Add a test for match scopes

diff --git a/src/test/mir-opt/match-arm-scopes.rs b/src/test/mir-opt/match-arm-scopes.rs
new file mode 100644 (file)
index 0000000..0f026b8
--- /dev/null
+++ b/src/test/mir-opt/match-arm-scopes.rs
@@ -0,0 +1,245 @@
+// Test that StorageDead and Drops are generated properly for bindings in
+// matches:
+// * The MIR should only contain a single drop of `s` and `t`: at the end
+//   of their respective arms.
+// * StorageDead and StorageLive statements are correctly matched up on
+//   non-unwind paths.
+// * The visibility scopes of the match arms should be disjoint, and contain.
+//   all of the bindings for that scope.
+// * No drop flags are used.
+
+#![feature(nll, bind_by_move_pattern_guards)]
+
+fn complicated_match(cond: bool, items: (bool, bool, String)) -> i32 {
+    match items {
+        (false, a, s) | (a, false, s) if if cond { return 3 } else { a } => 1,
+        (true, b, t) | (false, b, t) => 2,
+    }
+}
+
+const CASES: &[(bool, bool, bool, i32)] = &[
+    (false, false, false, 2),
+    (false, false, true, 1),
+    (false, true, false, 1),
+    (false, true, true, 2),
+    (true, false, false, 3),
+    (true, false, true, 3),
+    (true, true, false, 3),
+    (true, true, true, 2),
+];
+
+fn main() {
+    for &(cond, items_1, items_2, result) in CASES {
+        assert_eq!(
+            complicated_match(cond, (items_1, items_2, String::new())),
+            result,
+        );
+    }
+}
+
+// END RUST SOURCE
+// START rustc.complicated_match.SimplifyCfg-initial.after.mir
+// let mut _0: i32;
+// let mut _3: &bool;                   // Temp for fake borrow of `items.0`
+// let mut _4: &bool;                   // Temp for fake borrow of `items.1`
+// let _5: bool;                    // `a` in arm
+// let _6: &bool;                   // `a` in guard
+// let _7: std::string::String;     // `s` in arm
+// let _8: &std::string::String;    // `s` in guard
+// let mut _9: bool;                    // `if cond { return 3 } else { a }`
+// let mut _10: bool;                   // `cond`
+// let mut _11: !;                      // `return 3`
+// let mut _12: bool;                   // `if cond { return 3 } else { a }`
+// let mut _13: bool;                   // `cond`
+// let mut _14: !;                      // `return 3`
+// let _15: bool;                   // `b`
+// let _16: std::string::String;    // `t`
+// scope 1 {
+// }
+// scope 2 {
+// }
+// bb0: {
+//     FakeRead(ForMatchedPlace, _2);
+//     switchInt((_2.0: bool)) -> [false: bb2, otherwise: bb7];
+// }
+// bb1 (cleanup): {
+//     resume;
+// }
+// bb2: {
+//     falseEdges -> [real: bb10, imaginary: bb3];
+// }
+// bb3: {
+//     falseEdges -> [real: bb21, imaginary: bb4];
+// }
+// bb4: {
+//     falseEdges -> [real: bb31, imaginary: bb5];
+// }
+// bb5: {
+//     falseEdges -> [real: bb32, imaginary: bb6];
+// }
+// bb6: {
+//     unreachable;
+// }
+// bb7: {
+//     switchInt((_2.1: bool)) -> [false: bb3, otherwise: bb8];
+// }
+// bb8: {
+//     switchInt((_2.0: bool)) -> [false: bb5, otherwise: bb4];
+// }
+// bb9: {                               // arm 1
+//     _0 = const 1i32;
+//     drop(_7) -> [return: bb29, unwind: bb16];
+// }
+// bb10: {                              // guard - first time
+//     StorageLive(_6);
+//     _6 = &(_2.1: bool);
+//     StorageLive(_8);
+//     _8 = &(_2.2: std::string::String);
+//     _3 = &shallow (_2.0: bool);
+//     _4 = &shallow (_2.1: bool);
+//     StorageLive(_9);
+//     StorageLive(_10);
+//     _10 = _1;
+//     FakeRead(ForMatchedPlace, _10);
+//     switchInt(_10) -> [false: bb12, otherwise: bb11];
+// }
+// bb11: {
+//     falseEdges -> [real: bb14, imaginary: bb12];
+// }
+// bb12: {
+//     falseEdges -> [real: bb18, imaginary: bb13];
+// }
+// bb13: {
+//     unreachable;
+// }
+// bb14: {                              // `return 3` - first time
+//     _0 = const 3i32;
+//     StorageDead(_10);
+//     StorageDead(_9);
+//     StorageDead(_8);
+//     StorageDead(_6);
+//     goto -> bb17;
+// }
+// bb15: {
+//     return;
+// }
+// bb16 (cleanup): {
+//     drop(_2) -> bb1;
+// }
+// bb17: {
+//     drop(_2) -> [return: bb15, unwind: bb1];
+// }
+// bb18: {                              // `else` block - first time
+//     _9 = (*_6);
+//     StorageDead(_10);
+//     FakeRead(ForMatchGuard, _3);
+//     FakeRead(ForMatchGuard, _4);
+//     FakeRead(ForGuardBinding, _6);
+//     FakeRead(ForGuardBinding, _8);
+//     switchInt(move _9) -> [false: bb20, otherwise: bb19];
+// }
+// bb19: {
+//     StorageDead(_9);
+//     StorageLive(_5);
+//     _5 = (_2.1: bool);
+//     StorageLive(_7);
+//     _7 = move (_2.2: std::string::String);
+//     goto -> bb9;
+// }
+// bb20: {                              // guard otherwise case - first time
+//     StorageDead(_9);
+//     StorageDead(_8);
+//     StorageDead(_6);
+//     falseEdges -> [real: bb7, imaginary: bb3];
+// }
+// bb21: {                              // guard - second time
+//     StorageLive(_6);
+//     _6 = &(_2.0: bool);
+//     StorageLive(_8);
+//     _8 = &(_2.2: std::string::String);
+//     _3 = &shallow (_2.0: bool);
+//     _4 = &shallow (_2.1: bool);
+//     StorageLive(_12);
+//     StorageLive(_13);
+//     _13 = _1;
+//     FakeRead(ForMatchedPlace, _13);
+//     switchInt(_13) -> [false: bb23, otherwise: bb22];
+// }
+// bb22: {
+//     falseEdges -> [real: bb25, imaginary: bb23];
+// }
+// bb23: {
+//     falseEdges -> [real: bb26, imaginary: bb24];
+// }
+// bb24: {
+//     unreachable;
+// }
+// bb25: {                              // `return 3` - second time
+//     _0 = const 3i32;
+//     StorageDead(_13);
+//     StorageDead(_12);
+//     StorageDead(_8);
+//     StorageDead(_6);
+//     goto -> bb17;
+// }
+// bb26: {                              // `else` block - second time
+//     _12 = (*_6);
+//     StorageDead(_13);
+//     FakeRead(ForMatchGuard, _3);
+//     FakeRead(ForMatchGuard, _4);
+//     FakeRead(ForGuardBinding, _6);
+//     FakeRead(ForGuardBinding, _8);
+//     switchInt(move _12) -> [false: bb28, otherwise: bb27];
+// }
+// bb27: {                              // Guard otherwise case - second time
+//     StorageDead(_12);
+//     StorageLive(_5);
+//     _5 = (_2.0: bool);
+//     StorageLive(_7);
+//     _7 = move (_2.2: std::string::String);
+//     goto -> bb9;
+// }
+// bb28: {                              // rest of arm 1
+//     StorageDead(_12);
+//     StorageDead(_8);
+//     StorageDead(_6);
+//     falseEdges -> [real: bb8, imaginary: bb4];
+// }
+// bb29: {
+//     StorageDead(_7);
+//     StorageDead(_5);
+//     StorageDead(_8);
+//     StorageDead(_6);
+//     goto -> bb34;
+// }
+// bb30: {                              // arm 2
+//     _0 = const 2i32;
+//     drop(_16) -> [return: bb33, unwind: bb16];
+// }
+// bb31: {                              // bindings for arm 2 - first pattern
+//     StorageLive(_15);
+//     _15 = (_2.1: bool);
+//     StorageLive(_16);
+//     _16 = move (_2.2: std::string::String);
+//     goto -> bb30;
+// }
+// bb32: {                              // bindings for arm 2 - first pattern
+//     StorageLive(_15);
+//     _15 = (_2.1: bool);
+//     StorageLive(_16);
+//     _16 = move (_2.2: std::string::String);
+//     goto -> bb30;
+// }
+// bb33: {                              // rest of arm 2
+//     StorageDead(_16);
+//     StorageDead(_15);
+//     goto -> bb34;
+// }
+// bb34: {                              // end of match
+//     drop(_2) -> [return: bb15, unwind: bb1];
+// }
+// END rustc.complicated_match.SimplifyCfg-initial.after.mir
+// START rustc.complicated_match.ElaborateDrops.after.mir
+// let _16: std::string::String;      // No drop flags, which would come after this.
+// scope 1 {
+// END rustc.complicated_match.ElaborateDrops.after.mir