Change dest-prop/union.rs to be a unit test

Author: CastilloDel

tests/mir-opt/dest-prop/union.main.DestinationPropagation.panic-abort.diff

@@ -5,27 +5,33 @@
       let mut _0: ();
       let _1: main::Un;
       let mut _2: u32;
-      let mut _3: u32;
+      let _3: ();
+      let mut _4: u32;
       scope 1 {
           debug un => _1;
           scope 2 {
           }
-          scope 4 (inlined std::mem::drop::<u32>) {
-              debug _x => _3;
-          }
-      }
-      scope 3 (inlined val) {
       }
 
       bb0: {
           StorageLive(_1);
           StorageLive(_2);
-          _2 = const 1_u32;
-          _1 = Un { us: const 1_u32 };
+          _2 = val() -> [return: bb1, unwind unreachable];
+      }
+  
+      bb1: {
+          _1 = Un { us: move _2 };
           StorageDead(_2);
           StorageLive(_3);
-          _3 = (_1.0: u32);
+          StorageLive(_4);
+          _4 = (_1.0: u32);
+          _3 = std::mem::drop::<u32>(move _4) -> [return: bb2, unwind unreachable];
+      }
+  
+      bb2: {
+          StorageDead(_4);
           StorageDead(_3);
+          _0 = const ();
           StorageDead(_1);
           return;
       }

tests/mir-opt/dest-prop/union.main.DestinationPropagation.panic-unwind.diff

@@ -5,27 +5,33 @@
       let mut _0: ();
       let _1: main::Un;
       let mut _2: u32;
-      let mut _3: u32;
+      let _3: ();
+      let mut _4: u32;
       scope 1 {
           debug un => _1;
           scope 2 {
           }
-          scope 4 (inlined std::mem::drop::<u32>) {
-              debug _x => _3;
-          }
-      }
-      scope 3 (inlined val) {
       }
 
       bb0: {
           StorageLive(_1);
           StorageLive(_2);
-          _2 = const 1_u32;
-          _1 = Un { us: const 1_u32 };
+          _2 = val() -> [return: bb1, unwind continue];
+      }
+  
+      bb1: {
+          _1 = Un { us: move _2 };
           StorageDead(_2);
           StorageLive(_3);
-          _3 = (_1.0: u32);
+          StorageLive(_4);
+          _4 = (_1.0: u32);
+          _3 = std::mem::drop::<u32>(move _4) -> [return: bb2, unwind continue];
+      }
+  
+      bb2: {
+          StorageDead(_4);
           StorageDead(_3);
+          _0 = const ();
           StorageDead(_1);
           return;
       }

tests/mir-opt/dest-prop/union.rs

@@ -2,6 +2,7 @@
 // EMIT_MIR_FOR_EACH_PANIC_STRATEGY
 //! Tests that we can propagate into places that are projections into unions
 //@ compile-flags: -Zunsound-mir-opts
+//@ unit-test: DestinationPropagation
 fn val() -> u32 {
     1
 }