)>,
+{
+    type Output = G::Output;
+    extern "rust-call" fn call_once(self, (x,): (T,)) -> G::Output {
+        (self.1)((self.0)(x))
+    }
+}
+
+fn bad<T>(f: fn(&'static str) -> T) {
+    test(Compose(f, |_| {}));
+    //~^ ERROR: implementation of `FnOnce` is not general enough
+}
+
+fn main() {}