1 files changed, 76 insertions, 0 deletions
diff --git a/src/test/ui/transmutability/structs/repr/should_require_well_defined_layout.rs b/src/test/ui/transmutability/structs/repr/should_require_well_defined_layout.rs
new file mode 100644
index 000000000..556be989d
--- /dev/null
+++ b/src/test/ui/transmutability/structs/repr/should_require_well_defined_layout.rs
@@ -0,0 +1,76 @@
+//! A struct must have a well-defined layout to participate in a transmutation.
+
+#![crate_type = "lib"]
+#![feature(transmutability)]
+#![allow(dead_code, incomplete_features, non_camel_case_types)]
+
+mod assert {
+    use std::mem::BikeshedIntrinsicFrom;
+    pub struct Context;
+
+    pub fn is_maybe_transmutable<Src, Dst>()
+    where
+        Dst: BikeshedIntrinsicFrom<Src, Context, true, true, true, true>
+    {}
+}
+
+fn should_reject_repr_rust()
+{
+    fn unit() {
+        struct repr_rust;
+        assert::is_maybe_transmutable::<repr_rust, ()>(); //~ ERROR cannot be safely transmuted
+        assert::is_maybe_transmutable::<u128, repr_rust>(); //~ ERROR cannot be safely transmuted
+    }
+
+    fn tuple() {
+        struct repr_rust();
+        assert::is_maybe_transmutable::<repr_rust, ()>(); //~ ERROR cannot be safely transmuted
+        assert::is_maybe_transmutable::<u128, repr_rust>(); //~ ERROR cannot be safely transmuted
+    }
+
+    fn braces() {
+        struct repr_rust{}
+        assert::is_maybe_transmutable::<repr_rust, ()>(); //~ ERROR cannot be safely transmuted
+        assert::is_maybe_transmutable::<u128, repr_rust>(); //~ ERROR cannot be safely transmuted
+    }
+
+    fn aligned() {
+        #[repr(align(1))] struct repr_rust{}
+        assert::is_maybe_transmutable::<repr_rust, ()>(); //~ ERROR cannot be safely transmuted
+        assert::is_maybe_transmutable::<u128, repr_rust>(); //~ ERROR cannot be safely transmuted
+    }
+
+    fn packed() {
+        #[repr(packed)] struct repr_rust{}
+        assert::is_maybe_transmutable::<repr_rust, ()>(); //~ ERROR cannot be safely transmuted
+        assert::is_maybe_transmutable::<u128, repr_rust>(); //~ ERROR cannot be safely transmuted
+    }
+
+    fn nested() {
+        struct repr_rust;
+        #[repr(C)] struct repr_c(repr_rust);
+        assert::is_maybe_transmutable::<repr_c, ()>(); //~ ERROR cannot be safely transmuted
+        assert::is_maybe_transmutable::<u128, repr_c>(); //~ ERROR cannot be safely transmuted
+    }
+}
+
+fn should_accept_repr_C()
+{
+    fn unit() {
+        #[repr(C)] struct repr_c;
+        assert::is_maybe_transmutable::<repr_c, ()>();
+        assert::is_maybe_transmutable::<i128, repr_c>();
+    }
+
+    fn tuple() {
+        #[repr(C)] struct repr_c();
+        assert::is_maybe_transmutable::<repr_c, ()>();
+        assert::is_maybe_transmutable::<i128, repr_c>();
+    }
+
+    fn braces() {
+        #[repr(C)] struct repr_c{}
+        assert::is_maybe_transmutable::<repr_c, ()>();
+        assert::is_maybe_transmutable::<i128, repr_c>();
+    }
+}