unhinabited_enum_branching: Fix the pass when the enum is taken indirectly

If there is a projection on the place of the discriminent, the pass wouldn't trigger

3 files changed, 19 insertions, 69 deletions

diff --git a/compiler/rustc_mir/src/transform/uninhabited_enum_branching.rs b/compiler/rustc_mir/src/transform/uninhabited_enum_branching.rs
index 465832c89fd..5c6c158d46e 100644
--- a/compiler/rustc_mir/src/transform/uninhabited_enum_branching.rs
+++ b/compiler/rustc_mir/src/transform/uninhabited_enum_branching.rs
@@ -24,6 +24,7 @@ fn get_discriminant_local(terminator: &TerminatorKind<'_>) -> Option<Local> {
 /// discriminant is read from. Otherwise, returns None.
 fn get_switched_on_type<'tcx>(
     block_data: &BasicBlockData<'tcx>,
+    tcx: TyCtxt<'tcx>,
     body: &Body<'tcx>,
 ) -> Option<Ty<'tcx>> {
     let terminator = block_data.terminator();
@@ -36,12 +37,9 @@ fn get_switched_on_type<'tcx>(
         if let Some(StatementKind::Assign(box (l, Rvalue::Discriminant(place)))) = stmt_before_term
         {
             if l.as_local() == Some(local) {
-                if let Some(r_local) = place.as_local() {
-                    let ty = body.local_decls[r_local].ty;
-
-                    if ty.is_enum() {
-                        return Some(ty);
-                    }
+                let ty = place.ty(body, tcx).ty;
+                if ty.is_enum() {
+                    return Some(ty);
                 }
             }
         }
@@ -86,7 +84,7 @@ impl<'tcx> MirPass<'tcx> for UninhabitedEnumBranching {
             trace!("processing block {:?}", bb);
 
             let discriminant_ty =
-                if let Some(ty) = get_switched_on_type(&body.basic_blocks()[bb], body) {
+                if let Some(ty) = get_switched_on_type(&body.basic_blocks()[bb], tcx, body) {
                     ty
                 } else {
                     continue;
diff --git a/src/test/mir-opt/uninhabited_enum_branching2.main.SimplifyCfg-after-uninhabited-enum-branching.after.mir b/src/test/mir-opt/uninhabited_enum_branching2.main.SimplifyCfg-after-uninhabited-enum-branching.after.mir
index bb21ca46a70..373be9f174b 100644
--- a/src/test/mir-opt/uninhabited_enum_branching2.main.SimplifyCfg-after-uninhabited-enum-branching.after.mir
+++ b/src/test/mir-opt/uninhabited_enum_branching2.main.SimplifyCfg-after-uninhabited-enum-branching.after.mir
@@ -30,7 +30,7 @@ fn main() -> () {
         StorageLive(_4);                 // scope 1 at $DIR/uninhabited_enum_branching2.rs:21:11: 21:22
         _4 = &(_1.1: Test1);             // scope 1 at $DIR/uninhabited_enum_branching2.rs:21:11: 21:22
         _5 = discriminant((*_4));        // scope 1 at $DIR/uninhabited_enum_branching2.rs:22:9: 22:20
-        switchInt(move _5) -> [0_isize: bb2, 1_isize: bb3, 2_isize: bb4, otherwise: bb1]; // scope 1 at $DIR/uninhabited_enum_branching2.rs:22:9: 22:20
+        switchInt(move _5) -> [2_isize: bb2, otherwise: bb1]; // scope 1 at $DIR/uninhabited_enum_branching2.rs:22:9: 22:20
     }
 
     bb1: {
@@ -44,35 +44,10 @@ fn main() -> () {
                                          // + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [68], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [1], len: Size { raw: 1 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 1 }) }
         _3 = &(*_8);                     // scope 1 at $DIR/uninhabited_enum_branching2.rs:25:21: 25:24
         StorageDead(_8);                 // scope 1 at $DIR/uninhabited_enum_branching2.rs:25:23: 25:24
-        goto -> bb5;                     // scope 1 at $DIR/uninhabited_enum_branching2.rs:21:5: 26:6
+        goto -> bb3;                     // scope 1 at $DIR/uninhabited_enum_branching2.rs:21:5: 26:6
     }
 
     bb2: {
-        _3 = const "A(Empty)";           // scope 1 at $DIR/uninhabited_enum_branching2.rs:22:24: 22:34
-                                         // ty::Const
-                                         // + ty: &str
-                                         // + val: Value(Slice { data: Allocation { bytes: [65, 40, 69, 109, 112, 116, 121, 41], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [255], len: Size { raw: 8 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 8 })
-                                         // mir::Constant
-                                         // + span: $DIR/uninhabited_enum_branching2.rs:22:24: 22:34
-                                         // + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [65, 40, 69, 109, 112, 116, 121, 41], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [255], len: Size { raw: 8 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 8 }) }
-        goto -> bb5;                     // scope 1 at $DIR/uninhabited_enum_branching2.rs:21:5: 26:6
-    }
-
-    bb3: {
-        StorageLive(_6);                 // scope 1 at $DIR/uninhabited_enum_branching2.rs:23:24: 23:34
-        _6 = const "B(Empty)";           // scope 1 at $DIR/uninhabited_enum_branching2.rs:23:24: 23:34
-                                         // ty::Const
-                                         // + ty: &str
-                                         // + val: Value(Slice { data: Allocation { bytes: [66, 40, 69, 109, 112, 116, 121, 41], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [255], len: Size { raw: 8 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 8 })
-                                         // mir::Constant
-                                         // + span: $DIR/uninhabited_enum_branching2.rs:23:24: 23:34
-                                         // + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [66, 40, 69, 109, 112, 116, 121, 41], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [255], len: Size { raw: 8 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 8 }) }
-        _3 = &(*_6);                     // scope 1 at $DIR/uninhabited_enum_branching2.rs:23:24: 23:34
-        StorageDead(_6);                 // scope 1 at $DIR/uninhabited_enum_branching2.rs:23:33: 23:34
-        goto -> bb5;                     // scope 1 at $DIR/uninhabited_enum_branching2.rs:21:5: 26:6
-    }
-
-    bb4: {
         StorageLive(_7);                 // scope 1 at $DIR/uninhabited_enum_branching2.rs:24:21: 24:24
         _7 = const "C";                  // scope 1 at $DIR/uninhabited_enum_branching2.rs:24:21: 24:24
                                          // ty::Const
@@ -83,18 +58,18 @@ fn main() -> () {
                                          // + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [67], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [1], len: Size { raw: 1 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 1 }) }
         _3 = &(*_7);                     // scope 1 at $DIR/uninhabited_enum_branching2.rs:24:21: 24:24
         StorageDead(_7);                 // scope 1 at $DIR/uninhabited_enum_branching2.rs:24:23: 24:24
-        goto -> bb5;                     // scope 1 at $DIR/uninhabited_enum_branching2.rs:21:5: 26:6
+        goto -> bb3;                     // scope 1 at $DIR/uninhabited_enum_branching2.rs:21:5: 26:6
     }
 
-    bb5: {
+    bb3: {
         StorageDead(_4);                 // scope 1 at $DIR/uninhabited_enum_branching2.rs:26:6: 26:7
         StorageDead(_3);                 // scope 1 at $DIR/uninhabited_enum_branching2.rs:26:6: 26:7
         StorageLive(_9);                 // scope 1 at $DIR/uninhabited_enum_branching2.rs:28:5: 33:6
         _10 = discriminant((_1.1: Test1)); // scope 1 at $DIR/uninhabited_enum_branching2.rs:29:9: 29:20
-        switchInt(move _10) -> [0_isize: bb7, 1_isize: bb8, 2_isize: bb9, otherwise: bb6]; // scope 1 at $DIR/uninhabited_enum_branching2.rs:29:9: 29:20
+        switchInt(move _10) -> [2_isize: bb5, otherwise: bb4]; // scope 1 at $DIR/uninhabited_enum_branching2.rs:29:9: 29:20
     }
 
-    bb6: {
+    bb4: {
         StorageLive(_13);                // scope 1 at $DIR/uninhabited_enum_branching2.rs:32:21: 32:24
         _13 = const "D";                 // scope 1 at $DIR/uninhabited_enum_branching2.rs:32:21: 32:24
                                          // ty::Const
@@ -105,35 +80,10 @@ fn main() -> () {
                                          // + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [68], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [1], len: Size { raw: 1 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 1 }) }
         _9 = &(*_13);                    // scope 1 at $DIR/uninhabited_enum_branching2.rs:32:21: 32:24
         StorageDead(_13);                // scope 1 at $DIR/uninhabited_enum_branching2.rs:32:23: 32:24
-        goto -> bb10;                    // scope 1 at $DIR/uninhabited_enum_branching2.rs:28:5: 33:6
-    }
-
-    bb7: {
-        _9 = const "A(Empty)";           // scope 1 at $DIR/uninhabited_enum_branching2.rs:29:24: 29:34
-                                         // ty::Const
-                                         // + ty: &str
-                                         // + val: Value(Slice { data: Allocation { bytes: [65, 40, 69, 109, 112, 116, 121, 41], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [255], len: Size { raw: 8 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 8 })
-                                         // mir::Constant
-                                         // + span: $DIR/uninhabited_enum_branching2.rs:29:24: 29:34
-                                         // + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [65, 40, 69, 109, 112, 116, 121, 41], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [255], len: Size { raw: 8 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 8 }) }
-        goto -> bb10;                    // scope 1 at $DIR/uninhabited_enum_branching2.rs:28:5: 33:6
+        goto -> bb6;                     // scope 1 at $DIR/uninhabited_enum_branching2.rs:28:5: 33:6
     }
 
-    bb8: {
-        StorageLive(_11);                // scope 1 at $DIR/uninhabited_enum_branching2.rs:30:24: 30:34
-        _11 = const "B(Empty)";          // scope 1 at $DIR/uninhabited_enum_branching2.rs:30:24: 30:34
-                                         // ty::Const
-                                         // + ty: &str
-                                         // + val: Value(Slice { data: Allocation { bytes: [66, 40, 69, 109, 112, 116, 121, 41], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [255], len: Size { raw: 8 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 8 })
-                                         // mir::Constant
-                                         // + span: $DIR/uninhabited_enum_branching2.rs:30:24: 30:34
-                                         // + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [66, 40, 69, 109, 112, 116, 121, 41], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [255], len: Size { raw: 8 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 8 }) }
-        _9 = &(*_11);                    // scope 1 at $DIR/uninhabited_enum_branching2.rs:30:24: 30:34
-        StorageDead(_11);                // scope 1 at $DIR/uninhabited_enum_branching2.rs:30:33: 30:34
-        goto -> bb10;                    // scope 1 at $DIR/uninhabited_enum_branching2.rs:28:5: 33:6
-    }
-
-    bb9: {
+    bb5: {
         StorageLive(_12);                // scope 1 at $DIR/uninhabited_enum_branching2.rs:31:21: 31:24
         _12 = const "C";                 // scope 1 at $DIR/uninhabited_enum_branching2.rs:31:21: 31:24
                                          // ty::Const
@@ -144,10 +94,10 @@ fn main() -> () {
                                          // + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [67], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [1], len: Size { raw: 1 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 1 }) }
         _9 = &(*_12);                    // scope 1 at $DIR/uninhabited_enum_branching2.rs:31:21: 31:24
         StorageDead(_12);                // scope 1 at $DIR/uninhabited_enum_branching2.rs:31:23: 31:24
-        goto -> bb10;                    // scope 1 at $DIR/uninhabited_enum_branching2.rs:28:5: 33:6
+        goto -> bb6;                     // scope 1 at $DIR/uninhabited_enum_branching2.rs:28:5: 33:6
     }
 
-    bb10: {
+    bb6: {
         StorageDead(_9);                 // scope 1 at $DIR/uninhabited_enum_branching2.rs:33:6: 33:7
         _0 = const ();                   // scope 0 at $DIR/uninhabited_enum_branching2.rs:18:11: 34:2
         StorageDead(_1);                 // scope 0 at $DIR/uninhabited_enum_branching2.rs:34:1: 34:2
diff --git a/src/test/mir-opt/uninhabited_enum_branching2.main.UninhabitedEnumBranching.diff b/src/test/mir-opt/uninhabited_enum_branching2.main.UninhabitedEnumBranching.diff
index 387ab97dab4..f9488bae4c8 100644
--- a/src/test/mir-opt/uninhabited_enum_branching2.main.UninhabitedEnumBranching.diff
+++ b/src/test/mir-opt/uninhabited_enum_branching2.main.UninhabitedEnumBranching.diff
@@ -31,7 +31,8 @@
           StorageLive(_4);                 // scope 1 at $DIR/uninhabited_enum_branching2.rs:21:11: 21:22
           _4 = &(_1.1: Test1);             // scope 1 at $DIR/uninhabited_enum_branching2.rs:21:11: 21:22
           _5 = discriminant((*_4));        // scope 1 at $DIR/uninhabited_enum_branching2.rs:22:9: 22:20
-          switchInt(move _5) -> [0_isize: bb2, 1_isize: bb3, 2_isize: bb4, otherwise: bb1]; // scope 1 at $DIR/uninhabited_enum_branching2.rs:22:9: 22:20
+-         switchInt(move _5) -> [0_isize: bb2, 1_isize: bb3, 2_isize: bb4, otherwise: bb1]; // scope 1 at $DIR/uninhabited_enum_branching2.rs:22:9: 22:20
++         switchInt(move _5) -> [2_isize: bb4, otherwise: bb1]; // scope 1 at $DIR/uninhabited_enum_branching2.rs:22:9: 22:20
       }
   
       bb1: {
@@ -92,7 +93,8 @@
           StorageDead(_3);                 // scope 1 at $DIR/uninhabited_enum_branching2.rs:26:6: 26:7
           StorageLive(_9);                 // scope 1 at $DIR/uninhabited_enum_branching2.rs:28:5: 33:6
           _10 = discriminant((_1.1: Test1)); // scope 1 at $DIR/uninhabited_enum_branching2.rs:29:9: 29:20
-          switchInt(move _10) -> [0_isize: bb7, 1_isize: bb8, 2_isize: bb9, otherwise: bb6]; // scope 1 at $DIR/uninhabited_enum_branching2.rs:29:9: 29:20
+-         switchInt(move _10) -> [0_isize: bb7, 1_isize: bb8, 2_isize: bb9, otherwise: bb6]; // scope 1 at $DIR/uninhabited_enum_branching2.rs:29:9: 29:20
++         switchInt(move _10) -> [2_isize: bb9, otherwise: bb6]; // scope 1 at $DIR/uninhabited_enum_branching2.rs:29:9: 29:20
       }
   
       bb6: {