Update ub-uninhabit tests

Author: varkor

src/librustc/ty/sty.rs

@@ -1571,10 +1571,10 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
             }
             ty::Tuple(tys) => tys.iter().any(|ty| ty.conservative_is_uninhabited(tcx)),
             ty::Array(ty, len) => {
-                match len.val.try_to_scalar() {
+                match len.assert_usize(tcx) {
                     // If the array is definitely non-empty, it's uninhabited if
                     // the type of its elements is uninhabited.
-                    Some(n) if !n.is_null() => ty.conservative_is_uninhabited(tcx),
+                    Some(n) if n != 0 => ty.conservative_is_uninhabited(tcx),
                     _ => false
                 }
             }

src/test/ui/consts/const-eval/ub-uninhabit.rs

@@ -12,12 +12,12 @@ union TransmuteUnion<A: Clone + Copy, B: Clone + Copy> {
 }
 
 const BAD_BAD_BAD: Bar = unsafe { (TransmuteUnion::<(), Bar> { a: () }).b };
-//~^ ERROR this constant likely exhibits undefined behavior
+//~^ 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 { (TransmuteUnion::<(), [Bar; 1]> { a: () }).b };
-//~^ ERROR this constant likely exhibits undefined behavior
+//~^ ERROR it is undefined behavior to use this value
 
 fn main() {}

src/test/ui/consts/const-eval/ub-uninhabit.stderr

@@ -1,21 +1,21 @@
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/ub-uninhabit.rs:19:1
+  --> $DIR/ub-uninhabit.rs:13:1
    |
 LL | const BAD_BAD_BAD: Bar = unsafe { (TransmuteUnion::<(), Bar> { a: () }).b };
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a value of an uninhabited type
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/ub-uninhabit.rs:22:1
+  --> $DIR/ub-uninhabit.rs:16:1
    |
 LL | const BAD_BAD_REF: &Bar = unsafe { mem::transmute(1usize) };
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a value of an uninhabited type at .<deref>
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/ub-uninhabit.rs:25:1
+  --> $DIR/ub-uninhabit.rs:19:1
    |
 LL | const BAD_BAD_ARRAY: [Bar; 1] = unsafe { (TransmuteUnion::<(), [Bar; 1]> { a: () }).b };
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a value of an uninhabited type