Add regression test for #20533. Fixes #20533.

Author: nikomatsakis

src/test/compile-fail/variance-issue-20533.rs

@@ -0,0 +1,54 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Regression test for issue #20533. At some point, only 1 out of the
+// 3 errors below were being reported.
+
+use std::marker::PhantomData;
+
+fn foo<'a, T>(_x: &'a T) -> PhantomData<&'a ()> {
+    PhantomData
+}
+
+struct Wrap<T>(T);
+
+fn bar<'a, T>(_x: &'a T) -> Wrap<PhantomData<&'a ()>> {
+    Wrap(PhantomData)
+}
+
+struct Baked<'a>(PhantomData<&'a ()>);
+
+fn baz<'a, T>(_x: &'a T) -> Baked<'a> {
+    Baked(PhantomData)
+}
+
+struct AffineU32(u32);
+
+fn main() {
+    {
+        let a = AffineU32(1_u32);
+        let x = foo(&a);
+        drop(a); //~ ERROR cannot move out of `a`
+        drop(x);
+    }
+    {
+        let a = AffineU32(1_u32);
+        let x = bar(&a);
+        drop(a); //~ ERROR cannot move out of `a`
+        drop(x);
+    }
+    {
+        let a = AffineU32(1_u32);
+        let x = baz(&a);
+        drop(a); //~ ERROR cannot move out of `a`
+        drop(x);
+    }
+}
+