- // MIR for `map` before SimplifyLocals
+ // MIR for `map` after SimplifyLocals
  
  fn map(_1: Option<Box<()>>) -> Option<Box<()>> {
      debug x => _1;                       // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+0:8: +0:9
      let mut _0: std::option::Option<std::boxed::Box<()>>; // return place in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+0:31: +0:46
      let mut _2: isize;                   // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+2:9: +2:13
-     let _3: std::boxed::Box<()>;         // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+3:14: +3:15
-     let mut _4: std::boxed::Box<()>;     // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+3:25: +3:26
-     let mut _5: bool;                    // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+5:1: +5:2
-     let mut _6: isize;                   // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+5:1: +5:2
-     let mut _7: isize;                   // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+5:1: +5:2
      scope 1 {
          debug x => ((_0 as Some).0: std::boxed::Box<()>); // in scope 1 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+3:14: +3:15
      }
  
      bb0: {
          _2 = discriminant(_1);           // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+1:11: +1:12
          switchInt(move _2) -> [0_isize: bb2, otherwise: bb1]; // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+1:5: +1:12
      }
  
      bb1: {
          ((_0 as Some).0: std::boxed::Box<()>) = move ((_1 as Some).0: std::boxed::Box<()>); // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+3:14: +3:15
          Deinit(_0);                      // scope 1 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+3:20: +3:27
          discriminant(_0) = 1;            // scope 1 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+3:20: +3:27
          goto -> bb3;                     // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+3:26: +3:27
      }
  
      bb2: {
          Deinit(_0);                      // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+2:17: +2:21
          discriminant(_0) = 0;            // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+2:17: +2:21
          goto -> bb3;                     // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+2:17: +2:21
      }
  
      bb3: {
          return;                          // scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:+5:2: +5:2
      }
  }