mir: Add and fix tests for FalseUnwinds

Fix instructions on existing mir-opt tests after introducing false edges from
loops. Also, add a test for issue 46036: infinite loops.

src/test/compile-fail/issue-46036.rs

@@ -0,0 +1,23 @@
+// Copyright 2017 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.
+
+// Issue 46036: [NLL] false edges on infinite loops
+// Infinite loops should create false edges to the cleanup block.
+#![feature(nll)]
+
+struct Foo { x: &'static u32 }
+
+fn foo() {
+    let a = 3;
+    let foo = Foo { x: &a }; //~ ERROR E0597
+    loop { }
+}
+
+fn main() { }

src/test/mir-opt/end_region_2.rs

@@ -46,9 +46,12 @@ fn main() {
 //         _3 = &'23_1rs _2;
 //         StorageLive(_5);
 //         _5 = _2;
-//         switchInt(move _5) -> [0u8: bb3, otherwise: bb2];
+//         switchInt(move _5) -> [0u8: bb4, otherwise: bb3];
 //     }
 //     bb2: {
+//         ...
+//     }
+//     bb3: {
 //         _0 = ();
 //         StorageDead(_5);
 //         EndRegion('23_1rs);
@@ -56,7 +59,7 @@ fn main() {
 //         StorageDead(_2);
 //         return;
 //     }
-//     bb3: {
+//     bb4: {
 //         _4 = ();
 //         StorageDead(_5);
 //         StorageLive(_7);
@@ -67,6 +70,6 @@ fn main() {
 //         EndRegion('23_1rs);
 //         StorageDead(_3);
 //         StorageDead(_2);
-//         goto -> bb1;
+//         falseUnwind -> [real: bb1, cleanup: bb2];
 //     }
 // END rustc.main.SimplifyCfg-qualify-consts.after.mir

src/test/mir-opt/end_region_3.rs

@@ -48,9 +48,12 @@ fn main() {
 //         _3 = &'26_1rs _1;
 //         StorageLive(_5);
 //         _5 = _1;
-//         switchInt(move _5) -> [0u8: bb3, otherwise: bb2];
+//         switchInt(move _5) -> [0u8: bb4, otherwise: bb3];
 //     }
 //     bb2: {
+//         ...
+//     }
+//     bb3: {
 //         _0 = ();
 //         StorageDead(_5);
 //         EndRegion('26_1rs);
@@ -58,7 +61,7 @@ fn main() {
 //         StorageDead(_1);
 //         return;
 //     }
-//     bb3: {
+//     bb4: {
 //         _4 = ();
 //         StorageDead(_5);
 //         StorageLive(_7);
@@ -68,6 +71,6 @@ fn main() {
 //         StorageDead(_7);
 //         EndRegion('26_1rs);
 //         StorageDead(_3);
-//         goto -> bb1;
+//         falseUnwind -> [real: bb1, cleanup: bb2];
 //     }
 // END rustc.main.SimplifyCfg-qualify-consts.after.mir

src/test/mir-opt/end_region_9.rs

@@ -58,15 +58,17 @@ fn main() {
 //        StorageLive(_2);
 //        _2 = const 3i32;
 //        StorageLive(_4);
-//        goto -> bb1;
+//        goto -> bb2;
 //    }
-//
 //    bb1: {
-//        StorageLive(_7);
+//        ...
-//        _7 = _1;
-//        switchInt(move _7) -> [0u8: bb3, otherwise: bb2];
 //    }
 //    bb2: {
+//        StorageLive(_7);
+//        _7 = _1;
+//        switchInt(move _7) -> [0u8: bb4, otherwise: bb3];
+//    }
+//    bb3: {
 //        _0 = ();
 //        StorageDead(_7);
 //        EndRegion('33_0rs);
@@ -75,13 +77,13 @@ fn main() {
 //        StorageDead(_1);
 //        return;
 //    }
-//    bb3: {
+//    bb4: {
 //        _4 = &'33_0rs _2;
 //        _6 = ();
 //        StorageDead(_7);
 //        _1 = const true;
 //        _3 = ();
-//        goto -> bb1;
+//        falseUnwind -> [real: bb2, cleanup: bb1];
 //    }
 // }
 // END rustc.main.SimplifyCfg-qualify-consts.after.mir

src/test/mir-opt/end_region_cyclic.rs

@@ -131,7 +131,7 @@ fn query() -> bool { true }
 //         _1 = ();
 //         EndRegion('35_0rs);
 //         StorageDead(_2);
-//         goto -> bb1;
+//         falseUnwind -> [real: bb1, cleanup: bb2];
 //     }
 // }
 // END rustc.main.SimplifyCfg-qualify-consts.after.mir

src/test/mir-opt/issue-38669.rs

@@ -25,27 +25,29 @@ fn main() {
 //     bb0: {
 //         StorageLive(_1);
 //         _1 = const false;
-//         goto -> bb1;
+//         goto -> bb2;
 //     }
 //
 //     bb1: {
+//         resume;
+//     }
+//     bb2: {
 //         StorageLive(_4);
 //         _4 = _1;
-//         switchInt(move _4) -> [0u8: bb3, otherwise: bb2];
+//         switchInt(move _4) -> [0u8: bb4, otherwise: bb3];
 //     }
-//
+//     bb3: {
-//     bb2: {
 //         _0 = ();
 //         StorageDead(_4);
 //         StorageDead(_1);
 //         return;
 //     }
 //
-//     bb3: {
+//     bb4: {
 //         _3 = ();
 //         StorageDead(_4);
 //         _1 = const true;
 //         _2 = ();
-//         goto -> bb1;
+//         falseUnwind -> [real: bb2, cleanup: bb1];
 //     }
 // END rustc.main.SimplifyCfg-initial.after.mir