1 files changed, 36 insertions, 0 deletions
diff --git a/tests/ui/consts/miri_unleashed/mutable_references_err.rs b/tests/ui/consts/miri_unleashed/mutable_references_err.rs
new file mode 100644
index 000000000..6399b122b
--- /dev/null
+++ b/tests/ui/consts/miri_unleashed/mutable_references_err.rs
@@ -0,0 +1,36 @@
+// stderr-per-bitwidth
+// compile-flags: -Zunleash-the-miri-inside-of-you
+
+use std::cell::UnsafeCell;
+
+// this test ensures that our mutability story is sound
+
+struct Meh {
+    x: &'static UnsafeCell<i32>,
+}
+unsafe impl Sync for Meh {}
+
+// the following will never be ok! no interior mut behind consts, because
+// all allocs interned here will be marked immutable.
+const MUH: Meh = Meh { //~ ERROR: it is undefined behavior to use this value
+    x: &UnsafeCell::new(42),
+};
+
+struct Synced {
+    x: UnsafeCell<i32>,
+}
+unsafe impl Sync for Synced {}
+
+// Make sure we also catch this behind a type-erased `dyn Trait` reference.
+const SNEAKY: &dyn Sync = &Synced { x: UnsafeCell::new(42) };
+//~^ ERROR: it is undefined behavior to use this value
+
+// Make sure we also catch mutable references.
+const BLUNT: &mut i32 = &mut 42;
+//~^ ERROR: it is undefined behavior to use this value
+
+fn main() {
+    unsafe {
+        *MUH.x.get() = 99;
+    }
+}