Change way of checking SetDiscriminant

Author: pvdrz

src/librustc_mir/transform/check_consts/validation.rs

@@ -566,9 +566,8 @@ impl Visitor<'tcx> for Validator<'_, 'mir, 'tcx> {
             StatementKind::FakeRead(FakeReadCause::ForMatchedPlace, _) => {
                 self.check_op(ops::IfOrMatch);
             }
-            StatementKind::SetDiscriminant { ref place, .. } => {
-                let ctx = PlaceContext::MutatingUse(MutatingUseContext::Projection);
-                self.visit_place(&place, ctx, location)
+            StatementKind::SetDiscriminant { .. } => {
+                self.super_statement(statement, location)
             }
             // FIXME(eddyb) should these really do nothing?
             StatementKind::FakeRead(..) |