1 files changed, 38 insertions, 0 deletions
diff --git a/src/test/ui/transmutability/unions/should_reject_intersecting.rs b/src/test/ui/transmutability/unions/should_reject_intersecting.rs
new file mode 100644
index 000000000..58e399fb9
--- /dev/null
+++ b/src/test/ui/transmutability/unions/should_reject_intersecting.rs
@@ -0,0 +1,38 @@
+//! ALL valid bit patterns of the source must be valid bit patterns of the
+//! destination type, unless validity is assumed.
+
+#![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_transmutable<Src, Dst>()
+    where
+        Dst: BikeshedIntrinsicFrom<Src, Context, false, false, false, true>
+        // validity is NOT assumed ----------------------------^^^^^
+    {}
+}
+
+#[derive(Clone, Copy)] #[repr(u8)] enum Ox00 { V = 0x00 }
+#[derive(Clone, Copy)] #[repr(u8)] enum Ox7F { V = 0x7F }
+#[derive(Clone, Copy)] #[repr(u8)] enum OxFF { V = 0xFF }
+
+fn test() {
+    #[repr(C)]
+    union A {
+        a: Ox00,
+        b: Ox7F,
+    }
+
+    #[repr(C)]
+    union B {
+        a: Ox7F,
+        b: OxFF,
+    }
+
+    assert::is_transmutable::<A, B>(); //~ ERROR cannot be safely transmuted
+    assert::is_transmutable::<B, A>(); //~ ERROR cannot be safely transmuted
+}