Fix support for DSTs on #[pin_project(UnsafeUnpin)]

src/lib.rs

@@ -194,16 +194,16 @@ pub mod __private {
     // to making the type never implement Unpin), or provide an impl of `UnsafeUnpin`.
     // It is impossible for them to provide an impl of `Unpin`
     #[doc(hidden)]
-    pub struct Wrapper<'a, T>(T, PhantomData<&'a ()>);
+    pub struct Wrapper<'a, T: ?Sized>(PhantomData<&'a ()>, T);
 
     #[allow(unsafe_code)]
-    unsafe impl<T> UnsafeUnpin for Wrapper<'_, T> where T: UnsafeUnpin {}
+    unsafe impl<T: ?Sized> UnsafeUnpin for Wrapper<'_, T> where T: UnsafeUnpin {}
 
     // This is an internal helper struct used by `pin-project-internal`.
     //
     // See https://github.com/taiki-e/pin-project/pull/53 for more details.
     #[doc(hidden)]
-    pub struct AlwaysUnpin<'a, T: ?Sized>(PhantomData<T>, PhantomData<&'a ()>);
+    pub struct AlwaysUnpin<'a, T: ?Sized>(PhantomData<&'a ()>, PhantomData<T>);
 
     impl<T: ?Sized> Unpin for AlwaysUnpin<'_, T> {}
 }

tests/unsafe_unpin.rs

@@ -43,6 +43,26 @@ fn trivial_bounds() {
     }
 }
 
+#[test]
+fn dst() {
+    #[pin_project(UnsafeUnpin)]
+    pub struct A<T: ?Sized> {
+        x: T,
+    }
+
+    #[pin_project(UnsafeUnpin)]
+    pub struct B<T: ?Sized> {
+        #[pin]
+        x: T,
+    }
+
+    #[pin_project(UnsafeUnpin)]
+    pub struct C<T: ?Sized>(T);
+
+    #[pin_project(UnsafeUnpin)]
+    pub struct D<T: ?Sized>(#[pin] T);
+}
+
 #[test]
 fn test() {
     let mut x = OverlappingLifetimeNames { field1: 0, field2: 1, field3: &() };