Auto merge of #74019 - Manishearth:rollup-2st3jsk, r=Manishearth

Rollup of 12 pull requests

Successful merges:

 - #73140 (Fallback to xml.etree.ElementTree)
 - #73670 (Add `format_args_capture` feature)
 - #73693 (Use exhaustive match in const_prop.rs)
 - #73845 (Use &raw in A|Rc::as_ptr)
 - #73861 (Create E0768)
 - #73881 (Standardize bibliographic citations in rustc API docs)
 - #73925 (Improve comments from #72617, as suggested by RalfJung)
 - #73949 ([mir-opt] Fix mis-optimization and other issues with the SimplifyArmIdentity pass)
 - #73984 (Edit docs for rustc_data_structures::graph::scc)
 - #73985 (Fix "getting started" link)
 - #73997 (fix typo)
 - #73999 (Bump mingw-check CI image from Ubuntu 16.04 to 18.04.)

Failed merges:

 - #74000 (add `lazy_normalization_consts` feature gate)

r? @ghost

45 files changed, 1859 insertions, 123 deletions

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 373604adb05..aad495fa3fa 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -4,5 +4,5 @@ Thank you for your interest in contributing to Rust!
 
 To get started, read the [Getting Started] guide in the [rustc-dev-guide].
 
-[Getting Started]: https://rustc-dev-guide.rust-lang.org/getting-started.md
+[Getting Started]: https://rustc-dev-guide.rust-lang.org/getting-started.html
 [rustc-dev-guide]: https://rustc-dev-guide.rust-lang.org/
diff --git a/README.md b/README.md
index 70d3d51ce9b..639789123d8 100644
--- a/README.md
+++ b/README.md
@@ -26,7 +26,7 @@ The Rust build system uses a Python script called `x.py` to build the compiler,
 which manages the bootstrapping process. More information about it can be found 
 by running `./x.py --help` or reading the [rustc dev guide][rustcguidebuild].
 
-[gettingstarted]: https://rustc-dev-guide.rust-lang.org/getting-started.md
+[gettingstarted]: https://rustc-dev-guide.rust-lang.org/getting-started.html
 [rustcguidebuild]: https://rustc-dev-guide.rust-lang.org/building/how-to-build-and-run.html
 
 ### Building on a Unix-like system
diff --git a/src/ci/docker/host-x86_64/mingw-check/Dockerfile b/src/ci/docker/host-x86_64/mingw-check/Dockerfile
index e9570e8425e..e0607d298f4 100644
--- a/src/ci/docker/host-x86_64/mingw-check/Dockerfile
+++ b/src/ci/docker/host-x86_64/mingw-check/Dockerfile
@@ -1,4 +1,4 @@
-FROM ubuntu:16.04
+FROM ubuntu:18.04
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
   g++ \
diff --git a/src/doc/unstable-book/src/library-features/format-args-capture.md b/src/doc/unstable-book/src/library-features/format-args-capture.md
new file mode 100644
index 00000000000..64b1b3d81bd
--- /dev/null
+++ b/src/doc/unstable-book/src/library-features/format-args-capture.md
@@ -0,0 +1,47 @@
+# `format_args_capture`
+
+The tracking issue for this feature is: [#67984]
+
+[#67984]: https://github.com/rust-lang/rust/issues/67984
+
+------------------------
+
+Enables `format_args!` (and macros which use `format_args!` in their implementation, such
+as `format!`, `print!` and `panic!`) to capture variables from the surrounding scope.
+This avoids the need to pass named parameters when the binding in question
+already exists in scope.
+
+```rust
+#![feature(format_args_capture)]
+
+let (person, species, name) = ("Charlie Brown", "dog", "Snoopy");
+
+// captures named argument `person`
+print!("Hello {person}");
+
+// captures named arguments `species` and `name`
+format!("The {species}'s name is {name}.");
+```
+
+This also works for formatting parameters such as width and precision:
+
+```rust
+#![feature(format_args_capture)]
+
+let precision = 2;
+let s = format!("{:.precision$}", 1.324223);
+
+assert_eq!(&s, "1.32");
+```
+
+A non-exhaustive list of macros which benefit from this functionality include:
+- `format!`
+- `print!` and `println!`
+- `eprint!` and `eprintln!`
+- `write!` and `writeln!`
+- `panic!`
+- `unreachable!`
+- `unimplemented!`
+- `todo!`
+- `assert!` and similar
+- macros in many thirdparty crates, such as `log`
diff --git a/src/etc/htmldocck.py b/src/etc/htmldocck.py
index 7789b24b62c..2e7958325cd 100644
--- a/src/etc/htmldocck.py
+++ b/src/etc/htmldocck.py
@@ -114,7 +114,10 @@ try:
     from html.parser import HTMLParser
 except ImportError:
     from HTMLParser import HTMLParser
-from xml.etree import cElementTree as ET
+try:
+    from xml.etree import cElementTree as ET
+except ImportError:
+    from xml.etree import ElementTree as ET
 
 try:
     from html.entities import name2codepoint
diff --git a/src/liballoc/lib.rs b/src/liballoc/lib.rs
index 5f18fe8bfab..79bfd57a00f 100644
--- a/src/liballoc/lib.rs
+++ b/src/liballoc/lib.rs
@@ -100,6 +100,7 @@
 #![feature(fundamental)]
 #![feature(internal_uninit_const)]
 #![feature(lang_items)]
+#![feature(layout_for_ptr)]
 #![feature(libc)]
 #![feature(negative_impls)]
 #![feature(new_uninit)]
@@ -109,6 +110,7 @@
 #![feature(pattern)]
 #![feature(ptr_internals)]
 #![feature(ptr_offset_from)]
+#![feature(raw_ref_op)]
 #![feature(rustc_attrs)]
 #![feature(receiver_trait)]
 #![feature(min_specialization)]
diff --git a/src/liballoc/rc.rs b/src/liballoc/rc.rs
index 4d50ae9efca..fccdfa0dca9 100644
--- a/src/liballoc/rc.rs
+++ b/src/liballoc/rc.rs
@@ -245,7 +245,7 @@ use core::hash::{Hash, Hasher};
 use core::intrinsics::abort;
 use core::iter;
 use core::marker::{self, PhantomData, Unpin, Unsize};
-use core::mem::{self, align_of, align_of_val, forget, size_of_val};
+use core::mem::{self, align_of_val_raw, forget, size_of_val};
 use core::ops::{CoerceUnsized, Deref, DispatchFromDyn, Receiver};
 use core::pin::Pin;
 use core::ptr::{self, NonNull};
@@ -591,17 +591,11 @@ impl<T: ?Sized> Rc<T> {
     #[stable(feature = "weak_into_raw", since = "1.45.0")]
     pub fn as_ptr(this: &Self) -> *const T {
         let ptr: *mut RcBox<T> = NonNull::as_ptr(this.ptr);
-        let fake_ptr = ptr as *mut T;
 
-        // SAFETY: This cannot go through Deref::deref.
-        // Instead, we manually offset the pointer rather than manifesting a reference.
-        // This is so that the returned pointer retains the same provenance as our pointer.
-        // This is required so that e.g. `get_mut` can write through the pointer
-        // after the Rc is recovered through `from_raw`.
-        unsafe {
-            let offset = data_offset(&(*ptr).value);
-            set_data_ptr(fake_ptr, (ptr as *mut u8).offset(offset))
-        }
+        // SAFETY: This cannot go through Deref::deref or Rc::inner because
+        // this is required to retain raw/mut provenance such that e.g. `get_mut` can
+        // write through the pointer after the Rc is recovered through `from_raw`.
+        unsafe { &raw const (*ptr).value }
     }
 
     /// Constructs an `Rc<T>` from a raw pointer.
@@ -1647,6 +1641,7 @@ pub struct Weak<T: ?Sized> {
     // `Weak::new` sets this to `usize::MAX` so that it doesn’t need
     // to allocate space on the heap.  That's not a value a real pointer
     // will ever have because RcBox has alignment at least 2.
+    // This is only possible when `T: Sized`; unsized `T` never dangle.
     ptr: NonNull<RcBox<T>>,
 }
 
@@ -1708,9 +1703,18 @@ impl<T> Weak<T> {
     /// [`null`]: ../../std/ptr/fn.null.html
     #[stable(feature = "weak_into_raw", since = "1.45.0")]
     pub fn as_ptr(&self) -> *const T {
-        let offset = data_offset_sized::<T>();
-        let ptr = self.ptr.cast::<u8>().as_ptr().wrapping_offset(offset);
-        ptr as *const T
+        let ptr: *mut RcBox<T> = NonNull::as_ptr(self.ptr);
+
+        // SAFETY: we must offset the pointer manually, and said pointer may be
+        // a dangling weak (usize::MAX) if T is sized. data_offset is safe to call,
+        // because we know that a pointer to unsized T was derived from a real
+        // unsized T, as dangling weaks are only created for sized T. wrapping_offset
+        // is used so that we can use the same code path for the non-dangling
+        // unsized case and the potentially dangling sized case.
+        unsafe {
+            let offset = data_offset(ptr as *mut T);
+            set_data_ptr(ptr as *mut T, (ptr as *mut u8).wrapping_offset(offset))
+        }
     }
 
     /// Consumes the `Weak<T>` and turns it into a raw pointer.
@@ -2113,19 +2117,22 @@ impl<T: ?Sized> AsRef<T> for Rc<T> {
 #[stable(feature = "pin", since = "1.33.0")]
 impl<T: ?Sized> Unpin for Rc<T> {}
 
+/// Get the offset within an `ArcInner` for
+/// a payload of type described by a pointer.
+///
+/// # Safety
+///
+/// This has the same safety requirements as `align_of_val_raw`. In effect:
+///
+/// - This function is safe for any argument if `T` is sized, and
+/// - if `T` is unsized, the pointer must have appropriate pointer metadata
+///   aquired from the real instance that you are getting this offset for.
 unsafe fn data_offset<T: ?Sized>(ptr: *const T) -> isize {
     // Align the unsized value to the end of the `RcBox`.
     // Because it is ?Sized, it will always be the last field in memory.
     // Note: This is a detail of the current implementation of the compiler,
     // and is not a guaranteed language detail. Do not rely on it outside of std.
-    unsafe { data_offset_align(align_of_val(&*ptr)) }
-}
-
-/// Computes the offset of the data field within `RcBox`.
-///
-/// Unlike [`data_offset`], this doesn't need the pointer, but it works only on `T: Sized`.
-fn data_offset_sized<T>() -> isize {
-    data_offset_align(align_of::<T>())
+    unsafe { data_offset_align(align_of_val_raw(ptr)) }
 }
 
 #[inline]
diff --git a/src/liballoc/sync.rs b/src/liballoc/sync.rs
index 826f0c8fa83..ac3ce2255c8 100644
--- a/src/liballoc/sync.rs
+++ b/src/liballoc/sync.rs
@@ -16,7 +16,7 @@ use core::hash::{Hash, Hasher};
 use core::intrinsics::abort;
 use core::iter;
 use core::marker::{PhantomData, Unpin, Unsize};
-use core::mem::{self, align_of, align_of_val, size_of_val};
+use core::mem::{self, align_of_val, size_of_val};
 use core::ops::{CoerceUnsized, Deref, DispatchFromDyn, Receiver};
 use core::pin::Pin;
 use core::ptr::{self, NonNull};
@@ -267,6 +267,7 @@ pub struct Weak<T: ?Sized> {
     // `Weak::new` sets this to `usize::MAX` so that it doesn’t need
     // to allocate space on the heap.  That's not a value a real pointer
     // will ever have because RcBox has alignment at least 2.
+    // This is only possible when `T: Sized`; unsized `T` never dangle.
     ptr: NonNull<ArcInner<T>>,
 }
 
@@ -590,17 +591,11 @@ impl<T: ?Sized> Arc<T> {
     #[stable(feature = "weak_into_raw", since = "1.45.0")]
     pub fn as_ptr(this: &Self) -> *const T {
         let ptr: *mut ArcInner<T> = NonNull::as_ptr(this.ptr);
-        let fake_ptr = ptr as *mut T;
 
-        // SAFETY: This cannot go through Deref::deref.
-        // Instead, we manually offset the pointer rather than manifesting a reference.
-        // This is so that the returned pointer retains the same provenance as our pointer.
-        // This is required so that e.g. `get_mut` can write through the pointer
-        // after the Arc is recovered through `from_raw`.
-        unsafe {
-            let offset = data_offset(&(*ptr).data);
-            set_data_ptr(fake_ptr, (ptr as *mut u8).offset(offset))
-        }
+        // SAFETY: This cannot go through Deref::deref or RcBoxPtr::inner because
+        // this is required to retain raw/mut provenance such that e.g. `get_mut` can
+        // write through the pointer after the Rc is recovered through `from_raw`.
+        unsafe { &raw const (*ptr).data }
     }
 
     /// Constructs an `Arc<T>` from a raw pointer.
@@ -1476,9 +1471,18 @@ impl<T> Weak<T> {
     /// [`null`]: ../../std/ptr/fn.null.html
     #[stable(feature = "weak_into_raw", since = "1.45.0")]
     pub fn as_ptr(&self) -> *const T {
-        let offset = data_offset_sized::<T>();
-        let ptr = self.ptr.cast::<u8>().as_ptr().wrapping_offset(offset);
-        ptr as *const T
+        let ptr: *mut ArcInner<T> = NonNull::as_ptr(self.ptr);
+
+        // SAFETY: we must offset the pointer manually, and said pointer may be
+        // a dangling weak (usize::MAX) if T is sized. data_offset is safe to call,
+        // because we know that a pointer to unsized T was derived from a real
+        // unsized T, as dangling weaks are only created for sized T. wrapping_offset
+        // is used so that we can use the same code path for the non-dangling
+        // unsized case and the potentially dangling sized case.
+        unsafe {
+            let offset = data_offset(ptr as *mut T);
+            set_data_ptr(ptr as *mut T, (ptr as *mut u8).wrapping_offset(offset))
+        }
     }
 
     /// Consumes the `Weak<T>` and turns it into a raw pointer.
@@ -2270,7 +2274,16 @@ impl<T: ?Sized> AsRef<T> for Arc<T> {
 #[stable(feature = "pin", since = "1.33.0")]
 impl<T: ?Sized> Unpin for Arc<T> {}
 
-/// Computes the offset of the data field within `ArcInner`.
+/// Get the offset within an `ArcInner` for
+/// a payload of type described by a pointer.
+///
+/// # Safety
+///
+/// This has the same safety requirements as `align_of_val_raw`. In effect:
+///
+/// - This function is safe for any argument if `T` is sized, and
+/// - if `T` is unsized, the pointer must have appropriate pointer metadata
+///   aquired from the real instance that you are getting this offset for.
 unsafe fn data_offset<T: ?Sized>(ptr: *const T) -> isize {
     // Align the unsized value to the end of the `ArcInner`.
     // Because it is `?Sized`, it will always be the last field in memory.
@@ -2279,13 +2292,6 @@ unsafe fn data_offset<T: ?Sized>(ptr: *const T) -> isize {
     unsafe { data_offset_align(align_of_val(&*ptr)) }
 }
 
-/// Computes the offset of the data field within `ArcInner`.
-///
-/// Unlike [`data_offset`], this doesn't need the pointer, but it works only on `T: Sized`.
-fn data_offset_sized<T>() -> isize {
-    data_offset_align(align_of::<T>())
-}
-
 #[inline]
 fn data_offset_align(align: usize) -> isize {
     let layout = Layout::new::<ArcInner<()>>();
diff --git a/src/libcore/marker.rs b/src/libcore/marker.rs
index 6040dd31847..fdcfae8530a 100644
--- a/src/libcore/marker.rs
+++ b/src/libcore/marker.rs
@@ -694,7 +694,7 @@ mod impls {
 )]
 #[lang = "discriminant_kind"]
 pub trait DiscriminantKind {
-    /// The type of the dicriminant, which must satisfy the trait
+    /// The type of the discriminant, which must satisfy the trait
     /// bounds required by `mem::Discriminant`.
     type Discriminant: Clone + Copy + Debug + Eq + PartialEq + Hash + Send + Sync + Unpin;
 }
diff --git a/src/librustc_ast_pretty/pp.rs b/src/librustc_ast_pretty/pp.rs
index e6090db3284..4bb806a923e 100644
--- a/src/librustc_ast_pretty/pp.rs
+++ b/src/librustc_ast_pretty/pp.rs
@@ -1,10 +1,8 @@
 //! This pretty-printer is a direct reimplementation of Philip Karlton's
-//! Mesa pretty-printer, as described in appendix A of
-//!
-//! ```text
-//! STAN-CS-79-770: "Pretty Printing", by Derek C. Oppen.
-//! Stanford Department of Computer Science, 1979.
-//! ```
+//! Mesa pretty-printer, as described in the appendix to
+//! Derek C. Oppen, "Pretty Printing" (1979),
+//! Stanford Computer Science Department STAN-CS-79-770,
+//! <http://i.stanford.edu/pub/cstr/reports/cs/tr/79/770/CS-TR-79-770.pdf>.
 //!
 //! The algorithm's aim is to break a stream into as few lines as possible
 //! while respecting the indentation-consistency requirements of the enclosing
diff --git a/src/librustc_builtin_macros/format.rs b/src/librustc_builtin_macros/format.rs
index e574b076bf8..4cc83f8e31c 100644
--- a/src/librustc_builtin_macros/format.rs
+++ b/src/librustc_builtin_macros/format.rs
@@ -107,6 +107,9 @@ struct Context<'a, 'b> {
     arg_spans: Vec<Span>,
     /// All the formatting arguments that have formatting flags set, in order for diagnostics.
     arg_with_formatting: Vec<parse::FormatSpec<'a>>,
+
+    /// Whether this format string came from a string literal, as opposed to a macro.
+    is_literal: bool,
 }
 
 /// Parses the arguments from the given list of tokens, returning the diagnostic
@@ -498,10 +501,55 @@ impl<'a, 'b> Context<'a, 'b> {
                         self.verify_arg_type(Exact(idx), ty)
                     }
                     None => {
-                        let msg = format!("there is no argument named `{}`", name);
-                        let sp = *self.arg_spans.get(self.curpiece).unwrap_or(&self.fmtsp);
-                        let mut err = self.ecx.struct_span_err(sp, &msg[..]);
-                        err.emit();
+                        let capture_feature_enabled = self
+                            .ecx
+                            .ecfg
+                            .features
+                            .map_or(false, |features| features.format_args_capture);
+
+                        // For the moment capturing variables from format strings expanded from macros is
+                        // disabled (see RFC #2795)
+                        let can_capture = capture_feature_enabled && self.is_literal;
+
+                        if can_capture {
+                            // Treat this name as a variable to capture from the surrounding scope
+                            let idx = self.args.len();
+                            self.arg_types.push(Vec::new());
+                            self.arg_unique_types.push(Vec::new());
+                            self.args.push(
+                                self.ecx.expr_ident(self.fmtsp, Ident::new(name, self.fmtsp)),
+                            );
+                            self.names.insert(name, idx);
+                            self.verify_arg_type(Exact(idx), ty)
+                        } else {
+                            let msg = format!("there is no argument named `{}`", name);
+                            let sp = if self.is_literal {
+                                *self.arg_spans.get(self.curpiece).unwrap_or(&self.fmtsp)
+                            } else {
+                                self.fmtsp
+                            };
+                            let mut err = self.ecx.struct_span_err(sp, &msg[..]);
+
+                            if capture_feature_enabled && !self.is_literal {
+                                err.note(&format!(
+                                    "did you intend to capture a variable `{}` from \
+                                     the surrounding scope?",
+                                    name
+                                ));
+                                err.note(
+                                    "to avoid ambiguity, `format_args!` cannot capture variables \
+                                     when the format string is expanded from a macro",
+                                );
+                            } else if self.ecx.parse_sess().unstable_features.is_nightly_build() {
+                                err.help(&format!(
+                                    "if you intended to capture `{}` from the surrounding scope, add \
+                                     `#![feature(format_args_capture)]` to the crate attributes",
+                                    name
+                                ));
+                            }
+
+                            err.emit();
+                        }
                     }
                 }
             }
@@ -951,6 +999,7 @@ pub fn expand_preparsed_format_args(
         invalid_refs: Vec::new(),
         arg_spans,
         arg_with_formatting: Vec::new(),
+        is_literal: parser.is_literal,
     };
 
     // This needs to happen *after* the Parser has consumed all pieces to create all the spans
diff --git a/src/librustc_data_structures/graph/dominators/mod.rs b/src/librustc_data_structures/graph/dominators/mod.rs
index a7f9340dead..438a0d0c6ff 100644
--- a/src/librustc_data_structures/graph/dominators/mod.rs
+++ b/src/librustc_data_structures/graph/dominators/mod.rs
@@ -1,8 +1,9 @@
-//! Algorithm citation:
-//! A Simple, Fast Dominance Algorithm.
-//! Keith D. Cooper, Timothy J. Harvey, and Ken Kennedy
-//! Rice Computer Science TS-06-33870
-//! <https://www.cs.rice.edu/~keith/EMBED/dom.pdf>
+//! Finding the dominators in a control-flow graph.
+//!
+//! Algorithm based on Keith D. Cooper, Timothy J. Harvey, and Ken Kennedy,
+//! "A Simple, Fast Dominance Algorithm",
+//! Rice Computer Science TS-06-33870,
+//! <https://www.cs.rice.edu/~keith/EMBED/dom.pdf>.
 
 use super::iterate::reverse_post_order;
 use super::ControlFlowGraph;
diff --git a/src/librustc_data_structures/graph/scc/mod.rs b/src/librustc_data_structures/graph/scc/mod.rs
index 57eaf56f268..2db8e466e11 100644
--- a/src/librustc_data_structures/graph/scc/mod.rs
+++ b/src/librustc_data_structures/graph/scc/mod.rs
@@ -1,7 +1,9 @@
-//! Routine to compute the strongly connected components (SCCs) of a
-//! graph, as well as the resulting DAG if each SCC is replaced with a
-//! node in the graph. This uses Tarjan's algorithm that completes in
-//! O(n) time.
+//! Routine to compute the strongly connected components (SCCs) of a graph.
+//!
+//! Also computes as the resulting DAG if each SCC is replaced with a
+//! node in the graph. This uses [Tarjan's algorithm](
+//! https://en.wikipedia.org/wiki/Tarjan%27s_strongly_connected_components_algorithm)
+//! that completes in *O(n)* time.
 
 use crate::fx::FxHashSet;
 use crate::graph::vec_graph::VecGraph;
diff --git a/src/librustc_error_codes/error_codes.rs b/src/librustc_error_codes/error_codes.rs
index 00c072e1b04..f687221d78e 100644
--- a/src/librustc_error_codes/error_codes.rs
+++ b/src/librustc_error_codes/error_codes.rs
@@ -449,6 +449,7 @@ E0764: include_str!("./error_codes/E0764.md"),
 E0765: include_str!("./error_codes/E0765.md"),
 E0766: include_str!("./error_codes/E0766.md"),
 E0767: include_str!("./error_codes/E0767.md"),
+E0768: include_str!("./error_codes/E0768.md"),
 ;
 //  E0006, // merged with E0005
 //  E0008, // cannot bind by-move into a pattern guard
diff --git a/src/librustc_error_codes/error_codes/E0768.md b/src/librustc_error_codes/error_codes/E0768.md
new file mode 100644
index 00000000000..24169ef512e
--- /dev/null
+++ b/src/librustc_error_codes/error_codes/E0768.md
@@ -0,0 +1,13 @@
+A number in a non-decimal base has no digits.
+
+Erroneous code example:
+
+```compile_fail,E0768
+let s: i32 = 0b; // error!
+```
+
+To fix this error, add the missing digits:
+
+```
+let s: i32 = 0b1; // ok!
+```
diff --git a/src/librustc_feature/active.rs b/src/librustc_feature/active.rs
index b9a55377949..313744efb3f 100644
--- a/src/librustc_feature/active.rs
+++ b/src/librustc_feature/active.rs
@@ -567,6 +567,9 @@ declare_features! (
     /// Be more precise when looking for live drops in a const context.
     (active, const_precise_live_drops, "1.46.0", Some(73255), None),
 
+    /// Allows capturing variables in scope using format_args!
+    (active, format_args_capture, "1.46.0", Some(67984), None),
+
     // -------------------------------------------------------------------------
     // feature-group-end: actual feature gates
     // -------------------------------------------------------------------------
diff --git a/src/librustc_middle/mir/mod.rs b/src/librustc_middle/mir/mod.rs
index ad4e8b55b75..31b8de500e0 100644
--- a/src/librustc_middle/mir/mod.rs
+++ b/src/librustc_middle/mir/mod.rs
@@ -257,6 +257,18 @@ impl<'tcx> Body<'tcx> {
         (&mut self.basic_blocks, &mut self.local_decls)
     }
 
+    #[inline]
+    pub fn basic_blocks_local_decls_mut_and_var_debug_info(
+        &mut self,
+    ) -> (
+        &mut IndexVec<BasicBlock, BasicBlockData<'tcx>>,
+        &mut LocalDecls<'tcx>,
+        &mut Vec<VarDebugInfo<'tcx>>,
+    ) {
+        self.predecessor_cache.invalidate();
+        (&mut self.basic_blocks, &mut self.local_decls, &mut self.var_debug_info)
+    }
+
     /// Returns `true` if a cycle exists in the control-flow graph that is reachable from the
     /// `START_BLOCK`.
     pub fn is_cfg_cyclic(&self) -> bool {
diff --git a/src/librustc_mir/transform/const_prop.rs b/src/librustc_mir/transform/const_prop.rs
index 2c1565b5426..e4c1ca4e851 100644
--- a/src/librustc_mir/transform/const_prop.rs
+++ b/src/librustc_mir/transform/const_prop.rs
@@ -638,8 +638,20 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
 
                 return None;
             }
+            Rvalue::ThreadLocalRef(def_id) => {
+                trace!("skipping ThreadLocalRef({:?})", def_id);
 
-            _ => {}
+                return None;
+            }
+
+            // There's no other checking to do at this time.
+            Rvalue::Aggregate(..)
+            | Rvalue::Use(..)
+            | Rvalue::Repeat(..)
+            | Rvalue::Len(..)
+            | Rvalue::Cast(..)
+            | Rvalue::Discriminant(..)
+            | Rvalue::NullaryOp(..) => {}
         }
 
         // FIXME we need to revisit this for #67176
diff --git a/src/librustc_mir/transform/simplify_try.rs b/src/librustc_mir/transform/simplify_try.rs
index 50136ac3bec..97a01de867e 100644
--- a/src/librustc_mir/transform/simplify_try.rs
+++ b/src/librustc_mir/transform/simplify_try.rs
@@ -11,9 +11,10 @@
 
 use crate::transform::{simplify, MirPass, MirSource};
 use itertools::Itertools as _;
-use rustc_index::vec::IndexVec;
+use rustc_index::{bit_set::BitSet, vec::IndexVec};
+use rustc_middle::mir::visit::{NonUseContext, PlaceContext, Visitor};
 use rustc_middle::mir::*;
-use rustc_middle::ty::{Ty, TyCtxt};
+use rustc_middle::ty::{List, Ty, TyCtxt};
 use rustc_target::abi::VariantIdx;
 use std::iter::{Enumerate, Peekable};
 use std::slice::Iter;
@@ -73,9 +74,20 @@ struct ArmIdentityInfo<'tcx> {
 
     /// The statements that should be removed (turned into nops)
     stmts_to_remove: Vec<usize>,
+
+    /// Indices of debug variables that need to be adjusted to point to
+    // `{local_0}.{dbg_projection}`.
+    dbg_info_to_adjust: Vec<usize>,
+
+    /// The projection used to rewrite debug info.
+    dbg_projection: &'tcx List<PlaceElem<'tcx>>,
 }
 
-fn get_arm_identity_info<'a, 'tcx>(stmts: &'a [Statement<'tcx>]) -> Option<ArmIdentityInfo<'tcx>> {
+fn get_arm_identity_info<'a, 'tcx>(
+    stmts: &'a [Statement<'tcx>],
+    locals_count: usize,
+    debug_info: &'a [VarDebugInfo<'tcx>],
+) -> Option<ArmIdentityInfo<'tcx>> {
     // This can't possibly match unless there are at least 3 statements in the block
     // so fail fast on tiny blocks.
     if stmts.len() < 3 {
@@ -187,7 +199,7 @@ fn get_arm_identity_info<'a, 'tcx>(stmts: &'a [Statement<'tcx>]) -> Option<ArmId
     try_eat_storage_stmts(&mut stmt_iter, &mut storage_live_stmts, &mut storage_dead_stmts);
 
     let (get_variant_field_stmt, stmt) = stmt_iter.next()?;
-    let (local_tmp_s0, local_1, vf_s0) = match_get_variant_field(stmt)?;
+    let (local_tmp_s0, local_1, vf_s0, dbg_projection) = match_get_variant_field(stmt)?;
 
     try_eat_storage_stmts(&mut stmt_iter, &mut storage_live_stmts, &mut storage_dead_stmts);
 
@@ -228,6 +240,19 @@ fn get_arm_identity_info<'a, 'tcx>(stmts: &'a [Statement<'tcx>]) -> Option<ArmId
     let stmt_to_overwrite =
         nop_stmts.iter().find(|stmt_idx| live_idx < **stmt_idx && **stmt_idx < dead_idx);
 
+    let mut tmp_assigned_vars = BitSet::new_empty(locals_count);
+    for (l, r) in &tmp_assigns {
+        tmp_assigned_vars.insert(*l);
+        tmp_assigned_vars.insert(*r);
+    }
+
+    let mut dbg_info_to_adjust = Vec::new();
+    for (i, var_info) in debug_info.iter().enumerate() {
+        if tmp_assigned_vars.contains(var_info.place.local) {
+            dbg_info_to_adjust.push(i);
+        }
+    }
+
     Some(ArmIdentityInfo {
         local_temp_0: local_tmp_s0,
         local_1,
@@ -243,12 +268,16 @@ fn get_arm_identity_info<'a, 'tcx>(stmts: &'a [Statement<'tcx>]) -> Option<ArmId
         source_info: discr_stmt_source_info,
         storage_stmts,
         stmts_to_remove: nop_stmts,
+        dbg_info_to_adjust,
+        dbg_projection,
     })
 }
 
 fn optimization_applies<'tcx>(
     opt_info: &ArmIdentityInfo<'tcx>,
     local_decls: &IndexVec<Local, LocalDecl<'tcx>>,
+    local_uses: &IndexVec<Local, usize>,
+    var_debug_info: &[VarDebugInfo<'tcx>],
 ) -> bool {
     trace!("testing if optimization applies...");
 
@@ -273,6 +302,7 @@ fn optimization_applies<'tcx>(
     // Verify the assigment chain consists of the form b = a; c = b; d = c; etc...
     if opt_info.field_tmp_assignments.is_empty() {
         trace!("NO: no assignments found");
+        return false;
     }
     let mut last_assigned_to = opt_info.field_tmp_assignments[0].1;
     let source_local = last_assigned_to;
@@ -285,6 +315,35 @@ fn optimization_applies<'tcx>(
         last_assigned_to = *l;
     }
 
+    // Check that the first and last used locals are only used twice
+    // since they are of the form:
+    //
+    // ```
+    // _first = ((_x as Variant).n: ty);
+    // _n = _first;
+    // ...
+    // ((_y as Variant).n: ty) = _n;
+    // discriminant(_y) = z;
+    // ```
+    for (l, r) in &opt_info.field_tmp_assignments {
+        if local_uses[*l] != 2 {
+            warn!("NO: FAILED assignment chain local {:?} was used more than twice", l);
+            return false;
+        } else if local_uses[*r] != 2 {
+            warn!("NO: FAILED assignment chain local {:?} was used more than twice", r);
+            return false;
+        }
+    }
+
+    // Check that debug info only points to full Locals and not projections.
+    for dbg_idx in &opt_info.dbg_info_to_adjust {
+        let dbg_info = &var_debug_info[*dbg_idx];
+        if !dbg_info.place.projection.is_empty() {
+            trace!("NO: debug info for {:?} had a projection {:?}", dbg_info.name, dbg_info.place);
+            return false;
+        }
+    }
+
     if source_local != opt_info.local_temp_0 {
         trace!(
             "NO: start of assignment chain does not match enum variant temp: {:?} != {:?}",
@@ -312,11 +371,15 @@ impl<'tcx> MirPass<'tcx> for SimplifyArmIdentity {
         }
 
         trace!("running SimplifyArmIdentity on {:?}", source);
-        let (basic_blocks, local_decls) = body.basic_blocks_and_local_decls_mut();
+        let local_uses = LocalUseCounter::get_local_uses(body);
+        let (basic_blocks, local_decls, debug_info) =
+            body.basic_blocks_local_decls_mut_and_var_debug_info();
         for bb in basic_blocks {
-            if let Some(opt_info) = get_arm_identity_info(&bb.statements) {
+            if let Some(opt_info) =
+                get_arm_identity_info(&bb.statements, local_decls.len(), debug_info)
+            {
                 trace!("got opt_info = {:#?}", opt_info);
-                if !optimization_applies(&opt_info, local_decls) {
+                if !optimization_applies(&opt_info, local_decls, &local_uses, &debug_info) {
                     debug!("optimization skipped for {:?}", source);
                     continue;
                 }
@@ -352,23 +415,57 @@ impl<'tcx> MirPass<'tcx> for SimplifyArmIdentity {
 
                 bb.statements.retain(|stmt| stmt.kind != StatementKind::Nop);
 
+                // Fix the debug info to point to the right local
+                for dbg_index in opt_info.dbg_info_to_adjust {
+                    let dbg_info = &mut debug_info[dbg_index];
+                    assert!(dbg_info.place.projection.is_empty());
+                    dbg_info.place.local = opt_info.local_0;
+                    dbg_info.place.projection = opt_info.dbg_projection;
+                }
+
                 trace!("block is now {:?}", bb.statements);
             }
         }
     }
 }
 
+struct LocalUseCounter {
+    local_uses: IndexVec<Local, usize>,
+}
+
+impl LocalUseCounter {
+    fn get_local_uses<'tcx>(body: &Body<'tcx>) -> IndexVec<Local, usize> {
+        let mut counter = LocalUseCounter { local_uses: IndexVec::from_elem(0, &body.local_decls) };
+        counter.visit_body(body);
+        counter.local_uses
+    }
+}
+
+impl<'tcx> Visitor<'tcx> for LocalUseCounter {
+    fn visit_local(&mut self, local: &Local, context: PlaceContext, _location: Location) {
+        if context.is_storage_marker()
+            || context == PlaceContext::NonUse(NonUseContext::VarDebugInfo)
+        {
+            return;
+        }
+
+        self.local_uses[*local] += 1;
+    }
+}
+
 /// Match on:
 /// ```rust
 /// _LOCAL_INTO = ((_LOCAL_FROM as Variant).FIELD: TY);
 /// ```
-fn match_get_variant_field<'tcx>(stmt: &Statement<'tcx>) -> Option<(Local, Local, VarField<'tcx>)> {
+fn match_get_variant_field<'tcx>(
+    stmt: &Statement<'tcx>,
+) -> Option<(Local, Local, VarField<'tcx>, &'tcx List<PlaceElem<'tcx>>)> {
     match &stmt.kind {
         StatementKind::Assign(box (place_into, rvalue_from)) => match rvalue_from {
             Rvalue::Use(Operand::Copy(pf) | Operand::Move(pf)) => {
                 let local_into = place_into.as_local()?;
                 let (local_from, vf) = match_variant_field_place(*pf)?;
-                Some((local_into, local_from, vf))
+                Some((local_into, local_from, vf, pf.projection))
             }
             _ => None,
         },
diff --git a/src/librustc_parse/lexer/mod.rs b/src/librustc_parse/lexer/mod.rs
index 5050f03bea9..2b0e637c74e 100644
--- a/src/librustc_parse/lexer/mod.rs
+++ b/src/librustc_parse/lexer/mod.rs
@@ -391,7 +391,14 @@ impl<'a> StringReader<'a> {
             }
             rustc_lexer::LiteralKind::Int { base, empty_int } => {
                 return if empty_int {
-                    self.err_span_(start, suffix_start, "no valid digits found for number");
+                    self.sess
+                        .span_diagnostic
+                        .struct_span_err_with_code(
+                            self.mk_sp(start, suffix_start),
+                            "no valid digits found for number",
+                            error_code!(E0768),
+                        )
+                        .emit();
                     (token::Integer, sym::integer(0))
                 } else {
                     self.validate_int_literal(base, start, suffix_start);
diff --git a/src/librustc_parse_format/lib.rs b/src/librustc_parse_format/lib.rs
index a5b5a1090cb..7db62f3493e 100644
--- a/src/librustc_parse_format/lib.rs
+++ b/src/librustc_parse_format/lib.rs
@@ -190,7 +190,7 @@ pub struct Parser<'a> {
     /// Whether the source string is comes from `println!` as opposed to `format!` or `print!`
     append_newline: bool,
     /// Whether this formatting string is a literal or it comes from a macro.
-    is_literal: bool,
+    pub is_literal: bool,
     /// Start position of the current line.
     cur_line_start: usize,
     /// Start and end byte offset of every line of the format string. Excludes
diff --git a/src/librustc_span/hygiene.rs b/src/librustc_span/hygiene.rs
index 90f4cc09660..fef1e34a23b 100644
--- a/src/librustc_span/hygiene.rs
+++ b/src/librustc_span/hygiene.rs
@@ -1,9 +1,8 @@
-//! Machinery for hygienic macros, inspired by the `MTWT[1]` paper.
+//! Machinery for hygienic macros.
 //!
-//! `[1]` Matthew Flatt, Ryan Culpepper, David Darais, and Robert Bruce Findler. 2012.
-//! *Macros that work together: Compile-time bindings, partial expansion,
-//! and definition contexts*. J. Funct. Program. 22, 2 (March 2012), 181-216.
-//! DOI=10.1017/S0956796812000093 <https://doi.org/10.1017/S0956796812000093>
+//! Inspired by Matthew Flatt et al., “Macros That Work Together: Compile-Time Bindings, Partial
+//! Expansion, and Definition Contexts,” *Journal of Functional Programming* 22, no. 2
+//! (March 1, 2012): 181–216, <https://doi.org/10.1017/S0956796812000093>.
 
 // Hygiene data is stored in a global variable and accessed via TLS, which
 // means that accesses are somewhat expensive. (`HygieneData::with`
diff --git a/src/librustc_span/symbol.rs b/src/librustc_span/symbol.rs
index 12ac2ed1c0b..acc2a50abe8 100644
--- a/src/librustc_span/symbol.rs
+++ b/src/librustc_span/symbol.rs
@@ -342,6 +342,7 @@ symbols! {
         forbid,
         format_args,
         format_args_nl,
+        format_args_capture,
         from,
         From,
         from_desugaring,
diff --git a/src/libstd/panicking.rs b/src/libstd/panicking.rs
index 97d62d958ca..9542e7209b4 100644
--- a/src/libstd/panicking.rs
+++ b/src/libstd/panicking.rs
@@ -229,10 +229,10 @@ pub mod panic_count {
     thread_local! { static LOCAL_PANIC_COUNT: Cell<usize> = Cell::new(0) }
 
     // Sum of panic counts from all threads. The purpose of this is to have
-    // a fast path in `is_zero` (which is used by `panicking`). Access to
-    // this variable can be always be done with relaxed ordering because
-    // it is always guaranteed that, if `GLOBAL_PANIC_COUNT` is zero,
-    // `LOCAL_PANIC_COUNT` will be zero.
+    // a fast path in `is_zero` (which is used by `panicking`). In any particular
+    // thread, if that thread currently views `GLOBAL_PANIC_COUNT` as being zero,
+    // then `LOCAL_PANIC_COUNT` in that thread is zero. This invariant holds before
+    // and after increase and decrease, but not necessarily during their execution.
     static GLOBAL_PANIC_COUNT: AtomicUsize = AtomicUsize::new(0);
 
     pub fn increase() -> usize {
@@ -263,6 +263,12 @@ pub mod panic_count {
             // Fast path: if `GLOBAL_PANIC_COUNT` is zero, all threads
             // (including the current one) will have `LOCAL_PANIC_COUNT`
             // equal to zero, so TLS access can be avoided.
+            //
+            // In terms of performance, a relaxed atomic load is similar to a normal
+            // aligned memory read (e.g., a mov instruction in x86), but with some
+            // compiler optimization restrictions. On the other hand, a TLS access
+            // might require calling a non-inlinable function (such as `__tls_get_addr`
+            // when using the GD TLS model).
             true
         } else {
             is_zero_slow_path()
diff --git a/src/test/mir-opt/issue-73223.rs b/src/test/mir-opt/issue-73223.rs
new file mode 100644
index 00000000000..d93805e6cd1
--- /dev/null
+++ b/src/test/mir-opt/issue-73223.rs
@@ -0,0 +1,13 @@
+fn main() {
+    let split = match Some(1) {
+        Some(v) => v,
+        None => return,
+    };
+
+    let _prev = Some(split);
+    assert_eq!(split, 1);
+}
+
+// EMIT_MIR_FOR_EACH_BIT_WIDTH
+// EMIT_MIR rustc.main.SimplifyArmIdentity.diff
+// EMIT_MIR rustc.main.PreCodegen.diff
diff --git a/src/test/mir-opt/issue-73223/32bit/rustc.main.PreCodegen.diff b/src/test/mir-opt/issue-73223/32bit/rustc.main.PreCodegen.diff
new file mode 100644
index 00000000000..59c00e1b96f
--- /dev/null
+++ b/src/test/mir-opt/issue-73223/32bit/rustc.main.PreCodegen.diff
@@ -0,0 +1,252 @@
+- // MIR for `main` before PreCodegen
++ // MIR for `main` after PreCodegen
+  
+  fn main() -> () {
+      let mut _0: ();                      // return place in scope 0 at $DIR/issue-73223.rs:1:11: 1:11
+      let mut _1: std::option::Option<i32>; // in scope 0 at $DIR/issue-73223.rs:2:23: 2:30
+      let _2: i32;                         // in scope 0 at $DIR/issue-73223.rs:3:14: 3:15
+      let mut _4: i32;                     // in scope 0 at $DIR/issue-73223.rs:7:22: 7:27
+      let mut _5: (&i32, &i32);            // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _6: &i32;                    // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _9: bool;                    // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _10: bool;                   // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _11: i32;                    // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _12: i32;                    // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _13: &std::fmt::Arguments;       // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let _14: std::fmt::Arguments;        // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _15: &[&str];                // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _16: &[std::fmt::ArgumentV1]; // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let _17: &[std::fmt::ArgumentV1; 2]; // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let _18: [std::fmt::ArgumentV1; 2];  // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _19: (&&i32, &&i32);         // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _20: &&i32;                  // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _21: &i32;                       // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _22: &&i32;                  // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _23: &i32;                       // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _26: std::fmt::ArgumentV1;   // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _27: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _28: std::fmt::ArgumentV1;   // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _29: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      scope 1 {
+          debug split => _2;               // in scope 1 at $DIR/issue-73223.rs:2:9: 2:14
+          let _3: std::option::Option<i32>; // in scope 1 at $DIR/issue-73223.rs:7:9: 7:14
+          scope 3 {
+              debug _prev => _3;           // in scope 3 at $DIR/issue-73223.rs:7:9: 7:14
+              let _7: &i32;                // in scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+              let _8: &i32;                // in scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+              scope 4 {
+                  debug left_val => _7;    // in scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                  debug right_val => _8;   // in scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                  let _24: &&i32;          // in scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                  let _25: &&i32;          // in scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                  scope 5 {
+                      debug arg0 => _24;   // in scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                      debug arg1 => _25;   // in scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                      scope 6 {
+                          debug x => _24;  // in scope 6 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                          debug f => _27;  // in scope 6 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                          let mut _30: for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 6 at $SRC_DIR/libstd/macros.rs:LL:COL
+                          let mut _31: &core::fmt::Opaque; // in scope 6 at $SRC_DIR/libstd/macros.rs:LL:COL
+                      }
+                      scope 8 {
+                          debug x => _25;  // in scope 8 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                          debug f => _29;  // in scope 8 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                          let mut _32: for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 8 at $SRC_DIR/libstd/macros.rs:LL:COL
+                          let mut _33: &core::fmt::Opaque; // in scope 8 at $SRC_DIR/libstd/macros.rs:LL:COL
+                      }
+                  }
+                  scope 10 {
+                      debug pieces => _15; // in scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                      debug args => _16;   // in scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                      let mut _34: std::option::Option<&[std::fmt::rt::v1::Argument]>; // in scope 10 at $SRC_DIR/libstd/macros.rs:LL:COL
+                  }
+              }
+          }
+      }
+      scope 2 {
+          debug v => _2;                   // in scope 2 at $DIR/issue-73223.rs:3:14: 3:15
+      }
+      scope 7 {
+      }
+      scope 9 {
+      }
+  
+      bb0: {
+          StorageLive(_1);                 // scope 0 at $DIR/issue-73223.rs:2:23: 2:30
+          ((_1 as Some).0: i32) = const 1_i32; // scope 0 at $DIR/issue-73223.rs:2:23: 2:30
+                                           // ty::Const
+                                           // + ty: i32
+                                           // + val: Value(Scalar(0x00000001))
+                                           // mir::Constant
+                                           // + span: $DIR/issue-73223.rs:2:28: 2:29
+                                           // + literal: Const { ty: i32, val: Value(Scalar(0x00000001)) }
+          discriminant(_1) = 1;            // scope 0 at $DIR/issue-73223.rs:2:23: 2:30
+          _2 = ((_1 as Some).0: i32);      // scope 0 at $DIR/issue-73223.rs:3:14: 3:15
+          StorageDead(_1);                 // scope 0 at $DIR/issue-73223.rs:5:6: 5:7
+          StorageLive(_3);                 // scope 1 at $DIR/issue-73223.rs:7:9: 7:14
+          StorageLive(_4);                 // scope 1 at $DIR/issue-73223.rs:7:22: 7:27
+          _4 = _2;                         // scope 1 at $DIR/issue-73223.rs:7:22: 7:27
+          ((_3 as Some).0: i32) = move _4; // scope 1 at $DIR/issue-73223.rs:7:17: 7:28
+          discriminant(_3) = 1;            // scope 1 at $DIR/issue-73223.rs:7:17: 7:28
+          StorageDead(_4);                 // scope 1 at $DIR/issue-73223.rs:7:27: 7:28
+          StorageLive(_5);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_6);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _6 = &_2;                        // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          (_5.0: &i32) = move _6;          // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          (_5.1: &i32) = const main::promoted[1]; // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: &i32
+                                           // + val: Unevaluated(DefId(0:3 ~ issue_73223[317d]::main[0]), [], Some(promoted[1]))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // + literal: Const { ty: &i32, val: Unevaluated(DefId(0:3 ~ issue_73223[317d]::main[0]), [], Some(promoted[1])) }
+          StorageDead(_6);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_7);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _7 = (_5.0: &i32);               // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_8);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _8 = (_5.1: &i32);               // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_9);                 // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_10);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_11);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _11 = (*_7);                     // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_12);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _12 = (*_8);                     // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _10 = Eq(move _11, move _12);    // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_12);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_11);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _9 = Not(move _10);              // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_10);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          switchInt(_9) -> [false: bb1, otherwise: bb2]; // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      }
+  
+      bb1: {
+          StorageDead(_9);                 // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_8);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_7);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_5);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _0 = const ();                   // scope 0 at $DIR/issue-73223.rs:1:11: 9:2
+                                           // ty::Const
+                                           // + ty: ()
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $DIR/issue-73223.rs:1:11: 9:2
+                                           // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+          StorageDead(_3);                 // scope 1 at $DIR/issue-73223.rs:9:1: 9:2
+          return;                          // scope 0 at $DIR/issue-73223.rs:9:2: 9:2
+      }
+  
+      bb2: {
+          StorageLive(_14);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _15 = const main::promoted[0] as &[&str] (Pointer(Unsize)); // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: &[&str; 3]
+                                           // + val: Unevaluated(DefId(0:3 ~ issue_73223[317d]::main[0]), [], Some(promoted[0]))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // + literal: Const { ty: &[&str; 3], val: Unevaluated(DefId(0:3 ~ issue_73223[317d]::main[0]), [], Some(promoted[0])) }
+          StorageLive(_18);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_19);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_20);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_21);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _21 = _7;                        // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _20 = &_21;                      // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_22);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_23);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _23 = _8;                        // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _22 = &_23;                      // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          (_19.0: &&i32) = move _20;       // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          (_19.1: &&i32) = move _22;       // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_22);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_20);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _24 = (_19.0: &&i32);            // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _25 = (_19.1: &&i32);            // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_26);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _27 = const <&i32 as std::fmt::Debug>::fmt as for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> (Pointer(ReifyFnPointer)); // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {<&i32 as std::fmt::Debug>::fmt}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // + literal: Const { ty: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {<&i32 as std::fmt::Debug>::fmt}, val: Value(Scalar(<ZST>)) }
+          StorageLive(_30);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _30 = const std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>(move _27) -> bb3; // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: unsafe extern "rust-intrinsic" fn(for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) -> for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) -> for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb3: {
+          StorageLive(_31);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _31 = const std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>(move _24) -> bb4; // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: unsafe extern "rust-intrinsic" fn(&&i32) -> &core::fmt::Opaque {std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(&&i32) -> &core::fmt::Opaque {std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb4: {
+          (_26.0: &core::fmt::Opaque) = move _31; // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_26.1: for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) = move _30; // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_31);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_30);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageLive(_28);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _29 = const <&i32 as std::fmt::Debug>::fmt as for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> (Pointer(ReifyFnPointer)); // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {<&i32 as std::fmt::Debug>::fmt}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // + literal: Const { ty: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {<&i32 as std::fmt::Debug>::fmt}, val: Value(Scalar(<ZST>)) }
+          StorageLive(_32);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _32 = const std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>(move _29) -> bb5; // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: unsafe extern "rust-intrinsic" fn(for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) -> for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) -> for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb5: {
+          StorageLive(_33);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _33 = const std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>(move _25) -> bb6; // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: unsafe extern "rust-intrinsic" fn(&&i32) -> &core::fmt::Opaque {std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(&&i32) -> &core::fmt::Opaque {std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb6: {
+          (_28.0: &core::fmt::Opaque) = move _33; // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_28.1: for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) = move _32; // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_33);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_32);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _18 = [move _26, move _28];      // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_28);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_26);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _17 = &_18;                      // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _16 = move _17 as &[std::fmt::ArgumentV1] (Pointer(Unsize)); // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_34);                // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          discriminant(_34) = 0;           // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_14.0: &[&str]) = move _15;     // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_14.1: std::option::Option<&[std::fmt::rt::v1::Argument]>) = move _34; // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_14.2: &[std::fmt::ArgumentV1]) = move _16; // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_34);                // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _13 = &_14;                      // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          const std::rt::begin_panic_fmt(move _13); // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: for<'r, 's> fn(&'r std::fmt::Arguments<'s>) -> ! {std::rt::begin_panic_fmt}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libstd/macros.rs:LL:COL
+                                           // + literal: Const { ty: for<'r, 's> fn(&'r std::fmt::Arguments<'s>) -> ! {std::rt::begin_panic_fmt}, val: Value(Scalar(<ZST>)) }
+      }
+  }
+  
diff --git a/src/test/mir-opt/issue-73223/32bit/rustc.main.SimplifyArmIdentity.diff b/src/test/mir-opt/issue-73223/32bit/rustc.main.SimplifyArmIdentity.diff
new file mode 100644
index 00000000000..e5b4a032880
--- /dev/null
+++ b/src/test/mir-opt/issue-73223/32bit/rustc.main.SimplifyArmIdentity.diff
@@ -0,0 +1,376 @@
+- // MIR for `main` before SimplifyArmIdentity
++ // MIR for `main` after SimplifyArmIdentity
+  
+  fn main() -> () {
+      let mut _0: ();                      // return place in scope 0 at $DIR/issue-73223.rs:1:11: 1:11
+      let _1: i32;                         // in scope 0 at $DIR/issue-73223.rs:2:9: 2:14
+      let mut _2: std::option::Option<i32>; // in scope 0 at $DIR/issue-73223.rs:2:23: 2:30
+      let mut _3: isize;                   // in scope 0 at $DIR/issue-73223.rs:3:9: 3:16
+      let _4: i32;                         // in scope 0 at $DIR/issue-73223.rs:3:14: 3:15
+      let mut _5: !;                       // in scope 0 at $DIR/issue-73223.rs:4:17: 4:23
+      let mut _7: i32;                     // in scope 0 at $DIR/issue-73223.rs:7:22: 7:27
+      let _8: ();                          // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _9: (&i32, &i32);            // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _10: &i32;                   // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _11: &i32;                   // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _12: i32;                        // in scope 0 at $DIR/issue-73223.rs:8:23: 8:24
+      let mut _15: bool;                   // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _16: bool;                   // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _17: i32;                    // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _18: i32;                    // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _19: !;                      // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _20: &std::fmt::Arguments;   // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let _21: &std::fmt::Arguments;       // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let _22: std::fmt::Arguments;        // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _23: &[&str];                // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _24: &[&str; 3];             // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _25: &[&str; 3];                 // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _26: [&str; 3];                  // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _27: &str;                   // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _28: &str;                       // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _29: &str;                   // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _30: &str;                       // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _31: &str;                   // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _32: &str;                       // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _33: &[std::fmt::ArgumentV1]; // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _34: &[std::fmt::ArgumentV1; 2]; // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let _35: &[std::fmt::ArgumentV1; 2]; // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let _36: [std::fmt::ArgumentV1; 2];  // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _37: (&&i32, &&i32);         // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _38: &&i32;                  // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _39: &i32;                       // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _40: &&i32;                  // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _41: &i32;                       // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _44: std::fmt::ArgumentV1;   // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _45: &&i32;                  // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _46: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _47: std::fmt::ArgumentV1;   // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _48: &&i32;                  // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _49: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      scope 1 {
+          debug split => _1;               // in scope 1 at $DIR/issue-73223.rs:2:9: 2:14
+          let _6: std::option::Option<i32>; // in scope 1 at $DIR/issue-73223.rs:7:9: 7:14
+          scope 3 {
+              debug _prev => _6;           // in scope 3 at $DIR/issue-73223.rs:7:9: 7:14
+              let _13: &i32;               // in scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+              let _14: &i32;               // in scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+              let mut _51: &i32;           // in scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+              scope 4 {
+                  debug left_val => _13;   // in scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                  debug right_val => _14;  // in scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                  let _42: &&i32;          // in scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                  let _43: &&i32;          // in scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                  let mut _50: &[&str; 3]; // in scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                  scope 5 {
+                      debug arg0 => _42;   // in scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                      debug arg1 => _43;   // in scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                      scope 6 {
+                          debug x => _45;  // in scope 6 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                          debug f => _46;  // in scope 6 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                          let mut _52: for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 6 at $SRC_DIR/libstd/macros.rs:LL:COL
+                          let mut _53: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 6 at $SRC_DIR/libstd/macros.rs:LL:COL
+                          let mut _54: &core::fmt::Opaque; // in scope 6 at $SRC_DIR/libstd/macros.rs:LL:COL
+                          let mut _55: &&i32; // in scope 6 at $SRC_DIR/libstd/macros.rs:LL:COL
+                      }
+                      scope 8 {
+                          debug x => _48;  // in scope 8 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                          debug f => _49;  // in scope 8 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                          let mut _56: for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 8 at $SRC_DIR/libstd/macros.rs:LL:COL
+                          let mut _57: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 8 at $SRC_DIR/libstd/macros.rs:LL:COL
+                          let mut _58: &core::fmt::Opaque; // in scope 8 at $SRC_DIR/libstd/macros.rs:LL:COL
+                          let mut _59: &&i32; // in scope 8 at $SRC_DIR/libstd/macros.rs:LL:COL
+                      }
+                  }
+                  scope 10 {
+                      debug pieces => _23; // in scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                      debug args => _33;   // in scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                      let mut _60: &[&str]; // in scope 10 at $SRC_DIR/libstd/macros.rs:LL:COL
+                      let mut _61: std::option::Option<&[std::fmt::rt::v1::Argument]>; // in scope 10 at $SRC_DIR/libstd/macros.rs:LL:COL
+                      let mut _62: &[std::fmt::ArgumentV1]; // in scope 10 at $SRC_DIR/libstd/macros.rs:LL:COL
+                  }
+              }
+          }
+      }
+      scope 2 {
+          debug v => _4;                   // in scope 2 at $DIR/issue-73223.rs:3:14: 3:15
+      }
+      scope 7 {
+      }
+      scope 9 {
+      }
+  
+      bb0: {
+          StorageLive(_1);                 // scope 0 at $DIR/issue-73223.rs:2:9: 2:14
+          StorageLive(_2);                 // scope 0 at $DIR/issue-73223.rs:2:23: 2:30
+          ((_2 as Some).0: i32) = const 1_i32; // scope 0 at $DIR/issue-73223.rs:2:23: 2:30
+                                           // ty::Const
+                                           // + ty: i32
+                                           // + val: Value(Scalar(0x00000001))
+                                           // mir::Constant
+                                           // + span: $DIR/issue-73223.rs:2:28: 2:29
+                                           // + literal: Const { ty: i32, val: Value(Scalar(0x00000001)) }
+          discriminant(_2) = 1;            // scope 0 at $DIR/issue-73223.rs:2:23: 2:30
+          _3 = const 1_isize;              // scope 0 at $DIR/issue-73223.rs:3:9: 3:16
+                                           // ty::Const
+                                           // + ty: isize
+                                           // + val: Value(Scalar(0x00000001))
+                                           // mir::Constant
+                                           // + span: $DIR/issue-73223.rs:3:9: 3:16
+                                           // + literal: Const { ty: isize, val: Value(Scalar(0x00000001)) }
+          goto -> bb2;                     // scope 0 at $DIR/issue-73223.rs:3:9: 3:16
+      }
+  
+      bb1: {
+          _0 = const ();                   // scope 0 at $DIR/issue-73223.rs:4:17: 4:23
+                                           // ty::Const
+                                           // + ty: ()
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $DIR/issue-73223.rs:4:17: 4:23
+                                           // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+          StorageDead(_2);                 // scope 0 at $DIR/issue-73223.rs:5:6: 5:7
+          StorageDead(_1);                 // scope 0 at $DIR/issue-73223.rs:9:1: 9:2
+          goto -> bb3;                     // scope 0 at $DIR/issue-73223.rs:4:17: 4:23
+      }
+  
+      bb2: {
+          StorageLive(_4);                 // scope 0 at $DIR/issue-73223.rs:3:14: 3:15
+          _4 = ((_2 as Some).0: i32);      // scope 0 at $DIR/issue-73223.rs:3:14: 3:15
+          _1 = _4;                         // scope 2 at $DIR/issue-73223.rs:3:20: 3:21
+          StorageDead(_4);                 // scope 0 at $DIR/issue-73223.rs:3:21: 3:22
+          StorageDead(_2);                 // scope 0 at $DIR/issue-73223.rs:5:6: 5:7
+          StorageLive(_6);                 // scope 1 at $DIR/issue-73223.rs:7:9: 7:14
+          StorageLive(_7);                 // scope 1 at $DIR/issue-73223.rs:7:22: 7:27
+          _7 = _1;                         // scope 1 at $DIR/issue-73223.rs:7:22: 7:27
+          ((_6 as Some).0: i32) = move _7; // scope 1 at $DIR/issue-73223.rs:7:17: 7:28
+          discriminant(_6) = 1;            // scope 1 at $DIR/issue-73223.rs:7:17: 7:28
+          StorageDead(_7);                 // scope 1 at $DIR/issue-73223.rs:7:27: 7:28
+          StorageLive(_8);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_9);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_10);                // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _10 = &_1;                       // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_11);                // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _51 = const main::promoted[1];   // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: &i32
+                                           // + val: Unevaluated(DefId(0:3 ~ issue_73223[317d]::main[0]), [], Some(promoted[1]))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // + literal: Const { ty: &i32, val: Unevaluated(DefId(0:3 ~ issue_73223[317d]::main[0]), [], Some(promoted[1])) }
+          _11 = _51;                       // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          (_9.0: &i32) = move _10;         // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          (_9.1: &i32) = move _11;         // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_11);                // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_10);                // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_13);                // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _13 = (_9.0: &i32);              // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_14);                // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _14 = (_9.1: &i32);              // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_15);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_16);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_17);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _17 = (*_13);                    // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_18);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _18 = (*_14);                    // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _16 = Eq(move _17, move _18);    // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_18);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_17);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _15 = Not(move _16);             // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_16);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          switchInt(_15) -> [false: bb4, otherwise: bb5]; // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      }
+  
+      bb3: {
+          return;                          // scope 0 at $DIR/issue-73223.rs:9:2: 9:2
+      }
+  
+      bb4: {
+          _8 = const ();                   // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: ()
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+          StorageDead(_15);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_14);                // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_13);                // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_9);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_8);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _0 = const ();                   // scope 0 at $DIR/issue-73223.rs:1:11: 9:2
+                                           // ty::Const
+                                           // + ty: ()
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $DIR/issue-73223.rs:1:11: 9:2
+                                           // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+          StorageDead(_6);                 // scope 1 at $DIR/issue-73223.rs:9:1: 9:2
+          StorageDead(_1);                 // scope 0 at $DIR/issue-73223.rs:9:1: 9:2
+          goto -> bb3;                     // scope 0 at $DIR/issue-73223.rs:9:2: 9:2
+      }
+  
+      bb5: {
+          StorageLive(_19);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_20);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_21);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_22);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_23);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_24);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_25);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _50 = const main::promoted[0];   // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: &[&str; 3]
+                                           // + val: Unevaluated(DefId(0:3 ~ issue_73223[317d]::main[0]), [], Some(promoted[0]))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // + literal: Const { ty: &[&str; 3], val: Unevaluated(DefId(0:3 ~ issue_73223[317d]::main[0]), [], Some(promoted[0])) }
+          _25 = _50;                       // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _24 = _25;                       // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _23 = move _24 as &[&str] (Pointer(Unsize)); // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_24);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_33);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_34);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_35);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_36);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_37);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_38);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_39);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _39 = _13;                       // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _38 = &_39;                      // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_40);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_41);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _41 = _14;                       // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _40 = &_41;                      // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          (_37.0: &&i32) = move _38;       // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          (_37.1: &&i32) = move _40;       // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_40);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_38);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_42);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _42 = (_37.0: &&i32);            // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_43);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _43 = (_37.1: &&i32);            // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_44);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_45);                // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _45 = _42;                       // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_46);                // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _46 = const <&i32 as std::fmt::Debug>::fmt as for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> (Pointer(ReifyFnPointer)); // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {<&i32 as std::fmt::Debug>::fmt}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // + literal: Const { ty: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {<&i32 as std::fmt::Debug>::fmt}, val: Value(Scalar(<ZST>)) }
+          StorageLive(_52);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageLive(_53);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _53 = _46;                       // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _52 = const std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>(move _53) -> bb6; // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: unsafe extern "rust-intrinsic" fn(for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) -> for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) -> for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb6: {
+          StorageDead(_53);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageLive(_54);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageLive(_55);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _55 = _45;                       // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _54 = const std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>(move _55) -> bb7; // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: unsafe extern "rust-intrinsic" fn(&&i32) -> &core::fmt::Opaque {std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(&&i32) -> &core::fmt::Opaque {std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb7: {
+          StorageDead(_55);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_44.0: &core::fmt::Opaque) = move _54; // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_44.1: for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) = move _52; // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_54);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_52);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_46);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_45);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_47);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_48);                // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _48 = _43;                       // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_49);                // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _49 = const <&i32 as std::fmt::Debug>::fmt as for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> (Pointer(ReifyFnPointer)); // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {<&i32 as std::fmt::Debug>::fmt}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // + literal: Const { ty: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {<&i32 as std::fmt::Debug>::fmt}, val: Value(Scalar(<ZST>)) }
+          StorageLive(_56);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageLive(_57);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _57 = _49;                       // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _56 = const std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>(move _57) -> bb8; // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: unsafe extern "rust-intrinsic" fn(for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) -> for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) -> for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb8: {
+          StorageDead(_57);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageLive(_58);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageLive(_59);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _59 = _48;                       // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _58 = const std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>(move _59) -> bb9; // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: unsafe extern "rust-intrinsic" fn(&&i32) -> &core::fmt::Opaque {std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(&&i32) -> &core::fmt::Opaque {std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb9: {
+          StorageDead(_59);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_47.0: &core::fmt::Opaque) = move _58; // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_47.1: for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) = move _56; // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_58);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_56);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_49);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_48);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _36 = [move _44, move _47];      // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_47);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_44);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_43);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_42);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _35 = &_36;                      // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _34 = _35;                       // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _33 = move _34 as &[std::fmt::ArgumentV1] (Pointer(Unsize)); // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_34);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_60);                // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _60 = _23;                       // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageLive(_61);                // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          discriminant(_61) = 0;           // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageLive(_62);                // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _62 = _33;                       // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_22.0: &[&str]) = move _60;     // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_22.1: std::option::Option<&[std::fmt::rt::v1::Argument]>) = move _61; // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_22.2: &[std::fmt::ArgumentV1]) = move _62; // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_62);                // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_61);                // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_60);                // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_33);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_23);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _21 = &_22;                      // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _20 = _21;                       // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          const std::rt::begin_panic_fmt(move _20); // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: for<'r, 's> fn(&'r std::fmt::Arguments<'s>) -> ! {std::rt::begin_panic_fmt}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libstd/macros.rs:LL:COL
+                                           // + literal: Const { ty: for<'r, 's> fn(&'r std::fmt::Arguments<'s>) -> ! {std::rt::begin_panic_fmt}, val: Value(Scalar(<ZST>)) }
+      }
+  }
+  
diff --git a/src/test/mir-opt/issue-73223/64bit/rustc.main.PreCodegen.diff b/src/test/mir-opt/issue-73223/64bit/rustc.main.PreCodegen.diff
new file mode 100644
index 00000000000..59c00e1b96f
--- /dev/null
+++ b/src/test/mir-opt/issue-73223/64bit/rustc.main.PreCodegen.diff
@@ -0,0 +1,252 @@
+- // MIR for `main` before PreCodegen
++ // MIR for `main` after PreCodegen
+  
+  fn main() -> () {
+      let mut _0: ();                      // return place in scope 0 at $DIR/issue-73223.rs:1:11: 1:11
+      let mut _1: std::option::Option<i32>; // in scope 0 at $DIR/issue-73223.rs:2:23: 2:30
+      let _2: i32;                         // in scope 0 at $DIR/issue-73223.rs:3:14: 3:15
+      let mut _4: i32;                     // in scope 0 at $DIR/issue-73223.rs:7:22: 7:27
+      let mut _5: (&i32, &i32);            // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _6: &i32;                    // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _9: bool;                    // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _10: bool;                   // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _11: i32;                    // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _12: i32;                    // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _13: &std::fmt::Arguments;       // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let _14: std::fmt::Arguments;        // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _15: &[&str];                // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _16: &[std::fmt::ArgumentV1]; // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let _17: &[std::fmt::ArgumentV1; 2]; // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let _18: [std::fmt::ArgumentV1; 2];  // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _19: (&&i32, &&i32);         // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _20: &&i32;                  // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _21: &i32;                       // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _22: &&i32;                  // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _23: &i32;                       // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _26: std::fmt::ArgumentV1;   // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _27: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _28: std::fmt::ArgumentV1;   // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _29: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      scope 1 {
+          debug split => _2;               // in scope 1 at $DIR/issue-73223.rs:2:9: 2:14
+          let _3: std::option::Option<i32>; // in scope 1 at $DIR/issue-73223.rs:7:9: 7:14
+          scope 3 {
+              debug _prev => _3;           // in scope 3 at $DIR/issue-73223.rs:7:9: 7:14
+              let _7: &i32;                // in scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+              let _8: &i32;                // in scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+              scope 4 {
+                  debug left_val => _7;    // in scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                  debug right_val => _8;   // in scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                  let _24: &&i32;          // in scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                  let _25: &&i32;          // in scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                  scope 5 {
+                      debug arg0 => _24;   // in scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                      debug arg1 => _25;   // in scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                      scope 6 {
+                          debug x => _24;  // in scope 6 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                          debug f => _27;  // in scope 6 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                          let mut _30: for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 6 at $SRC_DIR/libstd/macros.rs:LL:COL
+                          let mut _31: &core::fmt::Opaque; // in scope 6 at $SRC_DIR/libstd/macros.rs:LL:COL
+                      }
+                      scope 8 {
+                          debug x => _25;  // in scope 8 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                          debug f => _29;  // in scope 8 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                          let mut _32: for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 8 at $SRC_DIR/libstd/macros.rs:LL:COL
+                          let mut _33: &core::fmt::Opaque; // in scope 8 at $SRC_DIR/libstd/macros.rs:LL:COL
+                      }
+                  }
+                  scope 10 {
+                      debug pieces => _15; // in scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                      debug args => _16;   // in scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                      let mut _34: std::option::Option<&[std::fmt::rt::v1::Argument]>; // in scope 10 at $SRC_DIR/libstd/macros.rs:LL:COL
+                  }
+              }
+          }
+      }
+      scope 2 {
+          debug v => _2;                   // in scope 2 at $DIR/issue-73223.rs:3:14: 3:15
+      }
+      scope 7 {
+      }
+      scope 9 {
+      }
+  
+      bb0: {
+          StorageLive(_1);                 // scope 0 at $DIR/issue-73223.rs:2:23: 2:30
+          ((_1 as Some).0: i32) = const 1_i32; // scope 0 at $DIR/issue-73223.rs:2:23: 2:30
+                                           // ty::Const
+                                           // + ty: i32
+                                           // + val: Value(Scalar(0x00000001))
+                                           // mir::Constant
+                                           // + span: $DIR/issue-73223.rs:2:28: 2:29
+                                           // + literal: Const { ty: i32, val: Value(Scalar(0x00000001)) }
+          discriminant(_1) = 1;            // scope 0 at $DIR/issue-73223.rs:2:23: 2:30
+          _2 = ((_1 as Some).0: i32);      // scope 0 at $DIR/issue-73223.rs:3:14: 3:15
+          StorageDead(_1);                 // scope 0 at $DIR/issue-73223.rs:5:6: 5:7
+          StorageLive(_3);                 // scope 1 at $DIR/issue-73223.rs:7:9: 7:14
+          StorageLive(_4);                 // scope 1 at $DIR/issue-73223.rs:7:22: 7:27
+          _4 = _2;                         // scope 1 at $DIR/issue-73223.rs:7:22: 7:27
+          ((_3 as Some).0: i32) = move _4; // scope 1 at $DIR/issue-73223.rs:7:17: 7:28
+          discriminant(_3) = 1;            // scope 1 at $DIR/issue-73223.rs:7:17: 7:28
+          StorageDead(_4);                 // scope 1 at $DIR/issue-73223.rs:7:27: 7:28
+          StorageLive(_5);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_6);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _6 = &_2;                        // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          (_5.0: &i32) = move _6;          // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          (_5.1: &i32) = const main::promoted[1]; // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: &i32
+                                           // + val: Unevaluated(DefId(0:3 ~ issue_73223[317d]::main[0]), [], Some(promoted[1]))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // + literal: Const { ty: &i32, val: Unevaluated(DefId(0:3 ~ issue_73223[317d]::main[0]), [], Some(promoted[1])) }
+          StorageDead(_6);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_7);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _7 = (_5.0: &i32);               // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_8);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _8 = (_5.1: &i32);               // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_9);                 // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_10);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_11);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _11 = (*_7);                     // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_12);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _12 = (*_8);                     // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _10 = Eq(move _11, move _12);    // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_12);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_11);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _9 = Not(move _10);              // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_10);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          switchInt(_9) -> [false: bb1, otherwise: bb2]; // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      }
+  
+      bb1: {
+          StorageDead(_9);                 // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_8);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_7);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_5);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _0 = const ();                   // scope 0 at $DIR/issue-73223.rs:1:11: 9:2
+                                           // ty::Const
+                                           // + ty: ()
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $DIR/issue-73223.rs:1:11: 9:2
+                                           // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+          StorageDead(_3);                 // scope 1 at $DIR/issue-73223.rs:9:1: 9:2
+          return;                          // scope 0 at $DIR/issue-73223.rs:9:2: 9:2
+      }
+  
+      bb2: {
+          StorageLive(_14);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _15 = const main::promoted[0] as &[&str] (Pointer(Unsize)); // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: &[&str; 3]
+                                           // + val: Unevaluated(DefId(0:3 ~ issue_73223[317d]::main[0]), [], Some(promoted[0]))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // + literal: Const { ty: &[&str; 3], val: Unevaluated(DefId(0:3 ~ issue_73223[317d]::main[0]), [], Some(promoted[0])) }
+          StorageLive(_18);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_19);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_20);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_21);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _21 = _7;                        // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _20 = &_21;                      // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_22);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_23);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _23 = _8;                        // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _22 = &_23;                      // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          (_19.0: &&i32) = move _20;       // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          (_19.1: &&i32) = move _22;       // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_22);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_20);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _24 = (_19.0: &&i32);            // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _25 = (_19.1: &&i32);            // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_26);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _27 = const <&i32 as std::fmt::Debug>::fmt as for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> (Pointer(ReifyFnPointer)); // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {<&i32 as std::fmt::Debug>::fmt}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // + literal: Const { ty: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {<&i32 as std::fmt::Debug>::fmt}, val: Value(Scalar(<ZST>)) }
+          StorageLive(_30);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _30 = const std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>(move _27) -> bb3; // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: unsafe extern "rust-intrinsic" fn(for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) -> for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) -> for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb3: {
+          StorageLive(_31);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _31 = const std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>(move _24) -> bb4; // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: unsafe extern "rust-intrinsic" fn(&&i32) -> &core::fmt::Opaque {std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(&&i32) -> &core::fmt::Opaque {std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb4: {
+          (_26.0: &core::fmt::Opaque) = move _31; // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_26.1: for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) = move _30; // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_31);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_30);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageLive(_28);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _29 = const <&i32 as std::fmt::Debug>::fmt as for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> (Pointer(ReifyFnPointer)); // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {<&i32 as std::fmt::Debug>::fmt}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // + literal: Const { ty: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {<&i32 as std::fmt::Debug>::fmt}, val: Value(Scalar(<ZST>)) }
+          StorageLive(_32);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _32 = const std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>(move _29) -> bb5; // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: unsafe extern "rust-intrinsic" fn(for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) -> for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) -> for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb5: {
+          StorageLive(_33);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _33 = const std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>(move _25) -> bb6; // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: unsafe extern "rust-intrinsic" fn(&&i32) -> &core::fmt::Opaque {std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(&&i32) -> &core::fmt::Opaque {std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb6: {
+          (_28.0: &core::fmt::Opaque) = move _33; // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_28.1: for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) = move _32; // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_33);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_32);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _18 = [move _26, move _28];      // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_28);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_26);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _17 = &_18;                      // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _16 = move _17 as &[std::fmt::ArgumentV1] (Pointer(Unsize)); // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_34);                // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          discriminant(_34) = 0;           // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_14.0: &[&str]) = move _15;     // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_14.1: std::option::Option<&[std::fmt::rt::v1::Argument]>) = move _34; // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_14.2: &[std::fmt::ArgumentV1]) = move _16; // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_34);                // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _13 = &_14;                      // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          const std::rt::begin_panic_fmt(move _13); // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: for<'r, 's> fn(&'r std::fmt::Arguments<'s>) -> ! {std::rt::begin_panic_fmt}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libstd/macros.rs:LL:COL
+                                           // + literal: Const { ty: for<'r, 's> fn(&'r std::fmt::Arguments<'s>) -> ! {std::rt::begin_panic_fmt}, val: Value(Scalar(<ZST>)) }
+      }
+  }
+  
diff --git a/src/test/mir-opt/issue-73223/64bit/rustc.main.SimplifyArmIdentity.diff b/src/test/mir-opt/issue-73223/64bit/rustc.main.SimplifyArmIdentity.diff
new file mode 100644
index 00000000000..0c2651dc3c6
--- /dev/null
+++ b/src/test/mir-opt/issue-73223/64bit/rustc.main.SimplifyArmIdentity.diff
@@ -0,0 +1,376 @@
+- // MIR for `main` before SimplifyArmIdentity
++ // MIR for `main` after SimplifyArmIdentity
+  
+  fn main() -> () {
+      let mut _0: ();                      // return place in scope 0 at $DIR/issue-73223.rs:1:11: 1:11
+      let _1: i32;                         // in scope 0 at $DIR/issue-73223.rs:2:9: 2:14
+      let mut _2: std::option::Option<i32>; // in scope 0 at $DIR/issue-73223.rs:2:23: 2:30
+      let mut _3: isize;                   // in scope 0 at $DIR/issue-73223.rs:3:9: 3:16
+      let _4: i32;                         // in scope 0 at $DIR/issue-73223.rs:3:14: 3:15
+      let mut _5: !;                       // in scope 0 at $DIR/issue-73223.rs:4:17: 4:23
+      let mut _7: i32;                     // in scope 0 at $DIR/issue-73223.rs:7:22: 7:27
+      let _8: ();                          // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _9: (&i32, &i32);            // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _10: &i32;                   // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _11: &i32;                   // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _12: i32;                        // in scope 0 at $DIR/issue-73223.rs:8:23: 8:24
+      let mut _15: bool;                   // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _16: bool;                   // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _17: i32;                    // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _18: i32;                    // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _19: !;                      // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _20: &std::fmt::Arguments;   // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let _21: &std::fmt::Arguments;       // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let _22: std::fmt::Arguments;        // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _23: &[&str];                // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _24: &[&str; 3];             // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _25: &[&str; 3];                 // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _26: [&str; 3];                  // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _27: &str;                   // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _28: &str;                       // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _29: &str;                   // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _30: &str;                       // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _31: &str;                   // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _32: &str;                       // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _33: &[std::fmt::ArgumentV1]; // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _34: &[std::fmt::ArgumentV1; 2]; // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let _35: &[std::fmt::ArgumentV1; 2]; // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let _36: [std::fmt::ArgumentV1; 2];  // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _37: (&&i32, &&i32);         // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _38: &&i32;                  // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _39: &i32;                       // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _40: &&i32;                  // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let _41: &i32;                       // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _44: std::fmt::ArgumentV1;   // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _45: &&i32;                  // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _46: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _47: std::fmt::ArgumentV1;   // in scope 0 at $SRC_DIR/libstd/macros.rs:LL:COL
+      let mut _48: &&i32;                  // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      let mut _49: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 0 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      scope 1 {
+          debug split => _1;               // in scope 1 at $DIR/issue-73223.rs:2:9: 2:14
+          let _6: std::option::Option<i32>; // in scope 1 at $DIR/issue-73223.rs:7:9: 7:14
+          scope 3 {
+              debug _prev => _6;           // in scope 3 at $DIR/issue-73223.rs:7:9: 7:14
+              let _13: &i32;               // in scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+              let _14: &i32;               // in scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+              let mut _51: &i32;           // in scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+              scope 4 {
+                  debug left_val => _13;   // in scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                  debug right_val => _14;  // in scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                  let _42: &&i32;          // in scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                  let _43: &&i32;          // in scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                  let mut _50: &[&str; 3]; // in scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                  scope 5 {
+                      debug arg0 => _42;   // in scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                      debug arg1 => _43;   // in scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                      scope 6 {
+                          debug x => _45;  // in scope 6 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                          debug f => _46;  // in scope 6 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                          let mut _52: for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 6 at $SRC_DIR/libstd/macros.rs:LL:COL
+                          let mut _53: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 6 at $SRC_DIR/libstd/macros.rs:LL:COL
+                          let mut _54: &core::fmt::Opaque; // in scope 6 at $SRC_DIR/libstd/macros.rs:LL:COL
+                          let mut _55: &&i32; // in scope 6 at $SRC_DIR/libstd/macros.rs:LL:COL
+                      }
+                      scope 8 {
+                          debug x => _48;  // in scope 8 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                          debug f => _49;  // in scope 8 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                          let mut _56: for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 8 at $SRC_DIR/libstd/macros.rs:LL:COL
+                          let mut _57: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>; // in scope 8 at $SRC_DIR/libstd/macros.rs:LL:COL
+                          let mut _58: &core::fmt::Opaque; // in scope 8 at $SRC_DIR/libstd/macros.rs:LL:COL
+                          let mut _59: &&i32; // in scope 8 at $SRC_DIR/libstd/macros.rs:LL:COL
+                      }
+                  }
+                  scope 10 {
+                      debug pieces => _23; // in scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                      debug args => _33;   // in scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                      let mut _60: &[&str]; // in scope 10 at $SRC_DIR/libstd/macros.rs:LL:COL
+                      let mut _61: std::option::Option<&[std::fmt::rt::v1::Argument]>; // in scope 10 at $SRC_DIR/libstd/macros.rs:LL:COL
+                      let mut _62: &[std::fmt::ArgumentV1]; // in scope 10 at $SRC_DIR/libstd/macros.rs:LL:COL
+                  }
+              }
+          }
+      }
+      scope 2 {
+          debug v => _4;                   // in scope 2 at $DIR/issue-73223.rs:3:14: 3:15
+      }
+      scope 7 {
+      }
+      scope 9 {
+      }
+  
+      bb0: {
+          StorageLive(_1);                 // scope 0 at $DIR/issue-73223.rs:2:9: 2:14
+          StorageLive(_2);                 // scope 0 at $DIR/issue-73223.rs:2:23: 2:30
+          ((_2 as Some).0: i32) = const 1_i32; // scope 0 at $DIR/issue-73223.rs:2:23: 2:30
+                                           // ty::Const
+                                           // + ty: i32
+                                           // + val: Value(Scalar(0x00000001))
+                                           // mir::Constant
+                                           // + span: $DIR/issue-73223.rs:2:28: 2:29
+                                           // + literal: Const { ty: i32, val: Value(Scalar(0x00000001)) }
+          discriminant(_2) = 1;            // scope 0 at $DIR/issue-73223.rs:2:23: 2:30
+          _3 = const 1_isize;              // scope 0 at $DIR/issue-73223.rs:3:9: 3:16
+                                           // ty::Const
+                                           // + ty: isize
+                                           // + val: Value(Scalar(0x0000000000000001))
+                                           // mir::Constant
+                                           // + span: $DIR/issue-73223.rs:3:9: 3:16
+                                           // + literal: Const { ty: isize, val: Value(Scalar(0x0000000000000001)) }
+          goto -> bb2;                     // scope 0 at $DIR/issue-73223.rs:3:9: 3:16
+      }
+  
+      bb1: {
+          _0 = const ();                   // scope 0 at $DIR/issue-73223.rs:4:17: 4:23
+                                           // ty::Const
+                                           // + ty: ()
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $DIR/issue-73223.rs:4:17: 4:23
+                                           // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+          StorageDead(_2);                 // scope 0 at $DIR/issue-73223.rs:5:6: 5:7
+          StorageDead(_1);                 // scope 0 at $DIR/issue-73223.rs:9:1: 9:2
+          goto -> bb3;                     // scope 0 at $DIR/issue-73223.rs:4:17: 4:23
+      }
+  
+      bb2: {
+          StorageLive(_4);                 // scope 0 at $DIR/issue-73223.rs:3:14: 3:15
+          _4 = ((_2 as Some).0: i32);      // scope 0 at $DIR/issue-73223.rs:3:14: 3:15
+          _1 = _4;                         // scope 2 at $DIR/issue-73223.rs:3:20: 3:21
+          StorageDead(_4);                 // scope 0 at $DIR/issue-73223.rs:3:21: 3:22
+          StorageDead(_2);                 // scope 0 at $DIR/issue-73223.rs:5:6: 5:7
+          StorageLive(_6);                 // scope 1 at $DIR/issue-73223.rs:7:9: 7:14
+          StorageLive(_7);                 // scope 1 at $DIR/issue-73223.rs:7:22: 7:27
+          _7 = _1;                         // scope 1 at $DIR/issue-73223.rs:7:22: 7:27
+          ((_6 as Some).0: i32) = move _7; // scope 1 at $DIR/issue-73223.rs:7:17: 7:28
+          discriminant(_6) = 1;            // scope 1 at $DIR/issue-73223.rs:7:17: 7:28
+          StorageDead(_7);                 // scope 1 at $DIR/issue-73223.rs:7:27: 7:28
+          StorageLive(_8);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_9);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_10);                // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _10 = &_1;                       // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_11);                // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _51 = const main::promoted[1];   // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: &i32
+                                           // + val: Unevaluated(DefId(0:3 ~ issue_73223[317d]::main[0]), [], Some(promoted[1]))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // + literal: Const { ty: &i32, val: Unevaluated(DefId(0:3 ~ issue_73223[317d]::main[0]), [], Some(promoted[1])) }
+          _11 = _51;                       // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          (_9.0: &i32) = move _10;         // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          (_9.1: &i32) = move _11;         // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_11);                // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_10);                // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_13);                // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _13 = (_9.0: &i32);              // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_14);                // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _14 = (_9.1: &i32);              // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_15);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_16);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_17);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _17 = (*_13);                    // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_18);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _18 = (*_14);                    // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _16 = Eq(move _17, move _18);    // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_18);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_17);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _15 = Not(move _16);             // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_16);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          switchInt(_15) -> [false: bb4, otherwise: bb5]; // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+      }
+  
+      bb3: {
+          return;                          // scope 0 at $DIR/issue-73223.rs:9:2: 9:2
+      }
+  
+      bb4: {
+          _8 = const ();                   // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: ()
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+          StorageDead(_15);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_14);                // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_13);                // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_9);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_8);                 // scope 3 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _0 = const ();                   // scope 0 at $DIR/issue-73223.rs:1:11: 9:2
+                                           // ty::Const
+                                           // + ty: ()
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $DIR/issue-73223.rs:1:11: 9:2
+                                           // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
+          StorageDead(_6);                 // scope 1 at $DIR/issue-73223.rs:9:1: 9:2
+          StorageDead(_1);                 // scope 0 at $DIR/issue-73223.rs:9:1: 9:2
+          goto -> bb3;                     // scope 0 at $DIR/issue-73223.rs:9:2: 9:2
+      }
+  
+      bb5: {
+          StorageLive(_19);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_20);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_21);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_22);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_23);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_24);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_25);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _50 = const main::promoted[0];   // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: &[&str; 3]
+                                           // + val: Unevaluated(DefId(0:3 ~ issue_73223[317d]::main[0]), [], Some(promoted[0]))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // + literal: Const { ty: &[&str; 3], val: Unevaluated(DefId(0:3 ~ issue_73223[317d]::main[0]), [], Some(promoted[0])) }
+          _25 = _50;                       // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _24 = _25;                       // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _23 = move _24 as &[&str] (Pointer(Unsize)); // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageDead(_24);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_33);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_34);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_35);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_36);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_37);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_38);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_39);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _39 = _13;                       // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _38 = &_39;                      // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_40);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_41);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _41 = _14;                       // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _40 = &_41;                      // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          (_37.0: &&i32) = move _38;       // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          (_37.1: &&i32) = move _40;       // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_40);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_38);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_42);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _42 = (_37.0: &&i32);            // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_43);                // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _43 = (_37.1: &&i32);            // scope 4 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_44);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_45);                // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _45 = _42;                       // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_46);                // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _46 = const <&i32 as std::fmt::Debug>::fmt as for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> (Pointer(ReifyFnPointer)); // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {<&i32 as std::fmt::Debug>::fmt}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // + literal: Const { ty: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {<&i32 as std::fmt::Debug>::fmt}, val: Value(Scalar(<ZST>)) }
+          StorageLive(_52);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageLive(_53);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _53 = _46;                       // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _52 = const std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>(move _53) -> bb6; // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: unsafe extern "rust-intrinsic" fn(for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) -> for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) -> for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb6: {
+          StorageDead(_53);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageLive(_54);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageLive(_55);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _55 = _45;                       // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _54 = const std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>(move _55) -> bb7; // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: unsafe extern "rust-intrinsic" fn(&&i32) -> &core::fmt::Opaque {std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(&&i32) -> &core::fmt::Opaque {std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb7: {
+          StorageDead(_55);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_44.0: &core::fmt::Opaque) = move _54; // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_44.1: for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) = move _52; // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_54);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_52);                // scope 7 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_46);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_45);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_47);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_48);                // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _48 = _43;                       // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          StorageLive(_49);                // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+          _49 = const <&i32 as std::fmt::Debug>::fmt as for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> (Pointer(ReifyFnPointer)); // scope 5 at $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {<&i32 as std::fmt::Debug>::fmt}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+                                           // + literal: Const { ty: for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {<&i32 as std::fmt::Debug>::fmt}, val: Value(Scalar(<ZST>)) }
+          StorageLive(_56);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageLive(_57);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _57 = _49;                       // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _56 = const std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>(move _57) -> bb8; // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: unsafe extern "rust-intrinsic" fn(for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) -> for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) -> for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error> {std::intrinsics::transmute::<for<'r, 's, 't0> fn(&'r &i32, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>, for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>>}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb8: {
+          StorageDead(_57);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageLive(_58);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageLive(_59);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _59 = _48;                       // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _58 = const std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>(move _59) -> bb9; // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: unsafe extern "rust-intrinsic" fn(&&i32) -> &core::fmt::Opaque {std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(&&i32) -> &core::fmt::Opaque {std::intrinsics::transmute::<&&i32, &core::fmt::Opaque>}, val: Value(Scalar(<ZST>)) }
+      }
+  
+      bb9: {
+          StorageDead(_59);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_47.0: &core::fmt::Opaque) = move _58; // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_47.1: for<'r, 's, 't0> fn(&'r core::fmt::Opaque, &'s mut std::fmt::Formatter<'t0>) -> std::result::Result<(), std::fmt::Error>) = move _56; // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_58);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_56);                // scope 9 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_49);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_48);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _36 = [move _44, move _47];      // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_47);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_44);                // scope 5 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_43);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_42);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _35 = &_36;                      // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _34 = _35;                       // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _33 = move _34 as &[std::fmt::ArgumentV1] (Pointer(Unsize)); // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_34);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageLive(_60);                // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _60 = _23;                       // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageLive(_61);                // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          discriminant(_61) = 0;           // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageLive(_62);                // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          _62 = _33;                       // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_22.0: &[&str]) = move _60;     // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_22.1: std::option::Option<&[std::fmt::rt::v1::Argument]>) = move _61; // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          (_22.2: &[std::fmt::ArgumentV1]) = move _62; // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_62);                // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_61);                // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_60);                // scope 10 at $SRC_DIR/libcore/fmt/mod.rs:LL:COL
+          StorageDead(_33);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          StorageDead(_23);                // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _21 = &_22;                      // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          _20 = _21;                       // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+          const std::rt::begin_panic_fmt(move _20); // scope 4 at $SRC_DIR/libstd/macros.rs:LL:COL
+                                           // ty::Const
+                                           // + ty: for<'r, 's> fn(&'r std::fmt::Arguments<'s>) -> ! {std::rt::begin_panic_fmt}
+                                           // + val: Value(Scalar(<ZST>))
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/libstd/macros.rs:LL:COL
+                                           // + literal: Const { ty: for<'r, 's> fn(&'r std::fmt::Arguments<'s>) -> ! {std::rt::begin_panic_fmt}, val: Value(Scalar(<ZST>)) }
+      }
+  }
+  
diff --git a/src/test/mir-opt/simplify-locals-removes-unused-discriminant-reads/32bit/rustc.map.SimplifyLocals.diff b/src/test/mir-opt/simplify-locals-removes-unused-discriminant-reads/32bit/rustc.map.SimplifyLocals.diff
index f0b696118e9..551f6db08a5 100644
--- a/src/test/mir-opt/simplify-locals-removes-unused-discriminant-reads/32bit/rustc.map.SimplifyLocals.diff
+++ b/src/test/mir-opt/simplify-locals-removes-unused-discriminant-reads/32bit/rustc.map.SimplifyLocals.diff
@@ -5,12 +5,12 @@
       debug x => _1;                       // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:1:8: 1:9
       let mut _0: std::option::Option<std::boxed::Box<()>>; // return place in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:1:31: 1:46
       let mut _2: isize;                   // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:9: 3:13
-      let _3: std::boxed::Box<()>;         // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:14: 4:15
+-     let _3: std::boxed::Box<()>;         // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:14: 4:15
 -     let mut _4: std::boxed::Box<()>;     // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:25: 4:26
 -     let mut _5: isize;                   // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:6:1: 6:2
 -     let mut _6: isize;                   // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:6:1: 6:2
       scope 1 {
-          debug x => _3;                   // in scope 1 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:14: 4:15
+          debug x => ((_0 as Some).0: std::boxed::Box<()>); // in scope 1 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:14: 4:15
       }
   
       bb0: {
diff --git a/src/test/mir-opt/simplify-locals-removes-unused-discriminant-reads/64bit/rustc.map.SimplifyLocals.diff b/src/test/mir-opt/simplify-locals-removes-unused-discriminant-reads/64bit/rustc.map.SimplifyLocals.diff
index 1ac6eb85441..388b382b86d 100644
--- a/src/test/mir-opt/simplify-locals-removes-unused-discriminant-reads/64bit/rustc.map.SimplifyLocals.diff
+++ b/src/test/mir-opt/simplify-locals-removes-unused-discriminant-reads/64bit/rustc.map.SimplifyLocals.diff
@@ -5,12 +5,12 @@
       debug x => _1;                       // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:1:8: 1:9
       let mut _0: std::option::Option<std::boxed::Box<()>>; // return place in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:1:31: 1:46
       let mut _2: isize;                   // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:9: 3:13
-      let _3: std::boxed::Box<()>;         // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:14: 4:15
+-     let _3: std::boxed::Box<()>;         // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:14: 4:15
 -     let mut _4: std::boxed::Box<()>;     // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:25: 4:26
 -     let mut _5: isize;                   // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:6:1: 6:2
 -     let mut _6: isize;                   // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:6:1: 6:2
       scope 1 {
-          debug x => _3;                   // in scope 1 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:14: 4:15
+          debug x => ((_0 as Some).0: std::boxed::Box<()>); // in scope 1 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:14: 4:15
       }
   
       bb0: {
diff --git a/src/test/mir-opt/simplify_try/rustc.try_identity.SimplifyArmIdentity.diff b/src/test/mir-opt/simplify_try/rustc.try_identity.SimplifyArmIdentity.diff
index 7f8366309c0..e6d794a7150 100644
--- a/src/test/mir-opt/simplify_try/rustc.try_identity.SimplifyArmIdentity.diff
+++ b/src/test/mir-opt/simplify_try/rustc.try_identity.SimplifyArmIdentity.diff
@@ -15,22 +15,27 @@
       let _10: u32;                        // in scope 0 at $DIR/simplify_try.rs:6:13: 6:15
       let mut _11: u32;                    // in scope 0 at $DIR/simplify_try.rs:7:8: 7:9
       scope 1 {
-          debug y => _2;                   // in scope 1 at $DIR/simplify_try.rs:6:9: 6:10
+-         debug y => _2;                   // in scope 1 at $DIR/simplify_try.rs:6:9: 6:10
++         debug y => ((_0 as Ok).0: u32);  // in scope 1 at $DIR/simplify_try.rs:6:9: 6:10
       }
       scope 2 {
-          debug err => _6;                 // in scope 2 at $DIR/simplify_try.rs:6:14: 6:15
+-         debug err => _6;                 // in scope 2 at $DIR/simplify_try.rs:6:14: 6:15
++         debug err => ((_0 as Err).0: i32); // in scope 2 at $DIR/simplify_try.rs:6:14: 6:15
           scope 3 {
               scope 7 {
-                  debug t => _9;           // in scope 7 at $SRC_DIR/libcore/convert/mod.rs:LL:COL
+-                 debug t => _9;           // in scope 7 at $SRC_DIR/libcore/convert/mod.rs:LL:COL
++                 debug t => ((_0 as Err).0: i32); // in scope 7 at $SRC_DIR/libcore/convert/mod.rs:LL:COL
               }
               scope 8 {
-                  debug v => _8;           // in scope 8 at $SRC_DIR/libcore/result.rs:LL:COL
+-                 debug v => _8;           // in scope 8 at $SRC_DIR/libcore/result.rs:LL:COL
++                 debug v => ((_0 as Err).0: i32); // in scope 8 at $SRC_DIR/libcore/result.rs:LL:COL
                   let mut _12: i32;        // in scope 8 at $DIR/simplify_try.rs:6:14: 6:15
               }
           }
       }
       scope 4 {
-          debug val => _10;                // in scope 4 at $DIR/simplify_try.rs:6:13: 6:15
+-         debug val => _10;                // in scope 4 at $DIR/simplify_try.rs:6:13: 6:15
++         debug val => ((_0 as Ok).0: u32); // in scope 4 at $DIR/simplify_try.rs:6:13: 6:15
           scope 5 {
           }
       }
diff --git a/src/test/mir-opt/simplify_try/rustc.try_identity.SimplifyBranchSame.after.mir b/src/test/mir-opt/simplify_try/rustc.try_identity.SimplifyBranchSame.after.mir
index be61e5e2a9f..24bde51c7d3 100644
--- a/src/test/mir-opt/simplify_try/rustc.try_identity.SimplifyBranchSame.after.mir
+++ b/src/test/mir-opt/simplify_try/rustc.try_identity.SimplifyBranchSame.after.mir
@@ -14,22 +14,22 @@ fn try_identity(_1: std::result::Result<u32, i32>) -> std::result::Result<u32, i
     let _10: u32;                        // in scope 0 at $DIR/simplify_try.rs:6:13: 6:15
     let mut _11: u32;                    // in scope 0 at $DIR/simplify_try.rs:7:8: 7:9
     scope 1 {
-        debug y => _2;                   // in scope 1 at $DIR/simplify_try.rs:6:9: 6:10
+        debug y => ((_0 as Ok).0: u32);  // in scope 1 at $DIR/simplify_try.rs:6:9: 6:10
     }
     scope 2 {
-        debug err => _6;                 // in scope 2 at $DIR/simplify_try.rs:6:14: 6:15
+        debug err => ((_0 as Err).0: i32); // in scope 2 at $DIR/simplify_try.rs:6:14: 6:15
         scope 3 {
             scope 7 {
-                debug t => _9;           // in scope 7 at $SRC_DIR/libcore/convert/mod.rs:LL:COL
+                debug t => ((_0 as Err).0: i32); // in scope 7 at $SRC_DIR/libcore/convert/mod.rs:LL:COL
             }
             scope 8 {
-                debug v => _8;           // in scope 8 at $SRC_DIR/libcore/result.rs:LL:COL
+                debug v => ((_0 as Err).0: i32); // in scope 8 at $SRC_DIR/libcore/result.rs:LL:COL
                 let mut _12: i32;        // in scope 8 at $DIR/simplify_try.rs:6:14: 6:15
             }
         }
     }
     scope 4 {
-        debug val => _10;                // in scope 4 at $DIR/simplify_try.rs:6:13: 6:15
+        debug val => ((_0 as Ok).0: u32); // in scope 4 at $DIR/simplify_try.rs:6:13: 6:15
         scope 5 {
         }
     }
diff --git a/src/test/mir-opt/simplify_try/rustc.try_identity.SimplifyLocals.after.mir b/src/test/mir-opt/simplify_try/rustc.try_identity.SimplifyLocals.after.mir
index b12036f6a03..929f04d4654 100644
--- a/src/test/mir-opt/simplify_try/rustc.try_identity.SimplifyLocals.after.mir
+++ b/src/test/mir-opt/simplify_try/rustc.try_identity.SimplifyLocals.after.mir
@@ -3,27 +3,22 @@
 fn try_identity(_1: std::result::Result<u32, i32>) -> std::result::Result<u32, i32> {
     debug x => _1;                       // in scope 0 at $DIR/simplify_try.rs:5:17: 5:18
     let mut _0: std::result::Result<u32, i32>; // return place in scope 0 at $DIR/simplify_try.rs:5:41: 5:57
-    let _2: u32;                         // in scope 0 at $DIR/simplify_try.rs:6:9: 6:10
-    let _3: i32;                         // in scope 0 at $DIR/simplify_try.rs:6:14: 6:15
-    let mut _4: i32;                     // in scope 0 at $DIR/simplify_try.rs:6:14: 6:15
-    let mut _5: i32;                     // in scope 0 at $DIR/simplify_try.rs:6:14: 6:15
-    let _6: u32;                         // in scope 0 at $DIR/simplify_try.rs:6:13: 6:15
     scope 1 {
-        debug y => _2;                   // in scope 1 at $DIR/simplify_try.rs:6:9: 6:10
+        debug y => ((_0 as Ok).0: u32);  // in scope 1 at $DIR/simplify_try.rs:6:9: 6:10
     }
     scope 2 {
-        debug err => _3;                 // in scope 2 at $DIR/simplify_try.rs:6:14: 6:15
+        debug err => ((_0 as Err).0: i32); // in scope 2 at $DIR/simplify_try.rs:6:14: 6:15
         scope 3 {
             scope 7 {
-                debug t => _5;           // in scope 7 at $SRC_DIR/libcore/convert/mod.rs:LL:COL
+                debug t => ((_0 as Err).0: i32); // in scope 7 at $SRC_DIR/libcore/convert/mod.rs:LL:COL
             }
             scope 8 {
-                debug v => _4;           // in scope 8 at $SRC_DIR/libcore/result.rs:LL:COL
+                debug v => ((_0 as Err).0: i32); // in scope 8 at $SRC_DIR/libcore/result.rs:LL:COL
             }
         }
     }
     scope 4 {
-        debug val => _6;                 // in scope 4 at $DIR/simplify_try.rs:6:13: 6:15
+        debug val => ((_0 as Ok).0: u32); // in scope 4 at $DIR/simplify_try.rs:6:13: 6:15
         scope 5 {
         }
     }
@@ -32,9 +27,7 @@ fn try_identity(_1: std::result::Result<u32, i32>) -> std::result::Result<u32, i
     }
 
     bb0: {
-        StorageLive(_2);                 // scope 0 at $DIR/simplify_try.rs:6:9: 6:10
         _0 = move _1;                    // scope 1 at $DIR/simplify_try.rs:7:5: 7:10
-        StorageDead(_2);                 // scope 0 at $DIR/simplify_try.rs:8:1: 8:2
         return;                          // scope 0 at $DIR/simplify_try.rs:8:2: 8:2
     }
 }
diff --git a/src/test/ui/fmt/feature-gate-format-args-capture.rs b/src/test/ui/fmt/feature-gate-format-args-capture.rs
new file mode 100644
index 00000000000..21af9161091
--- /dev/null
+++ b/src/test/ui/fmt/feature-gate-format-args-capture.rs
@@ -0,0 +1,6 @@
+fn main() {
+    format!("{foo}");                //~ ERROR: there is no argument named `foo`
+
+    // panic! doesn't hit format_args! unless there are two or more arguments.
+    panic!("{foo} {bar}", bar=1);    //~ ERROR: there is no argument named `foo`
+}
diff --git a/src/test/ui/fmt/feature-gate-format-args-capture.stderr b/src/test/ui/fmt/feature-gate-format-args-capture.stderr
new file mode 100644
index 00000000000..f08f1651cb6
--- /dev/null
+++ b/src/test/ui/fmt/feature-gate-format-args-capture.stderr
@@ -0,0 +1,18 @@
+error: there is no argument named `foo`
+  --> $DIR/feature-gate-format-args-capture.rs:2:14
+   |
+LL |     format!("{foo}");
+   |              ^^^^^
+   |
+   = help: if you intended to capture `foo` from the surrounding scope, add `#![feature(format_args_capture)]` to the crate attributes
+
+error: there is no argument named `foo`
+  --> $DIR/feature-gate-format-args-capture.rs:5:13
+   |
+LL |     panic!("{foo} {bar}", bar=1);
+   |             ^^^^^
+   |
+   = help: if you intended to capture `foo` from the surrounding scope, add `#![feature(format_args_capture)]` to the crate attributes
+
+error: aborting due to 2 previous errors
+
diff --git a/src/test/ui/fmt/format-args-capture-macro-hygiene.rs b/src/test/ui/fmt/format-args-capture-macro-hygiene.rs
new file mode 100644
index 00000000000..6ca7dcc216f
--- /dev/null
+++ b/src/test/ui/fmt/format-args-capture-macro-hygiene.rs
@@ -0,0 +1,6 @@
+#![feature(format_args_capture)]
+
+fn main() {
+    format!(concat!("{foo}"));         //~ ERROR: there is no argument named `foo`
+    format!(concat!("{ba", "r} {}"), 1);     //~ ERROR: there is no argument named `bar`
+}
diff --git a/src/test/ui/fmt/format-args-capture-macro-hygiene.stderr b/src/test/ui/fmt/format-args-capture-macro-hygiene.stderr
new file mode 100644
index 00000000000..0c5915149cd
--- /dev/null
+++ b/src/test/ui/fmt/format-args-capture-macro-hygiene.stderr
@@ -0,0 +1,22 @@
+error: there is no argument named `foo`
+  --> $DIR/format-args-capture-macro-hygiene.rs:4:13
+   |
+LL |     format!(concat!("{foo}"));
+   |             ^^^^^^^^^^^^^^^^
+   |
+   = note: did you intend to capture a variable `foo` from the surrounding scope?
+   = note: to avoid ambiguity, `format_args!` cannot capture variables when the format string is expanded from a macro
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: there is no argument named `bar`
+  --> $DIR/format-args-capture-macro-hygiene.rs:5:13
+   |
+LL |     format!(concat!("{ba", "r} {}"), 1);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: did you intend to capture a variable `bar` from the surrounding scope?
+   = note: to avoid ambiguity, `format_args!` cannot capture variables when the format string is expanded from a macro
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 2 previous errors
+
diff --git a/src/test/ui/fmt/format-args-capture-missing-variables.rs b/src/test/ui/fmt/format-args-capture-missing-variables.rs
new file mode 100644
index 00000000000..3c596ae3bb8
--- /dev/null
+++ b/src/test/ui/fmt/format-args-capture-missing-variables.rs
@@ -0,0 +1,22 @@
+#![feature(format_args_capture)]
+
+fn main() {
+    format!("{} {foo} {} {bar} {}", 1, 2, 3);
+    //~^ ERROR: cannot find value `foo` in this scope
+    //~^^ ERROR: cannot find value `bar` in this scope
+
+    format!("{foo}");                //~ ERROR: cannot find value `foo` in this scope
+
+    format!("{valuea} {valueb}", valuea=5, valuec=7);
+    //~^ ERROR cannot find value `valueb` in this scope
+    //~^^ ERROR named argument never used
+
+    format!(r##"
+
+        {foo}
+
+    "##);
+    //~^^^^^ ERROR: cannot find value `foo` in this scope
+
+    panic!("{foo} {bar}", bar=1);    //~ ERROR: cannot find value `foo` in this scope
+}
diff --git a/src/test/ui/fmt/format-args-capture-missing-variables.stderr b/src/test/ui/fmt/format-args-capture-missing-variables.stderr
new file mode 100644
index 00000000000..c3d740eef9d
--- /dev/null
+++ b/src/test/ui/fmt/format-args-capture-missing-variables.stderr
@@ -0,0 +1,52 @@
+error: named argument never used
+  --> $DIR/format-args-capture-missing-variables.rs:10:51
+   |
+LL |     format!("{valuea} {valueb}", valuea=5, valuec=7);
+   |             -------------------                   ^ named argument never used
+   |             |
+   |             formatting specifier missing
+
+error[E0425]: cannot find value `foo` in this scope
+  --> $DIR/format-args-capture-missing-variables.rs:4:13
+   |
+LL |     format!("{} {foo} {} {bar} {}", 1, 2, 3);
+   |             ^^^^^^^^^^^^^^^^^^^^^^ not found in this scope
+
+error[E0425]: cannot find value `bar` in this scope
+  --> $DIR/format-args-capture-missing-variables.rs:4:13
+   |
+LL |     format!("{} {foo} {} {bar} {}", 1, 2, 3);
+   |             ^^^^^^^^^^^^^^^^^^^^^^ not found in this scope
+
+error[E0425]: cannot find value `foo` in this scope
+  --> $DIR/format-args-capture-missing-variables.rs:8:13
+   |
+LL |     format!("{foo}");
+   |             ^^^^^^^ not found in this scope
+
+error[E0425]: cannot find value `valueb` in this scope
+  --> $DIR/format-args-capture-missing-variables.rs:10:13
+   |
+LL |     format!("{valuea} {valueb}", valuea=5, valuec=7);
+   |             ^^^^^^^^^^^^^^^^^^^ not found in this scope
+
+error[E0425]: cannot find value `foo` in this scope
+  --> $DIR/format-args-capture-missing-variables.rs:14:13
+   |
+LL |       format!(r##"
+   |  _____________^
+LL | |
+LL | |         {foo}
+LL | |
+LL | |     "##);
+   | |_______^ not found in this scope
+
+error[E0425]: cannot find value `foo` in this scope
+  --> $DIR/format-args-capture-missing-variables.rs:21:12
+   |
+LL |     panic!("{foo} {bar}", bar=1);
+   |            ^^^^^^^^^^^^^ not found in this scope
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0425`.
diff --git a/src/test/ui/fmt/format-args-capture.rs b/src/test/ui/fmt/format-args-capture.rs
new file mode 100644
index 00000000000..7490632110c
--- /dev/null
+++ b/src/test/ui/fmt/format-args-capture.rs
@@ -0,0 +1,64 @@
+// run-pass
+// ignore-wasm32
+// ignore-wasm64
+#![feature(format_args_capture)]
+
+fn main() {
+    named_argument_takes_precedence_to_captured();
+    panic_with_single_argument_does_not_get_formatted();
+    panic_with_multiple_arguments_is_formatted();
+    formatting_parameters_can_be_captured();
+}
+
+fn named_argument_takes_precedence_to_captured() {
+    let foo = "captured";
+    let s = format!("{foo}", foo="named");
+    assert_eq!(&s, "named");
+
+    let s = format!("{foo}-{foo}-{foo}", foo="named");
+    assert_eq!(&s, "named-named-named");
+
+    let s = format!("{}-{bar}-{foo}", "positional", bar="named");
+    assert_eq!(&s, "positional-named-captured");
+}
+
+fn panic_with_single_argument_does_not_get_formatted() {
+    // panic! with a single argument does not perform string formatting.
+    // RFC #2795 suggests that this may need to change so that captured arguments are formatted.
+    // For stability reasons this will need to part of an edition change.
+
+    let msg = std::panic::catch_unwind(|| {
+        panic!("{foo}");
+    }).unwrap_err();
+
+    assert_eq!(msg.downcast_ref::<&str>(), Some(&"{foo}"))
+}
+
+fn panic_with_multiple_arguments_is_formatted() {
+    let foo = "captured";
+
+    let msg = std::panic::catch_unwind(|| {
+        panic!("{}-{bar}-{foo}", "positional", bar="named");
+    }).unwrap_err();
+
+    assert_eq!(msg.downcast_ref::<String>(), Some(&"positional-named-captured".to_string()))
+}
+
+fn formatting_parameters_can_be_captured() {
+    let width = 9;
+    let precision = 3;
+
+    let x = 7.0;
+
+    let s = format!("{x:width$}");
+    assert_eq!(&s, "        7");
+
+    let s = format!("{x:<width$}");
+    assert_eq!(&s, "7        ");
+
+    let s = format!("{x:-^width$}");
+    assert_eq!(&s, "----7----");
+
+    let s = format!("{x:-^width$.precision$}");
+    assert_eq!(&s, "--7.000--");
+}
diff --git a/src/test/ui/if/ifmt-bad-arg.stderr b/src/test/ui/if/ifmt-bad-arg.stderr
index 3e5f5a63742..0ff478826f7 100644
--- a/src/test/ui/if/ifmt-bad-arg.stderr
+++ b/src/test/ui/if/ifmt-bad-arg.stderr
@@ -63,18 +63,24 @@ error: there is no argument named `foo`
    |
 LL |     format!("{} {foo} {} {bar} {}", 1, 2, 3);
    |                 ^^^^^
+   |
+   = help: if you intended to capture `foo` from the surrounding scope, add `#![feature(format_args_capture)]` to the crate attributes
 
 error: there is no argument named `bar`
   --> $DIR/ifmt-bad-arg.rs:27:26
    |
 LL |     format!("{} {foo} {} {bar} {}", 1, 2, 3);
    |                          ^^^^^
+   |
+   = help: if you intended to capture `bar` from the surrounding scope, add `#![feature(format_args_capture)]` to the crate attributes
 
 error: there is no argument named `foo`
   --> $DIR/ifmt-bad-arg.rs:31:14
    |
 LL |     format!("{foo}");
    |              ^^^^^
+   |
+   = help: if you intended to capture `foo` from the surrounding scope, add `#![feature(format_args_capture)]` to the crate attributes
 
 error: multiple unused formatting arguments
   --> $DIR/ifmt-bad-arg.rs:32:17
@@ -155,6 +161,8 @@ error: there is no argument named `valueb`
    |
 LL |     format!("{valuea} {valueb}", valuea=5, valuec=7);
    |                       ^^^^^^^^
+   |
+   = help: if you intended to capture `valueb` from the surrounding scope, add `#![feature(format_args_capture)]` to the crate attributes
 
 error: named argument never used
   --> $DIR/ifmt-bad-arg.rs:45:51
@@ -205,6 +213,8 @@ error: there is no argument named `foo`
    |
 LL |         {foo}
    |         ^^^^^
+   |
+   = help: if you intended to capture `foo` from the surrounding scope, add `#![feature(format_args_capture)]` to the crate attributes
 
 error: invalid format string: expected `'}'`, found `'t'`
   --> $DIR/ifmt-bad-arg.rs:75:1
diff --git a/src/test/ui/parser/issue-1802-1.stderr b/src/test/ui/parser/issue-1802-1.stderr
index b7d003df56b..954cc0beeef 100644
--- a/src/test/ui/parser/issue-1802-1.stderr
+++ b/src/test/ui/parser/issue-1802-1.stderr
@@ -1,4 +1,4 @@
-error: no valid digits found for number
+error[E0768]: no valid digits found for number
   --> $DIR/issue-1802-1.rs:5:16
    |
 LL |     log(error, 0b);
@@ -6,3 +6,4 @@ LL |     log(error, 0b);
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0768`.
diff --git a/src/test/ui/parser/issue-1802-2.stderr b/src/test/ui/parser/issue-1802-2.stderr
index 8491dd07cb7..49043d07b35 100644
--- a/src/test/ui/parser/issue-1802-2.stderr
+++ b/src/test/ui/parser/issue-1802-2.stderr
@@ -1,4 +1,4 @@
-error: no valid digits found for number
+error[E0768]: no valid digits found for number
   --> $DIR/issue-1802-2.rs:5:16
    |
 LL |     log(error, 0b);
@@ -6,3 +6,4 @@ LL |     log(error, 0b);
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0768`.
diff --git a/src/test/ui/parser/lex-bad-numeric-literals.stderr b/src/test/ui/parser/lex-bad-numeric-literals.stderr
index 151480dd012..f05d6160302 100644
--- a/src/test/ui/parser/lex-bad-numeric-literals.stderr
+++ b/src/test/ui/parser/lex-bad-numeric-literals.stderr
@@ -46,7 +46,7 @@ error: hexadecimal float literal is not supported
 LL |     0x9.0e-9;
    |     ^^^^^^^^
 
-error: no valid digits found for number
+error[E0768]: no valid digits found for number
   --> $DIR/lex-bad-numeric-literals.rs:11:5
    |
 LL |     0o;
@@ -64,31 +64,31 @@ error: hexadecimal float literal is not supported
 LL |     0x539.0;
    |     ^^^^^^^
 
-error: no valid digits found for number
+error[E0768]: no valid digits found for number
   --> $DIR/lex-bad-numeric-literals.rs:18:5
    |
 LL |     0x;
    |     ^^
 
-error: no valid digits found for number
+error[E0768]: no valid digits found for number
   --> $DIR/lex-bad-numeric-literals.rs:19:5
    |
 LL |     0xu32;
    |     ^^
 
-error: no valid digits found for number
+error[E0768]: no valid digits found for number
   --> $DIR/lex-bad-numeric-literals.rs:20:5
    |
 LL |     0ou32;
    |     ^^
 
-error: no valid digits found for number
+error[E0768]: no valid digits found for number
   --> $DIR/lex-bad-numeric-literals.rs:21:5
    |
 LL |     0bu32;
    |     ^^
 
-error: no valid digits found for number
+error[E0768]: no valid digits found for number
   --> $DIR/lex-bad-numeric-literals.rs:22:5
    |
 LL |     0b;
@@ -138,3 +138,4 @@ LL |     0b101f64;
 
 error: aborting due to 23 previous errors
 
+For more information about this error, try `rustc --explain E0768`.