Correct test for enum representation with explicit #[repr]

Author: Ulrik Sverdrup

Diff for: src/test/run-pass/enum-discrim-manual-sizing-2.rs

@@ -91,19 +91,22 @@ pub fn main() {
     assert_eq!(size_of::<Eint<()>>(), size_of::<isize>());
     assert_eq!(size_of::<Euint<()>>(), size_of::<usize>());
 
-    assert!(size_of::<Ei8<&i32>>() > 1);
-    assert!(size_of::<Eu8<&i32>>() > 1);
-    assert!(size_of::<Ei16<&i32>>() > 2);
-    assert!(size_of::<Eu16<&i32>>() > 2);
-    assert!(size_of::<Ei32<&i32>>() > 4);
-    assert!(size_of::<Eu32<&i32>>() > 4);
-    assert!(size_of::<Ei64<&i32>>() > 8);
-    assert!(size_of::<Eu64<&i32>>() > 8);
-    assert!(size_of::<Eint<&i32>>() > size_of::<isize>());
-    assert!(size_of::<Euint<&i32>>() > size_of::<usize>());
-
-    assert!(size_of::<EC<&i32>>() > size_of::<EC<()>>());
-
+    // check that the non-nullable pointer optimization is absent
+    let ptrsize = size_of::<&i32>();
+    assert!(size_of::<Ei8<&i32>>() > ptrsize);
+    assert!(size_of::<Eu8<&i32>>() > ptrsize);
+    assert!(size_of::<Ei16<&i32>>() > ptrsize);
+    assert!(size_of::<Eu16<&i32>>() > ptrsize);
+    assert!(size_of::<Ei32<&i32>>() > ptrsize);
+    assert!(size_of::<Eu32<&i32>>() > ptrsize);
+    assert!(size_of::<Ei64<&i32>>() > ptrsize);
+    assert!(size_of::<Eu64<&i32>>() > ptrsize);
+    assert!(size_of::<Eint<&i32>>() > ptrsize);
+    assert!(size_of::<Euint<&i32>>() > ptrsize);
+
+    assert!(size_of::<EC<&i32>>() > ptrsize);
+
+    // test that a zero payload does not influence the discriminant
     let zero: &i32 = unsafe { zeroed() };
     assert!(match Eu8::_Some(zero) {
         Eu8::_Some(_) => true,