move_ref_patterns: introduce tests

bindings_after_at: harden tests

src/test/ui/pattern/move-ref-patterns/move-ref-patterns-closure-captures.rs

@@ -0,0 +1,34 @@
+#![feature(move_ref_pattern)]
+
+fn main() {
+    struct U;
+    fn accept_fn_once(_: &impl FnOnce()) {}
+    fn accept_fn_mut(_: &impl FnMut()) {}
+    fn accept_fn(_: &impl Fn()) {}
+
+    let mut tup = (U, U, U);
+    let (ref _x0, _x1, ref mut _x2) = tup;
+    let c1 = || {
+        //~^ ERROR expected a closure that implements the `FnMut`
+        //~| ERROR expected a closure that implements the `Fn`
+        drop::<&U>(_x0);
+        drop::<U>(_x1);
+        drop::<&mut U>(_x2);
+    };
+    accept_fn_once(&c1);
+    accept_fn_mut(&c1);
+    accept_fn(&c1);
+
+    let c2 = || {
+        //~^ ERROR expected a closure that implements the `Fn`
+        drop::<&U>(_x0);
+        drop::<&mut U>(_x2);
+    };
+    accept_fn_mut(&c2);
+    accept_fn(&c2);
+
+    let c3 = || {
+        drop::<&U>(_x0);
+    };
+    accept_fn(&c3);
+}