- // MIR for `main` before Derefer
+ // MIR for `main` after Derefer
  
  fn main() -> () {
      let mut _0: ();
      let _1: bool;
      let _3: ();
      let mut _4: &&&&bool;
      let _5: &&&bool;
      let _6: &&bool;
      let _7: &bool;
+     let mut _10: &&&bool;
+     let mut _11: &&bool;
+     let mut _12: &bool;
+     let mut _13: &&&bool;
+     let mut _14: &&bool;
+     let mut _15: &bool;
      scope 1 {
          debug b => _1;
          let _2: bool;
          scope 2 {
              debug d => _2;
              let _8: i32;
              let _9: i32;
              scope 3 {
                  debug x => _8;
              }
              scope 4 {
                  debug y => _9;
              }
          }
      }
  
      bb0: {
          StorageLive(_1);
          _1 = foo() -> [return: bb1, unwind continue];
      }
  
      bb1: {
          StorageLive(_2);
          _2 = foo() -> [return: bb2, unwind continue];
      }
  
      bb2: {
          StorageLive(_3);
          StorageLive(_4);
          StorageLive(_5);
          StorageLive(_6);
          StorageLive(_7);
          _7 = &_1;
          _6 = &_7;
          _5 = &_6;
          _4 = &_5;
-         PlaceMention((*(*(*(*_4)))));
-         switchInt((*(*(*(*_4))))) -> [0: bb3, otherwise: bb4];
+         _10 = deref_copy (*_4);
+         _11 = deref_copy (*_10);
+         _12 = deref_copy (*_11);
+         PlaceMention((*_12));
+         _13 = deref_copy (*_4);
+         _14 = deref_copy (*_13);
+         _15 = deref_copy (*_14);
+         switchInt((*_15)) -> [0: bb3, otherwise: bb4];
      }
  
      bb3: {
          _3 = const ();
          goto -> bb5;
      }
  
      bb4: {
          StorageLive(_8);
          _8 = const 5_i32;
          _3 = const ();
          StorageDead(_8);
          goto -> bb5;
      }
  
      bb5: {
          StorageDead(_7);
          StorageDead(_6);
          StorageDead(_5);
          StorageDead(_4);
          StorageDead(_3);
          StorageLive(_9);
          _9 = const 42_i32;
          _0 = const ();
          StorageDead(_9);
          StorageDead(_2);
          StorageDead(_1);
          return;
      }
  }