1 files changed, 77 insertions, 0 deletions

diff --git a/src/test/ui/issues/issue-24805-dropck-itemless.rs b/src/test/ui/issues/issue-24805-dropck-itemless.rs
new file mode 100644
index 000000000..45761b61c
--- /dev/null
+++ b/src/test/ui/issues/issue-24805-dropck-itemless.rs
@@ -0,0 +1,77 @@
+// run-pass
+
+// Check that item-less traits do not cause dropck to inject extra
+// region constraints.
+
+#![allow(non_camel_case_types)]
+
+#![feature(dropck_eyepatch)]
+
+trait UserDefined { }
+
+impl UserDefined for i32 { }
+impl<'a, T> UserDefined for &'a T { }
+
+// e.g., `impl_drop!(Send, D_Send)` expands to:
+//   ```rust
+//   struct D_Send<T:Send>(T);
+//   impl<T:Send> Drop for D_Send<T> { fn drop(&mut self) { } }
+//   ```
+macro_rules! impl_drop {
+    ($Bound:ident, $Id:ident) => {
+        struct $Id<T: $Bound>(#[allow(unused_tuple_struct_fields)] T);
+        unsafe impl <#[may_dangle] T: $Bound> Drop for $Id<T> {
+            fn drop(&mut self) { }
+        }
+    }
+}
+
+impl_drop!{Send,         D_Send}
+impl_drop!{Sized,        D_Sized}
+
+// See note below regarding Issue 24895
+// impl_drop!{Copy,         D_Copy}
+
+impl_drop!{Sync,         D_Sync}
+impl_drop!{UserDefined,  D_UserDefined}
+
+macro_rules! body {
+    ($id:ident) => { {
+        // `_d` and `d1` are assigned the *same* lifetime by region inference ...
+        let (_d, d1);
+
+        d1 = $id(1);
+        // ... we store a reference to `d1` within `_d` ...
+        _d = $id(&d1);
+
+        // ... a *conservative* dropck will thus complain, because it
+        // thinks Drop of _d could access the already dropped `d1`.
+    } }
+}
+
+fn f_send() { body!(D_Send) }
+fn f_sized() { body!(D_Sized) }
+fn f_sync() { body!(D_Sync) }
+
+// Issue 24895: Copy: Clone implies `impl<T:Copy> Drop for ...` can
+// access a user-defined clone() method, which causes this test case
+// to fail.
+//
+// If 24895 is resolved by removing the `Copy: Clone` relationship,
+// then this definition and the call below should be uncommented. If
+// it is resolved by deciding to keep the `Copy: Clone` relationship,
+// then this comment and the associated bits of code can all be
+// removed.
+
+// fn f_copy() { body!(D_Copy) }
+
+fn f_userdefined() { body!(D_UserDefined) }
+
+fn main() {
+    f_send();
+    f_sized();
+    // See note above regarding Issue 24895.
+    // f_copy();
+    f_sync();
+    f_userdefined();
+}