1 files changed, 42 insertions, 0 deletions
diff --git a/src/test/ui/extern/extern-types-thin-pointer.rs b/src/test/ui/extern/extern-types-thin-pointer.rs
new file mode 100644
index 000000000..b85fc4886
--- /dev/null
+++ b/src/test/ui/extern/extern-types-thin-pointer.rs
@@ -0,0 +1,42 @@
+// run-pass
+#![allow(dead_code)]
+// Test that pointers and references to extern types are thin, ie they have the same size and
+// alignment as a pointer to ().
+#![feature(extern_types)]
+
+use std::mem::{align_of, size_of};
+
+extern "C" {
+    type A;
+}
+
+struct Foo {
+    x: u8,
+    tail: A,
+}
+
+struct Bar<T: ?Sized> {
+    x: u8,
+    tail: T,
+}
+
+fn assert_thin<T: ?Sized>() {
+    assert_eq!(size_of::<*const T>(), size_of::<*const ()>());
+    assert_eq!(align_of::<*const T>(), align_of::<*const ()>());
+
+    assert_eq!(size_of::<*mut T>(), size_of::<*mut ()>());
+    assert_eq!(align_of::<*mut T>(), align_of::<*mut ()>());
+
+    assert_eq!(size_of::<&T>(), size_of::<&()>());
+    assert_eq!(align_of::<&T>(), align_of::<&()>());
+
+    assert_eq!(size_of::<&mut T>(), size_of::<&mut ()>());
+    assert_eq!(align_of::<&mut T>(), align_of::<&mut ()>());
+}
+
+fn main() {
+    assert_thin::<A>();
+    assert_thin::<Foo>();
+    assert_thin::<Bar<A>>();
+    assert_thin::<Bar<Bar<A>>>();
+}