Auto merge of #52046 - cramertj:fix-generator-mir, r=eddyb

Ensure StorageDead is created even if variable initialization fails

Rebase and slight cleanup of https://github.com/rust-lang/rust/pull/51109
Fixes https://github.com/rust-lang/rust/issues/49232

r? @eddyb

2 files changed, 149 insertions, 1 deletions

diff --git a/src/test/mir-opt/issue-49232.rs b/src/test/mir-opt/issue-49232.rs
new file mode 100644
index 00000000000..8e5a94abeed
--- /dev/null
+++ b/src/test/mir-opt/issue-49232.rs
@@ -0,0 +1,148 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// We must mark a variable whose initialization fails due to an
+// abort statement as StorageDead.
+
+fn main() {
+    loop {
+        let beacon = {
+            match true {
+                false => 4,
+                true => break,
+            }
+        };
+        drop(&beacon);
+    }
+}
+
+// END RUST SOURCE
+// START rustc.main.mir_map.0.mir
+// fn main() -> (){
+//     let mut _0: ();
+//     scope 1 {
+//     }
+//     scope 2 {
+//         let _2: i32;
+//     }
+//     let mut _1: ();
+//     let mut _3: bool;
+//     let mut _4: u8;
+//     let mut _5: !;
+//     let mut _6: ();
+//     let mut _7: &i32;
+//     bb0: {
+//         goto -> bb1;
+//     }
+//     bb1: {
+//         falseUnwind -> [real: bb3, cleanup: bb4];
+//     }
+//     bb2: {
+//         goto -> bb29;
+//     }
+//     bb3: {
+//         StorageLive(_2);
+//         StorageLive(_3);
+//         _3 = const true;
+//         _4 = discriminant(_3);
+//         switchInt(_3) -> [false: bb11, otherwise: bb10];
+//     }
+//     bb4: {
+//         resume;
+//     }
+//     bb5: {
+//         _2 = const 4i32;
+//         goto -> bb14;
+//     }
+//     bb6: {
+//         _0 = ();
+//         goto -> bb15;
+//     }
+//     bb7: {
+//         falseEdges -> [real: bb12, imaginary: bb8];
+//     }
+//     bb8: {
+//         falseEdges -> [real: bb13, imaginary: bb9];
+//     }
+//     bb9: {
+//         unreachable;
+//     }
+//     bb10: {
+//         goto -> bb8;
+//     }
+//     bb11: {
+//         goto -> bb7;
+//     }
+//     bb12: {
+//         goto -> bb5;
+//     }
+//     bb13: {
+//         goto -> bb6;
+//     }
+//     bb14: {
+//         StorageDead(_3);
+//         StorageLive(_7);
+//         _7 = &_2;
+//         _6 = const std::mem::drop(move _7) -> [return: bb28, unwind: bb4];
+//     }
+//     bb15: {
+//         goto -> bb16;
+//     }
+//     bb16: {
+//         goto -> bb17;
+//     }
+//     bb17: {
+//         goto -> bb18;
+//     }
+//     bb18: {
+//         goto -> bb19;
+//     }
+//     bb19: {
+//         goto -> bb20;
+//     }
+//     bb20: {
+//         StorageDead(_3);
+//         goto -> bb21;
+//     }
+//     bb21: {
+//         goto -> bb22;
+//     }
+//     bb22: {
+//         StorageDead(_2);
+//         goto -> bb23;
+//     }
+//     bb23: {
+//         goto -> bb24;
+//     }
+//     bb24: {
+//         goto -> bb25;
+//     }
+//     bb25: {
+//         goto -> bb2;
+//     }
+//     bb26: {
+//         _5 = ();
+//         unreachable;
+//     }
+//     bb27: {
+//         StorageDead(_5);
+//         goto -> bb14;
+//     }
+//     bb28: {
+//         StorageDead(_7);
+//         _1 = ();
+//         StorageDead(_2);
+//         goto -> bb1;
+//     }
+//     bb29: {
+//         return;
+//     }
+// }
+// END rustc.main.mir_map.0.mir
diff --git a/src/test/mir-opt/storage_ranges.rs b/src/test/mir-opt/storage_ranges.rs
index 41eaf67d292..16e30f84d17 100644
--- a/src/test/mir-opt/storage_ranges.rs
+++ b/src/test/mir-opt/storage_ranges.rs
@@ -31,8 +31,8 @@ fn main() {
 //         StorageDead(_5);
 //         _3 = &_4;
 //         _2 = ();
-//         StorageDead(_3);
 //         StorageDead(_4);
+//         StorageDead(_3);
 //         StorageLive(_6);
 //         _6 = const 1i32;
 //         _0 = ();