MIR validation: check switch_ty

Author: RalfJung

src/librustc_mir/transform/validate.rs

@@ -121,7 +121,18 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
             TerminatorKind::Goto { target } => {
                 self.check_edge(location, *target, EdgeKind::Normal);
             }
-            TerminatorKind::SwitchInt { targets, values, .. } => {
+            TerminatorKind::SwitchInt { targets, values, switch_ty, discr } => {
+                let ty = discr.ty(&self.body.local_decls, self.tcx);
+                if ty != *switch_ty {
+                    self.fail(
+                        location,
+                        format!(
+                            "encountered `SwitchInt` terminator with type mismatch: {:?} != {:?}",
+                            ty,
+                            switch_ty,
+                        ),
+                    );
+                }
                 if targets.len() != values.len() + 1 {
                     self.fail(
                         location,