1 files changed, 23 insertions, 0 deletions

diff --git a/tests/ui/issues/issue-26905.rs b/tests/ui/issues/issue-26905.rs
new file mode 100644
index 00000000000..4c5c67d58bc
--- /dev/null
+++ b/tests/ui/issues/issue-26905.rs
@@ -0,0 +1,23 @@
+#![feature(unsize, coerce_unsized)]
+
+// Verfies that non-PhantomData ZSTs still cause coercions to fail.
+// They might have additional semantics that we don't want to bulldoze.
+
+use std::marker::{Unsize, PhantomData};
+use std::ops::CoerceUnsized;
+
+struct NotPhantomData<T: ?Sized>(PhantomData<T>);
+
+struct MyRc<T: ?Sized> {
+    _ptr: *const T,
+    _boo: NotPhantomData<T>,
+}
+
+impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<MyRc<U>> for MyRc<T>{ } //~ERROR
+
+fn main() {
+    let data = [1, 2, 3];
+    let iter = data.iter();
+    let x = MyRc { _ptr: &iter, _boo: NotPhantomData(PhantomData) };
+    let _y: MyRc<dyn Iterator<Item=&u32>> = x;
+}