1 files changed, 22 insertions, 0 deletions
diff --git a/src/test/ui/cast/casts-differing-anon.rs b/src/test/ui/cast/casts-differing-anon.rs
new file mode 100644
index 000000000..d4a0f9613
--- /dev/null
+++ b/src/test/ui/cast/casts-differing-anon.rs
@@ -0,0 +1,22 @@
+use std::fmt;
+
+fn foo() -> Box<impl fmt::Debug+?Sized> {
+    let x : Box<[u8]> = Box::new([0]);
+    x
+}
+fn bar() -> Box<impl fmt::Debug+?Sized> {
+    let y: Box<dyn fmt::Debug> = Box::new([0]);
+    y
+}
+
+fn main() {
+    let f = foo();
+    let b = bar();
+
+    // this is an `*mut [u8]` in practice
+    let f_raw : *mut _ = Box::into_raw(f);
+    // this is an `*mut fmt::Debug` in practice
+    let mut b_raw = Box::into_raw(b);
+    // ... and they should not be mixable
+    b_raw = f_raw as *mut _; //~ ERROR is invalid
+}