1 files changed, 45 insertions, 0 deletions
diff --git a/tests/ui/layout/null-pointer-optimization-sizes.rs b/tests/ui/layout/null-pointer-optimization-sizes.rs
new file mode 100644
index 00000000000..95310b32e25
--- /dev/null
+++ b/tests/ui/layout/null-pointer-optimization-sizes.rs
@@ -0,0 +1,45 @@
+//! null pointer optimization preserves type sizes.
+//!
+//! Verifies that Option<T> has the same size as T for non-null pointer types,
+//! and for custom enums that have a niche.
+
+//@ run-pass
+
+// Needs for Nothing variat in Enum
+#![allow(dead_code)]
+
+use std::mem;
+
+enum E<T> {
+    Thing(isize, T),
+    Nothing((), ((), ()), [i8; 0]),
+}
+
+struct S<T>(isize, T);
+
+// These are macros so we get useful assert messages.
+
+macro_rules! check_option {
+    ($T:ty) => {
+        assert_eq!(mem::size_of::<Option<$T>>(), mem::size_of::<$T>());
+    };
+}
+
+macro_rules! check_fancy {
+    ($T:ty) => {
+        assert_eq!(mem::size_of::<E<$T>>(), mem::size_of::<S<$T>>());
+    };
+}
+
+macro_rules! check_type {
+    ($T:ty) => {{
+        check_option!($T);
+        check_fancy!($T);
+    }};
+}
+
+pub fn main() {
+    check_type!(&'static isize);
+    check_type!(Box<isize>);
+    check_type!(extern "C" fn());
+}