- // MIR for `main` before ConstProp
+ // MIR for `main` after ConstProp
  
  fn main() -> () {
      let mut _0: ();                      // return place in scope 0 at $DIR/issue-66971.rs:15:11: 15:11
      let _1: ();                          // in scope 0 at $DIR/issue-66971.rs:16:5: 16:23
      let mut _2: ((), u8, u8);            // in scope 0 at $DIR/issue-66971.rs:16:12: 16:22
      let mut _3: ();                      // in scope 0 at $DIR/issue-66971.rs:16:13: 16:15
  
      bb0: {
          StorageLive(_1);                 // scope 0 at $DIR/issue-66971.rs:16:5: 16:23
          StorageLive(_2);                 // scope 0 at $DIR/issue-66971.rs:16:12: 16:22
          StorageLive(_3);                 // scope 0 at $DIR/issue-66971.rs:16:13: 16:15
-         _3 = ();                         // scope 0 at $DIR/issue-66971.rs:16:13: 16:15
+         _3 = const ();                   // scope 0 at $DIR/issue-66971.rs:16:13: 16:15
+                                          // ty::Const
+                                          // + ty: ()
+                                          // + val: Value(Scalar(<ZST>))
+                                          // mir::Constant
+                                          // + span: $DIR/issue-66971.rs:16:13: 16:15
+                                          // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
          _2 = (move _3, const 0_u8, const 0_u8); // scope 0 at $DIR/issue-66971.rs:16:12: 16:22
                                           // ty::Const
                                           // + ty: u8
                                           // + val: Value(Scalar(0x00))
                                           // mir::Constant
                                           // + span: $DIR/issue-66971.rs:16:17: 16:18
                                           // + literal: Const { ty: u8, val: Value(Scalar(0x00)) }
                                           // ty::Const
                                           // + ty: u8
                                           // + val: Value(Scalar(0x00))
                                           // mir::Constant
                                           // + span: $DIR/issue-66971.rs:16:20: 16:21
                                           // + literal: Const { ty: u8, val: Value(Scalar(0x00)) }
          StorageDead(_3);                 // scope 0 at $DIR/issue-66971.rs:16:21: 16:22
          _1 = const encode(move _2) -> bb1; // scope 0 at $DIR/issue-66971.rs:16:5: 16:23
                                           // ty::Const
                                           // + ty: fn(((), u8, u8)) {encode}
                                           // + val: Value(Scalar(<ZST>))
                                           // mir::Constant
                                           // + span: $DIR/issue-66971.rs:16:5: 16:11
                                           // + literal: Const { ty: fn(((), u8, u8)) {encode}, val: Value(Scalar(<ZST>)) }
      }
  
      bb1: {
          StorageDead(_2);                 // scope 0 at $DIR/issue-66971.rs:16:22: 16:23
          StorageDead(_1);                 // scope 0 at $DIR/issue-66971.rs:16:23: 16:24
          _0 = const ();                   // scope 0 at $DIR/issue-66971.rs:15:11: 17:2
                                           // ty::Const
                                           // + ty: ()
                                           // + val: Value(Scalar(<ZST>))
                                           // mir::Constant
                                           // + span: $DIR/issue-66971.rs:15:11: 17:2
                                           // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
          return;                          // scope 0 at $DIR/issue-66971.rs:17:2: 17:2
      }
  }