Rollup merge of #73442 - davidtwco:issue-72181-pretty-print-const-val-enum-no-variants, r=oli-obk

pretty/mir: const value enums with no variants

Fixes #72181.

This PR modifies the pretty printer and const eval in the MIR so that `destructure_const` (used in `pretty_print_const_value`) can handle enums with no variants (or types containing enums with no variants).

I'm not convinced that this is the correct approach, folks more familiar with `destructure_const` would be able to say - happy to adjust the PR. Looking through `destructure_const` and the functions that it invokes, it didn't seem like it was written to handle zero-variant-enums - I assume that case is handled earlier in some way so `destructure_const` doesn't need to under normal circumstances. It didn't seem like it would be straightforward to make `destructure_const` handle this case in a first-class-feeling way (e.g. adding a `Variants::None` variant), so this PR makes some minimal changes to avoid ICEs.

13 files changed, 618 insertions, 0 deletions

diff --git a/src/test/mir-opt/issue-72181-1.rs b/src/test/mir-opt/issue-72181-1.rs
new file mode 100644
index 00000000000..6d65f847a2c
--- /dev/null
+++ b/src/test/mir-opt/issue-72181-1.rs
@@ -0,0 +1,21 @@
+// compile-flags: -Z mir-opt-level=1
+// Regression test for #72181, this ICE requires `-Z mir-opt-level=1` flags.
+
+#![feature(never_type)]
+#![allow(unused, invalid_value)]
+
+enum Void {}
+
+// EMIT_MIR rustc.f.mir_map.0.mir
+fn f(v: Void) -> ! {
+    match v {}
+}
+
+// EMIT_MIR rustc.main.mir_map.0.mir
+fn main() {
+    let v: Void = unsafe {
+        std::mem::transmute::<(), Void>(())
+    };
+
+    f(v);
+}
diff --git a/src/test/mir-opt/issue-72181-1/rustc.f.mir_map.0.mir b/src/test/mir-opt/issue-72181-1/rustc.f.mir_map.0.mir
new file mode 100644
index 00000000000..1821365898e
--- /dev/null
+++ b/src/test/mir-opt/issue-72181-1/rustc.f.mir_map.0.mir
@@ -0,0 +1,37 @@
+// MIR for `f` 0 mir_map
+
+fn f(_1: Void) -> ! {
+    debug v => _1;                       // in scope 0 at $DIR/issue-72181-1.rs:10:6: 10:7
+    let mut _0: !;                       // return place in scope 0 at $DIR/issue-72181-1.rs:10:18: 10:19
+    let mut _2: !;                       // in scope 0 at $DIR/issue-72181-1.rs:10:20: 12:2
+    let mut _3: !;                       // in scope 0 at $DIR/issue-72181-1.rs:11:5: 11:15
+
+    bb0: {
+        StorageLive(_2);                 // scope 0 at $DIR/issue-72181-1.rs:10:20: 12:2
+        StorageLive(_3);                 // scope 0 at $DIR/issue-72181-1.rs:11:5: 11:15
+        FakeRead(ForMatchedPlace, _1);   // scope 0 at $DIR/issue-72181-1.rs:11:11: 11:12
+        unreachable;                     // scope 0 at $DIR/issue-72181-1.rs:11:11: 11:12
+    }
+
+    bb1 (cleanup): {
+        resume;                          // scope 0 at $DIR/issue-72181-1.rs:10:1: 12:2
+    }
+
+    bb2: {
+        unreachable;                     // scope 0 at $DIR/issue-72181-1.rs:11:5: 11:15
+    }
+
+    bb3: {
+        StorageDead(_3);                 // scope 0 at $DIR/issue-72181-1.rs:11:14: 11:15
+        unreachable;                     // scope 0 at $DIR/issue-72181-1.rs:10:20: 12:2
+    }
+
+    bb4: {
+        StorageDead(_2);                 // scope 0 at $DIR/issue-72181-1.rs:12:1: 12:2
+        goto -> bb5;                     // scope 0 at $DIR/issue-72181-1.rs:12:2: 12:2
+    }
+
+    bb5: {
+        return;                          // scope 0 at $DIR/issue-72181-1.rs:12:2: 12:2
+    }
+}
diff --git a/src/test/mir-opt/issue-72181-1/rustc.main.mir_map.0.mir b/src/test/mir-opt/issue-72181-1/rustc.main.mir_map.0.mir
new file mode 100644
index 00000000000..b87d0294fb8
--- /dev/null
+++ b/src/test/mir-opt/issue-72181-1/rustc.main.mir_map.0.mir
@@ -0,0 +1,67 @@
+// MIR for `main` 0 mir_map
+
+| User Type Annotations
+| 0: Canonical { max_universe: U0, variables: [], value: Ty(Void) } at $DIR/issue-72181-1.rs:16:12: 16:16
+| 1: Canonical { max_universe: U0, variables: [], value: Ty(Void) } at $DIR/issue-72181-1.rs:16:12: 16:16
+|
+fn main() -> () {
+    let mut _0: ();                      // return place in scope 0 at $DIR/issue-72181-1.rs:15:11: 15:11
+    let mut _1: !;                       // in scope 0 at $DIR/issue-72181-1.rs:15:11: 21:2
+    let _2: Void as UserTypeProjection { base: UserType(0), projs: [] }; // in scope 0 at $DIR/issue-72181-1.rs:16:9: 16:10
+    let mut _3: ();                      // in scope 0 at $DIR/issue-72181-1.rs:17:41: 17:43
+    let _4: !;                           // in scope 0 at $DIR/issue-72181-1.rs:20:5: 20:9
+    let mut _5: Void;                    // in scope 0 at $DIR/issue-72181-1.rs:20:7: 20:8
+    scope 1 {
+        debug v => _2;                   // in scope 1 at $DIR/issue-72181-1.rs:16:9: 16:10
+    }
+    scope 2 {
+    }
+
+    bb0: {
+        StorageLive(_2);                 // scope 0 at $DIR/issue-72181-1.rs:16:9: 16:10
+        StorageLive(_3);                 // scope 2 at $DIR/issue-72181-1.rs:17:41: 17:43
+        _3 = ();                         // scope 2 at $DIR/issue-72181-1.rs:17:41: 17:43
+        _2 = const std::intrinsics::transmute::<(), Void>(move _3) -> [return: bb2, unwind: bb1]; // scope 2 at $DIR/issue-72181-1.rs:17:9: 17:44
+                                         // ty::Const
+                                         // + ty: unsafe extern "rust-intrinsic" fn(()) -> Void {std::intrinsics::transmute::<(), Void>}
+                                         // + val: Value(Scalar(<ZST>))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181-1.rs:17:9: 17:40
+                                         // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(()) -> Void {std::intrinsics::transmute::<(), Void>}, val: Value(Scalar(<ZST>)) }
+    }
+
+    bb1 (cleanup): {
+        resume;                          // scope 0 at $DIR/issue-72181-1.rs:15:1: 21:2
+    }
+
+    bb2: {
+        StorageDead(_3);                 // scope 2 at $DIR/issue-72181-1.rs:17:43: 17:44
+        FakeRead(ForLet, _2);            // scope 0 at $DIR/issue-72181-1.rs:16:9: 16:10
+        AscribeUserType(_2, o, UserTypeProjection { base: UserType(1), projs: [] }); // scope 0 at $DIR/issue-72181-1.rs:16:12: 16:16
+        StorageLive(_4);                 // scope 1 at $DIR/issue-72181-1.rs:20:5: 20:9
+        StorageLive(_5);                 // scope 1 at $DIR/issue-72181-1.rs:20:7: 20:8
+        _5 = move _2;                    // scope 1 at $DIR/issue-72181-1.rs:20:7: 20:8
+        const f(move _5) -> bb1;         // scope 1 at $DIR/issue-72181-1.rs:20:5: 20:9
+                                         // ty::Const
+                                         // + ty: fn(Void) -> ! {f}
+                                         // + val: Value(Scalar(<ZST>))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181-1.rs:20:5: 20:6
+                                         // + literal: Const { ty: fn(Void) -> ! {f}, val: Value(Scalar(<ZST>)) }
+    }
+
+    bb3: {
+        StorageDead(_5);                 // scope 1 at $DIR/issue-72181-1.rs:20:8: 20:9
+        StorageDead(_4);                 // scope 1 at $DIR/issue-72181-1.rs:20:9: 20:10
+        StorageDead(_2);                 // scope 0 at $DIR/issue-72181-1.rs:21:1: 21:2
+        unreachable;                     // scope 0 at $DIR/issue-72181-1.rs:15:11: 21:2
+    }
+
+    bb4: {
+        goto -> bb5;                     // scope 0 at $DIR/issue-72181-1.rs:21:2: 21:2
+    }
+
+    bb5: {
+        return;                          // scope 0 at $DIR/issue-72181-1.rs:21:2: 21:2
+    }
+}
diff --git a/src/test/mir-opt/issue-72181.rs b/src/test/mir-opt/issue-72181.rs
new file mode 100644
index 00000000000..9373ce12032
--- /dev/null
+++ b/src/test/mir-opt/issue-72181.rs
@@ -0,0 +1,28 @@
+// compile-flags: -Z mir-opt-level=1
+// Regression test for #72181, this ICE requires `-Z mir-opt-level=1` flags.
+
+use std::mem;
+
+#[derive(Copy, Clone)]
+enum Never {}
+
+union Foo {
+    a: u64,
+    b: Never
+}
+
+// EMIT_MIR_FOR_EACH_BIT_WIDTH
+// EMIT_MIR rustc.foo.mir_map.0.mir
+fn foo(xs: [(Never, u32); 1]) -> u32 { xs[0].1 }
+
+// EMIT_MIR rustc.bar.mir_map.0.mir
+fn bar([(_, x)]: [(Never, u32); 1]) -> u32 { x }
+
+// EMIT_MIR_FOR_EACH_BIT_WIDTH
+// EMIT_MIR rustc.main.mir_map.0.mir
+fn main() {
+    let _ = mem::size_of::<Foo>();
+
+    let f = [Foo { a: 42 }, Foo { a: 10 }];
+    let _ = unsafe { f[0].a };
+}
diff --git a/src/test/mir-opt/issue-72181/32bit/rustc.bar.mir_map.0.mir b/src/test/mir-opt/issue-72181/32bit/rustc.bar.mir_map.0.mir
new file mode 100644
index 00000000000..29654c2b1f8
--- /dev/null
+++ b/src/test/mir-opt/issue-72181/32bit/rustc.bar.mir_map.0.mir
@@ -0,0 +1,25 @@
+// MIR for `bar` 0 mir_map
+
+fn bar(_1: [(Never, u32); 1]) -> u32 {
+    let mut _0: u32;                     // return place in scope 0 at $DIR/issue-72181.rs:19:40: 19:43
+    let _2: u32;                         // in scope 0 at $DIR/issue-72181.rs:19:13: 19:14
+    scope 1 {
+        debug x => _2;                   // in scope 1 at $DIR/issue-72181.rs:19:13: 19:14
+    }
+
+    bb0: {
+        StorageLive(_2);                 // scope 0 at $DIR/issue-72181.rs:19:13: 19:14
+        _2 = (_1[0 of 1].1: u32);        // scope 0 at $DIR/issue-72181.rs:19:13: 19:14
+        _0 = _2;                         // scope 1 at $DIR/issue-72181.rs:19:46: 19:47
+        StorageDead(_2);                 // scope 0 at $DIR/issue-72181.rs:19:48: 19:49
+        goto -> bb2;                     // scope 0 at $DIR/issue-72181.rs:19:49: 19:49
+    }
+
+    bb1 (cleanup): {
+        resume;                          // scope 0 at $DIR/issue-72181.rs:19:1: 19:49
+    }
+
+    bb2: {
+        return;                          // scope 0 at $DIR/issue-72181.rs:19:49: 19:49
+    }
+}
diff --git a/src/test/mir-opt/issue-72181/32bit/rustc.foo.mir_map.0.mir b/src/test/mir-opt/issue-72181/32bit/rustc.foo.mir_map.0.mir
new file mode 100644
index 00000000000..776eb61a526
--- /dev/null
+++ b/src/test/mir-opt/issue-72181/32bit/rustc.foo.mir_map.0.mir
@@ -0,0 +1,37 @@
+// MIR for `foo` 0 mir_map
+
+fn foo(_1: [(Never, u32); 1]) -> u32 {
+    debug xs => _1;                      // in scope 0 at $DIR/issue-72181.rs:16:8: 16:10
+    let mut _0: u32;                     // return place in scope 0 at $DIR/issue-72181.rs:16:34: 16:37
+    let _2: usize;                       // in scope 0 at $DIR/issue-72181.rs:16:43: 16:44
+    let mut _3: usize;                   // in scope 0 at $DIR/issue-72181.rs:16:40: 16:45
+    let mut _4: bool;                    // in scope 0 at $DIR/issue-72181.rs:16:40: 16:45
+
+    bb0: {
+        StorageLive(_2);                 // scope 0 at $DIR/issue-72181.rs:16:43: 16:44
+        _2 = const 0usize;               // scope 0 at $DIR/issue-72181.rs:16:43: 16:44
+                                         // ty::Const
+                                         // + ty: usize
+                                         // + val: Value(Scalar(0x00000000))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181.rs:16:43: 16:44
+                                         // + literal: Const { ty: usize, val: Value(Scalar(0x00000000)) }
+        _3 = Len(_1);                    // scope 0 at $DIR/issue-72181.rs:16:40: 16:45
+        _4 = Lt(_2, _3);                 // scope 0 at $DIR/issue-72181.rs:16:40: 16:45
+        assert(move _4, "index out of bounds: the len is {} but the index is {}", move _3, _2) -> [success: bb2, unwind: bb1]; // scope 0 at $DIR/issue-72181.rs:16:40: 16:45
+    }
+
+    bb1 (cleanup): {
+        resume;                          // scope 0 at $DIR/issue-72181.rs:16:1: 16:49
+    }
+
+    bb2: {
+        _0 = (_1[_2].1: u32);            // scope 0 at $DIR/issue-72181.rs:16:40: 16:47
+        StorageDead(_2);                 // scope 0 at $DIR/issue-72181.rs:16:48: 16:49
+        goto -> bb3;                     // scope 0 at $DIR/issue-72181.rs:16:49: 16:49
+    }
+
+    bb3: {
+        return;                          // scope 0 at $DIR/issue-72181.rs:16:49: 16:49
+    }
+}
diff --git a/src/test/mir-opt/issue-72181/32bit/rustc.main.mir_map.0.mir b/src/test/mir-opt/issue-72181/32bit/rustc.main.mir_map.0.mir
new file mode 100644
index 00000000000..aa44dcd8eae
--- /dev/null
+++ b/src/test/mir-opt/issue-72181/32bit/rustc.main.mir_map.0.mir
@@ -0,0 +1,93 @@
+// MIR for `main` 0 mir_map
+
+fn main() -> () {
+    let mut _0: ();                      // return place in scope 0 at $DIR/issue-72181.rs:23:11: 23:11
+    let mut _1: usize;                   // in scope 0 at $DIR/issue-72181.rs:24:13: 24:34
+    let mut _3: Foo;                     // in scope 0 at $DIR/issue-72181.rs:26:14: 26:27
+    let mut _4: Foo;                     // in scope 0 at $DIR/issue-72181.rs:26:29: 26:42
+    let mut _5: u64;                     // in scope 0 at $DIR/issue-72181.rs:27:13: 27:30
+    let _6: usize;                       // in scope 0 at $DIR/issue-72181.rs:27:24: 27:25
+    let mut _7: usize;                   // in scope 0 at $DIR/issue-72181.rs:27:22: 27:26
+    let mut _8: bool;                    // in scope 0 at $DIR/issue-72181.rs:27:22: 27:26
+    scope 1 {
+        let _2: [Foo; 2];                // in scope 1 at $DIR/issue-72181.rs:26:9: 26:10
+        scope 2 {
+            debug f => _2;               // in scope 2 at $DIR/issue-72181.rs:26:9: 26:10
+            scope 3 {
+            }
+            scope 4 {
+            }
+        }
+    }
+
+    bb0: {
+        StorageLive(_1);                 // scope 0 at $DIR/issue-72181.rs:24:13: 24:34
+        _1 = const std::mem::size_of::<Foo>() -> [return: bb2, unwind: bb1]; // scope 0 at $DIR/issue-72181.rs:24:13: 24:34
+                                         // ty::Const
+                                         // + ty: fn() -> usize {std::mem::size_of::<Foo>}
+                                         // + val: Value(Scalar(<ZST>))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181.rs:24:13: 24:32
+                                         // + literal: Const { ty: fn() -> usize {std::mem::size_of::<Foo>}, val: Value(Scalar(<ZST>)) }
+    }
+
+    bb1 (cleanup): {
+        resume;                          // scope 0 at $DIR/issue-72181.rs:23:1: 28:2
+    }
+
+    bb2: {
+        StorageDead(_1);                 // scope 0 at $DIR/issue-72181.rs:24:34: 24:35
+        StorageLive(_2);                 // scope 1 at $DIR/issue-72181.rs:26:9: 26:10
+        StorageLive(_3);                 // scope 1 at $DIR/issue-72181.rs:26:14: 26:27
+        _3 = Foo { a: const 42u64 };     // scope 1 at $DIR/issue-72181.rs:26:14: 26:27
+                                         // ty::Const
+                                         // + ty: u64
+                                         // + val: Value(Scalar(0x000000000000002a))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181.rs:26:23: 26:25
+                                         // + literal: Const { ty: u64, val: Value(Scalar(0x000000000000002a)) }
+        StorageLive(_4);                 // scope 1 at $DIR/issue-72181.rs:26:29: 26:42
+        _4 = Foo { a: const 10u64 };     // scope 1 at $DIR/issue-72181.rs:26:29: 26:42
+                                         // ty::Const
+                                         // + ty: u64
+                                         // + val: Value(Scalar(0x000000000000000a))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181.rs:26:38: 26:40
+                                         // + literal: Const { ty: u64, val: Value(Scalar(0x000000000000000a)) }
+        _2 = [move _3, move _4];         // scope 1 at $DIR/issue-72181.rs:26:13: 26:43
+        StorageDead(_4);                 // scope 1 at $DIR/issue-72181.rs:26:42: 26:43
+        StorageDead(_3);                 // scope 1 at $DIR/issue-72181.rs:26:42: 26:43
+        FakeRead(ForLet, _2);            // scope 1 at $DIR/issue-72181.rs:26:9: 26:10
+        StorageLive(_5);                 // scope 2 at $DIR/issue-72181.rs:27:13: 27:30
+        StorageLive(_6);                 // scope 4 at $DIR/issue-72181.rs:27:24: 27:25
+        _6 = const 0usize;               // scope 4 at $DIR/issue-72181.rs:27:24: 27:25
+                                         // ty::Const
+                                         // + ty: usize
+                                         // + val: Value(Scalar(0x00000000))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181.rs:27:24: 27:25
+                                         // + literal: Const { ty: usize, val: Value(Scalar(0x00000000)) }
+        _7 = Len(_2);                    // scope 4 at $DIR/issue-72181.rs:27:22: 27:26
+        _8 = Lt(_6, _7);                 // scope 4 at $DIR/issue-72181.rs:27:22: 27:26
+        assert(move _8, "index out of bounds: the len is {} but the index is {}", move _7, _6) -> [success: bb3, unwind: bb1]; // scope 4 at $DIR/issue-72181.rs:27:22: 27:26
+    }
+
+    bb3: {
+        _5 = (_2[_6].0: u64);            // scope 4 at $DIR/issue-72181.rs:27:22: 27:28
+        StorageDead(_6);                 // scope 2 at $DIR/issue-72181.rs:27:30: 27:31
+        StorageDead(_5);                 // scope 2 at $DIR/issue-72181.rs:27:30: 27:31
+        _0 = const ();                   // scope 0 at $DIR/issue-72181.rs:23:11: 28:2
+                                         // ty::Const
+                                         // + ty: ()
+                                         // + val: Value(Scalar(<ZST>))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181.rs:23:11: 28:2
+                                         // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+        StorageDead(_2);                 // scope 1 at $DIR/issue-72181.rs:28:1: 28:2
+        goto -> bb4;                     // scope 0 at $DIR/issue-72181.rs:28:2: 28:2
+    }
+
+    bb4: {
+        return;                          // scope 0 at $DIR/issue-72181.rs:28:2: 28:2
+    }
+}
diff --git a/src/test/mir-opt/issue-72181/64bit/rustc.bar.mir_map.0.mir b/src/test/mir-opt/issue-72181/64bit/rustc.bar.mir_map.0.mir
new file mode 100644
index 00000000000..29654c2b1f8
--- /dev/null
+++ b/src/test/mir-opt/issue-72181/64bit/rustc.bar.mir_map.0.mir
@@ -0,0 +1,25 @@
+// MIR for `bar` 0 mir_map
+
+fn bar(_1: [(Never, u32); 1]) -> u32 {
+    let mut _0: u32;                     // return place in scope 0 at $DIR/issue-72181.rs:19:40: 19:43
+    let _2: u32;                         // in scope 0 at $DIR/issue-72181.rs:19:13: 19:14
+    scope 1 {
+        debug x => _2;                   // in scope 1 at $DIR/issue-72181.rs:19:13: 19:14
+    }
+
+    bb0: {
+        StorageLive(_2);                 // scope 0 at $DIR/issue-72181.rs:19:13: 19:14
+        _2 = (_1[0 of 1].1: u32);        // scope 0 at $DIR/issue-72181.rs:19:13: 19:14
+        _0 = _2;                         // scope 1 at $DIR/issue-72181.rs:19:46: 19:47
+        StorageDead(_2);                 // scope 0 at $DIR/issue-72181.rs:19:48: 19:49
+        goto -> bb2;                     // scope 0 at $DIR/issue-72181.rs:19:49: 19:49
+    }
+
+    bb1 (cleanup): {
+        resume;                          // scope 0 at $DIR/issue-72181.rs:19:1: 19:49
+    }
+
+    bb2: {
+        return;                          // scope 0 at $DIR/issue-72181.rs:19:49: 19:49
+    }
+}
diff --git a/src/test/mir-opt/issue-72181/64bit/rustc.foo.mir_map.0.mir b/src/test/mir-opt/issue-72181/64bit/rustc.foo.mir_map.0.mir
new file mode 100644
index 00000000000..639019eaf9c
--- /dev/null
+++ b/src/test/mir-opt/issue-72181/64bit/rustc.foo.mir_map.0.mir
@@ -0,0 +1,37 @@
+// MIR for `foo` 0 mir_map
+
+fn foo(_1: [(Never, u32); 1]) -> u32 {
+    debug xs => _1;                      // in scope 0 at $DIR/issue-72181.rs:16:8: 16:10
+    let mut _0: u32;                     // return place in scope 0 at $DIR/issue-72181.rs:16:34: 16:37
+    let _2: usize;                       // in scope 0 at $DIR/issue-72181.rs:16:43: 16:44
+    let mut _3: usize;                   // in scope 0 at $DIR/issue-72181.rs:16:40: 16:45
+    let mut _4: bool;                    // in scope 0 at $DIR/issue-72181.rs:16:40: 16:45
+
+    bb0: {
+        StorageLive(_2);                 // scope 0 at $DIR/issue-72181.rs:16:43: 16:44
+        _2 = const 0usize;               // scope 0 at $DIR/issue-72181.rs:16:43: 16:44
+                                         // ty::Const
+                                         // + ty: usize
+                                         // + val: Value(Scalar(0x0000000000000000))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181.rs:16:43: 16:44
+                                         // + literal: Const { ty: usize, val: Value(Scalar(0x0000000000000000)) }
+        _3 = Len(_1);                    // scope 0 at $DIR/issue-72181.rs:16:40: 16:45
+        _4 = Lt(_2, _3);                 // scope 0 at $DIR/issue-72181.rs:16:40: 16:45
+        assert(move _4, "index out of bounds: the len is {} but the index is {}", move _3, _2) -> [success: bb2, unwind: bb1]; // scope 0 at $DIR/issue-72181.rs:16:40: 16:45
+    }
+
+    bb1 (cleanup): {
+        resume;                          // scope 0 at $DIR/issue-72181.rs:16:1: 16:49
+    }
+
+    bb2: {
+        _0 = (_1[_2].1: u32);            // scope 0 at $DIR/issue-72181.rs:16:40: 16:47
+        StorageDead(_2);                 // scope 0 at $DIR/issue-72181.rs:16:48: 16:49
+        goto -> bb3;                     // scope 0 at $DIR/issue-72181.rs:16:49: 16:49
+    }
+
+    bb3: {
+        return;                          // scope 0 at $DIR/issue-72181.rs:16:49: 16:49
+    }
+}
diff --git a/src/test/mir-opt/issue-72181/64bit/rustc.main.mir_map.0.mir b/src/test/mir-opt/issue-72181/64bit/rustc.main.mir_map.0.mir
new file mode 100644
index 00000000000..4098e0e295c
--- /dev/null
+++ b/src/test/mir-opt/issue-72181/64bit/rustc.main.mir_map.0.mir
@@ -0,0 +1,93 @@
+// MIR for `main` 0 mir_map
+
+fn main() -> () {
+    let mut _0: ();                      // return place in scope 0 at $DIR/issue-72181.rs:23:11: 23:11
+    let mut _1: usize;                   // in scope 0 at $DIR/issue-72181.rs:24:13: 24:34
+    let mut _3: Foo;                     // in scope 0 at $DIR/issue-72181.rs:26:14: 26:27
+    let mut _4: Foo;                     // in scope 0 at $DIR/issue-72181.rs:26:29: 26:42
+    let mut _5: u64;                     // in scope 0 at $DIR/issue-72181.rs:27:13: 27:30
+    let _6: usize;                       // in scope 0 at $DIR/issue-72181.rs:27:24: 27:25
+    let mut _7: usize;                   // in scope 0 at $DIR/issue-72181.rs:27:22: 27:26
+    let mut _8: bool;                    // in scope 0 at $DIR/issue-72181.rs:27:22: 27:26
+    scope 1 {
+        let _2: [Foo; 2];                // in scope 1 at $DIR/issue-72181.rs:26:9: 26:10
+        scope 2 {
+            debug f => _2;               // in scope 2 at $DIR/issue-72181.rs:26:9: 26:10
+            scope 3 {
+            }
+            scope 4 {
+            }
+        }
+    }
+
+    bb0: {
+        StorageLive(_1);                 // scope 0 at $DIR/issue-72181.rs:24:13: 24:34
+        _1 = const std::mem::size_of::<Foo>() -> [return: bb2, unwind: bb1]; // scope 0 at $DIR/issue-72181.rs:24:13: 24:34
+                                         // ty::Const
+                                         // + ty: fn() -> usize {std::mem::size_of::<Foo>}
+                                         // + val: Value(Scalar(<ZST>))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181.rs:24:13: 24:32
+                                         // + literal: Const { ty: fn() -> usize {std::mem::size_of::<Foo>}, val: Value(Scalar(<ZST>)) }
+    }
+
+    bb1 (cleanup): {
+        resume;                          // scope 0 at $DIR/issue-72181.rs:23:1: 28:2
+    }
+
+    bb2: {
+        StorageDead(_1);                 // scope 0 at $DIR/issue-72181.rs:24:34: 24:35
+        StorageLive(_2);                 // scope 1 at $DIR/issue-72181.rs:26:9: 26:10
+        StorageLive(_3);                 // scope 1 at $DIR/issue-72181.rs:26:14: 26:27
+        _3 = Foo { a: const 42u64 };     // scope 1 at $DIR/issue-72181.rs:26:14: 26:27
+                                         // ty::Const
+                                         // + ty: u64
+                                         // + val: Value(Scalar(0x000000000000002a))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181.rs:26:23: 26:25
+                                         // + literal: Const { ty: u64, val: Value(Scalar(0x000000000000002a)) }
+        StorageLive(_4);                 // scope 1 at $DIR/issue-72181.rs:26:29: 26:42
+        _4 = Foo { a: const 10u64 };     // scope 1 at $DIR/issue-72181.rs:26:29: 26:42
+                                         // ty::Const
+                                         // + ty: u64
+                                         // + val: Value(Scalar(0x000000000000000a))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181.rs:26:38: 26:40
+                                         // + literal: Const { ty: u64, val: Value(Scalar(0x000000000000000a)) }
+        _2 = [move _3, move _4];         // scope 1 at $DIR/issue-72181.rs:26:13: 26:43
+        StorageDead(_4);                 // scope 1 at $DIR/issue-72181.rs:26:42: 26:43
+        StorageDead(_3);                 // scope 1 at $DIR/issue-72181.rs:26:42: 26:43
+        FakeRead(ForLet, _2);            // scope 1 at $DIR/issue-72181.rs:26:9: 26:10
+        StorageLive(_5);                 // scope 2 at $DIR/issue-72181.rs:27:13: 27:30
+        StorageLive(_6);                 // scope 4 at $DIR/issue-72181.rs:27:24: 27:25
+        _6 = const 0usize;               // scope 4 at $DIR/issue-72181.rs:27:24: 27:25
+                                         // ty::Const
+                                         // + ty: usize
+                                         // + val: Value(Scalar(0x0000000000000000))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181.rs:27:24: 27:25
+                                         // + literal: Const { ty: usize, val: Value(Scalar(0x0000000000000000)) }
+        _7 = Len(_2);                    // scope 4 at $DIR/issue-72181.rs:27:22: 27:26
+        _8 = Lt(_6, _7);                 // scope 4 at $DIR/issue-72181.rs:27:22: 27:26
+        assert(move _8, "index out of bounds: the len is {} but the index is {}", move _7, _6) -> [success: bb3, unwind: bb1]; // scope 4 at $DIR/issue-72181.rs:27:22: 27:26
+    }
+
+    bb3: {
+        _5 = (_2[_6].0: u64);            // scope 4 at $DIR/issue-72181.rs:27:22: 27:28
+        StorageDead(_6);                 // scope 2 at $DIR/issue-72181.rs:27:30: 27:31
+        StorageDead(_5);                 // scope 2 at $DIR/issue-72181.rs:27:30: 27:31
+        _0 = const ();                   // scope 0 at $DIR/issue-72181.rs:23:11: 28:2
+                                         // ty::Const
+                                         // + ty: ()
+                                         // + val: Value(Scalar(<ZST>))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181.rs:23:11: 28:2
+                                         // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+        StorageDead(_2);                 // scope 1 at $DIR/issue-72181.rs:28:1: 28:2
+        goto -> bb4;                     // scope 0 at $DIR/issue-72181.rs:28:2: 28:2
+    }
+
+    bb4: {
+        return;                          // scope 0 at $DIR/issue-72181.rs:28:2: 28:2
+    }
+}
diff --git a/src/test/mir-opt/issue-72181/rustc.bar.mir_map.0.mir b/src/test/mir-opt/issue-72181/rustc.bar.mir_map.0.mir
new file mode 100644
index 00000000000..3b6dc46d055
--- /dev/null
+++ b/src/test/mir-opt/issue-72181/rustc.bar.mir_map.0.mir
@@ -0,0 +1,25 @@
+// MIR for `bar` 0 mir_map
+
+fn bar(_1: [(Never, u32); 1]) -> u32 {
+    let mut _0: u32;                     // return place in scope 0 at $DIR/issue-72181.rs:18:40: 18:43
+    let _2: u32;                         // in scope 0 at $DIR/issue-72181.rs:18:13: 18:14
+    scope 1 {
+        debug x => _2;                   // in scope 1 at $DIR/issue-72181.rs:18:13: 18:14
+    }
+
+    bb0: {
+        StorageLive(_2);                 // scope 0 at $DIR/issue-72181.rs:18:13: 18:14
+        _2 = (_1[0 of 1].1: u32);        // scope 0 at $DIR/issue-72181.rs:18:13: 18:14
+        _0 = _2;                         // scope 1 at $DIR/issue-72181.rs:18:46: 18:47
+        StorageDead(_2);                 // scope 0 at $DIR/issue-72181.rs:18:48: 18:49
+        goto -> bb2;                     // scope 0 at $DIR/issue-72181.rs:18:49: 18:49
+    }
+
+    bb1 (cleanup): {
+        resume;                          // scope 0 at $DIR/issue-72181.rs:18:1: 18:49
+    }
+
+    bb2: {
+        return;                          // scope 0 at $DIR/issue-72181.rs:18:49: 18:49
+    }
+}
diff --git a/src/test/mir-opt/issue-72181/rustc.foo.mir_map.0.mir b/src/test/mir-opt/issue-72181/rustc.foo.mir_map.0.mir
new file mode 100644
index 00000000000..2941e282cf4
--- /dev/null
+++ b/src/test/mir-opt/issue-72181/rustc.foo.mir_map.0.mir
@@ -0,0 +1,37 @@
+// MIR for `foo` 0 mir_map
+
+fn foo(_1: [(Never, u32); 1]) -> u32 {
+    debug xs => _1;                      // in scope 0 at $DIR/issue-72181.rs:15:8: 15:10
+    let mut _0: u32;                     // return place in scope 0 at $DIR/issue-72181.rs:15:34: 15:37
+    let _2: usize;                       // in scope 0 at $DIR/issue-72181.rs:15:43: 15:44
+    let mut _3: usize;                   // in scope 0 at $DIR/issue-72181.rs:15:40: 15:45
+    let mut _4: bool;                    // in scope 0 at $DIR/issue-72181.rs:15:40: 15:45
+
+    bb0: {
+        StorageLive(_2);                 // scope 0 at $DIR/issue-72181.rs:15:43: 15:44
+        _2 = const 0usize;               // scope 0 at $DIR/issue-72181.rs:15:43: 15:44
+                                         // ty::Const
+                                         // + ty: usize
+                                         // + val: Value(Scalar(0x0000000000000000))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181.rs:15:43: 15:44
+                                         // + literal: Const { ty: usize, val: Value(Scalar(0x0000000000000000)) }
+        _3 = Len(_1);                    // scope 0 at $DIR/issue-72181.rs:15:40: 15:45
+        _4 = Lt(_2, _3);                 // scope 0 at $DIR/issue-72181.rs:15:40: 15:45
+        assert(move _4, "index out of bounds: the len is {} but the index is {}", move _3, _2) -> [success: bb2, unwind: bb1]; // scope 0 at $DIR/issue-72181.rs:15:40: 15:45
+    }
+
+    bb1 (cleanup): {
+        resume;                          // scope 0 at $DIR/issue-72181.rs:15:1: 15:49
+    }
+
+    bb2: {
+        _0 = (_1[_2].1: u32);            // scope 0 at $DIR/issue-72181.rs:15:40: 15:47
+        StorageDead(_2);                 // scope 0 at $DIR/issue-72181.rs:15:48: 15:49
+        goto -> bb3;                     // scope 0 at $DIR/issue-72181.rs:15:49: 15:49
+    }
+
+    bb3: {
+        return;                          // scope 0 at $DIR/issue-72181.rs:15:49: 15:49
+    }
+}
diff --git a/src/test/mir-opt/issue-72181/rustc.main.mir_map.0.mir b/src/test/mir-opt/issue-72181/rustc.main.mir_map.0.mir
new file mode 100644
index 00000000000..65f4de0e235
--- /dev/null
+++ b/src/test/mir-opt/issue-72181/rustc.main.mir_map.0.mir
@@ -0,0 +1,93 @@
+// MIR for `main` 0 mir_map
+
+fn main() -> () {
+    let mut _0: ();                      // return place in scope 0 at $DIR/issue-72181.rs:21:11: 21:11
+    let mut _1: usize;                   // in scope 0 at $DIR/issue-72181.rs:22:13: 22:34
+    let mut _3: Foo;                     // in scope 0 at $DIR/issue-72181.rs:24:14: 24:27
+    let mut _4: Foo;                     // in scope 0 at $DIR/issue-72181.rs:24:29: 24:42
+    let mut _5: u64;                     // in scope 0 at $DIR/issue-72181.rs:25:13: 25:30
+    let _6: usize;                       // in scope 0 at $DIR/issue-72181.rs:25:24: 25:25
+    let mut _7: usize;                   // in scope 0 at $DIR/issue-72181.rs:25:22: 25:26
+    let mut _8: bool;                    // in scope 0 at $DIR/issue-72181.rs:25:22: 25:26
+    scope 1 {
+        let _2: [Foo; 2];                // in scope 1 at $DIR/issue-72181.rs:24:9: 24:10
+        scope 2 {
+            debug f => _2;               // in scope 2 at $DIR/issue-72181.rs:24:9: 24:10
+            scope 3 {
+            }
+            scope 4 {
+            }
+        }
+    }
+
+    bb0: {
+        StorageLive(_1);                 // scope 0 at $DIR/issue-72181.rs:22:13: 22:34
+        _1 = const std::mem::size_of::<Foo>() -> [return: bb2, unwind: bb1]; // scope 0 at $DIR/issue-72181.rs:22:13: 22:34
+                                         // ty::Const
+                                         // + ty: fn() -> usize {std::mem::size_of::<Foo>}
+                                         // + val: Value(Scalar(<ZST>))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181.rs:22:13: 22:32
+                                         // + literal: Const { ty: fn() -> usize {std::mem::size_of::<Foo>}, val: Value(Scalar(<ZST>)) }
+    }
+
+    bb1 (cleanup): {
+        resume;                          // scope 0 at $DIR/issue-72181.rs:21:1: 26:2
+    }
+
+    bb2: {
+        StorageDead(_1);                 // scope 0 at $DIR/issue-72181.rs:22:34: 22:35
+        StorageLive(_2);                 // scope 1 at $DIR/issue-72181.rs:24:9: 24:10
+        StorageLive(_3);                 // scope 1 at $DIR/issue-72181.rs:24:14: 24:27
+        _3 = Foo { a: const 42u64 };     // scope 1 at $DIR/issue-72181.rs:24:14: 24:27
+                                         // ty::Const
+                                         // + ty: u64
+                                         // + val: Value(Scalar(0x000000000000002a))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181.rs:24:23: 24:25
+                                         // + literal: Const { ty: u64, val: Value(Scalar(0x000000000000002a)) }
+        StorageLive(_4);                 // scope 1 at $DIR/issue-72181.rs:24:29: 24:42
+        _4 = Foo { a: const 10u64 };     // scope 1 at $DIR/issue-72181.rs:24:29: 24:42
+                                         // ty::Const
+                                         // + ty: u64
+                                         // + val: Value(Scalar(0x000000000000000a))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181.rs:24:38: 24:40
+                                         // + literal: Const { ty: u64, val: Value(Scalar(0x000000000000000a)) }
+        _2 = [move _3, move _4];         // scope 1 at $DIR/issue-72181.rs:24:13: 24:43
+        StorageDead(_4);                 // scope 1 at $DIR/issue-72181.rs:24:42: 24:43
+        StorageDead(_3);                 // scope 1 at $DIR/issue-72181.rs:24:42: 24:43
+        FakeRead(ForLet, _2);            // scope 1 at $DIR/issue-72181.rs:24:9: 24:10
+        StorageLive(_5);                 // scope 2 at $DIR/issue-72181.rs:25:13: 25:30
+        StorageLive(_6);                 // scope 4 at $DIR/issue-72181.rs:25:24: 25:25
+        _6 = const 0usize;               // scope 4 at $DIR/issue-72181.rs:25:24: 25:25
+                                         // ty::Const
+                                         // + ty: usize
+                                         // + val: Value(Scalar(0x0000000000000000))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181.rs:25:24: 25:25
+                                         // + literal: Const { ty: usize, val: Value(Scalar(0x0000000000000000)) }
+        _7 = Len(_2);                    // scope 4 at $DIR/issue-72181.rs:25:22: 25:26
+        _8 = Lt(_6, _7);                 // scope 4 at $DIR/issue-72181.rs:25:22: 25:26
+        assert(move _8, "index out of bounds: the len is {} but the index is {}", move _7, _6) -> [success: bb3, unwind: bb1]; // scope 4 at $DIR/issue-72181.rs:25:22: 25:26
+    }
+
+    bb3: {
+        _5 = (_2[_6].0: u64);            // scope 4 at $DIR/issue-72181.rs:25:22: 25:28
+        StorageDead(_6);                 // scope 2 at $DIR/issue-72181.rs:25:30: 25:31
+        StorageDead(_5);                 // scope 2 at $DIR/issue-72181.rs:25:30: 25:31
+        _0 = const ();                   // scope 0 at $DIR/issue-72181.rs:21:11: 26:2
+                                         // ty::Const
+                                         // + ty: ()
+                                         // + val: Value(Scalar(<ZST>))
+                                         // mir::Constant
+                                         // + span: $DIR/issue-72181.rs:21:11: 26:2
+                                         // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+        StorageDead(_2);                 // scope 1 at $DIR/issue-72181.rs:26:1: 26:2
+        goto -> bb4;                     // scope 0 at $DIR/issue-72181.rs:26:2: 26:2
+    }
+
+    bb4: {
+        return;                          // scope 0 at $DIR/issue-72181.rs:26:2: 26:2
+    }
+}