Rollup merge of #107662 - cjgillot:copy-projection, r=oli-obk

Turn projections into copies in CopyProp.

The current implementation can leave behind projections that are moved out several times.

This PR widens the check to turn such moves into copies: a move out of a projection of a copy is equivalent to a copy of the original projection.

diff --combined tests/mir-opt/simple_option_map_e2e.ezmap.PreCodegen.after.mir
index e338f15b4853144be1b1019369f36759a6572516,69d12bc2d5394e28255da860170f5d5e8777a94b..66ba4df767ccf2ff004604ac17d3070affa706c1
--- 1/tests/mir-opt/simple_option_map_e2e.ezmap.PreCodegen.after.mir
--- 2/tests/mir-opt/simple_option_map_e2e.ezmap.PreCodegen.after.mir
+++ b/tests/mir-opt/simple_option_map_e2e.ezmap.PreCodegen.after.mir
@@@ -4,22 -4,25 +4,22 @@@ fn ezmap(_1: Option<i32>) -> Option<i32
      debug x => _1;                       // in scope 0 at $DIR/simple_option_map_e2e.rs:+0:14: +0:15
      let mut _0: std::option::Option<i32>; // return place in scope 0 at $DIR/simple_option_map_e2e.rs:+0:33: +0:44
      let mut _2: [closure@$DIR/simple_option_map_e2e.rs:14:12: 14:15]; // in scope 0 at $DIR/simple_option_map_e2e.rs:+1:12: +1:21
 -    let mut _7: i32;                     // in scope 0 at $DIR/simple_option_map_e2e.rs:7:25: 7:29
      scope 1 (inlined map::<i32, i32, [closure@$DIR/simple_option_map_e2e.rs:14:12: 14:15]>) { // at $DIR/simple_option_map_e2e.rs:14:5: 14:22
          debug slf => _1;                 // in scope 1 at $DIR/simple_option_map_e2e.rs:2:17: 2:20
          debug f => _2;                   // in scope 1 at $DIR/simple_option_map_e2e.rs:2:33: 2:34
          let mut _3: isize;               // in scope 1 at $DIR/simple_option_map_e2e.rs:7:9: 7:16
          let _4: i32;                     // in scope 1 at $DIR/simple_option_map_e2e.rs:7:14: 7:15
          let mut _5: i32;                 // in scope 1 at $DIR/simple_option_map_e2e.rs:7:25: 7:29
 -        let mut _6: (i32,);              // in scope 1 at $DIR/simple_option_map_e2e.rs:7:25: 7:29
          scope 2 {
              debug x => _4;               // in scope 2 at $DIR/simple_option_map_e2e.rs:7:14: 7:15
              scope 3 (inlined ezmap::{closure#0}) { // at $DIR/simple_option_map_e2e.rs:7:25: 7:29
 -                debug n => _7;           // in scope 3 at $DIR/simple_option_map_e2e.rs:+1:13: +1:14
 +                debug n => _4;           // in scope 3 at $DIR/simple_option_map_e2e.rs:+1:13: +1:14
              }
          }
      }
  
      bb0: {
          StorageLive(_2);                 // scope 0 at $DIR/simple_option_map_e2e.rs:+1:12: +1:21
 -        StorageLive(_4);                 // scope 0 at $DIR/simple_option_map_e2e.rs:+1:5: +1:22
          _3 = discriminant(_1);           // scope 1 at $DIR/simple_option_map_e2e.rs:6:11: 6:14
          switchInt(move _3) -> [0: bb1, 1: bb3, otherwise: bb2]; // scope 1 at $DIR/simple_option_map_e2e.rs:6:5: 6:14
      }
@@@ -34,15 -37,22 +34,15 @@@
      }
  
      bb3: {
-         _4 = move ((_1 as Some).0: i32); // scope 1 at $DIR/simple_option_map_e2e.rs:7:14: 7:15
+         _4 = ((_1 as Some).0: i32);      // scope 1 at $DIR/simple_option_map_e2e.rs:7:14: 7:15
          StorageLive(_5);                 // scope 2 at $DIR/simple_option_map_e2e.rs:7:25: 7:29
 -        StorageLive(_6);                 // scope 2 at $DIR/simple_option_map_e2e.rs:7:25: 7:29
 -        _6 = (move _4,);                 // scope 2 at $DIR/simple_option_map_e2e.rs:7:25: 7:29
 -        StorageLive(_7);                 // scope 2 at $DIR/simple_option_map_e2e.rs:7:25: 7:29
 -        _7 = move (_6.0: i32);           // scope 2 at $DIR/simple_option_map_e2e.rs:7:25: 7:29
 -        _5 = Add(_7, const 1_i32);       // scope 3 at $DIR/simple_option_map_e2e.rs:+1:16: +1:21
 -        StorageDead(_7);                 // scope 2 at $DIR/simple_option_map_e2e.rs:7:25: 7:29
 -        StorageDead(_6);                 // scope 2 at $DIR/simple_option_map_e2e.rs:7:28: 7:29
 +        _5 = Add(_4, const 1_i32);       // scope 3 at $DIR/simple_option_map_e2e.rs:+1:16: +1:21
          _0 = Option::<i32>::Some(move _5); // scope 2 at $DIR/simple_option_map_e2e.rs:7:20: 7:30
          StorageDead(_5);                 // scope 2 at $DIR/simple_option_map_e2e.rs:7:29: 7:30
          goto -> bb4;                     // scope 1 at $DIR/simple_option_map_e2e.rs:10:1: 10:2
      }
  
      bb4: {
 -        StorageDead(_4);                 // scope 0 at $DIR/simple_option_map_e2e.rs:+1:5: +1:22
          StorageDead(_2);                 // scope 0 at $DIR/simple_option_map_e2e.rs:+1:21: +1:22
          return;                          // scope 0 at $DIR/simple_option_map_e2e.rs:+2:2: +2:2
      }