1 files changed, 24 insertions, 0 deletions
diff --git a/src/test/ui/consts/const-eval/ub-uninhabit.rs b/src/test/ui/consts/const-eval/ub-uninhabit.rs
new file mode 100644
index 000000000..33fbd14c4
--- /dev/null
+++ b/src/test/ui/consts/const-eval/ub-uninhabit.rs
@@ -0,0 +1,24 @@
+// stderr-per-bitwidth
+#![allow(const_err)] // make sure we cannot allow away the errors tested here
+
+use std::mem;
+
+#[derive(Copy, Clone)]
+enum Bar {}
+
+#[repr(C)]
+union MaybeUninit<T: Copy> {
+    uninit: (),
+    init: T,
+}
+
+const BAD_BAD_BAD: Bar = unsafe { MaybeUninit { uninit: () }.init };
+//~^ ERROR it is undefined behavior to use this value
+
+const BAD_BAD_REF: &Bar = unsafe { mem::transmute(1usize) };
+//~^ ERROR it is undefined behavior to use this value
+
+const BAD_BAD_ARRAY: [Bar; 1] = unsafe { MaybeUninit { uninit: () }.init };
+//~^ ERROR it is undefined behavior to use this value
+
+fn main() {}