Auto merge of #133841 - matthiaskrgr:rollup-2snj3hc, r=matthiaskrgr

Rollup of 6 pull requests

Successful merges:

 - #133651 (Update `NonZero` and `NonNull` to not field-project (per MCP#807))
 - #133764 (rustdoc: Rename `set_back_info` to `restore_module_data`.)
 - #133784 (Fix MutVisitor's default implementations to visit Stmt's and BinOp's spans)
 - #133798 (stop replacing bivariant args with `'static` when computing closure requirements)
 - #133804 (Improve code for FileName retrieval in rustdoc)
 - #133817 (Use `eprintln` instead of `println` in bootstrap/compiletest/tidy)

Failed merges:

 - #133810 (remove unnecessary `eval_verify_bound`)

r? `@ghost`
`@rustbot` modify labels: rollup

62 files changed, 913 insertions, 830 deletions

diff --git a/compiler/rustc_ast/src/mut_visit.rs b/compiler/rustc_ast/src/mut_visit.rs
index 196fcc1af30..622c260868e 100644
--- a/compiler/rustc_ast/src/mut_visit.rs
+++ b/compiler/rustc_ast/src/mut_visit.rs
@@ -1625,9 +1625,10 @@ pub fn walk_expr<T: MutVisitor>(vis: &mut T, Expr { kind, id, span, attrs, token
             visit_thin_exprs(vis, call_args);
             vis.visit_span(span);
         }
-        ExprKind::Binary(_binop, lhs, rhs) => {
+        ExprKind::Binary(binop, lhs, rhs) => {
             vis.visit_expr(lhs);
             vis.visit_expr(rhs);
+            vis.visit_span(&mut binop.span);
         }
         ExprKind::Unary(_unop, ohs) => vis.visit_expr(ohs),
         ExprKind::Cast(expr, ty) => {
@@ -1785,20 +1786,21 @@ pub fn noop_filter_map_expr<T: MutVisitor>(vis: &mut T, mut e: P<Expr>) -> Optio
 
 pub fn walk_flat_map_stmt<T: MutVisitor>(
     vis: &mut T,
-    Stmt { kind, mut span, mut id }: Stmt,
+    Stmt { kind, span, mut id }: Stmt,
 ) -> SmallVec<[Stmt; 1]> {
     vis.visit_id(&mut id);
-    let stmts: SmallVec<_> = walk_flat_map_stmt_kind(vis, kind)
+    let mut stmts: SmallVec<[Stmt; 1]> = walk_flat_map_stmt_kind(vis, kind)
         .into_iter()
         .map(|kind| Stmt { id, kind, span })
         .collect();
-    if stmts.len() > 1 {
-        panic!(
+    match stmts.len() {
+        0 => {}
+        1 => vis.visit_span(&mut stmts[0].span),
+        2.. => panic!(
             "cloning statement `NodeId`s is prohibited by default, \
              the visitor should implement custom statement visiting"
-        );
+        ),
     }
-    vis.visit_span(&mut span);
     stmts
 }
 
diff --git a/compiler/rustc_borrowck/src/region_infer/mod.rs b/compiler/rustc_borrowck/src/region_infer/mod.rs
index 99af5500ac6..0eecf98a6ed 100644
--- a/compiler/rustc_borrowck/src/region_infer/mod.rs
+++ b/compiler/rustc_borrowck/src/region_infer/mod.rs
@@ -973,25 +973,20 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         propagated_outlives_requirements: &mut Vec<ClosureOutlivesRequirement<'tcx>>,
     ) -> bool {
         let tcx = infcx.tcx;
-
-        let TypeTest { generic_kind, lower_bound, span: _, verify_bound: _ } = type_test;
+        let TypeTest { generic_kind, lower_bound, span: blame_span, ref verify_bound } = *type_test;
 
         let generic_ty = generic_kind.to_ty(tcx);
         let Some(subject) = self.try_promote_type_test_subject(infcx, generic_ty) else {
             return false;
         };
 
-        debug!("subject = {:?}", subject);
-
-        let r_scc = self.constraint_sccs.scc(*lower_bound);
-
+        let r_scc = self.constraint_sccs.scc(lower_bound);
         debug!(
             "lower_bound = {:?} r_scc={:?} universe={:?}",
             lower_bound,
             r_scc,
             self.constraint_sccs.annotation(r_scc).min_universe()
         );
-
         // If the type test requires that `T: 'a` where `'a` is a
         // placeholder from another universe, that effectively requires
         // `T: 'static`, so we have to propagate that requirement.
@@ -1004,7 +999,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             propagated_outlives_requirements.push(ClosureOutlivesRequirement {
                 subject,
                 outlived_free_region: static_r,
-                blame_span: type_test.span,
+                blame_span,
                 category: ConstraintCategory::Boring,
             });
 
@@ -1031,12 +1026,12 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             // where `ur` is a local bound -- we are sometimes in a
             // position to prove things that our caller cannot. See
             // #53570 for an example.
-            if self.eval_verify_bound(infcx, generic_ty, ur, &type_test.verify_bound) {
+            if self.eval_verify_bound(infcx, generic_ty, ur, &verify_bound) {
                 continue;
             }
 
             let non_local_ub = self.universal_region_relations.non_local_upper_bounds(ur);
-            debug!("try_promote_type_test: non_local_ub={:?}", non_local_ub);
+            debug!(?non_local_ub);
 
             // This is slightly too conservative. To show T: '1, given `'2: '1`
             // and `'3: '1` we only need to prove that T: '2 *or* T: '3, but to
@@ -1049,10 +1044,10 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                 let requirement = ClosureOutlivesRequirement {
                     subject,
                     outlived_free_region: upper_bound,
-                    blame_span: type_test.span,
+                    blame_span,
                     category: ConstraintCategory::Boring,
                 };
-                debug!("try_promote_type_test: pushing {:#?}", requirement);
+                debug!(?requirement, "adding closure requirement");
                 propagated_outlives_requirements.push(requirement);
             }
         }
@@ -1063,44 +1058,14 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     /// variables in the type `T` with an equal universal region from the
     /// closure signature.
     /// This is not always possible, so this is a fallible process.
-    #[instrument(level = "debug", skip(self, infcx))]
+    #[instrument(level = "debug", skip(self, infcx), ret)]
     fn try_promote_type_test_subject(
         &self,
         infcx: &InferCtxt<'tcx>,
         ty: Ty<'tcx>,
     ) -> Option<ClosureOutlivesSubject<'tcx>> {
         let tcx = infcx.tcx;
-
-        // Opaque types' args may include useless lifetimes.
-        // We will replace them with ReStatic.
-        struct OpaqueFolder<'tcx> {
-            tcx: TyCtxt<'tcx>,
-        }
-        impl<'tcx> ty::TypeFolder<TyCtxt<'tcx>> for OpaqueFolder<'tcx> {
-            fn cx(&self) -> TyCtxt<'tcx> {
-                self.tcx
-            }
-            fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
-                use ty::TypeSuperFoldable as _;
-                let tcx = self.tcx;
-                let &ty::Alias(ty::Opaque, ty::AliasTy { args, def_id, .. }) = t.kind() else {
-                    return t.super_fold_with(self);
-                };
-                let args = std::iter::zip(args, tcx.variances_of(def_id)).map(|(arg, v)| {
-                    match (arg.unpack(), v) {
-                        (ty::GenericArgKind::Lifetime(_), ty::Bivariant) => {
-                            tcx.lifetimes.re_static.into()
-                        }
-                        _ => arg.fold_with(self),
-                    }
-                });
-                Ty::new_opaque(tcx, def_id, tcx.mk_args_from_iter(args))
-            }
-        }
-
-        let ty = ty.fold_with(&mut OpaqueFolder { tcx });
         let mut failed = false;
-
         let ty = fold_regions(tcx, ty, |r, _depth| {
             let r_vid = self.to_region_vid(r);
             let r_scc = self.constraint_sccs.scc(r_vid);
diff --git a/library/core/src/num/nonzero.rs b/library/core/src/num/nonzero.rs
index e97af081143..a9294306b1b 100644
--- a/library/core/src/num/nonzero.rs
+++ b/library/core/src/num/nonzero.rs
@@ -37,6 +37,8 @@ pub unsafe trait ZeroablePrimitive: Sized + Copy + private::Sealed {
 macro_rules! impl_zeroable_primitive {
     ($($NonZeroInner:ident ( $primitive:ty )),+ $(,)?) => {
         mod private {
+            use super::*;
+
             #[unstable(
                 feature = "nonzero_internals",
                 reason = "implementation detail which may disappear or be replaced at any time",
@@ -45,7 +47,11 @@ macro_rules! impl_zeroable_primitive {
             pub trait Sealed {}
 
             $(
-                #[derive(Debug, Clone, Copy, PartialEq)]
+                // This inner type is never shown directly, so intentionally does not have Debug
+                #[expect(missing_debug_implementations)]
+                // Since this struct is non-generic and derives Copy,
+                // the derived Clone is `*self` and thus doesn't field-project.
+                #[derive(Clone, Copy)]
                 #[repr(transparent)]
                 #[rustc_layout_scalar_valid_range_start(1)]
                 #[rustc_nonnull_optimization_guaranteed]
@@ -55,6 +61,16 @@ macro_rules! impl_zeroable_primitive {
                     issue = "none"
                 )]
                 pub struct $NonZeroInner($primitive);
+
+                // This is required to allow matching a constant.  We don't get it from a derive
+                // because the derived `PartialEq` would do a field projection, which is banned
+                // by <https://github.com/rust-lang/compiler-team/issues/807>.
+                #[unstable(
+                    feature = "nonzero_internals",
+                    reason = "implementation detail which may disappear or be replaced at any time",
+                    issue = "none"
+                )]
+                impl StructuralPartialEq for $NonZeroInner {}
             )+
         }
 
@@ -172,7 +188,7 @@ where
 {
     #[inline]
     fn clone(&self) -> Self {
-        Self(self.0)
+        *self
     }
 }
 
@@ -440,15 +456,21 @@ where
     #[rustc_const_stable(feature = "const_nonzero_get", since = "1.34.0")]
     #[inline]
     pub const fn get(self) -> T {
-        // FIXME: This can be changed to simply `self.0` once LLVM supports `!range` metadata
-        // for function arguments: https://github.com/llvm/llvm-project/issues/76628
-        //
         // Rustc can set range metadata only if it loads `self` from
         // memory somewhere. If the value of `self` was from by-value argument
         // of some not-inlined function, LLVM don't have range metadata
         // to understand that the value cannot be zero.
         //
-        // For now, using the transmute `assume`s the range at runtime.
+        // Using the transmute `assume`s the range at runtime.
+        //
+        // Even once LLVM supports `!range` metadata for function arguments
+        // (see <https://github.com/llvm/llvm-project/issues/76628>), this can't
+        // be `.0` because MCP#807 bans field-projecting into `scalar_valid_range`
+        // types, and it arguably wouldn't want to be anyway because if this is
+        // MIR-inlined, there's no opportunity to put that argument metadata anywhere.
+        //
+        // The good answer here will eventually be pattern types, which will hopefully
+        // allow it to go back to `.0`, maybe with a cast of some sort.
         //
         // SAFETY: `ZeroablePrimitive` guarantees that the size and bit validity
         // of `.0` is such that this transmute is sound.
diff --git a/library/core/src/ptr/non_null.rs b/library/core/src/ptr/non_null.rs
index d37b7eedfcb..0ad1cad6914 100644
--- a/library/core/src/ptr/non_null.rs
+++ b/library/core/src/ptr/non_null.rs
@@ -7,7 +7,7 @@ use crate::pin::PinCoerceUnsized;
 use crate::ptr::Unique;
 use crate::slice::{self, SliceIndex};
 use crate::ub_checks::assert_unsafe_precondition;
-use crate::{fmt, hash, intrinsics, ptr};
+use crate::{fmt, hash, intrinsics, mem, ptr};
 
 /// `*mut T` but non-zero and [covariant].
 ///
@@ -69,6 +69,8 @@ use crate::{fmt, hash, intrinsics, ptr};
 #[rustc_nonnull_optimization_guaranteed]
 #[rustc_diagnostic_item = "NonNull"]
 pub struct NonNull<T: ?Sized> {
+    // Remember to use `.as_ptr()` instead of `.pointer`, as field projecting to
+    // this is banned by <https://github.com/rust-lang/compiler-team/issues/807>.
     pointer: *const T,
 }
 
@@ -282,7 +284,7 @@ impl<T: ?Sized> NonNull<T> {
     pub fn addr(self) -> NonZero<usize> {
         // SAFETY: The pointer is guaranteed by the type to be non-null,
         // meaning that the address will be non-zero.
-        unsafe { NonZero::new_unchecked(self.pointer.addr()) }
+        unsafe { NonZero::new_unchecked(self.as_ptr().addr()) }
     }
 
     /// Creates a new pointer with the given address and the [provenance][crate::ptr#provenance] of
@@ -296,7 +298,7 @@ impl<T: ?Sized> NonNull<T> {
     #[stable(feature = "strict_provenance", since = "1.84.0")]
     pub fn with_addr(self, addr: NonZero<usize>) -> Self {
         // SAFETY: The result of `ptr::from::with_addr` is non-null because `addr` is guaranteed to be non-zero.
-        unsafe { NonNull::new_unchecked(self.pointer.with_addr(addr.get()) as *mut _) }
+        unsafe { NonNull::new_unchecked(self.as_ptr().with_addr(addr.get()) as *mut _) }
     }
 
     /// Creates a new pointer by mapping `self`'s address to a new one, preserving the
@@ -335,7 +337,12 @@ impl<T: ?Sized> NonNull<T> {
     #[must_use]
     #[inline(always)]
     pub const fn as_ptr(self) -> *mut T {
-        self.pointer as *mut T
+        // This is a transmute for the same reasons as `NonZero::get`.
+
+        // SAFETY: `NonNull` is `transparent` over a `*const T`, and `*const T`
+        // and `*mut T` have the same layout, so transitively we can transmute
+        // our `NonNull` to a `*mut T` directly.
+        unsafe { mem::transmute::<Self, *mut T>(self) }
     }
 
     /// Returns a shared reference to the value. If the value may be uninitialized, [`as_uninit_ref`]
@@ -484,7 +491,7 @@ impl<T: ?Sized> NonNull<T> {
         // Additionally safety contract of `offset` guarantees that the resulting pointer is
         // pointing to an allocation, there can't be an allocation at null, thus it's safe to
         // construct `NonNull`.
-        unsafe { NonNull { pointer: intrinsics::offset(self.pointer, count) } }
+        unsafe { NonNull { pointer: intrinsics::offset(self.as_ptr(), count) } }
     }
 
     /// Calculates the offset from a pointer in bytes.
@@ -508,7 +515,7 @@ impl<T: ?Sized> NonNull<T> {
         // Additionally safety contract of `offset` guarantees that the resulting pointer is
         // pointing to an allocation, there can't be an allocation at null, thus it's safe to
         // construct `NonNull`.
-        unsafe { NonNull { pointer: self.pointer.byte_offset(count) } }
+        unsafe { NonNull { pointer: self.as_ptr().byte_offset(count) } }
     }
 
     /// Adds an offset to a pointer (convenience for `.offset(count as isize)`).
@@ -560,7 +567,7 @@ impl<T: ?Sized> NonNull<T> {
         // Additionally safety contract of `offset` guarantees that the resulting pointer is
         // pointing to an allocation, there can't be an allocation at null, thus it's safe to
         // construct `NonNull`.
-        unsafe { NonNull { pointer: intrinsics::offset(self.pointer, count) } }
+        unsafe { NonNull { pointer: intrinsics::offset(self.as_ptr(), count) } }
     }
 
     /// Calculates the offset from a pointer in bytes (convenience for `.byte_offset(count as isize)`).
@@ -584,7 +591,7 @@ impl<T: ?Sized> NonNull<T> {
         // Additionally safety contract of `add` guarantees that the resulting pointer is pointing
         // to an allocation, there can't be an allocation at null, thus it's safe to construct
         // `NonNull`.
-        unsafe { NonNull { pointer: self.pointer.byte_add(count) } }
+        unsafe { NonNull { pointer: self.as_ptr().byte_add(count) } }
     }
 
     /// Subtracts an offset from a pointer (convenience for
@@ -666,7 +673,7 @@ impl<T: ?Sized> NonNull<T> {
         // Additionally safety contract of `sub` guarantees that the resulting pointer is pointing
         // to an allocation, there can't be an allocation at null, thus it's safe to construct
         // `NonNull`.
-        unsafe { NonNull { pointer: self.pointer.byte_sub(count) } }
+        unsafe { NonNull { pointer: self.as_ptr().byte_sub(count) } }
     }
 
     /// Calculates the distance between two pointers within the same allocation. The returned value is in
@@ -763,7 +770,7 @@ impl<T: ?Sized> NonNull<T> {
         T: Sized,
     {
         // SAFETY: the caller must uphold the safety contract for `offset_from`.
-        unsafe { self.pointer.offset_from(origin.pointer) }
+        unsafe { self.as_ptr().offset_from(origin.as_ptr()) }
     }
 
     /// Calculates the distance between two pointers within the same allocation. The returned value is in
@@ -781,7 +788,7 @@ impl<T: ?Sized> NonNull<T> {
     #[rustc_const_stable(feature = "non_null_convenience", since = "1.80.0")]
     pub const unsafe fn byte_offset_from<U: ?Sized>(self, origin: NonNull<U>) -> isize {
         // SAFETY: the caller must uphold the safety contract for `byte_offset_from`.
-        unsafe { self.pointer.byte_offset_from(origin.pointer) }
+        unsafe { self.as_ptr().byte_offset_from(origin.as_ptr()) }
     }
 
     // N.B. `wrapping_offset``, `wrapping_add`, etc are not implemented because they can wrap to null
@@ -856,7 +863,7 @@ impl<T: ?Sized> NonNull<T> {
         T: Sized,
     {
         // SAFETY: the caller must uphold the safety contract for `sub_ptr`.
-        unsafe { self.pointer.sub_ptr(subtracted.pointer) }
+        unsafe { self.as_ptr().sub_ptr(subtracted.as_ptr()) }
     }
 
     /// Calculates the distance between two pointers within the same allocation, *where it's known that
@@ -875,7 +882,7 @@ impl<T: ?Sized> NonNull<T> {
     #[rustc_const_unstable(feature = "const_ptr_sub_ptr", issue = "95892")]
     pub const unsafe fn byte_sub_ptr<U: ?Sized>(self, origin: NonNull<U>) -> usize {
         // SAFETY: the caller must uphold the safety contract for `byte_sub_ptr`.
-        unsafe { self.pointer.byte_sub_ptr(origin.pointer) }
+        unsafe { self.as_ptr().byte_sub_ptr(origin.as_ptr()) }
     }
 
     /// Reads the value from `self` without moving it. This leaves the
@@ -893,7 +900,7 @@ impl<T: ?Sized> NonNull<T> {
         T: Sized,
     {
         // SAFETY: the caller must uphold the safety contract for `read`.
-        unsafe { ptr::read(self.pointer) }
+        unsafe { ptr::read(self.as_ptr()) }
     }
 
     /// Performs a volatile read of the value from `self` without moving it. This
@@ -914,7 +921,7 @@ impl<T: ?Sized> NonNull<T> {
         T: Sized,
     {
         // SAFETY: the caller must uphold the safety contract for `read_volatile`.
-        unsafe { ptr::read_volatile(self.pointer) }
+        unsafe { ptr::read_volatile(self.as_ptr()) }
     }
 
     /// Reads the value from `self` without moving it. This leaves the
@@ -934,7 +941,7 @@ impl<T: ?Sized> NonNull<T> {
         T: Sized,
     {
         // SAFETY: the caller must uphold the safety contract for `read_unaligned`.
-        unsafe { ptr::read_unaligned(self.pointer) }
+        unsafe { ptr::read_unaligned(self.as_ptr()) }
     }
 
     /// Copies `count * size_of<T>` bytes from `self` to `dest`. The source
@@ -954,7 +961,7 @@ impl<T: ?Sized> NonNull<T> {
         T: Sized,
     {
         // SAFETY: the caller must uphold the safety contract for `copy`.
-        unsafe { ptr::copy(self.pointer, dest.as_ptr(), count) }
+        unsafe { ptr::copy(self.as_ptr(), dest.as_ptr(), count) }
     }
 
     /// Copies `count * size_of<T>` bytes from `self` to `dest`. The source
@@ -974,7 +981,7 @@ impl<T: ?Sized> NonNull<T> {
         T: Sized,
     {
         // SAFETY: the caller must uphold the safety contract for `copy_nonoverlapping`.
-        unsafe { ptr::copy_nonoverlapping(self.pointer, dest.as_ptr(), count) }
+        unsafe { ptr::copy_nonoverlapping(self.as_ptr(), dest.as_ptr(), count) }
     }
 
     /// Copies `count * size_of<T>` bytes from `src` to `self`. The source
@@ -994,7 +1001,7 @@ impl<T: ?Sized> NonNull<T> {
         T: Sized,
     {
         // SAFETY: the caller must uphold the safety contract for `copy`.
-        unsafe { ptr::copy(src.pointer, self.as_ptr(), count) }
+        unsafe { ptr::copy(src.as_ptr(), self.as_ptr(), count) }
     }
 
     /// Copies `count * size_of<T>` bytes from `src` to `self`. The source
@@ -1014,7 +1021,7 @@ impl<T: ?Sized> NonNull<T> {
         T: Sized,
     {
         // SAFETY: the caller must uphold the safety contract for `copy_nonoverlapping`.
-        unsafe { ptr::copy_nonoverlapping(src.pointer, self.as_ptr(), count) }
+        unsafe { ptr::copy_nonoverlapping(src.as_ptr(), self.as_ptr(), count) }
     }
 
     /// Executes the destructor (if any) of the pointed-to value.
@@ -1201,7 +1208,7 @@ impl<T: ?Sized> NonNull<T> {
 
         {
             // SAFETY: `align` has been checked to be a power of 2 above.
-            unsafe { ptr::align_offset(self.pointer, align) }
+            unsafe { ptr::align_offset(self.as_ptr(), align) }
         }
     }
 
@@ -1229,7 +1236,7 @@ impl<T: ?Sized> NonNull<T> {
     where
         T: Sized,
     {
-        self.pointer.is_aligned()
+        self.as_ptr().is_aligned()
     }
 
     /// Returns whether the pointer is aligned to `align`.
@@ -1266,7 +1273,7 @@ impl<T: ?Sized> NonNull<T> {
     #[must_use]
     #[unstable(feature = "pointer_is_aligned_to", issue = "96284")]
     pub fn is_aligned_to(self, align: usize) -> bool {
-        self.pointer.is_aligned_to(align)
+        self.as_ptr().is_aligned_to(align)
     }
 }
 
diff --git a/src/bootstrap/src/bin/main.rs b/src/bootstrap/src/bin/main.rs
index ee813de1c9e..74dfe2e7ec8 100644
--- a/src/bootstrap/src/bin/main.rs
+++ b/src/bootstrap/src/bin/main.rs
@@ -48,9 +48,9 @@ fn main() {
             err => {
                 drop(err);
                 if let Ok(pid) = pid {
-                    println!("WARNING: build directory locked by process {pid}, waiting for lock");
+                    eprintln!("WARNING: build directory locked by process {pid}, waiting for lock");
                 } else {
-                    println!("WARNING: build directory locked, waiting for lock");
+                    eprintln!("WARNING: build directory locked, waiting for lock");
                 }
                 let mut lock = t!(build_lock.write());
                 t!(lock.write(process::id().to_string().as_ref()));
@@ -70,13 +70,13 @@ fn main() {
     // changelog warning, not the `x.py setup` message.
     let suggest_setup = config.config.is_none() && !matches!(config.cmd, Subcommand::Setup { .. });
     if suggest_setup {
-        println!("WARNING: you have not made a `config.toml`");
-        println!(
+        eprintln!("WARNING: you have not made a `config.toml`");
+        eprintln!(
             "HELP: consider running `./x.py setup` or copying `config.example.toml` by running \
             `cp config.example.toml config.toml`"
         );
     } else if let Some(suggestion) = &changelog_suggestion {
-        println!("{suggestion}");
+        eprintln!("{suggestion}");
     }
 
     let pre_commit = config.src.join(".git").join("hooks").join("pre-commit");
@@ -86,13 +86,13 @@ fn main() {
     Build::new(config).build();
 
     if suggest_setup {
-        println!("WARNING: you have not made a `config.toml`");
-        println!(
+        eprintln!("WARNING: you have not made a `config.toml`");
+        eprintln!(
             "HELP: consider running `./x.py setup` or copying `config.example.toml` by running \
             `cp config.example.toml config.toml`"
         );
     } else if let Some(suggestion) = &changelog_suggestion {
-        println!("{suggestion}");
+        eprintln!("{suggestion}");
     }
 
     // Give a warning if the pre-commit script is in pre-commit and not pre-push.
@@ -102,14 +102,14 @@ fn main() {
     if fs::read_to_string(pre_commit).is_ok_and(|contents| {
         contents.contains("https://github.com/rust-lang/rust/issues/77620#issuecomment-705144570")
     }) {
-        println!(
+        eprintln!(
             "WARNING: You have the pre-push script installed to .git/hooks/pre-commit. \
                   Consider moving it to .git/hooks/pre-push instead, which runs less often."
         );
     }
 
     if suggest_setup || changelog_suggestion.is_some() {
-        println!("NOTE: this message was printed twice to make it more likely to be seen");
+        eprintln!("NOTE: this message was printed twice to make it more likely to be seen");
     }
 
     if dump_bootstrap_shims {
diff --git a/src/bootstrap/src/bin/rustc.rs b/src/bootstrap/src/bin/rustc.rs
index 88595ff7e51..e57ed488f97 100644
--- a/src/bootstrap/src/bin/rustc.rs
+++ b/src/bootstrap/src/bin/rustc.rs
@@ -306,7 +306,7 @@ fn main() {
         // should run on success, after this block.
     }
     if verbose > 0 {
-        println!("\nDid not run successfully: {status}\n{cmd:?}\n-------------");
+        eprintln!("\nDid not run successfully: {status}\n{cmd:?}\n-------------");
     }
 
     if let Some(mut on_fail) = on_fail {
diff --git a/src/bootstrap/src/core/build_steps/check.rs b/src/bootstrap/src/core/build_steps/check.rs
index d46c0ab7fef..2af2e83db8f 100644
--- a/src/bootstrap/src/core/build_steps/check.rs
+++ b/src/bootstrap/src/core/build_steps/check.rs
@@ -287,7 +287,7 @@ impl Step for CodegenBackend {
     fn run(self, builder: &Builder<'_>) {
         // FIXME: remove once https://github.com/rust-lang/rust/issues/112393 is resolved
         if builder.build.config.vendor && self.backend == "gcc" {
-            println!("Skipping checking of `rustc_codegen_gcc` with vendoring enabled.");
+            eprintln!("Skipping checking of `rustc_codegen_gcc` with vendoring enabled.");
             return;
         }
 
diff --git a/src/bootstrap/src/core/build_steps/compile.rs b/src/bootstrap/src/core/build_steps/compile.rs
index 0cacd6e4f37..4419b11ac19 100644
--- a/src/bootstrap/src/core/build_steps/compile.rs
+++ b/src/bootstrap/src/core/build_steps/compile.rs
@@ -1611,7 +1611,7 @@ impl Step for Sysroot {
         let sysroot = sysroot_dir(compiler.stage);
 
         builder
-            .verbose(|| println!("Removing sysroot {} to avoid caching bugs", sysroot.display()));
+            .verbose(|| eprintln!("Removing sysroot {} to avoid caching bugs", sysroot.display()));
         let _ = fs::remove_dir_all(&sysroot);
         t!(fs::create_dir_all(&sysroot));
 
@@ -1681,7 +1681,7 @@ impl Step for Sysroot {
                     return true;
                 }
                 if !filtered_files.iter().all(|f| f != path.file_name().unwrap()) {
-                    builder.verbose_than(1, || println!("ignoring {}", path.display()));
+                    builder.verbose_than(1, || eprintln!("ignoring {}", path.display()));
                     false
                 } else {
                     true
@@ -2240,7 +2240,7 @@ pub fn stream_cargo(
         cargo.arg(arg);
     }
 
-    builder.verbose(|| println!("running: {cargo:?}"));
+    builder.verbose(|| eprintln!("running: {cargo:?}"));
 
     if builder.config.dry_run() {
         return true;
@@ -2261,12 +2261,12 @@ pub fn stream_cargo(
             Ok(msg) => {
                 if builder.config.json_output {
                     // Forward JSON to stdout.
-                    println!("{line}");
+                    eprintln!("{line}");
                 }
                 cb(msg)
             }
             // If this was informational, just print it out and continue
-            Err(_) => println!("{line}"),
+            Err(_) => eprintln!("{line}"),
         }
     }
 
diff --git a/src/bootstrap/src/core/build_steps/dist.rs b/src/bootstrap/src/core/build_steps/dist.rs
index a636c4a9ef1..b1401431f2c 100644
--- a/src/bootstrap/src/core/build_steps/dist.rs
+++ b/src/bootstrap/src/core/build_steps/dist.rs
@@ -2080,7 +2080,7 @@ fn maybe_install_llvm(
     {
         let mut cmd = command(llvm_config);
         cmd.arg("--libfiles");
-        builder.verbose(|| println!("running {cmd:?}"));
+        builder.verbose(|| eprintln!("running {cmd:?}"));
         let files = cmd.run_capture_stdout(builder).stdout();
         let build_llvm_out = &builder.llvm_out(builder.config.build);
         let target_llvm_out = &builder.llvm_out(target);
diff --git a/src/bootstrap/src/core/build_steps/format.rs b/src/bootstrap/src/core/build_steps/format.rs
index 29a96f77672..d32e06d8748 100644
--- a/src/bootstrap/src/core/build_steps/format.rs
+++ b/src/bootstrap/src/core/build_steps/format.rs
@@ -107,10 +107,10 @@ fn print_paths(verb: &str, adjective: Option<&str>, paths: &[String]) {
         if let Some(adjective) = adjective { format!("{adjective} ") } else { String::new() };
     if len <= 10 {
         for path in paths {
-            println!("fmt: {verb} {adjective}file {path}");
+            eprintln!("fmt: {verb} {adjective}file {path}");
         }
     } else {
-        println!("fmt: {verb} {len} {adjective}files");
+        eprintln!("fmt: {verb} {len} {adjective}files");
     }
 }
 
@@ -199,7 +199,7 @@ pub fn format(build: &Builder<'_>, check: bool, all: bool, paths: &[PathBuf]) {
                 match get_modified_rs_files(build) {
                     Ok(Some(files)) => {
                         if files.is_empty() {
-                            println!("fmt info: No modified files detected for formatting.");
+                            eprintln!("fmt info: No modified files detected for formatting.");
                             return;
                         }
 
diff --git a/src/bootstrap/src/core/build_steps/setup.rs b/src/bootstrap/src/core/build_steps/setup.rs
index 3a8f9e48c0d..1af7b954f5e 100644
--- a/src/bootstrap/src/core/build_steps/setup.rs
+++ b/src/bootstrap/src/core/build_steps/setup.rs
@@ -134,7 +134,7 @@ impl Step for Profile {
                     t!(fs::remove_file(path));
                 }
                 _ => {
-                    println!("Exiting.");
+                    eprintln!("Exiting.");
                     crate::exit!(1);
                 }
             }
@@ -184,15 +184,15 @@ pub fn setup(config: &Config, profile: Profile) {
         Profile::Dist => &["dist", "build"],
     };
 
-    println!();
+    eprintln!();
 
-    println!("To get started, try one of the following commands:");
+    eprintln!("To get started, try one of the following commands:");
     for cmd in suggestions {
-        println!("- `x.py {cmd}`");
+        eprintln!("- `x.py {cmd}`");
     }
 
     if profile != Profile::Dist {
-        println!(
+        eprintln!(
             "For more suggestions, see https://rustc-dev-guide.rust-lang.org/building/suggested.html"
         );
     }
@@ -224,7 +224,7 @@ fn setup_config_toml(path: &PathBuf, profile: Profile, config: &Config) {
     t!(fs::write(path, settings));
 
     let include_path = profile.include_path(&config.src);
-    println!("`x.py` will now use the configuration at {}", include_path.display());
+    eprintln!("`x.py` will now use the configuration at {}", include_path.display());
 }
 
 /// Creates a toolchain link for stage1 using `rustup`
@@ -256,7 +256,7 @@ impl Step for Link {
         }
 
         if !rustup_installed(builder) {
-            println!("WARNING: `rustup` is not installed; Skipping `stage1` toolchain linking.");
+            eprintln!("WARNING: `rustup` is not installed; Skipping `stage1` toolchain linking.");
             return;
         }
 
@@ -296,7 +296,7 @@ fn attempt_toolchain_link(builder: &Builder<'_>, stage_path: &str) {
     }
 
     if try_link_toolchain(builder, stage_path) {
-        println!(
+        eprintln!(
             "Added `stage1` rustup toolchain; try `cargo +stage1 build` on a separate rust project to run a newly-built toolchain"
         );
     } else {
@@ -321,14 +321,14 @@ fn toolchain_is_linked(builder: &Builder<'_>) -> bool {
                 return false;
             }
             // The toolchain has already been linked.
-            println!(
+            eprintln!(
                 "`stage1` toolchain already linked; not attempting to link `stage1` toolchain"
             );
         }
         None => {
             // In this case, we don't know if the `stage1` toolchain has been linked;
             // but `rustup` failed, so let's not go any further.
-            println!(
+            eprintln!(
                 "`rustup` failed to list current toolchains; not attempting to link `stage1` toolchain"
             );
         }
@@ -389,9 +389,9 @@ pub fn interactive_path() -> io::Result<Profile> {
         input.parse()
     }
 
-    println!("Welcome to the Rust project! What do you want to do with x.py?");
+    eprintln!("Welcome to the Rust project! What do you want to do with x.py?");
     for ((letter, _), profile) in abbrev_all() {
-        println!("{}) {}: {}", letter, profile, profile.purpose());
+        eprintln!("{}) {}: {}", letter, profile, profile.purpose());
     }
     let template = loop {
         print!(
@@ -488,7 +488,7 @@ fn install_git_hook_maybe(builder: &Builder<'_>, config: &Config) -> io::Result<
         return Ok(());
     }
 
-    println!(
+    eprintln!(
         "\nRust's CI will automatically fail if it doesn't pass `tidy`, the internal tool for ensuring code quality.
 If you'd like, x.py can install a git hook for you that will automatically run `test tidy` before
 pushing your code to ensure your code is up to par. If you decide later that this behavior is
@@ -496,7 +496,7 @@ undesirable, simply delete the `pre-push` file from .git/hooks."
     );
 
     if prompt_user("Would you like to install the git hook?: [y/N]")? != Some(PromptResult::Yes) {
-        println!("Ok, skipping installation!");
+        eprintln!("Ok, skipping installation!");
         return Ok(());
     }
     if !hooks_dir.exists() {
@@ -513,7 +513,7 @@ undesirable, simply delete the `pre-push` file from .git/hooks."
             );
             return Err(e);
         }
-        Ok(_) => println!("Linked `src/etc/pre-push.sh` to `.git/hooks/pre-push`"),
+        Ok(_) => eprintln!("Linked `src/etc/pre-push.sh` to `.git/hooks/pre-push`"),
     };
     Ok(())
 }
@@ -654,7 +654,7 @@ impl Step for Editor {
                 if let Some(editor_kind) = editor_kind {
                     while !t!(create_editor_settings_maybe(config, editor_kind.clone())) {}
                 } else {
-                    println!("Ok, skipping editor setup!");
+                    eprintln!("Ok, skipping editor setup!");
                 }
             }
             Err(e) => eprintln!("Could not determine the editor: {e}"),
@@ -687,7 +687,7 @@ fn create_editor_settings_maybe(config: &Config, editor: EditorKind) -> io::Resu
             mismatched_settings = Some(false);
         }
     }
-    println!(
+    eprintln!(
         "\nx.py can automatically install the recommended `{settings_filename}` file for rustc development"
     );
 
@@ -706,7 +706,7 @@ fn create_editor_settings_maybe(config: &Config, editor: EditorKind) -> io::Resu
         Some(PromptResult::Yes) => true,
         Some(PromptResult::Print) => false,
         _ => {
-            println!("Ok, skipping settings!");
+            eprintln!("Ok, skipping settings!");
             return Ok(true);
         }
     };
@@ -733,9 +733,9 @@ fn create_editor_settings_maybe(config: &Config, editor: EditorKind) -> io::Resu
             _ => "Created",
         };
         fs::write(&settings_path, editor.settings_template())?;
-        println!("{verb} `{}`", settings_filename);
+        eprintln!("{verb} `{}`", settings_filename);
     } else {
-        println!("\n{}", editor.settings_template());
+        eprintln!("\n{}", editor.settings_template());
     }
     Ok(should_create)
 }
diff --git a/src/bootstrap/src/core/build_steps/suggest.rs b/src/bootstrap/src/core/build_steps/suggest.rs
index ba9b1b2fc33..7b2d9fff8f5 100644
--- a/src/bootstrap/src/core/build_steps/suggest.rs
+++ b/src/bootstrap/src/core/build_steps/suggest.rs
@@ -66,6 +66,6 @@ pub fn suggest(builder: &Builder<'_>, run: bool) {
             build.build();
         }
     } else {
-        println!("HELP: consider using the `--run` flag to automatically run suggested tests");
+        eprintln!("HELP: consider using the `--run` flag to automatically run suggested tests");
     }
 }
diff --git a/src/bootstrap/src/core/build_steps/test.rs b/src/bootstrap/src/core/build_steps/test.rs
index 161157acffe..6da37530d96 100644
--- a/src/bootstrap/src/core/build_steps/test.rs
+++ b/src/bootstrap/src/core/build_steps/test.rs
@@ -471,11 +471,11 @@ impl Miri {
         // We re-use the `cargo` from above.
         cargo.arg("--print-sysroot");
 
-        builder.verbose(|| println!("running: {cargo:?}"));
+        builder.verbose(|| eprintln!("running: {cargo:?}"));
         let stdout = cargo.run_capture_stdout(builder).stdout();
         // Output is "<sysroot>\n".
         let sysroot = stdout.trim_end();
-        builder.verbose(|| println!("`cargo miri setup --print-sysroot` said: {sysroot:?}"));
+        builder.verbose(|| eprintln!("`cargo miri setup --print-sysroot` said: {sysroot:?}"));
         PathBuf::from(sysroot)
     }
 }
@@ -2478,7 +2478,7 @@ fn markdown_test(builder: &Builder<'_>, compiler: Compiler, markdown: &Path) ->
         }
     }
 
-    builder.verbose(|| println!("doc tests for: {}", markdown.display()));
+    builder.verbose(|| eprintln!("doc tests for: {}", markdown.display()));
     let mut cmd = builder.rustdoc_cmd(compiler);
     builder.add_rust_test_threads(&mut cmd);
     // allow for unstable options such as new editions
diff --git a/src/bootstrap/src/core/builder/cargo.rs b/src/bootstrap/src/core/builder/cargo.rs
index 77f6edaabb2..38abca8b8da 100644
--- a/src/bootstrap/src/core/builder/cargo.rs
+++ b/src/bootstrap/src/core/builder/cargo.rs
@@ -523,7 +523,7 @@ impl Builder<'_> {
 
         let sysroot_str = sysroot.as_os_str().to_str().expect("sysroot should be UTF-8");
         if self.is_verbose() && !matches!(self.config.dry_run, DryRun::SelfCheck) {
-            println!("using sysroot {sysroot_str}");
+            eprintln!("using sysroot {sysroot_str}");
         }
 
         let mut rustflags = Rustflags::new(target);
diff --git a/src/bootstrap/src/core/builder/mod.rs b/src/bootstrap/src/core/builder/mod.rs
index 026c26479d3..ffe3e053e72 100644
--- a/src/bootstrap/src/core/builder/mod.rs
+++ b/src/bootstrap/src/core/builder/mod.rs
@@ -392,14 +392,14 @@ impl StepDescription {
     fn is_excluded(&self, builder: &Builder<'_>, pathset: &PathSet) -> bool {
         if builder.config.skip.iter().any(|e| pathset.has(e, builder.kind)) {
             if !matches!(builder.config.dry_run, DryRun::SelfCheck) {
-                println!("Skipping {pathset:?} because it is excluded");
+                eprintln!("Skipping {pathset:?} because it is excluded");
             }
             return true;
         }
 
         if !builder.config.skip.is_empty() && !matches!(builder.config.dry_run, DryRun::SelfCheck) {
             builder.verbose(|| {
-                println!(
+                eprintln!(
                     "{:?} not skipped for {:?} -- not in {:?}",
                     pathset, self.name, builder.config.skip
                 )
@@ -1437,11 +1437,11 @@ impl<'a> Builder<'a> {
                 panic!("{}", out);
             }
             if let Some(out) = self.cache.get(&step) {
-                self.verbose_than(1, || println!("{}c {:?}", "  ".repeat(stack.len()), step));
+                self.verbose_than(1, || eprintln!("{}c {:?}", "  ".repeat(stack.len()), step));
 
                 return out;
             }
-            self.verbose_than(1, || println!("{}> {:?}", "  ".repeat(stack.len()), step));
+            self.verbose_than(1, || eprintln!("{}> {:?}", "  ".repeat(stack.len()), step));
             stack.push(Box::new(step.clone()));
         }
 
@@ -1462,7 +1462,7 @@ impl<'a> Builder<'a> {
             let step_string = format!("{step:?}");
             let brace_index = step_string.find('{').unwrap_or(0);
             let type_string = type_name::<S>();
-            println!(
+            eprintln!(
                 "[TIMING] {} {} -- {}.{:03}",
                 &type_string.strip_prefix("bootstrap::").unwrap_or(type_string),
                 &step_string[brace_index..],
@@ -1479,7 +1479,9 @@ impl<'a> Builder<'a> {
             let cur_step = stack.pop().expect("step stack empty");
             assert_eq!(cur_step.downcast_ref(), Some(&step));
         }
-        self.verbose_than(1, || println!("{}< {:?}", "  ".repeat(self.stack.borrow().len()), step));
+        self.verbose_than(1, || {
+            eprintln!("{}< {:?}", "  ".repeat(self.stack.borrow().len()), step)
+        });
         self.cache.put(step, out.clone());
         out
     }
diff --git a/src/bootstrap/src/core/config/config.rs b/src/bootstrap/src/core/config/config.rs
index b06147055f2..aa5cce2fb1b 100644
--- a/src/bootstrap/src/core/config/config.rs
+++ b/src/bootstrap/src/core/config/config.rs
@@ -1293,7 +1293,7 @@ impl Config {
                     .map(|change_id| change_id.inner.map(crate::find_recent_config_change_ids))
                 {
                     if !changes.is_empty() {
-                        println!(
+                        eprintln!(
                             "WARNING: There have been changes to x.py since you last updated:\n{}",
                             crate::human_readable_changes(&changes)
                         );
@@ -1559,7 +1559,7 @@ impl Config {
         }
 
         if cargo_clippy.is_some() && rustc.is_none() {
-            println!(
+            eprintln!(
                 "WARNING: Using `build.cargo-clippy` without `build.rustc` usually fails due to toolchain conflict."
             );
         }
@@ -1841,7 +1841,7 @@ impl Config {
 
             // FIXME: Remove this option at the end of 2024.
             if parallel_compiler.is_some() {
-                println!(
+                eprintln!(
                     "WARNING: The `rust.parallel-compiler` option is deprecated and does nothing. The parallel compiler (with one thread) is now the default"
                 );
             }
@@ -1873,7 +1873,7 @@ impl Config {
                         if available_backends.contains(&backend) {
                             panic!("Invalid value '{s}' for 'rust.codegen-backends'. Instead, please use '{backend}'.");
                         } else {
-                            println!("HELP: '{s}' for 'rust.codegen-backends' might fail. \
+                            eprintln!("HELP: '{s}' for 'rust.codegen-backends' might fail. \
                                 Codegen backends are mostly defined without the '{CODEGEN_BACKEND_PREFIX}' prefix. \
                                 In this case, it would be referred to as '{backend}'.");
                         }
@@ -1902,7 +1902,7 @@ impl Config {
         // tests may fail due to using a different channel than the one used by the compiler during tests.
         if let Some(commit) = &config.download_rustc_commit {
             if is_user_configured_rust_channel {
-                println!(
+                eprintln!(
                     "WARNING: `rust.download-rustc` is enabled. The `rust.channel` option will be overridden by the CI rustc's channel."
                 );
 
@@ -1992,10 +1992,10 @@ impl Config {
 
             if config.llvm_from_ci {
                 let warn = |option: &str| {
-                    println!(
+                    eprintln!(
                         "WARNING: `{option}` will only be used on `compiler/rustc_llvm` build, not for the LLVM build."
                     );
-                    println!(
+                    eprintln!(
                         "HELP: To use `{option}` for LLVM builds, set `download-ci-llvm` option to false."
                     );
                 };
@@ -2014,12 +2014,12 @@ impl Config {
                 // if they've chosen a different value.
 
                 if libzstd.is_some() {
-                    println!(
+                    eprintln!(
                         "WARNING: when using `download-ci-llvm`, the local `llvm.libzstd` option, \
                         like almost all `llvm.*` options, will be ignored and set by the LLVM CI \
                         artifacts builder config."
                     );
-                    println!(
+                    eprintln!(
                         "HELP: To use `llvm.libzstd` for LLVM/LLD builds, set `download-ci-llvm` option to false."
                     );
                 }
@@ -2088,7 +2088,7 @@ impl Config {
                             if available_backends.contains(&backend) {
                                 panic!("Invalid value '{s}' for 'target.{triple}.codegen-backends'. Instead, please use '{backend}'.");
                             } else {
-                                println!("HELP: '{s}' for 'target.{triple}.codegen-backends' might fail. \
+                                eprintln!("HELP: '{s}' for 'target.{triple}.codegen-backends' might fail. \
                                     Codegen backends are mostly defined without the '{CODEGEN_BACKEND_PREFIX}' prefix. \
                                     In this case, it would be referred to as '{backend}'.");
                             }
@@ -2304,7 +2304,7 @@ impl Config {
         if self.dry_run() {
             return Ok(());
         }
-        self.verbose(|| println!("running: {cmd:?}"));
+        self.verbose(|| eprintln!("running: {cmd:?}"));
         build_helper::util::try_run(cmd, self.is_verbose())
     }
 
@@ -2479,7 +2479,7 @@ impl Config {
                         // This happens when LLVM submodule is updated in CI, we should disable ci-rustc without an error
                         // to not break CI. For non-CI environments, we should return an error.
                         if CiEnv::is_ci() {
-                            println!("WARNING: LLVM submodule has changes, `download-rustc` will be disabled.");
+                            eprintln!("WARNING: LLVM submodule has changes, `download-rustc` will be disabled.");
                             return None;
                         } else {
                             panic!("ERROR: LLVM submodule has changes, `download-rustc` can't be used.");
@@ -2490,8 +2490,8 @@ impl Config {
                         let ci_config_toml = match self.get_builder_toml("ci-rustc") {
                             Ok(ci_config_toml) => ci_config_toml,
                             Err(e) if e.to_string().contains("unknown field") => {
-                                println!("WARNING: CI rustc has some fields that are no longer supported in bootstrap; download-rustc will be disabled.");
-                                println!("HELP: Consider rebasing to a newer commit if available.");
+                                eprintln!("WARNING: CI rustc has some fields that are no longer supported in bootstrap; download-rustc will be disabled.");
+                                eprintln!("HELP: Consider rebasing to a newer commit if available.");
                                 return None;
                             },
                             Err(e) => {
@@ -2516,7 +2516,7 @@ impl Config {
                             .is_some_and(|s| s == "1" || s == "true");
 
                         if disable_ci_rustc_if_incompatible && res.is_err() {
-                            println!("WARNING: download-rustc is disabled with `DISABLE_CI_RUSTC_IF_INCOMPATIBLE` env.");
+                            eprintln!("WARNING: download-rustc is disabled with `DISABLE_CI_RUSTC_IF_INCOMPATIBLE` env.");
                             return None;
                         }
 
@@ -2701,7 +2701,7 @@ impl Config {
             return;
         }
 
-        println!("Updating submodule {relative_path}");
+        eprintln!("Updating submodule {relative_path}");
         self.check_run(
             helpers::git(Some(&self.src))
                 .run_always()
@@ -2824,7 +2824,7 @@ impl Config {
             Some(StringOrBool::Bool(true)) => false,
             Some(StringOrBool::String(s)) if s == "if-unchanged" => {
                 if !self.rust_info.is_managed_git_subrepository() {
-                    println!(
+                    eprintln!(
                         "ERROR: `download-rustc=if-unchanged` is only compatible with Git managed sources."
                     );
                     crate::exit!(1);
@@ -2857,10 +2857,10 @@ impl Config {
                 if if_unchanged {
                     return None;
                 }
-                println!("ERROR: could not find commit hash for downloading rustc");
-                println!("HELP: maybe your repository history is too shallow?");
-                println!("HELP: consider setting `rust.download-rustc=false` in config.toml");
-                println!("HELP: or fetch enough history to include one upstream commit");
+                eprintln!("ERROR: could not find commit hash for downloading rustc");
+                eprintln!("HELP: maybe your repository history is too shallow?");
+                eprintln!("HELP: consider setting `rust.download-rustc=false` in config.toml");
+                eprintln!("HELP: or fetch enough history to include one upstream commit");
                 crate::exit!(1);
             }
         };
@@ -2899,7 +2899,7 @@ impl Config {
         let if_unchanged = || {
             if self.rust_info.is_from_tarball() {
                 // Git is needed for running "if-unchanged" logic.
-                println!(
+                eprintln!(
                     "WARNING: 'if-unchanged' has no effect on tarball sources; ignoring `download-ci-llvm`."
                 );
                 return false;
@@ -2948,10 +2948,10 @@ impl Config {
         // Only commits merged by bors will have CI artifacts.
         let commit = get_closest_merge_commit(Some(&self.src), &self.git_config(), &[]).unwrap();
         if commit.is_empty() {
-            println!("error: could not find commit hash for downloading components from CI");
-            println!("help: maybe your repository history is too shallow?");
-            println!("help: consider disabling `{option_name}`");
-            println!("help: or fetch enough history to include one upstream commit");
+            eprintln!("error: could not find commit hash for downloading components from CI");
+            eprintln!("help: maybe your repository history is too shallow?");
+            eprintln!("help: consider disabling `{option_name}`");
+            eprintln!("help: or fetch enough history to include one upstream commit");
             crate::exit!(1);
         }
 
@@ -2963,14 +2963,14 @@ impl Config {
         if has_changes {
             if if_unchanged {
                 if self.is_verbose() {
-                    println!(
+                    eprintln!(
                         "warning: saw changes to one of {modified_paths:?} since {commit}; \
                             ignoring `{option_name}`"
                     );
                 }
                 return None;
             }
-            println!(
+            eprintln!(
                 "warning: `{option_name}` is enabled, but there are changes to one of {modified_paths:?}"
             );
         }
@@ -3007,7 +3007,7 @@ pub(crate) fn check_incompatible_options_for_ci_llvm(
         ($current:expr, $expected:expr) => {
             if let Some(current) = &$current {
                 if Some(current) != $expected.as_ref() {
-                    println!(
+                    eprintln!(
                         "WARNING: `llvm.{}` has no effect with `llvm.download-ci-llvm`. \
                         Current value: {:?}, Expected value(s): {}{:?}",
                         stringify!($expected).replace("_", "-"),
@@ -3112,7 +3112,7 @@ fn check_incompatible_options_for_ci_rustc(
         ($current:expr, $expected:expr, $config_section:expr) => {
             if let Some(current) = &$current {
                 if Some(current) != $expected.as_ref() {
-                    println!(
+                    eprintln!(
                         "WARNING: `{}` has no effect with `rust.download-rustc`. \
                         Current value: {:?}, Expected value(s): {}{:?}",
                         format!("{}.{}", $config_section, stringify!($expected).replace("_", "-")),
diff --git a/src/bootstrap/src/core/config/flags.rs b/src/bootstrap/src/core/config/flags.rs
index bfeb811508c..66b9f5ed84e 100644
--- a/src/bootstrap/src/core/config/flags.rs
+++ b/src/bootstrap/src/core/config/flags.rs
@@ -196,12 +196,12 @@ impl Flags {
         if let Ok(HelpVerboseOnly { help: true, verbose: 1.., cmd: subcommand }) =
             HelpVerboseOnly::try_parse_from(normalize_args(args))
         {
-            println!("NOTE: updating submodules before printing available paths");
+            eprintln!("NOTE: updating submodules before printing available paths");
             let config = Config::parse(Self::parse(&[String::from("build")]));
             let build = Build::new(config);
             let paths = Builder::get_help(&build, subcommand);
             if let Some(s) = paths {
-                println!("{s}");
+                eprintln!("{s}");
             } else {
                 panic!("No paths available for subcommand `{}`", subcommand.as_str());
             }
diff --git a/src/bootstrap/src/core/download.rs b/src/bootstrap/src/core/download.rs
index db35e6907e6..05b91c518cf 100644
--- a/src/bootstrap/src/core/download.rs
+++ b/src/bootstrap/src/core/download.rs
@@ -77,7 +77,7 @@ impl Config {
         if self.dry_run() && !cmd.run_always {
             return true;
         }
-        self.verbose(|| println!("running: {cmd:?}"));
+        self.verbose(|| eprintln!("running: {cmd:?}"));
         check_run(cmd, self.is_verbose())
     }
 
@@ -144,7 +144,7 @@ impl Config {
     /// Please see <https://nixos.org/patchelf.html> for more information
     fn fix_bin_or_dylib(&self, fname: &Path) {
         assert_eq!(SHOULD_FIX_BINS_AND_DYLIBS.get(), Some(&true));
-        println!("attempting to patch {}", fname.display());
+        eprintln!("attempting to patch {}", fname.display());
 
         // Only build `.nix-deps` once.
         static NIX_DEPS_DIR: OnceLock<PathBuf> = OnceLock::new();
@@ -206,7 +206,7 @@ impl Config {
     }
 
     fn download_file(&self, url: &str, dest_path: &Path, help_on_error: &str) {
-        self.verbose(|| println!("download {url}"));
+        self.verbose(|| eprintln!("download {url}"));
         // Use a temporary file in case we crash while downloading, to avoid a corrupt download in cache/.
         let tempfile = self.tempdir().join(dest_path.file_name().unwrap());
         // While bootstrap itself only supports http and https downloads, downstream forks might
@@ -226,7 +226,7 @@ impl Config {
     }
 
     fn download_http_with_retries(&self, tempfile: &Path, url: &str, help_on_error: &str) {
-        println!("downloading {url}");
+        eprintln!("downloading {url}");
         // Try curl. If that fails and we are on windows, fallback to PowerShell.
         // options should be kept in sync with
         // src/bootstrap/src/core/download.rs
@@ -341,7 +341,7 @@ impl Config {
             short_path = short_path.strip_prefix(pattern).unwrap_or(short_path);
             let dst_path = dst.join(short_path);
             self.verbose(|| {
-                println!("extracting {} to {}", original_path.display(), dst.display())
+                eprintln!("extracting {} to {}", original_path.display(), dst.display())
             });
             if !t!(member.unpack_in(dst)) {
                 panic!("path traversal attack ??");
@@ -365,7 +365,7 @@ impl Config {
     pub(crate) fn verify(&self, path: &Path, expected: &str) -> bool {
         use sha2::Digest;
 
-        self.verbose(|| println!("verifying {}", path.display()));
+        self.verbose(|| eprintln!("verifying {}", path.display()));
 
         if self.dry_run() {
             return false;
@@ -391,7 +391,7 @@ impl Config {
         let verified = checksum == expected;
 
         if !verified {
-            println!(
+            eprintln!(
                 "invalid checksum: \n\
                 found:    {checksum}\n\
                 expected: {expected}",
@@ -421,7 +421,7 @@ enum DownloadSource {
 /// Functions that are only ever called once, but named for clarify and to avoid thousand-line functions.
 impl Config {
     pub(crate) fn download_clippy(&self) -> PathBuf {
-        self.verbose(|| println!("downloading stage0 clippy artifacts"));
+        self.verbose(|| eprintln!("downloading stage0 clippy artifacts"));
 
         let date = &self.stage0_metadata.compiler.date;
         let version = &self.stage0_metadata.compiler.version;
@@ -518,7 +518,7 @@ impl Config {
     }
 
     pub(crate) fn download_ci_rustc(&self, commit: &str) {
-        self.verbose(|| println!("using downloaded stage2 artifacts from CI (commit {commit})"));
+        self.verbose(|| eprintln!("using downloaded stage2 artifacts from CI (commit {commit})"));
 
         let version = self.artifact_version_part(commit);
         // download-rustc doesn't need its own cargo, it can just use beta's. But it does need the
@@ -539,7 +539,7 @@ impl Config {
 
     #[cfg(not(feature = "bootstrap-self-test"))]
     pub(crate) fn download_beta_toolchain(&self) {
-        self.verbose(|| println!("downloading stage0 beta artifacts"));
+        self.verbose(|| eprintln!("downloading stage0 beta artifacts"));
 
         let date = &self.stage0_metadata.compiler.date;
         let version = &self.stage0_metadata.compiler.version;
@@ -677,7 +677,7 @@ impl Config {
                     return;
                 } else {
                     self.verbose(|| {
-                        println!(
+                        eprintln!(
                             "ignoring cached file {} due to failed verification",
                             tarball.display()
                         )
@@ -776,10 +776,10 @@ download-rustc = false
                     t!(check_incompatible_options_for_ci_llvm(current_config_toml, ci_config_toml));
                 }
                 Err(e) if e.to_string().contains("unknown field") => {
-                    println!(
+                    eprintln!(
                         "WARNING: CI LLVM has some fields that are no longer supported in bootstrap; download-ci-llvm will be disabled."
                     );
-                    println!("HELP: Consider rebasing to a newer commit if available.");
+                    eprintln!("HELP: Consider rebasing to a newer commit if available.");
                 }
                 Err(e) => {
                     eprintln!("ERROR: Failed to parse CI LLVM config.toml: {e}");
diff --git a/src/bootstrap/src/core/sanity.rs b/src/bootstrap/src/core/sanity.rs
index dcf68cbeeda..71e7f40f032 100644
--- a/src/bootstrap/src/core/sanity.rs
+++ b/src/bootstrap/src/core/sanity.rs
@@ -237,11 +237,11 @@ than building it.
                 stage0_supported_target_list.intersection(&missing_targets_hashset).collect();
 
             if !duplicated_targets.is_empty() {
-                println!(
+                eprintln!(
                     "Following targets supported from the stage0 compiler, please remove them from STAGE0_MISSING_TARGETS list."
                 );
                 for duplicated_target in duplicated_targets {
-                    println!("  {duplicated_target}");
+                    eprintln!("  {duplicated_target}");
                 }
                 std::process::exit(1);
             }
diff --git a/src/bootstrap/src/lib.rs b/src/bootstrap/src/lib.rs
index 0ecf61ffcd9..5f778223d7d 100644
--- a/src/bootstrap/src/lib.rs
+++ b/src/bootstrap/src/lib.rs
@@ -406,11 +406,11 @@ impl Build {
             .unwrap()
             .trim();
         if local_release.split('.').take(2).eq(version.split('.').take(2)) {
-            build.verbose(|| println!("auto-detected local-rebuild {local_release}"));
+            build.verbose(|| eprintln!("auto-detected local-rebuild {local_release}"));
             build.local_rebuild = true;
         }
 
-        build.verbose(|| println!("finding compilers"));
+        build.verbose(|| eprintln!("finding compilers"));
         utils::cc_detect::find(&build);
         // When running `setup`, the profile is about to change, so any requirements we have now may
         // be different on the next invocation. Don't check for them until the next time x.py is
@@ -418,7 +418,7 @@ impl Build {
         //
         // Similarly, for `setup` we don't actually need submodules or cargo metadata.
         if !matches!(build.config.cmd, Subcommand::Setup { .. }) {
-            build.verbose(|| println!("running sanity check"));
+            build.verbose(|| eprintln!("running sanity check"));
             crate::core::sanity::check(&mut build);
 
             // Make sure we update these before gathering metadata so we don't get an error about missing
@@ -436,7 +436,7 @@ impl Build {
             // Now, update all existing submodules.
             build.update_existing_submodules();
 
-            build.verbose(|| println!("learning about cargo"));
+            build.verbose(|| eprintln!("learning about cargo"));
             crate::core::metadata::build(&mut build);
         }
 
@@ -605,7 +605,7 @@ impl Build {
         let stamp = dir.join(".stamp");
         let mut cleared = false;
         if mtime(&stamp) < mtime(input) {
-            self.verbose(|| println!("Dirty - {}", dir.display()));
+            self.verbose(|| eprintln!("Dirty - {}", dir.display()));
             let _ = fs::remove_dir_all(dir);
             cleared = true;
         } else if stamp.exists() {
@@ -890,7 +890,7 @@ impl Build {
         let executed_at = std::panic::Location::caller();
 
         self.verbose(|| {
-            println!("running: {command:?} (created at {created_at}, executed at {executed_at})")
+            eprintln!("running: {command:?} (created at {created_at}, executed at {executed_at})")
         });
 
         let cmd = command.as_command_mut();
@@ -947,7 +947,7 @@ Executed at: {executed_at}"#,
 
         let fail = |message: &str, output: CommandOutput| -> ! {
             if self.is_verbose() {
-                println!("{message}");
+                eprintln!("{message}");
             } else {
                 let (stdout, stderr) = (output.stdout_if_present(), output.stderr_if_present());
                 // If the command captures output, the user would not see any indication that
@@ -957,16 +957,16 @@ Executed at: {executed_at}"#,
                     if let Some(stdout) =
                         output.stdout_if_present().take_if(|s| !s.trim().is_empty())
                     {
-                        println!("STDOUT:\n{stdout}\n");
+                        eprintln!("STDOUT:\n{stdout}\n");
                     }
                     if let Some(stderr) =
                         output.stderr_if_present().take_if(|s| !s.trim().is_empty())
                     {
-                        println!("STDERR:\n{stderr}\n");
+                        eprintln!("STDERR:\n{stderr}\n");
                     }
-                    println!("Command {command:?} has failed. Rerun with -v to see more details.");
+                    eprintln!("Command {command:?} has failed. Rerun with -v to see more details.");
                 } else {
-                    println!("Command has failed. Rerun with -v to see more details.");
+                    eprintln!("Command has failed. Rerun with -v to see more details.");
                 }
             }
             exit!(1);
@@ -1011,7 +1011,7 @@ Executed at: {executed_at}"#,
         match self.config.dry_run {
             DryRun::SelfCheck => (),
             DryRun::Disabled | DryRun::UserSelected => {
-                println!("{msg}");
+                eprintln!("{msg}");
             }
         }
     }
@@ -1666,7 +1666,7 @@ Executed at: {executed_at}"#,
         if self.config.dry_run() {
             return;
         }
-        self.verbose_than(1, || println!("Copy/Link {src:?} to {dst:?}"));
+        self.verbose_than(1, || eprintln!("Copy/Link {src:?} to {dst:?}"));
         if src == dst {
             return;
         }
@@ -1775,7 +1775,7 @@ Executed at: {executed_at}"#,
             return;
         }
         let dst = dstdir.join(src.file_name().unwrap());
-        self.verbose_than(1, || println!("Install {src:?} to {dst:?}"));
+        self.verbose_than(1, || eprintln!("Install {src:?} to {dst:?}"));
         t!(fs::create_dir_all(dstdir));
         if !src.exists() {
             panic!("ERROR: File \"{}\" not found!", src.display());
diff --git a/src/bootstrap/src/utils/cc_detect.rs b/src/bootstrap/src/utils/cc_detect.rs
index 0df00469452..e8d5b60948a 100644
--- a/src/bootstrap/src/utils/cc_detect.rs
+++ b/src/bootstrap/src/utils/cc_detect.rs
@@ -155,15 +155,15 @@ pub fn find_target(build: &Build, target: TargetSelection) {
         build.cxx.borrow_mut().insert(target, compiler);
     }
 
-    build.verbose(|| println!("CC_{} = {:?}", target.triple, build.cc(target)));
-    build.verbose(|| println!("CFLAGS_{} = {cflags:?}", target.triple));
+    build.verbose(|| eprintln!("CC_{} = {:?}", target.triple, build.cc(target)));
+    build.verbose(|| eprintln!("CFLAGS_{} = {cflags:?}", target.triple));
     if let Ok(cxx) = build.cxx(target) {
         let cxxflags = build.cflags(target, GitRepo::Rustc, CLang::Cxx);
-        build.verbose(|| println!("CXX_{} = {cxx:?}", target.triple));
-        build.verbose(|| println!("CXXFLAGS_{} = {cxxflags:?}", target.triple));
+        build.verbose(|| eprintln!("CXX_{} = {cxx:?}", target.triple));
+        build.verbose(|| eprintln!("CXXFLAGS_{} = {cxxflags:?}", target.triple));
     }
     if let Some(ar) = ar {
-        build.verbose(|| println!("AR_{} = {ar:?}", target.triple));
+        build.verbose(|| eprintln!("AR_{} = {ar:?}", target.triple));
         build.ar.borrow_mut().insert(target, ar);
     }
 
diff --git a/src/bootstrap/src/utils/helpers.rs b/src/bootstrap/src/utils/helpers.rs
index 923cc2dfc28..c0d52fd3430 100644
--- a/src/bootstrap/src/utils/helpers.rs
+++ b/src/bootstrap/src/utils/helpers.rs
@@ -135,7 +135,7 @@ impl Drop for TimeIt {
     fn drop(&mut self) {
         let time = self.1.elapsed();
         if !self.0 {
-            println!("\tfinished in {}.{:03} seconds", time.as_secs(), time.subsec_millis());
+            eprintln!("\tfinished in {}.{:03} seconds", time.as_secs(), time.subsec_millis());
         }
     }
 }
@@ -267,12 +267,12 @@ pub fn check_run(cmd: &mut BootstrapCommand, print_cmd_on_fail: bool) -> bool {
     let status = match cmd.as_command_mut().status() {
         Ok(status) => status,
         Err(e) => {
-            println!("failed to execute command: {cmd:?}\nERROR: {e}");
+            eprintln!("failed to execute command: {cmd:?}\nERROR: {e}");
             return false;
         }
     };
     if !status.success() && print_cmd_on_fail {
-        println!(
+        eprintln!(
             "\n\ncommand did not execute successfully: {cmd:?}\n\
              expected success, got: {status}\n\n"
         );
diff --git a/src/bootstrap/src/utils/metrics.rs b/src/bootstrap/src/utils/metrics.rs
index 3b31fa36e88..2b393215f91 100644
--- a/src/bootstrap/src/utils/metrics.rs
+++ b/src/bootstrap/src/utils/metrics.rs
@@ -184,7 +184,7 @@ impl BuildMetrics {
                 if version.format_version == CURRENT_FORMAT_VERSION {
                     t!(serde_json::from_slice::<JsonRoot>(&contents)).invocations
                 } else {
-                    println!(
+                    eprintln!(
                         "WARNING: overriding existing build/metrics.json, as it's not \
                          compatible with build metrics format version {CURRENT_FORMAT_VERSION}."
                     );
diff --git a/src/bootstrap/src/utils/render_tests.rs b/src/bootstrap/src/utils/render_tests.rs
index eb2c8254dc0..27e1c5d01b7 100644
--- a/src/bootstrap/src/utils/render_tests.rs
+++ b/src/bootstrap/src/utils/render_tests.rs
@@ -56,7 +56,7 @@ fn run_tests(builder: &Builder<'_>, cmd: &mut BootstrapCommand, stream: bool) ->
     let cmd = cmd.as_command_mut();
     cmd.stdout(Stdio::piped());
 
-    builder.verbose(|| println!("running: {cmd:?}"));
+    builder.verbose(|| eprintln!("running: {cmd:?}"));
 
     let mut process = cmd.spawn().unwrap();
 
@@ -71,7 +71,7 @@ fn run_tests(builder: &Builder<'_>, cmd: &mut BootstrapCommand, stream: bool) ->
 
     let result = process.wait_with_output().unwrap();
     if !result.status.success() && builder.is_verbose() {
-        println!(
+        eprintln!(
             "\n\ncommand did not execute successfully: {cmd:?}\n\
              expected success, got: {}",
             result.status
@@ -135,7 +135,9 @@ impl<'a> Renderer<'a> {
         if self.up_to_date_tests > 0 {
             let n = self.up_to_date_tests;
             let s = if n > 1 { "s" } else { "" };
-            println!("help: ignored {n} up-to-date test{s}; use `--force-rerun` to prevent this\n");
+            eprintln!(
+                "help: ignored {n} up-to-date test{s}; use `--force-rerun` to prevent this\n"
+            );
         }
     }
 
@@ -190,7 +192,7 @@ impl<'a> Renderer<'a> {
         if let Some(exec_time) = test.exec_time {
             print!(" ({exec_time:.2?})");
         }
-        println!();
+        eprintln!();
     }
 
     fn render_test_outcome_terse(&mut self, outcome: Outcome<'_>, test: &TestOutcome) {
@@ -200,7 +202,7 @@ impl<'a> Renderer<'a> {
                 let executed = format!("{:>width$}", self.executed_tests - 1, width = total.len());
                 print!(" {executed}/{total}");
             }
-            println!();
+            eprintln!();
             self.terse_tests_in_line = 0;
         }
 
@@ -212,31 +214,31 @@ impl<'a> Renderer<'a> {
     fn render_suite_outcome(&self, outcome: Outcome<'_>, suite: &SuiteOutcome) {
         // The terse output doesn't end with a newline, so we need to add it ourselves.
         if !self.builder.config.verbose_tests {
-            println!();
+            eprintln!();
         }
 
         if !self.failures.is_empty() {
-            println!("\nfailures:\n");
+            eprintln!("\nfailures:\n");
             for failure in &self.failures {
                 if failure.stdout.is_some() || failure.message.is_some() {
-                    println!("---- {} stdout ----", failure.name);
+                    eprintln!("---- {} stdout ----", failure.name);
                     if let Some(stdout) = &failure.stdout {
-                        println!("{stdout}");
+                        eprintln!("{stdout}");
                     }
                     if let Some(message) = &failure.message {
-                        println!("NOTE: {message}");
+                        eprintln!("NOTE: {message}");
                     }
                 }
             }
 
-            println!("\nfailures:");
+            eprintln!("\nfailures:");
             for failure in &self.failures {
-                println!("    {}", failure.name);
+                eprintln!("    {}", failure.name);
             }
         }
 
         if !self.benches.is_empty() {
-            println!("\nbenchmarks:");
+            eprintln!("\nbenchmarks:");
 
             let mut rows = Vec::new();
             for bench in &self.benches {
@@ -251,13 +253,13 @@ impl<'a> Renderer<'a> {
             let max_1 = rows.iter().map(|r| r.1.len()).max().unwrap_or(0);
             let max_2 = rows.iter().map(|r| r.2.len()).max().unwrap_or(0);
             for row in &rows {
-                println!("    {:<max_0$} {:>max_1$} {:>max_2$}", row.0, row.1, row.2);
+                eprintln!("    {:<max_0$} {:>max_1$} {:>max_2$}", row.0, row.1, row.2);
             }
         }
 
         print!("\ntest result: ");
         self.builder.colored_stdout(|stdout| outcome.write_long(stdout)).unwrap();
-        println!(
+        eprintln!(
             ". {} passed; {} failed; {} ignored; {} measured; {} filtered out{time}\n",
             suite.passed,
             suite.failed,
@@ -274,7 +276,7 @@ impl<'a> Renderer<'a> {
     fn render_message(&mut self, message: Message) {
         match message {
             Message::Suite(SuiteMessage::Started { test_count }) => {
-                println!("\nrunning {test_count} tests");
+                eprintln!("\nrunning {test_count} tests");
                 self.executed_tests = 0;
                 self.terse_tests_in_line = 0;
                 self.tests_count = Some(test_count);
@@ -314,7 +316,7 @@ impl<'a> Renderer<'a> {
                 self.failures.push(outcome);
             }
             Message::Test(TestMessage::Timeout { name }) => {
-                println!("test {name} has been running for a long time");
+                eprintln!("test {name} has been running for a long time");
             }
             Message::Test(TestMessage::Started) => {} // Not useful
         }
diff --git a/src/bootstrap/src/utils/tarball.rs b/src/bootstrap/src/utils/tarball.rs
index 3c6c7a7fa18..f60498a4872 100644
--- a/src/bootstrap/src/utils/tarball.rs
+++ b/src/bootstrap/src/utils/tarball.rs
@@ -344,7 +344,7 @@ impl<'a> Tarball<'a> {
         // For `x install` tarball files aren't needed, so we can speed up the process by not producing them.
         let compression_profile = if self.builder.kind == Kind::Install {
             self.builder.verbose(|| {
-                println!("Forcing dist.compression-profile = 'no-op' for `x install`.")
+                eprintln!("Forcing dist.compression-profile = 'no-op' for `x install`.")
             });
             // "no-op" indicates that the rust-installer won't produce compressed tarball sources.
             "no-op"
diff --git a/src/librustdoc/formats/renderer.rs b/src/librustdoc/formats/renderer.rs
index 582ef7d2c48..5e4e6f27a15 100644
--- a/src/librustdoc/formats/renderer.rs
+++ b/src/librustdoc/formats/renderer.rs
@@ -17,17 +17,18 @@ pub(crate) trait FormatRenderer<'tcx>: Sized {
     ///
     /// This is true for html, and false for json. See #80664
     const RUN_ON_MODULE: bool;
+
     /// This associated type is the type where the current module information is stored.
     ///
     /// For each module, we go through their items by calling for each item:
     ///
-    /// 1. save_module_data
-    /// 2. item
-    /// 3. set_back_info
+    /// 1. `save_module_data`
+    /// 2. `item`
+    /// 3. `restore_module_data`
     ///
-    /// However,the `item` method might update information in `self` (for example if the child is
-    /// a module). To prevent it to impact the other children of the current module, we need to
-    /// reset the information between each call to `item` by using `set_back_info`.
+    /// This is because the `item` method might update information in `self` (for example if the child
+    /// is a module). To prevent it from impacting the other children of the current module, we need to
+    /// reset the information between each call to `item` by using `restore_module_data`.
     type ModuleData;
 
     /// Sets up any state required for the renderer. When this is called the cache has already been
@@ -41,18 +42,18 @@ pub(crate) trait FormatRenderer<'tcx>: Sized {
 
     /// This method is called right before call [`Self::item`]. This method returns a type
     /// containing information that needs to be reset after the [`Self::item`] method has been
-    /// called with the [`Self::set_back_info`] method.
+    /// called with the [`Self::restore_module_data`] method.
     ///
     /// In short it goes like this:
     ///
     /// ```ignore (not valid code)
-    /// let reset_data = type.save_module_data();
-    /// type.item(item)?;
-    /// type.set_back_info(reset_data);
+    /// let reset_data = renderer.save_module_data();
+    /// renderer.item(item)?;
+    /// renderer.restore_module_data(reset_data);
     /// ```
     fn save_module_data(&mut self) -> Self::ModuleData;
     /// Used to reset current module's information.
-    fn set_back_info(&mut self, info: Self::ModuleData);
+    fn restore_module_data(&mut self, info: Self::ModuleData);
 
     /// Renders a single non-module item. This means no recursive sub-item rendering is required.
     fn item(&mut self, item: clean::Item) -> Result<(), Error>;
@@ -91,7 +92,7 @@ fn run_format_inner<'tcx, T: FormatRenderer<'tcx>>(
         for it in module.items {
             let info = cx.save_module_data();
             run_format_inner(cx, it, prof)?;
-            cx.set_back_info(info);
+            cx.restore_module_data(info);
         }
 
         cx.mod_item_out()?;
diff --git a/src/librustdoc/html/render/context.rs b/src/librustdoc/html/render/context.rs
index 40468aef4db..2d5df75e7dc 100644
--- a/src/librustdoc/html/render/context.rs
+++ b/src/librustdoc/html/render/context.rs
@@ -601,7 +601,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
         self.info
     }
 
-    fn set_back_info(&mut self, info: Self::ModuleData) {
+    fn restore_module_data(&mut self, info: Self::ModuleData) {
         self.info = info;
     }
 
diff --git a/src/librustdoc/html/sources.rs b/src/librustdoc/html/sources.rs
index c37506e3588..9827f97d28d 100644
--- a/src/librustdoc/html/sources.rs
+++ b/src/librustdoc/html/sources.rs
@@ -9,7 +9,7 @@ use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
 use rustc_hir::def_id::LOCAL_CRATE;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::Session;
-use rustc_span::{FileName, sym};
+use rustc_span::{FileName, FileNameDisplayPreference, RealFileName, sym};
 use tracing::info;
 
 use crate::clean;
@@ -50,8 +50,14 @@ struct LocalSourcesCollector<'a, 'tcx> {
     src_root: &'a Path,
 }
 
-fn is_real_and_local(span: clean::Span, sess: &Session) -> bool {
-    span.cnum(sess) == LOCAL_CRATE && span.filename(sess).is_real()
+fn filename_real_and_local(span: clean::Span, sess: &Session) -> Option<RealFileName> {
+    if span.cnum(sess) == LOCAL_CRATE
+        && let FileName::Real(file) = span.filename(sess)
+    {
+        Some(file)
+    } else {
+        None
+    }
 }
 
 impl LocalSourcesCollector<'_, '_> {
@@ -60,16 +66,8 @@ impl LocalSourcesCollector<'_, '_> {
         let span = item.span(self.tcx);
         let Some(span) = span else { return };
         // skip all synthetic "files"
-        if !is_real_and_local(span, sess) {
-            return;
-        }
-        let filename = span.filename(sess);
-        let p = if let FileName::Real(file) = filename {
-            match file.into_local_path() {
-                Some(p) => p,
-                None => return,
-            }
-        } else {
+        let Some(p) = filename_real_and_local(span, sess).and_then(|file| file.into_local_path())
+        else {
             return;
         };
         if self.local_sources.contains_key(&*p) {
@@ -135,8 +133,7 @@ impl DocVisitor<'_> for SourceCollector<'_, '_> {
         // If we're not rendering sources, there's nothing to do.
         // If we're including source files, and we haven't seen this file yet,
         // then we need to render it out to the filesystem.
-        if is_real_and_local(span, sess) {
-            let filename = span.filename(sess);
+        if let Some(filename) = filename_real_and_local(span, sess) {
             let span = span.inner();
             let pos = sess.source_map().lookup_source_file(span.lo());
             let file_span = span.with_lo(pos.start_pos).with_hi(pos.end_position());
@@ -152,7 +149,7 @@ impl DocVisitor<'_> for SourceCollector<'_, '_> {
                         span,
                         format!(
                             "failed to render source code for `{filename}`: {e}",
-                            filename = filename.prefer_local(),
+                            filename = filename.to_string_lossy(FileNameDisplayPreference::Local),
                         ),
                     );
                     false
@@ -168,18 +165,13 @@ impl SourceCollector<'_, '_> {
     /// Renders the given filename into its corresponding HTML source file.
     fn emit_source(
         &mut self,
-        filename: &FileName,
+        file: &RealFileName,
         file_span: rustc_span::Span,
     ) -> Result<(), Error> {
-        let p = match *filename {
-            FileName::Real(ref file) => {
-                if let Some(local_path) = file.local_path() {
-                    local_path.to_path_buf()
-                } else {
-                    unreachable!("only the current crate should have sources emitted");
-                }
-            }
-            _ => return Ok(()),
+        let p = if let Some(local_path) = file.local_path() {
+            local_path.to_path_buf()
+        } else {
+            unreachable!("only the current crate should have sources emitted");
         };
         if self.emitted_local_sources.contains(&*p) {
             // We've already emitted this source
@@ -233,8 +225,10 @@ impl SourceCollector<'_, '_> {
         cur.push(&fname);
 
         let title = format!("{} - source", src_fname.to_string_lossy());
-        let desc =
-            format!("Source of the Rust file `{}`.", filename.prefer_remapped_unconditionaly());
+        let desc = format!(
+            "Source of the Rust file `{}`.",
+            file.to_string_lossy(FileNameDisplayPreference::Remapped)
+        );
         let page = layout::Page {
             title: &title,
             css_class: "src",
diff --git a/src/librustdoc/json/mod.rs b/src/librustdoc/json/mod.rs
index 9efcf6b4983..789a5614967 100644
--- a/src/librustdoc/json/mod.rs
+++ b/src/librustdoc/json/mod.rs
@@ -163,11 +163,10 @@ impl<'tcx> FormatRenderer<'tcx> for JsonRenderer<'tcx> {
     }
 
     fn save_module_data(&mut self) -> Self::ModuleData {
-        unreachable!("RUN_ON_MODULE = false should never call save_module_data")
+        unreachable!("RUN_ON_MODULE = false, should never call save_module_data")
     }
-
-    fn set_back_info(&mut self, _info: Self::ModuleData) {
-        unreachable!("RUN_ON_MODULE = false should never call set_back_info")
+    fn restore_module_data(&mut self, _info: Self::ModuleData) {
+        unreachable!("RUN_ON_MODULE = false, should never call set_back_info")
     }
 
     /// Inserts an item into the index. This should be used rather than directly calling insert on
@@ -248,7 +247,7 @@ impl<'tcx> FormatRenderer<'tcx> for JsonRenderer<'tcx> {
     }
 
     fn mod_item_in(&mut self, _item: &clean::Item) -> Result<(), Error> {
-        unreachable!("RUN_ON_MODULE = false should never call mod_item_in")
+        unreachable!("RUN_ON_MODULE = false, should never call mod_item_in")
     }
 
     fn after_krate(&mut self) -> Result<(), Error> {
diff --git a/src/tools/compiletest/src/compute_diff.rs b/src/tools/compiletest/src/compute_diff.rs
index 92c80c27de0..3ace6c5b6d7 100644
--- a/src/tools/compiletest/src/compute_diff.rs
+++ b/src/tools/compiletest/src/compute_diff.rs
@@ -144,7 +144,7 @@ where
     }
 
     if !wrote_data {
-        println!("note: diff is identical to nightly rustdoc");
+        eprintln!("note: diff is identical to nightly rustdoc");
         assert!(diff_output.metadata().unwrap().len() == 0);
         return false;
     } else if verbose {
diff --git a/src/tools/compiletest/src/debuggers.rs b/src/tools/compiletest/src/debuggers.rs
index b605bc813f1..e75c8a5993e 100644
--- a/src/tools/compiletest/src/debuggers.rs
+++ b/src/tools/compiletest/src/debuggers.rs
@@ -20,7 +20,7 @@ pub(crate) fn configure_gdb(config: &Config) -> Option<Arc<Config>> {
     }
 
     if config.remote_test_client.is_some() && !config.target.contains("android") {
-        println!(
+        eprintln!(
             "WARNING: debuginfo tests are not available when \
              testing with remote"
         );
@@ -28,7 +28,7 @@ pub(crate) fn configure_gdb(config: &Config) -> Option<Arc<Config>> {
     }
 
     if config.target.contains("android") {
-        println!(
+        eprintln!(
             "{} debug-info test uses tcp 5039 port.\
              please reserve it",
             config.target
@@ -50,7 +50,7 @@ pub(crate) fn configure_lldb(config: &Config) -> Option<Arc<Config>> {
     config.lldb_python_dir.as_ref()?;
 
     if let Some(350) = config.lldb_version {
-        println!(
+        eprintln!(
             "WARNING: The used version of LLDB (350) has a \
              known issue that breaks debuginfo tests. See \
              issue #32520 for more information. Skipping all \
diff --git a/src/tools/compiletest/src/lib.rs b/src/tools/compiletest/src/lib.rs
index bf4a3124075..447568065f5 100644
--- a/src/tools/compiletest/src/lib.rs
+++ b/src/tools/compiletest/src/lib.rs
@@ -188,8 +188,8 @@ pub fn parse_config(args: Vec<String>) -> Config {
     let (argv0, args_) = args.split_first().unwrap();
     if args.len() == 1 || args[1] == "-h" || args[1] == "--help" {
         let message = format!("Usage: {} [OPTIONS] [TESTNAME...]", argv0);
-        println!("{}", opts.usage(&message));
-        println!();
+        eprintln!("{}", opts.usage(&message));
+        eprintln!();
         panic!()
     }
 
@@ -200,8 +200,8 @@ pub fn parse_config(args: Vec<String>) -> Config {
 
     if matches.opt_present("h") || matches.opt_present("help") {
         let message = format!("Usage: {} [OPTIONS]  [TESTNAME...]", argv0);
-        println!("{}", opts.usage(&message));
-        println!();
+        eprintln!("{}", opts.usage(&message));
+        eprintln!();
         panic!()
     }
 
@@ -501,7 +501,7 @@ pub fn run_tests(config: Arc<Config>) {
             // easy to miss which tests failed, and as such fail to reproduce
             // the failure locally.
 
-            println!(
+            eprintln!(
                 "Some tests failed in compiletest suite={}{} mode={} host={} target={}",
                 config.suite,
                 config
diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
index 84269fd44a1..8c747a1d93f 100644
--- a/src/tools/compiletest/src/runtest.rs
+++ b/src/tools/compiletest/src/runtest.rs
@@ -774,20 +774,20 @@ impl<'test> TestCx<'test> {
                 unexpected.len(),
                 not_found.len()
             ));
-            println!("status: {}\ncommand: {}\n", proc_res.status, proc_res.cmdline);
+            eprintln!("status: {}\ncommand: {}\n", proc_res.status, proc_res.cmdline);
             if !unexpected.is_empty() {
-                println!("{}", "--- unexpected errors (from JSON output) ---".green());
+                eprintln!("{}", "--- unexpected errors (from JSON output) ---".green());
                 for error in &unexpected {
-                    println!("{}", error.render_for_expected());
+                    eprintln!("{}", error.render_for_expected());
                 }
-                println!("{}", "---".green());
+                eprintln!("{}", "---".green());
             }
             if !not_found.is_empty() {
-                println!("{}", "--- not found errors (from test file) ---".red());
+                eprintln!("{}", "--- not found errors (from test file) ---".red());
                 for error in &not_found {
-                    println!("{}", error.render_for_expected());
+                    eprintln!("{}", error.render_for_expected());
                 }
-                println!("{}", "---\n".red());
+                eprintln!("{}", "---\n".red());
             }
             panic!("errors differ from expected");
         }
@@ -1876,18 +1876,18 @@ impl<'test> TestCx<'test> {
 
     fn maybe_dump_to_stdout(&self, out: &str, err: &str) {
         if self.config.verbose {
-            println!("------stdout------------------------------");
-            println!("{}", out);
-            println!("------stderr------------------------------");
-            println!("{}", err);
-            println!("------------------------------------------");
+            eprintln!("------stdout------------------------------");
+            eprintln!("{}", out);
+            eprintln!("------stderr------------------------------");
+            eprintln!("{}", err);
+            eprintln!("------------------------------------------");
         }
     }
 
     fn error(&self, err: &str) {
         match self.revision {
-            Some(rev) => println!("\nerror in revision `{}`: {}", rev, err),
-            None => println!("\nerror: {}", err),
+            Some(rev) => eprintln!("\nerror in revision `{}`: {}", rev, err),
+            None => eprintln!("\nerror: {}", err),
         }
     }
 
@@ -1972,7 +1972,7 @@ impl<'test> TestCx<'test> {
         if !self.config.has_html_tidy {
             return;
         }
-        println!("info: generating a diff against nightly rustdoc");
+        eprintln!("info: generating a diff against nightly rustdoc");
 
         let suffix =
             self.safe_revision().map_or("nightly".into(), |path| path.to_owned() + "-nightly");
@@ -2082,7 +2082,7 @@ impl<'test> TestCx<'test> {
                 .output()
                 .unwrap();
             assert!(output.status.success());
-            println!("{}", String::from_utf8_lossy(&output.stdout));
+            eprintln!("{}", String::from_utf8_lossy(&output.stdout));
             eprintln!("{}", String::from_utf8_lossy(&output.stderr));
         } else {
             use colored::Colorize;
@@ -2482,7 +2482,7 @@ impl<'test> TestCx<'test> {
                 )"#
             )
             .replace_all(&output, |caps: &Captures<'_>| {
-                println!("{}", &caps[0]);
+                eprintln!("{}", &caps[0]);
                 caps[0].replace(r"\", "/")
             })
             .replace("\r\n", "\n")
@@ -2581,16 +2581,16 @@ impl<'test> TestCx<'test> {
         if let Err(err) = fs::write(&actual_path, &actual) {
             self.fatal(&format!("failed to write {stream} to `{actual_path:?}`: {err}",));
         }
-        println!("Saved the actual {stream} to {actual_path:?}");
+        eprintln!("Saved the actual {stream} to {actual_path:?}");
 
         let expected_path =
             expected_output_path(self.testpaths, self.revision, &self.config.compare_mode, stream);
 
         if !self.config.bless {
             if expected.is_empty() {
-                println!("normalized {}:\n{}\n", stream, actual);
+                eprintln!("normalized {}:\n{}\n", stream, actual);
             } else {
-                println!("diff of {stream}:\n");
+                eprintln!("diff of {stream}:\n");
                 if let Some(diff_command) = self.config.diff_command.as_deref() {
                     let mut args = diff_command.split_whitespace();
                     let name = args.next().unwrap();
@@ -2625,10 +2625,10 @@ impl<'test> TestCx<'test> {
             if let Err(err) = fs::write(&expected_path, &actual) {
                 self.fatal(&format!("failed to write {stream} to `{expected_path:?}`: {err}"));
             }
-            println!("Blessing the {stream} of {test_name} in {expected_path:?}");
+            eprintln!("Blessing the {stream} of {test_name} in {expected_path:?}");
         }
 
-        println!("\nThe actual {0} differed from the expected {0}.", stream);
+        eprintln!("\nThe actual {0} differed from the expected {0}.", stream);
 
         if self.config.bless { 0 } else { 1 }
     }
@@ -2707,7 +2707,7 @@ impl<'test> TestCx<'test> {
         fs::create_dir_all(&incremental_dir).unwrap();
 
         if self.config.verbose {
-            println!("init_incremental_test: incremental_dir={}", incremental_dir.display());
+            eprintln!("init_incremental_test: incremental_dir={}", incremental_dir.display());
         }
     }
 
@@ -2765,7 +2765,7 @@ impl ProcRes {
             }
         }
 
-        println!(
+        eprintln!(
             "status: {}\ncommand: {}\n{}\n{}\n",
             self.status,
             self.cmdline,
@@ -2776,7 +2776,7 @@ impl ProcRes {
 
     pub fn fatal(&self, err: Option<&str>, on_failure: impl FnOnce()) -> ! {
         if let Some(e) = err {
-            println!("\nerror: {}", e);
+            eprintln!("\nerror: {}", e);
         }
         self.print_info();
         on_failure();
diff --git a/src/tools/compiletest/src/runtest/codegen_units.rs b/src/tools/compiletest/src/runtest/codegen_units.rs
index 6c866cbef21..6acd140183d 100644
--- a/src/tools/compiletest/src/runtest/codegen_units.rs
+++ b/src/tools/compiletest/src/runtest/codegen_units.rs
@@ -64,13 +64,13 @@ impl TestCx<'_> {
         if !missing.is_empty() {
             missing.sort();
 
-            println!("\nThese items should have been contained but were not:\n");
+            eprintln!("\nThese items should have been contained but were not:\n");
 
             for item in &missing {
-                println!("{}", item);
+                eprintln!("{}", item);
             }
 
-            println!("\n");
+            eprintln!("\n");
         }
 
         if !unexpected.is_empty() {
@@ -80,24 +80,24 @@ impl TestCx<'_> {
                 sorted
             };
 
-            println!("\nThese items were contained but should not have been:\n");
+            eprintln!("\nThese items were contained but should not have been:\n");
 
             for item in sorted {
-                println!("{}", item);
+                eprintln!("{}", item);
             }
 
-            println!("\n");
+            eprintln!("\n");
         }
 
         if !wrong_cgus.is_empty() {
             wrong_cgus.sort_by_key(|pair| pair.0.name.clone());
-            println!("\nThe following items were assigned to wrong codegen units:\n");
+            eprintln!("\nThe following items were assigned to wrong codegen units:\n");
 
             for &(ref expected_item, ref actual_item) in &wrong_cgus {
-                println!("{}", expected_item.name);
-                println!("  expected: {}", codegen_units_to_str(&expected_item.codegen_units));
-                println!("  actual:   {}", codegen_units_to_str(&actual_item.codegen_units));
-                println!();
+                eprintln!("{}", expected_item.name);
+                eprintln!("  expected: {}", codegen_units_to_str(&expected_item.codegen_units));
+                eprintln!("  actual:   {}", codegen_units_to_str(&actual_item.codegen_units));
+                eprintln!();
             }
         }
 
diff --git a/src/tools/compiletest/src/runtest/debuginfo.rs b/src/tools/compiletest/src/runtest/debuginfo.rs
index c621c22ac99..7322e730e53 100644
--- a/src/tools/compiletest/src/runtest/debuginfo.rs
+++ b/src/tools/compiletest/src/runtest/debuginfo.rs
@@ -260,7 +260,7 @@ impl TestCx<'_> {
                 cmdline,
             };
             if adb.kill().is_err() {
-                println!("Adb process is already finished.");
+                eprintln!("Adb process is already finished.");
             }
         } else {
             let rust_src_root =
@@ -275,7 +275,7 @@ impl TestCx<'_> {
 
             match self.config.gdb_version {
                 Some(version) => {
-                    println!("NOTE: compiletest thinks it is using GDB version {}", version);
+                    eprintln!("NOTE: compiletest thinks it is using GDB version {}", version);
 
                     if version > extract_gdb_version("7.4").unwrap() {
                         // Add the directory containing the pretty printers to
@@ -297,7 +297,7 @@ impl TestCx<'_> {
                     }
                 }
                 _ => {
-                    println!(
+                    eprintln!(
                         "NOTE: compiletest does not know which version of \
                          GDB it is using"
                     );
@@ -392,10 +392,10 @@ impl TestCx<'_> {
 
         match self.config.lldb_version {
             Some(ref version) => {
-                println!("NOTE: compiletest thinks it is using LLDB version {}", version);
+                eprintln!("NOTE: compiletest thinks it is using LLDB version {}", version);
             }
             _ => {
-                println!(
+                eprintln!(
                     "NOTE: compiletest does not know which version of \
                      LLDB it is using"
                 );
diff --git a/src/tools/compiletest/src/runtest/rustdoc_json.rs b/src/tools/compiletest/src/runtest/rustdoc_json.rs
index 31fdb0a5d13..84376d346af 100644
--- a/src/tools/compiletest/src/runtest/rustdoc_json.rs
+++ b/src/tools/compiletest/src/runtest/rustdoc_json.rs
@@ -29,7 +29,7 @@ impl TestCx<'_> {
 
         if !res.status.success() {
             self.fatal_proc_rec_with_ctx("jsondocck failed!", &res, |_| {
-                println!("Rustdoc Output:");
+                eprintln!("Rustdoc Output:");
                 proc_res.print_info();
             })
         }
diff --git a/src/tools/compiletest/src/runtest/ui.rs b/src/tools/compiletest/src/runtest/ui.rs
index bb747c68029..414f1a6adb3 100644
--- a/src/tools/compiletest/src/runtest/ui.rs
+++ b/src/tools/compiletest/src/runtest/ui.rs
@@ -109,10 +109,10 @@ impl TestCx<'_> {
         }
 
         if errors > 0 {
-            println!("To update references, rerun the tests and pass the `--bless` flag");
+            eprintln!("To update references, rerun the tests and pass the `--bless` flag");
             let relative_path_to_file =
                 self.testpaths.relative_dir.join(self.testpaths.file.file_name().unwrap());
-            println!(
+            eprintln!(
                 "To only update this specific test, also pass `--test-args {}`",
                 relative_path_to_file.display(),
             );
diff --git a/src/tools/compiletest/src/util.rs b/src/tools/compiletest/src/util.rs
index bff02f1db9f..7b50e62c29b 100644
--- a/src/tools/compiletest/src/util.rs
+++ b/src/tools/compiletest/src/util.rs
@@ -30,7 +30,7 @@ fn path_div() -> &'static str {
 pub fn logv(config: &Config, s: String) {
     debug!("{}", s);
     if config.verbose {
-        println!("{}", s);
+        eprintln!("{}", s);
     }
 }
 
diff --git a/src/tools/tidy/src/error_codes.rs b/src/tools/tidy/src/error_codes.rs
index e2d1b85797f..9dc49b57d59 100644
--- a/src/tools/tidy/src/error_codes.rs
+++ b/src/tools/tidy/src/error_codes.rs
@@ -38,7 +38,7 @@ const IGNORE_UI_TEST_CHECK: &[&str] =
 macro_rules! verbose_print {
     ($verbose:expr, $($fmt:tt)*) => {
         if $verbose {
-            println!("{}", format_args!($($fmt)*));
+            eprintln!("{}", format_args!($($fmt)*));
         }
     };
 }
@@ -49,8 +49,8 @@ pub fn check(root_path: &Path, search_paths: &[&Path], verbose: bool, bad: &mut
     // Stage 1: create list
     let error_codes = extract_error_codes(root_path, &mut errors);
     if verbose {
-        println!("Found {} error codes", error_codes.len());
-        println!("Highest error code: `{}`", error_codes.iter().max().unwrap());
+        eprintln!("Found {} error codes", error_codes.len());
+        eprintln!("Highest error code: `{}`", error_codes.iter().max().unwrap());
     }
 
     // Stage 2: check list has docs
diff --git a/src/tools/tidy/src/features.rs b/src/tools/tidy/src/features.rs
index 4f24eb21242..4607d041577 100644
--- a/src/tools/tidy/src/features.rs
+++ b/src/tools/tidy/src/features.rs
@@ -158,14 +158,14 @@ pub fn check(
         .collect::<Vec<_>>();
 
     for &(name, _) in gate_untested.iter() {
-        println!("Expected a gate test for the feature '{name}'.");
-        println!(
+        eprintln!("Expected a gate test for the feature '{name}'.");
+        eprintln!(
             "Hint: create a failing test file named 'tests/ui/feature-gates/feature-gate-{}.rs',\
                 \n      with its failures due to missing usage of `#![feature({})]`.",
             name.replace("_", "-"),
             name
         );
-        println!(
+        eprintln!(
             "Hint: If you already have such a test and don't want to rename it,\
                 \n      you can also add a // gate-test-{} line to the test file.",
             name
@@ -218,7 +218,7 @@ pub fn check(
 
         lines.sort();
         for line in lines {
-            println!("* {line}");
+            eprintln!("* {line}");
         }
     }
 
diff --git a/src/tools/tidy/src/unstable_book.rs b/src/tools/tidy/src/unstable_book.rs
index 8be25b98df0..06d238ef5e4 100644
--- a/src/tools/tidy/src/unstable_book.rs
+++ b/src/tools/tidy/src/unstable_book.rs
@@ -118,16 +118,16 @@ pub fn check(path: &Path, features: CollectedFeatures, bad: &mut bool) {
     // List unstable features that don't have Unstable Book sections.
     // Remove the comment marker if you want the list printed.
     /*
-    println!("Lib features without unstable book sections:");
+    eprintln!("Lib features without unstable book sections:");
     for feature_name in &unstable_lang_feature_names -
                         &unstable_book_lang_features_section_file_names {
-        println!("    * {} {:?}", feature_name, lib_features[&feature_name].tracking_issue);
+        eprintln!("    * {} {:?}", feature_name, lib_features[&feature_name].tracking_issue);
     }
 
-    println!("Lang features without unstable book sections:");
+    eprintln!("Lang features without unstable book sections:");
     for feature_name in &unstable_lib_feature_names-
                         &unstable_book_lib_features_section_file_names {
-        println!("    * {} {:?}", feature_name, lang_features[&feature_name].tracking_issue);
+        eprintln!("    * {} {:?}", feature_name, lang_features[&feature_name].tracking_issue);
     }
     // */
 }
diff --git a/src/tools/tidy/src/x_version.rs b/src/tools/tidy/src/x_version.rs
index 489343561e1..b43d56202c9 100644
--- a/src/tools/tidy/src/x_version.rs
+++ b/src/tools/tidy/src/x_version.rs
@@ -42,7 +42,7 @@ pub fn check(root: &Path, cargo: &Path, bad: &mut bool) {
 
         if let Some(expected) = get_x_wrapper_version(root, cargo) {
             if installed < expected {
-                return println!(
+                return eprintln!(
                     "Current version of x is {installed}, but the latest version is {expected}\nConsider updating to the newer version of x by running `cargo install --path src/tools/x`"
                 );
             }
diff --git a/tests/mir-opt/pre-codegen/issue_117368_print_invalid_constant.main.GVN.32bit.panic-abort.diff b/tests/mir-opt/pre-codegen/issue_117368_print_invalid_constant.main.GVN.32bit.panic-abort.diff
index 87fbcca9177..027c71dfaae 100644
--- a/tests/mir-opt/pre-codegen/issue_117368_print_invalid_constant.main.GVN.32bit.panic-abort.diff
+++ b/tests/mir-opt/pre-codegen/issue_117368_print_invalid_constant.main.GVN.32bit.panic-abort.diff
@@ -31,7 +31,6 @@
               }
           }
           scope 9 (inlined NonNull::<[u8]>::as_ptr) {
-              let mut _17: *const [u8];
           }
       }
       scope 3 (inlined #[track_caller] Option::<Layout>::unwrap) {
@@ -102,16 +101,9 @@
           StorageDead(_16);
           StorageDead(_12);
           StorageDead(_6);
--         StorageLive(_17);
-+         nop;
-          _17 = copy (_5.0: *const [u8]);
--         _4 = move _17 as *mut [u8] (PtrToPtr);
--         StorageDead(_17);
-+         _4 = copy _17 as *mut [u8] (PtrToPtr);
-+         nop;
+          _4 = copy _5 as *mut [u8] (Transmute);
           StorageDead(_5);
--         _3 = move _4 as *mut u8 (PtrToPtr);
-+         _3 = copy _17 as *mut u8 (PtrToPtr);
+          _3 = move _4 as *mut u8 (PtrToPtr);
           StorageDead(_4);
           StorageDead(_3);
 -         StorageDead(_1);
diff --git a/tests/mir-opt/pre-codegen/issue_117368_print_invalid_constant.main.GVN.32bit.panic-unwind.diff b/tests/mir-opt/pre-codegen/issue_117368_print_invalid_constant.main.GVN.32bit.panic-unwind.diff
index 5fcece2280d..88bd4628c29 100644
--- a/tests/mir-opt/pre-codegen/issue_117368_print_invalid_constant.main.GVN.32bit.panic-unwind.diff
+++ b/tests/mir-opt/pre-codegen/issue_117368_print_invalid_constant.main.GVN.32bit.panic-unwind.diff
@@ -20,7 +20,6 @@
           scope 5 (inlined <std::alloc::Global as Allocator>::allocate) {
           }
           scope 6 (inlined NonNull::<[u8]>::as_ptr) {
-              let mut _12: *const [u8];
           }
       }
       scope 3 (inlined #[track_caller] Option::<Layout>::unwrap) {
@@ -45,16 +44,9 @@
   
       bb1: {
           StorageDead(_6);
--         StorageLive(_12);
-+         nop;
-          _12 = copy (_5.0: *const [u8]);
--         _4 = move _12 as *mut [u8] (PtrToPtr);
--         StorageDead(_12);
-+         _4 = copy _12 as *mut [u8] (PtrToPtr);
-+         nop;
+          _4 = copy _5 as *mut [u8] (Transmute);
           StorageDead(_5);
--         _3 = move _4 as *mut u8 (PtrToPtr);
-+         _3 = copy _12 as *mut u8 (PtrToPtr);
+          _3 = move _4 as *mut u8 (PtrToPtr);
           StorageDead(_4);
           StorageDead(_3);
 -         StorageDead(_1);
diff --git a/tests/mir-opt/pre-codegen/issue_117368_print_invalid_constant.main.GVN.64bit.panic-abort.diff b/tests/mir-opt/pre-codegen/issue_117368_print_invalid_constant.main.GVN.64bit.panic-abort.diff
index 13258c17160..ebf305a6f1b 100644
--- a/tests/mir-opt/pre-codegen/issue_117368_print_invalid_constant.main.GVN.64bit.panic-abort.diff
+++ b/tests/mir-opt/pre-codegen/issue_117368_print_invalid_constant.main.GVN.64bit.panic-abort.diff
@@ -31,7 +31,6 @@
               }
           }
           scope 9 (inlined NonNull::<[u8]>::as_ptr) {
-              let mut _17: *const [u8];
           }
       }
       scope 3 (inlined #[track_caller] Option::<Layout>::unwrap) {
@@ -102,16 +101,9 @@
           StorageDead(_16);
           StorageDead(_12);
           StorageDead(_6);
--         StorageLive(_17);
-+         nop;
-          _17 = copy (_5.0: *const [u8]);
--         _4 = move _17 as *mut [u8] (PtrToPtr);
--         StorageDead(_17);
-+         _4 = copy _17 as *mut [u8] (PtrToPtr);
-+         nop;
+          _4 = copy _5 as *mut [u8] (Transmute);
           StorageDead(_5);
--         _3 = move _4 as *mut u8 (PtrToPtr);
-+         _3 = copy _17 as *mut u8 (PtrToPtr);
+          _3 = move _4 as *mut u8 (PtrToPtr);
           StorageDead(_4);
           StorageDead(_3);
 -         StorageDead(_1);
diff --git a/tests/mir-opt/pre-codegen/issue_117368_print_invalid_constant.main.GVN.64bit.panic-unwind.diff b/tests/mir-opt/pre-codegen/issue_117368_print_invalid_constant.main.GVN.64bit.panic-unwind.diff
index 0821ea272bf..0c52f1e0583 100644
--- a/tests/mir-opt/pre-codegen/issue_117368_print_invalid_constant.main.GVN.64bit.panic-unwind.diff
+++ b/tests/mir-opt/pre-codegen/issue_117368_print_invalid_constant.main.GVN.64bit.panic-unwind.diff
@@ -20,7 +20,6 @@
           scope 5 (inlined <std::alloc::Global as Allocator>::allocate) {
           }
           scope 6 (inlined NonNull::<[u8]>::as_ptr) {
-              let mut _12: *const [u8];
           }
       }
       scope 3 (inlined #[track_caller] Option::<Layout>::unwrap) {
@@ -45,16 +44,9 @@
   
       bb1: {
           StorageDead(_6);
--         StorageLive(_12);
-+         nop;
-          _12 = copy (_5.0: *const [u8]);
--         _4 = move _12 as *mut [u8] (PtrToPtr);
--         StorageDead(_12);
-+         _4 = copy _12 as *mut [u8] (PtrToPtr);
-+         nop;
+          _4 = copy _5 as *mut [u8] (Transmute);
           StorageDead(_5);
--         _3 = move _4 as *mut u8 (PtrToPtr);
-+         _3 = copy _12 as *mut u8 (PtrToPtr);
+          _3 = move _4 as *mut u8 (PtrToPtr);
           StorageDead(_4);
           StorageDead(_3);
 -         StorageDead(_1);
diff --git a/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-abort.mir b/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-abort.mir
index bd56ab67e00..a3308cc5df1 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-abort.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-abort.mir
@@ -4,28 +4,28 @@ fn enumerated_loop(_1: &[T], _2: impl Fn(usize, &T)) -> () {
     debug slice => _1;
     debug f => _2;
     let mut _0: ();
-    let mut _11: std::slice::Iter<'_, T>;
-    let mut _12: std::iter::Enumerate<std::slice::Iter<'_, T>>;
-    let mut _13: std::iter::Enumerate<std::slice::Iter<'_, T>>;
-    let mut _21: std::option::Option<(usize, &T)>;
-    let mut _24: &impl Fn(usize, &T);
-    let mut _25: (usize, &T);
-    let _26: ();
+    let mut _13: std::slice::Iter<'_, T>;
+    let mut _14: std::iter::Enumerate<std::slice::Iter<'_, T>>;
+    let mut _15: std::iter::Enumerate<std::slice::Iter<'_, T>>;
+    let mut _23: std::option::Option<(usize, &T)>;
+    let mut _26: &impl Fn(usize, &T);
+    let mut _27: (usize, &T);
+    let _28: ();
     scope 1 {
-        debug iter => _13;
-        let _22: usize;
-        let _23: &T;
+        debug iter => _15;
+        let _24: usize;
+        let _25: &T;
         scope 2 {
-            debug i => _22;
-            debug x => _23;
+            debug i => _24;
+            debug x => _25;
         }
         scope 18 (inlined <Enumerate<std::slice::Iter<'_, T>> as Iterator>::next) {
-            let mut _14: &mut std::slice::Iter<'_, T>;
-            let mut _15: std::option::Option<&T>;
-            let mut _19: (usize, bool);
-            let mut _20: (usize, &T);
+            let mut _16: &mut std::slice::Iter<'_, T>;
+            let mut _17: std::option::Option<&T>;
+            let mut _21: (usize, bool);
+            let mut _22: (usize, &T);
             scope 19 {
-                let _18: usize;
+                let _20: usize;
                 scope 24 {
                 }
             }
@@ -40,8 +40,8 @@ fn enumerated_loop(_1: &[T], _2: impl Fn(usize, &T)) -> () {
                 }
             }
             scope 25 (inlined <Option<&T> as Try>::branch) {
-                let mut _16: isize;
-                let _17: &T;
+                let mut _18: isize;
+                let _19: &T;
                 scope 26 {
                 }
             }
@@ -50,13 +50,14 @@ fn enumerated_loop(_1: &[T], _2: impl Fn(usize, &T)) -> () {
     scope 3 (inlined core::slice::<impl [T]>::iter) {
         scope 4 (inlined std::slice::Iter::<'_, T>::new) {
             let _3: usize;
-            let mut _7: *mut T;
-            let mut _8: *mut T;
-            let mut _10: *const T;
+            let mut _5: std::ptr::NonNull<[T]>;
+            let mut _9: *mut T;
+            let mut _10: *mut T;
+            let mut _12: *const T;
             scope 5 {
-                let _6: std::ptr::NonNull<T>;
+                let _8: std::ptr::NonNull<T>;
                 scope 6 {
-                    let _9: *const T;
+                    let _11: *const T;
                     scope 7 {
                     }
                     scope 12 (inlined without_provenance::<T>) {
@@ -72,7 +73,8 @@ fn enumerated_loop(_1: &[T], _2: impl Fn(usize, &T)) -> () {
                     }
                 }
                 scope 10 (inlined NonNull::<[T]>::cast::<T>) {
-                    let mut _5: *const T;
+                    let mut _6: *mut [T];
+                    let mut _7: *const T;
                     scope 11 (inlined NonNull::<[T]>::as_ptr) {
                     }
                 }
@@ -87,76 +89,82 @@ fn enumerated_loop(_1: &[T], _2: impl Fn(usize, &T)) -> () {
     }
 
     bb0: {
-        StorageLive(_11);
+        StorageLive(_13);
         StorageLive(_3);
-        StorageLive(_6);
-        StorageLive(_4);
-        StorageLive(_5);
+        StorageLive(_8);
         _3 = PtrMetadata(copy _1);
+        StorageLive(_5);
+        StorageLive(_4);
         _4 = &raw const (*_1);
-        _5 = copy _4 as *const T (PtrToPtr);
-        _6 = NonNull::<T> { pointer: copy _5 };
-        StorageLive(_9);
+        _5 = NonNull::<[T]> { pointer: move _4 };
+        StorageDead(_4);
+        StorageLive(_6);
+        StorageLive(_7);
+        _6 = copy _5 as *mut [T] (Transmute);
+        _7 = copy _6 as *const T (PtrToPtr);
+        _8 = NonNull::<T> { pointer: move _7 };
+        StorageDead(_7);
+        StorageDead(_6);
+        StorageDead(_5);
+        StorageLive(_11);
         switchInt(const <T as std::mem::SizedTypeProperties>::IS_ZST) -> [0: bb1, otherwise: bb2];
     }
 
     bb1: {
-        StorageLive(_8);
-        StorageLive(_7);
-        _7 = copy _4 as *mut T (PtrToPtr);
-        _8 = Offset(copy _7, copy _3);
-        StorageDead(_7);
-        _9 = move _8 as *const T (PtrToPtr);
-        StorageDead(_8);
+        StorageLive(_10);
+        StorageLive(_9);
+        _9 = copy _8 as *mut T (Transmute);
+        _10 = Offset(copy _9, copy _3);
+        StorageDead(_9);
+        _11 = move _10 as *const T (PtrToPtr);
+        StorageDead(_10);
         goto -> bb3;
     }
 
     bb2: {
-        _9 = copy _3 as *const T (Transmute);
+        _11 = copy _3 as *const T (Transmute);
         goto -> bb3;
     }
 
     bb3: {
-        StorageLive(_10);
-        _10 = copy _9;
-        _11 = std::slice::Iter::<'_, T> { ptr: copy _6, end_or_len: move _10, _marker: const ZeroSized: PhantomData<&T> };
-        StorageDead(_10);
-        StorageDead(_9);
-        StorageDead(_5);
-        StorageDead(_4);
-        StorageDead(_6);
-        StorageDead(_3);
-        _12 = Enumerate::<std::slice::Iter<'_, T>> { iter: copy _11, count: const 0_usize };
+        StorageLive(_12);
+        _12 = copy _11;
+        _13 = std::slice::Iter::<'_, T> { ptr: copy _8, end_or_len: move _12, _marker: const ZeroSized: PhantomData<&T> };
+        StorageDead(_12);
         StorageDead(_11);
-        StorageLive(_13);
-        _13 = copy _12;
+        StorageDead(_8);
+        StorageDead(_3);
+        _14 = Enumerate::<std::slice::Iter<'_, T>> { iter: copy _13, count: const 0_usize };
+        StorageDead(_13);
+        StorageLive(_15);
+        _15 = copy _14;
         goto -> bb4;
     }
 
     bb4: {
+        StorageLive(_23);
+        StorageLive(_20);
         StorageLive(_21);
-        StorageLive(_18);
-        StorageLive(_19);
-        StorageLive(_15);
-        StorageLive(_14);
-        _14 = &mut (_13.0: std::slice::Iter<'_, T>);
-        _15 = <std::slice::Iter<'_, T> as Iterator>::next(move _14) -> [return: bb5, unwind unreachable];
+        StorageLive(_17);
+        StorageLive(_16);
+        _16 = &mut (_15.0: std::slice::Iter<'_, T>);
+        _17 = <std::slice::Iter<'_, T> as Iterator>::next(move _16) -> [return: bb5, unwind unreachable];
     }
 
     bb5: {
-        StorageDead(_14);
-        StorageLive(_16);
-        _16 = discriminant(_15);
-        switchInt(move _16) -> [0: bb6, 1: bb8, otherwise: bb11];
+        StorageDead(_16);
+        StorageLive(_18);
+        _18 = discriminant(_17);
+        switchInt(move _18) -> [0: bb6, 1: bb8, otherwise: bb11];
     }
 
     bb6: {
-        StorageDead(_16);
-        StorageDead(_15);
-        StorageDead(_19);
         StorageDead(_18);
+        StorageDead(_17);
         StorageDead(_21);
-        StorageDead(_13);
+        StorageDead(_20);
+        StorageDead(_23);
+        StorageDead(_15);
         drop(_2) -> [return: bb7, unwind unreachable];
     }
 
@@ -165,35 +173,35 @@ fn enumerated_loop(_1: &[T], _2: impl Fn(usize, &T)) -> () {
     }
 
     bb8: {
-        _17 = move ((_15 as Some).0: &T);
-        StorageDead(_16);
-        StorageDead(_15);
-        _18 = copy (_13.1: usize);
-        _19 = AddWithOverflow(copy (_13.1: usize), const 1_usize);
-        assert(!move (_19.1: bool), "attempt to compute `{} + {}`, which would overflow", copy (_13.1: usize), const 1_usize) -> [success: bb9, unwind unreachable];
+        _19 = move ((_17 as Some).0: &T);
+        StorageDead(_18);
+        StorageDead(_17);
+        _20 = copy (_15.1: usize);
+        _21 = AddWithOverflow(copy (_15.1: usize), const 1_usize);
+        assert(!move (_21.1: bool), "attempt to compute `{} + {}`, which would overflow", copy (_15.1: usize), const 1_usize) -> [success: bb9, unwind unreachable];
     }
 
     bb9: {
-        (_13.1: usize) = move (_19.0: usize);
-        StorageLive(_20);
-        _20 = (copy _18, copy _17);
-        _21 = Option::<(usize, &T)>::Some(move _20);
+        (_15.1: usize) = move (_21.0: usize);
+        StorageLive(_22);
+        _22 = (copy _20, copy _19);
+        _23 = Option::<(usize, &T)>::Some(move _22);
+        StorageDead(_22);
+        StorageDead(_21);
         StorageDead(_20);
-        StorageDead(_19);
-        StorageDead(_18);
-        _22 = copy (((_21 as Some).0: (usize, &T)).0: usize);
-        _23 = copy (((_21 as Some).0: (usize, &T)).1: &T);
-        StorageLive(_24);
-        _24 = &_2;
-        StorageLive(_25);
-        _25 = (copy _22, copy _23);
-        _26 = <impl Fn(usize, &T) as Fn<(usize, &T)>>::call(move _24, move _25) -> [return: bb10, unwind unreachable];
+        _24 = copy (((_23 as Some).0: (usize, &T)).0: usize);
+        _25 = copy (((_23 as Some).0: (usize, &T)).1: &T);
+        StorageLive(_26);
+        _26 = &_2;
+        StorageLive(_27);
+        _27 = (copy _24, copy _25);
+        _28 = <impl Fn(usize, &T) as Fn<(usize, &T)>>::call(move _26, move _27) -> [return: bb10, unwind unreachable];
     }
 
     bb10: {
-        StorageDead(_25);
-        StorageDead(_24);
-        StorageDead(_21);
+        StorageDead(_27);
+        StorageDead(_26);
+        StorageDead(_23);
         goto -> bb4;
     }
 
diff --git a/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-unwind.mir b/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-unwind.mir
index 57f09a4631b..2a837fabd4c 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-unwind.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-unwind.mir
@@ -4,34 +4,35 @@ fn enumerated_loop(_1: &[T], _2: impl Fn(usize, &T)) -> () {
     debug slice => _1;
     debug f => _2;
     let mut _0: ();
-    let mut _11: std::slice::Iter<'_, T>;
-    let mut _12: std::iter::Enumerate<std::slice::Iter<'_, T>>;
-    let mut _13: std::iter::Enumerate<std::slice::Iter<'_, T>>;
-    let mut _14: &mut std::iter::Enumerate<std::slice::Iter<'_, T>>;
-    let mut _15: std::option::Option<(usize, &T)>;
-    let mut _16: isize;
-    let mut _19: &impl Fn(usize, &T);
-    let mut _20: (usize, &T);
-    let _21: ();
+    let mut _13: std::slice::Iter<'_, T>;
+    let mut _14: std::iter::Enumerate<std::slice::Iter<'_, T>>;
+    let mut _15: std::iter::Enumerate<std::slice::Iter<'_, T>>;
+    let mut _16: &mut std::iter::Enumerate<std::slice::Iter<'_, T>>;
+    let mut _17: std::option::Option<(usize, &T)>;
+    let mut _18: isize;
+    let mut _21: &impl Fn(usize, &T);
+    let mut _22: (usize, &T);
+    let _23: ();
     scope 1 {
-        debug iter => _13;
-        let _17: usize;
-        let _18: &T;
+        debug iter => _15;
+        let _19: usize;
+        let _20: &T;
         scope 2 {
-            debug i => _17;
-            debug x => _18;
+            debug i => _19;
+            debug x => _20;
         }
     }
     scope 3 (inlined core::slice::<impl [T]>::iter) {
         scope 4 (inlined std::slice::Iter::<'_, T>::new) {
             let _3: usize;
-            let mut _7: *mut T;
-            let mut _8: *mut T;
-            let mut _10: *const T;
+            let mut _5: std::ptr::NonNull<[T]>;
+            let mut _9: *mut T;
+            let mut _10: *mut T;
+            let mut _12: *const T;
             scope 5 {
-                let _6: std::ptr::NonNull<T>;
+                let _8: std::ptr::NonNull<T>;
                 scope 6 {
-                    let _9: *const T;
+                    let _11: *const T;
                     scope 7 {
                     }
                     scope 12 (inlined without_provenance::<T>) {
@@ -47,7 +48,8 @@ fn enumerated_loop(_1: &[T], _2: impl Fn(usize, &T)) -> () {
                     }
                 }
                 scope 10 (inlined NonNull::<[T]>::cast::<T>) {
-                    let mut _5: *const T;
+                    let mut _6: *mut [T];
+                    let mut _7: *const T;
                     scope 11 (inlined NonNull::<[T]>::as_ptr) {
                     }
                 }
@@ -62,66 +64,72 @@ fn enumerated_loop(_1: &[T], _2: impl Fn(usize, &T)) -> () {
     }
 
     bb0: {
-        StorageLive(_11);
+        StorageLive(_13);
         StorageLive(_3);
-        StorageLive(_6);
-        StorageLive(_4);
-        StorageLive(_5);
+        StorageLive(_8);
         _3 = PtrMetadata(copy _1);
+        StorageLive(_5);
+        StorageLive(_4);
         _4 = &raw const (*_1);
-        _5 = copy _4 as *const T (PtrToPtr);
-        _6 = NonNull::<T> { pointer: copy _5 };
-        StorageLive(_9);
+        _5 = NonNull::<[T]> { pointer: move _4 };
+        StorageDead(_4);
+        StorageLive(_6);
+        StorageLive(_7);
+        _6 = copy _5 as *mut [T] (Transmute);
+        _7 = copy _6 as *const T (PtrToPtr);
+        _8 = NonNull::<T> { pointer: move _7 };
+        StorageDead(_7);
+        StorageDead(_6);
+        StorageDead(_5);
+        StorageLive(_11);
         switchInt(const <T as std::mem::SizedTypeProperties>::IS_ZST) -> [0: bb1, otherwise: bb2];
     }
 
     bb1: {
-        StorageLive(_8);
-        StorageLive(_7);
-        _7 = copy _4 as *mut T (PtrToPtr);
-        _8 = Offset(copy _7, copy _3);
-        StorageDead(_7);
-        _9 = move _8 as *const T (PtrToPtr);
-        StorageDead(_8);
+        StorageLive(_10);
+        StorageLive(_9);
+        _9 = copy _8 as *mut T (Transmute);
+        _10 = Offset(copy _9, copy _3);
+        StorageDead(_9);
+        _11 = move _10 as *const T (PtrToPtr);
+        StorageDead(_10);
         goto -> bb3;
     }
 
     bb2: {
-        _9 = copy _3 as *const T (Transmute);
+        _11 = copy _3 as *const T (Transmute);
         goto -> bb3;
     }
 
     bb3: {
-        StorageLive(_10);
-        _10 = copy _9;
-        _11 = std::slice::Iter::<'_, T> { ptr: copy _6, end_or_len: move _10, _marker: const ZeroSized: PhantomData<&T> };
-        StorageDead(_10);
-        StorageDead(_9);
-        StorageDead(_5);
-        StorageDead(_4);
-        StorageDead(_6);
-        StorageDead(_3);
-        _12 = Enumerate::<std::slice::Iter<'_, T>> { iter: copy _11, count: const 0_usize };
+        StorageLive(_12);
+        _12 = copy _11;
+        _13 = std::slice::Iter::<'_, T> { ptr: copy _8, end_or_len: move _12, _marker: const ZeroSized: PhantomData<&T> };
+        StorageDead(_12);
         StorageDead(_11);
-        StorageLive(_13);
-        _13 = copy _12;
+        StorageDead(_8);
+        StorageDead(_3);
+        _14 = Enumerate::<std::slice::Iter<'_, T>> { iter: copy _13, count: const 0_usize };
+        StorageDead(_13);
+        StorageLive(_15);
+        _15 = copy _14;
         goto -> bb4;
     }
 
     bb4: {
-        StorageLive(_15);
-        _14 = &mut _13;
-        _15 = <Enumerate<std::slice::Iter<'_, T>> as Iterator>::next(move _14) -> [return: bb5, unwind: bb11];
+        StorageLive(_17);
+        _16 = &mut _15;
+        _17 = <Enumerate<std::slice::Iter<'_, T>> as Iterator>::next(move _16) -> [return: bb5, unwind: bb11];
     }
 
     bb5: {
-        _16 = discriminant(_15);
-        switchInt(move _16) -> [0: bb6, 1: bb8, otherwise: bb10];
+        _18 = discriminant(_17);
+        switchInt(move _18) -> [0: bb6, 1: bb8, otherwise: bb10];
     }
 
     bb6: {
+        StorageDead(_17);
         StorageDead(_15);
-        StorageDead(_13);
         drop(_2) -> [return: bb7, unwind continue];
     }
 
@@ -130,19 +138,19 @@ fn enumerated_loop(_1: &[T], _2: impl Fn(usize, &T)) -> () {
     }
 
     bb8: {
-        _17 = copy (((_15 as Some).0: (usize, &T)).0: usize);
-        _18 = copy (((_15 as Some).0: (usize, &T)).1: &T);
-        StorageLive(_19);
-        _19 = &_2;
-        StorageLive(_20);
-        _20 = (copy _17, copy _18);
-        _21 = <impl Fn(usize, &T) as Fn<(usize, &T)>>::call(move _19, move _20) -> [return: bb9, unwind: bb11];
+        _19 = copy (((_17 as Some).0: (usize, &T)).0: usize);
+        _20 = copy (((_17 as Some).0: (usize, &T)).1: &T);
+        StorageLive(_21);
+        _21 = &_2;
+        StorageLive(_22);
+        _22 = (copy _19, copy _20);
+        _23 = <impl Fn(usize, &T) as Fn<(usize, &T)>>::call(move _21, move _22) -> [return: bb9, unwind: bb11];
     }
 
     bb9: {
-        StorageDead(_20);
-        StorageDead(_19);
-        StorageDead(_15);
+        StorageDead(_22);
+        StorageDead(_21);
+        StorageDead(_17);
         goto -> bb4;
     }
 
diff --git a/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-abort.mir b/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-abort.mir
index 4050304f469..063045caebb 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-abort.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-abort.mir
@@ -4,31 +4,32 @@ fn forward_loop(_1: &[T], _2: impl Fn(&T)) -> () {
     debug slice => _1;
     debug f => _2;
     let mut _0: ();
-    let mut _11: std::slice::Iter<'_, T>;
-    let mut _12: std::slice::Iter<'_, T>;
-    let mut _13: &mut std::slice::Iter<'_, T>;
-    let mut _14: std::option::Option<&T>;
-    let mut _15: isize;
-    let mut _17: &impl Fn(&T);
-    let mut _18: (&T,);
-    let _19: ();
+    let mut _13: std::slice::Iter<'_, T>;
+    let mut _14: std::slice::Iter<'_, T>;
+    let mut _15: &mut std::slice::Iter<'_, T>;
+    let mut _16: std::option::Option<&T>;
+    let mut _17: isize;
+    let mut _19: &impl Fn(&T);
+    let mut _20: (&T,);
+    let _21: ();
     scope 1 {
-        debug iter => _12;
-        let _16: &T;
+        debug iter => _14;
+        let _18: &T;
         scope 2 {
-            debug x => _16;
+            debug x => _18;
         }
     }
     scope 3 (inlined core::slice::<impl [T]>::iter) {
         scope 4 (inlined std::slice::Iter::<'_, T>::new) {
             let _3: usize;
-            let mut _7: *mut T;
-            let mut _8: *mut T;
-            let mut _10: *const T;
+            let mut _5: std::ptr::NonNull<[T]>;
+            let mut _9: *mut T;
+            let mut _10: *mut T;
+            let mut _12: *const T;
             scope 5 {
-                let _6: std::ptr::NonNull<T>;
+                let _8: std::ptr::NonNull<T>;
                 scope 6 {
-                    let _9: *const T;
+                    let _11: *const T;
                     scope 7 {
                     }
                     scope 12 (inlined without_provenance::<T>) {
@@ -44,7 +45,8 @@ fn forward_loop(_1: &[T], _2: impl Fn(&T)) -> () {
                     }
                 }
                 scope 10 (inlined NonNull::<[T]>::cast::<T>) {
-                    let mut _5: *const T;
+                    let mut _6: *mut [T];
+                    let mut _7: *const T;
                     scope 11 (inlined NonNull::<[T]>::as_ptr) {
                     }
                 }
@@ -56,62 +58,68 @@ fn forward_loop(_1: &[T], _2: impl Fn(&T)) -> () {
 
     bb0: {
         StorageLive(_3);
-        StorageLive(_6);
-        StorageLive(_4);
-        StorageLive(_5);
+        StorageLive(_8);
         _3 = PtrMetadata(copy _1);
+        StorageLive(_5);
+        StorageLive(_4);
         _4 = &raw const (*_1);
-        _5 = copy _4 as *const T (PtrToPtr);
-        _6 = NonNull::<T> { pointer: copy _5 };
-        StorageLive(_9);
+        _5 = NonNull::<[T]> { pointer: move _4 };
+        StorageDead(_4);
+        StorageLive(_6);
+        StorageLive(_7);
+        _6 = copy _5 as *mut [T] (Transmute);
+        _7 = copy _6 as *const T (PtrToPtr);
+        _8 = NonNull::<T> { pointer: move _7 };
+        StorageDead(_7);
+        StorageDead(_6);
+        StorageDead(_5);
+        StorageLive(_11);
         switchInt(const <T as std::mem::SizedTypeProperties>::IS_ZST) -> [0: bb1, otherwise: bb2];
     }
 
     bb1: {
-        StorageLive(_8);
-        StorageLive(_7);
-        _7 = copy _4 as *mut T (PtrToPtr);
-        _8 = Offset(copy _7, copy _3);
-        StorageDead(_7);
-        _9 = move _8 as *const T (PtrToPtr);
-        StorageDead(_8);
+        StorageLive(_10);
+        StorageLive(_9);
+        _9 = copy _8 as *mut T (Transmute);
+        _10 = Offset(copy _9, copy _3);
+        StorageDead(_9);
+        _11 = move _10 as *const T (PtrToPtr);
+        StorageDead(_10);
         goto -> bb3;
     }
 
     bb2: {
-        _9 = copy _3 as *const T (Transmute);
+        _11 = copy _3 as *const T (Transmute);
         goto -> bb3;
     }
 
     bb3: {
-        StorageLive(_10);
-        _10 = copy _9;
-        _11 = std::slice::Iter::<'_, T> { ptr: copy _6, end_or_len: move _10, _marker: const ZeroSized: PhantomData<&T> };
-        StorageDead(_10);
-        StorageDead(_9);
-        StorageDead(_5);
-        StorageDead(_4);
-        StorageDead(_6);
-        StorageDead(_3);
         StorageLive(_12);
         _12 = copy _11;
+        _13 = std::slice::Iter::<'_, T> { ptr: copy _8, end_or_len: move _12, _marker: const ZeroSized: PhantomData<&T> };
+        StorageDead(_12);
+        StorageDead(_11);
+        StorageDead(_8);
+        StorageDead(_3);
+        StorageLive(_14);
+        _14 = copy _13;
         goto -> bb4;
     }
 
     bb4: {
-        StorageLive(_14);
-        _13 = &mut _12;
-        _14 = <std::slice::Iter<'_, T> as Iterator>::next(move _13) -> [return: bb5, unwind unreachable];
+        StorageLive(_16);
+        _15 = &mut _14;
+        _16 = <std::slice::Iter<'_, T> as Iterator>::next(move _15) -> [return: bb5, unwind unreachable];
     }
 
     bb5: {
-        _15 = discriminant(_14);
-        switchInt(move _15) -> [0: bb6, 1: bb8, otherwise: bb10];
+        _17 = discriminant(_16);
+        switchInt(move _17) -> [0: bb6, 1: bb8, otherwise: bb10];
     }
 
     bb6: {
+        StorageDead(_16);
         StorageDead(_14);
-        StorageDead(_12);
         drop(_2) -> [return: bb7, unwind unreachable];
     }
 
@@ -120,18 +128,18 @@ fn forward_loop(_1: &[T], _2: impl Fn(&T)) -> () {
     }
 
     bb8: {
-        _16 = copy ((_14 as Some).0: &T);
-        StorageLive(_17);
-        _17 = &_2;
-        StorageLive(_18);
-        _18 = (copy _16,);
-        _19 = <impl Fn(&T) as Fn<(&T,)>>::call(move _17, move _18) -> [return: bb9, unwind unreachable];
+        _18 = copy ((_16 as Some).0: &T);
+        StorageLive(_19);
+        _19 = &_2;
+        StorageLive(_20);
+        _20 = (copy _18,);
+        _21 = <impl Fn(&T) as Fn<(&T,)>>::call(move _19, move _20) -> [return: bb9, unwind unreachable];
     }
 
     bb9: {
-        StorageDead(_18);
-        StorageDead(_17);
-        StorageDead(_14);
+        StorageDead(_20);
+        StorageDead(_19);
+        StorageDead(_16);
         goto -> bb4;
     }
 
diff --git a/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-unwind.mir b/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-unwind.mir
index 2c3d7ab1e4a..d401ed8fcf3 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-unwind.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-unwind.mir
@@ -4,31 +4,32 @@ fn forward_loop(_1: &[T], _2: impl Fn(&T)) -> () {
     debug slice => _1;
     debug f => _2;
     let mut _0: ();
-    let mut _11: std::slice::Iter<'_, T>;
-    let mut _12: std::slice::Iter<'_, T>;
-    let mut _13: &mut std::slice::Iter<'_, T>;
-    let mut _14: std::option::Option<&T>;
-    let mut _15: isize;
-    let mut _17: &impl Fn(&T);
-    let mut _18: (&T,);
-    let _19: ();
+    let mut _13: std::slice::Iter<'_, T>;
+    let mut _14: std::slice::Iter<'_, T>;
+    let mut _15: &mut std::slice::Iter<'_, T>;
+    let mut _16: std::option::Option<&T>;
+    let mut _17: isize;
+    let mut _19: &impl Fn(&T);
+    let mut _20: (&T,);
+    let _21: ();
     scope 1 {
-        debug iter => _12;
-        let _16: &T;
+        debug iter => _14;
+        let _18: &T;
         scope 2 {
-            debug x => _16;
+            debug x => _18;
         }
     }
     scope 3 (inlined core::slice::<impl [T]>::iter) {
         scope 4 (inlined std::slice::Iter::<'_, T>::new) {
             let _3: usize;
-            let mut _7: *mut T;
-            let mut _8: *mut T;
-            let mut _10: *const T;
+            let mut _5: std::ptr::NonNull<[T]>;
+            let mut _9: *mut T;
+            let mut _10: *mut T;
+            let mut _12: *const T;
             scope 5 {
-                let _6: std::ptr::NonNull<T>;
+                let _8: std::ptr::NonNull<T>;
                 scope 6 {
-                    let _9: *const T;
+                    let _11: *const T;
                     scope 7 {
                     }
                     scope 12 (inlined without_provenance::<T>) {
@@ -44,7 +45,8 @@ fn forward_loop(_1: &[T], _2: impl Fn(&T)) -> () {
                     }
                 }
                 scope 10 (inlined NonNull::<[T]>::cast::<T>) {
-                    let mut _5: *const T;
+                    let mut _6: *mut [T];
+                    let mut _7: *const T;
                     scope 11 (inlined NonNull::<[T]>::as_ptr) {
                     }
                 }
@@ -56,62 +58,68 @@ fn forward_loop(_1: &[T], _2: impl Fn(&T)) -> () {
 
     bb0: {
         StorageLive(_3);
-        StorageLive(_6);
-        StorageLive(_4);
-        StorageLive(_5);
+        StorageLive(_8);
         _3 = PtrMetadata(copy _1);
+        StorageLive(_5);
+        StorageLive(_4);
         _4 = &raw const (*_1);
-        _5 = copy _4 as *const T (PtrToPtr);
-        _6 = NonNull::<T> { pointer: copy _5 };
-        StorageLive(_9);
+        _5 = NonNull::<[T]> { pointer: move _4 };
+        StorageDead(_4);
+        StorageLive(_6);
+        StorageLive(_7);
+        _6 = copy _5 as *mut [T] (Transmute);
+        _7 = copy _6 as *const T (PtrToPtr);
+        _8 = NonNull::<T> { pointer: move _7 };
+        StorageDead(_7);
+        StorageDead(_6);
+        StorageDead(_5);
+        StorageLive(_11);
         switchInt(const <T as std::mem::SizedTypeProperties>::IS_ZST) -> [0: bb1, otherwise: bb2];
     }
 
     bb1: {
-        StorageLive(_8);
-        StorageLive(_7);
-        _7 = copy _4 as *mut T (PtrToPtr);
-        _8 = Offset(copy _7, copy _3);
-        StorageDead(_7);
-        _9 = move _8 as *const T (PtrToPtr);
-        StorageDead(_8);
+        StorageLive(_10);
+        StorageLive(_9);
+        _9 = copy _8 as *mut T (Transmute);
+        _10 = Offset(copy _9, copy _3);
+        StorageDead(_9);
+        _11 = move _10 as *const T (PtrToPtr);
+        StorageDead(_10);
         goto -> bb3;
     }
 
     bb2: {
-        _9 = copy _3 as *const T (Transmute);
+        _11 = copy _3 as *const T (Transmute);
         goto -> bb3;
     }
 
     bb3: {
-        StorageLive(_10);
-        _10 = copy _9;
-        _11 = std::slice::Iter::<'_, T> { ptr: copy _6, end_or_len: move _10, _marker: const ZeroSized: PhantomData<&T> };
-        StorageDead(_10);
-        StorageDead(_9);
-        StorageDead(_5);
-        StorageDead(_4);
-        StorageDead(_6);
-        StorageDead(_3);
         StorageLive(_12);
         _12 = copy _11;
+        _13 = std::slice::Iter::<'_, T> { ptr: copy _8, end_or_len: move _12, _marker: const ZeroSized: PhantomData<&T> };
+        StorageDead(_12);
+        StorageDead(_11);
+        StorageDead(_8);
+        StorageDead(_3);
+        StorageLive(_14);
+        _14 = copy _13;
         goto -> bb4;
     }
 
     bb4: {
-        StorageLive(_14);
-        _13 = &mut _12;
-        _14 = <std::slice::Iter<'_, T> as Iterator>::next(move _13) -> [return: bb5, unwind: bb11];
+        StorageLive(_16);
+        _15 = &mut _14;
+        _16 = <std::slice::Iter<'_, T> as Iterator>::next(move _15) -> [return: bb5, unwind: bb11];
     }
 
     bb5: {
-        _15 = discriminant(_14);
-        switchInt(move _15) -> [0: bb6, 1: bb8, otherwise: bb10];
+        _17 = discriminant(_16);
+        switchInt(move _17) -> [0: bb6, 1: bb8, otherwise: bb10];
     }
 
     bb6: {
+        StorageDead(_16);
         StorageDead(_14);
-        StorageDead(_12);
         drop(_2) -> [return: bb7, unwind continue];
     }
 
@@ -120,18 +128,18 @@ fn forward_loop(_1: &[T], _2: impl Fn(&T)) -> () {
     }
 
     bb8: {
-        _16 = copy ((_14 as Some).0: &T);
-        StorageLive(_17);
-        _17 = &_2;
-        StorageLive(_18);
-        _18 = (copy _16,);
-        _19 = <impl Fn(&T) as Fn<(&T,)>>::call(move _17, move _18) -> [return: bb9, unwind: bb11];
+        _18 = copy ((_16 as Some).0: &T);
+        StorageLive(_19);
+        _19 = &_2;
+        StorageLive(_20);
+        _20 = (copy _18,);
+        _21 = <impl Fn(&T) as Fn<(&T,)>>::call(move _19, move _20) -> [return: bb9, unwind: bb11];
     }
 
     bb9: {
-        StorageDead(_18);
-        StorageDead(_17);
-        StorageDead(_14);
+        StorageDead(_20);
+        StorageDead(_19);
+        StorageDead(_16);
         goto -> bb4;
     }
 
diff --git a/tests/mir-opt/pre-codegen/slice_iter.reverse_loop.PreCodegen.after.panic-abort.mir b/tests/mir-opt/pre-codegen/slice_iter.reverse_loop.PreCodegen.after.panic-abort.mir
index a6ccd435c40..deb12c4f1c2 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.reverse_loop.PreCodegen.after.panic-abort.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.reverse_loop.PreCodegen.after.panic-abort.mir
@@ -4,34 +4,35 @@ fn reverse_loop(_1: &[T], _2: impl Fn(&T)) -> () {
     debug slice => _1;
     debug f => _2;
     let mut _0: ();
-    let mut _11: std::slice::Iter<'_, T>;
-    let mut _12: std::iter::Rev<std::slice::Iter<'_, T>>;
-    let mut _13: std::iter::Rev<std::slice::Iter<'_, T>>;
-    let mut _15: std::option::Option<&T>;
-    let mut _16: isize;
-    let mut _18: &impl Fn(&T);
-    let mut _19: (&T,);
-    let _20: ();
+    let mut _13: std::slice::Iter<'_, T>;
+    let mut _14: std::iter::Rev<std::slice::Iter<'_, T>>;
+    let mut _15: std::iter::Rev<std::slice::Iter<'_, T>>;
+    let mut _17: std::option::Option<&T>;
+    let mut _18: isize;
+    let mut _20: &impl Fn(&T);
+    let mut _21: (&T,);
+    let _22: ();
     scope 1 {
-        debug iter => _13;
-        let _17: &T;
+        debug iter => _15;
+        let _19: &T;
         scope 2 {
-            debug x => _17;
+            debug x => _19;
         }
         scope 18 (inlined <Rev<std::slice::Iter<'_, T>> as Iterator>::next) {
-            let mut _14: &mut std::slice::Iter<'_, T>;
+            let mut _16: &mut std::slice::Iter<'_, T>;
         }
     }
     scope 3 (inlined core::slice::<impl [T]>::iter) {
         scope 4 (inlined std::slice::Iter::<'_, T>::new) {
             let _3: usize;
-            let mut _7: *mut T;
-            let mut _8: *mut T;
-            let mut _10: *const T;
+            let mut _5: std::ptr::NonNull<[T]>;
+            let mut _9: *mut T;
+            let mut _10: *mut T;
+            let mut _12: *const T;
             scope 5 {
-                let _6: std::ptr::NonNull<T>;
+                let _8: std::ptr::NonNull<T>;
                 scope 6 {
-                    let _9: *const T;
+                    let _11: *const T;
                     scope 7 {
                     }
                     scope 12 (inlined without_provenance::<T>) {
@@ -47,7 +48,8 @@ fn reverse_loop(_1: &[T], _2: impl Fn(&T)) -> () {
                     }
                 }
                 scope 10 (inlined NonNull::<[T]>::cast::<T>) {
-                    let mut _5: *const T;
+                    let mut _6: *mut [T];
+                    let mut _7: *const T;
                     scope 11 (inlined NonNull::<[T]>::as_ptr) {
                     }
                 }
@@ -62,68 +64,74 @@ fn reverse_loop(_1: &[T], _2: impl Fn(&T)) -> () {
     }
 
     bb0: {
-        StorageLive(_11);
+        StorageLive(_13);
         StorageLive(_3);
-        StorageLive(_6);
-        StorageLive(_4);
-        StorageLive(_5);
+        StorageLive(_8);
         _3 = PtrMetadata(copy _1);
+        StorageLive(_5);
+        StorageLive(_4);
         _4 = &raw const (*_1);
-        _5 = copy _4 as *const T (PtrToPtr);
-        _6 = NonNull::<T> { pointer: copy _5 };
-        StorageLive(_9);
+        _5 = NonNull::<[T]> { pointer: move _4 };
+        StorageDead(_4);
+        StorageLive(_6);
+        StorageLive(_7);
+        _6 = copy _5 as *mut [T] (Transmute);
+        _7 = copy _6 as *const T (PtrToPtr);
+        _8 = NonNull::<T> { pointer: move _7 };
+        StorageDead(_7);
+        StorageDead(_6);
+        StorageDead(_5);
+        StorageLive(_11);
         switchInt(const <T as std::mem::SizedTypeProperties>::IS_ZST) -> [0: bb1, otherwise: bb2];
     }
 
     bb1: {
-        StorageLive(_8);
-        StorageLive(_7);
-        _7 = copy _4 as *mut T (PtrToPtr);
-        _8 = Offset(copy _7, copy _3);
-        StorageDead(_7);
-        _9 = move _8 as *const T (PtrToPtr);
-        StorageDead(_8);
+        StorageLive(_10);
+        StorageLive(_9);
+        _9 = copy _8 as *mut T (Transmute);
+        _10 = Offset(copy _9, copy _3);
+        StorageDead(_9);
+        _11 = move _10 as *const T (PtrToPtr);
+        StorageDead(_10);
         goto -> bb3;
     }
 
     bb2: {
-        _9 = copy _3 as *const T (Transmute);
+        _11 = copy _3 as *const T (Transmute);
         goto -> bb3;
     }
 
     bb3: {
-        StorageLive(_10);
-        _10 = copy _9;
-        _11 = std::slice::Iter::<'_, T> { ptr: copy _6, end_or_len: move _10, _marker: const ZeroSized: PhantomData<&T> };
-        StorageDead(_10);
-        StorageDead(_9);
-        StorageDead(_5);
-        StorageDead(_4);
-        StorageDead(_6);
-        StorageDead(_3);
-        _12 = Rev::<std::slice::Iter<'_, T>> { iter: copy _11 };
+        StorageLive(_12);
+        _12 = copy _11;
+        _13 = std::slice::Iter::<'_, T> { ptr: copy _8, end_or_len: move _12, _marker: const ZeroSized: PhantomData<&T> };
+        StorageDead(_12);
         StorageDead(_11);
-        StorageLive(_13);
-        _13 = copy _12;
+        StorageDead(_8);
+        StorageDead(_3);
+        _14 = Rev::<std::slice::Iter<'_, T>> { iter: copy _13 };
+        StorageDead(_13);
+        StorageLive(_15);
+        _15 = copy _14;
         goto -> bb4;
     }
 
     bb4: {
-        StorageLive(_15);
-        StorageLive(_14);
-        _14 = &mut (_13.0: std::slice::Iter<'_, T>);
-        _15 = <std::slice::Iter<'_, T> as DoubleEndedIterator>::next_back(move _14) -> [return: bb5, unwind unreachable];
+        StorageLive(_17);
+        StorageLive(_16);
+        _16 = &mut (_15.0: std::slice::Iter<'_, T>);
+        _17 = <std::slice::Iter<'_, T> as DoubleEndedIterator>::next_back(move _16) -> [return: bb5, unwind unreachable];
     }
 
     bb5: {
-        StorageDead(_14);
-        _16 = discriminant(_15);
-        switchInt(move _16) -> [0: bb6, 1: bb8, otherwise: bb10];
+        StorageDead(_16);
+        _18 = discriminant(_17);
+        switchInt(move _18) -> [0: bb6, 1: bb8, otherwise: bb10];
     }
 
     bb6: {
+        StorageDead(_17);
         StorageDead(_15);
-        StorageDead(_13);
         drop(_2) -> [return: bb7, unwind unreachable];
     }
 
@@ -132,18 +140,18 @@ fn reverse_loop(_1: &[T], _2: impl Fn(&T)) -> () {
     }
 
     bb8: {
-        _17 = copy ((_15 as Some).0: &T);
-        StorageLive(_18);
-        _18 = &_2;
-        StorageLive(_19);
-        _19 = (copy _17,);
-        _20 = <impl Fn(&T) as Fn<(&T,)>>::call(move _18, move _19) -> [return: bb9, unwind unreachable];
+        _19 = copy ((_17 as Some).0: &T);
+        StorageLive(_20);
+        _20 = &_2;
+        StorageLive(_21);
+        _21 = (copy _19,);
+        _22 = <impl Fn(&T) as Fn<(&T,)>>::call(move _20, move _21) -> [return: bb9, unwind unreachable];
     }
 
     bb9: {
-        StorageDead(_19);
-        StorageDead(_18);
-        StorageDead(_15);
+        StorageDead(_21);
+        StorageDead(_20);
+        StorageDead(_17);
         goto -> bb4;
     }
 
diff --git a/tests/mir-opt/pre-codegen/slice_iter.reverse_loop.PreCodegen.after.panic-unwind.mir b/tests/mir-opt/pre-codegen/slice_iter.reverse_loop.PreCodegen.after.panic-unwind.mir
index df11c8e3b49..acd5323eb7a 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.reverse_loop.PreCodegen.after.panic-unwind.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.reverse_loop.PreCodegen.after.panic-unwind.mir
@@ -4,34 +4,35 @@ fn reverse_loop(_1: &[T], _2: impl Fn(&T)) -> () {
     debug slice => _1;
     debug f => _2;
     let mut _0: ();
-    let mut _11: std::slice::Iter<'_, T>;
-    let mut _12: std::iter::Rev<std::slice::Iter<'_, T>>;
-    let mut _13: std::iter::Rev<std::slice::Iter<'_, T>>;
-    let mut _15: std::option::Option<&T>;
-    let mut _16: isize;
-    let mut _18: &impl Fn(&T);
-    let mut _19: (&T,);
-    let _20: ();
+    let mut _13: std::slice::Iter<'_, T>;
+    let mut _14: std::iter::Rev<std::slice::Iter<'_, T>>;
+    let mut _15: std::iter::Rev<std::slice::Iter<'_, T>>;
+    let mut _17: std::option::Option<&T>;
+    let mut _18: isize;
+    let mut _20: &impl Fn(&T);
+    let mut _21: (&T,);
+    let _22: ();
     scope 1 {
-        debug iter => _13;
-        let _17: &T;
+        debug iter => _15;
+        let _19: &T;
         scope 2 {
-            debug x => _17;
+            debug x => _19;
         }
         scope 18 (inlined <Rev<std::slice::Iter<'_, T>> as Iterator>::next) {
-            let mut _14: &mut std::slice::Iter<'_, T>;
+            let mut _16: &mut std::slice::Iter<'_, T>;
         }
     }
     scope 3 (inlined core::slice::<impl [T]>::iter) {
         scope 4 (inlined std::slice::Iter::<'_, T>::new) {
             let _3: usize;
-            let mut _7: *mut T;
-            let mut _8: *mut T;
-            let mut _10: *const T;
+            let mut _5: std::ptr::NonNull<[T]>;
+            let mut _9: *mut T;
+            let mut _10: *mut T;
+            let mut _12: *const T;
             scope 5 {
-                let _6: std::ptr::NonNull<T>;
+                let _8: std::ptr::NonNull<T>;
                 scope 6 {
-                    let _9: *const T;
+                    let _11: *const T;
                     scope 7 {
                     }
                     scope 12 (inlined without_provenance::<T>) {
@@ -47,7 +48,8 @@ fn reverse_loop(_1: &[T], _2: impl Fn(&T)) -> () {
                     }
                 }
                 scope 10 (inlined NonNull::<[T]>::cast::<T>) {
-                    let mut _5: *const T;
+                    let mut _6: *mut [T];
+                    let mut _7: *const T;
                     scope 11 (inlined NonNull::<[T]>::as_ptr) {
                     }
                 }
@@ -62,68 +64,74 @@ fn reverse_loop(_1: &[T], _2: impl Fn(&T)) -> () {
     }
 
     bb0: {
-        StorageLive(_11);
+        StorageLive(_13);
         StorageLive(_3);
-        StorageLive(_6);
-        StorageLive(_4);
-        StorageLive(_5);
+        StorageLive(_8);
         _3 = PtrMetadata(copy _1);
+        StorageLive(_5);
+        StorageLive(_4);
         _4 = &raw const (*_1);
-        _5 = copy _4 as *const T (PtrToPtr);
-        _6 = NonNull::<T> { pointer: copy _5 };
-        StorageLive(_9);
+        _5 = NonNull::<[T]> { pointer: move _4 };
+        StorageDead(_4);
+        StorageLive(_6);
+        StorageLive(_7);
+        _6 = copy _5 as *mut [T] (Transmute);
+        _7 = copy _6 as *const T (PtrToPtr);
+        _8 = NonNull::<T> { pointer: move _7 };
+        StorageDead(_7);
+        StorageDead(_6);
+        StorageDead(_5);
+        StorageLive(_11);
         switchInt(const <T as std::mem::SizedTypeProperties>::IS_ZST) -> [0: bb1, otherwise: bb2];
     }
 
     bb1: {
-        StorageLive(_8);
-        StorageLive(_7);
-        _7 = copy _4 as *mut T (PtrToPtr);
-        _8 = Offset(copy _7, copy _3);
-        StorageDead(_7);
-        _9 = move _8 as *const T (PtrToPtr);
-        StorageDead(_8);
+        StorageLive(_10);
+        StorageLive(_9);
+        _9 = copy _8 as *mut T (Transmute);
+        _10 = Offset(copy _9, copy _3);
+        StorageDead(_9);
+        _11 = move _10 as *const T (PtrToPtr);
+        StorageDead(_10);
         goto -> bb3;
     }
 
     bb2: {
-        _9 = copy _3 as *const T (Transmute);
+        _11 = copy _3 as *const T (Transmute);
         goto -> bb3;
     }
 
     bb3: {
-        StorageLive(_10);
-        _10 = copy _9;
-        _11 = std::slice::Iter::<'_, T> { ptr: copy _6, end_or_len: move _10, _marker: const ZeroSized: PhantomData<&T> };
-        StorageDead(_10);
-        StorageDead(_9);
-        StorageDead(_5);
-        StorageDead(_4);
-        StorageDead(_6);
-        StorageDead(_3);
-        _12 = Rev::<std::slice::Iter<'_, T>> { iter: copy _11 };
+        StorageLive(_12);
+        _12 = copy _11;
+        _13 = std::slice::Iter::<'_, T> { ptr: copy _8, end_or_len: move _12, _marker: const ZeroSized: PhantomData<&T> };
+        StorageDead(_12);
         StorageDead(_11);
-        StorageLive(_13);
-        _13 = copy _12;
+        StorageDead(_8);
+        StorageDead(_3);
+        _14 = Rev::<std::slice::Iter<'_, T>> { iter: copy _13 };
+        StorageDead(_13);
+        StorageLive(_15);
+        _15 = copy _14;
         goto -> bb4;
     }
 
     bb4: {
-        StorageLive(_15);
-        StorageLive(_14);
-        _14 = &mut (_13.0: std::slice::Iter<'_, T>);
-        _15 = <std::slice::Iter<'_, T> as DoubleEndedIterator>::next_back(move _14) -> [return: bb5, unwind: bb11];
+        StorageLive(_17);
+        StorageLive(_16);
+        _16 = &mut (_15.0: std::slice::Iter<'_, T>);
+        _17 = <std::slice::Iter<'_, T> as DoubleEndedIterator>::next_back(move _16) -> [return: bb5, unwind: bb11];
     }
 
     bb5: {
-        StorageDead(_14);
-        _16 = discriminant(_15);
-        switchInt(move _16) -> [0: bb6, 1: bb8, otherwise: bb10];
+        StorageDead(_16);
+        _18 = discriminant(_17);
+        switchInt(move _18) -> [0: bb6, 1: bb8, otherwise: bb10];
     }
 
     bb6: {
+        StorageDead(_17);
         StorageDead(_15);
-        StorageDead(_13);
         drop(_2) -> [return: bb7, unwind continue];
     }
 
@@ -132,18 +140,18 @@ fn reverse_loop(_1: &[T], _2: impl Fn(&T)) -> () {
     }
 
     bb8: {
-        _17 = copy ((_15 as Some).0: &T);
-        StorageLive(_18);
-        _18 = &_2;
-        StorageLive(_19);
-        _19 = (copy _17,);
-        _20 = <impl Fn(&T) as Fn<(&T,)>>::call(move _18, move _19) -> [return: bb9, unwind: bb11];
+        _19 = copy ((_17 as Some).0: &T);
+        StorageLive(_20);
+        _20 = &_2;
+        StorageLive(_21);
+        _21 = (copy _19,);
+        _22 = <impl Fn(&T) as Fn<(&T,)>>::call(move _20, move _21) -> [return: bb9, unwind: bb11];
     }
 
     bb9: {
-        StorageDead(_19);
-        StorageDead(_18);
-        StorageDead(_15);
+        StorageDead(_21);
+        StorageDead(_20);
+        StorageDead(_17);
         goto -> bb4;
     }
 
diff --git a/tests/mir-opt/pre-codegen/slice_iter.slice_iter_generic_is_empty.PreCodegen.after.panic-abort.mir b/tests/mir-opt/pre-codegen/slice_iter.slice_iter_generic_is_empty.PreCodegen.after.panic-abort.mir
index f8b0e749bfc..22be48c47b2 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.slice_iter_generic_is_empty.PreCodegen.after.panic-abort.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.slice_iter_generic_is_empty.PreCodegen.after.panic-abort.mir
@@ -15,11 +15,11 @@ fn slice_iter_generic_is_empty(_1: &std::slice::Iter<'_, T>) -> bool {
             scope 4 {
                 scope 8 (inlined <NonNull<T> as PartialEq>::eq) {
                     let mut _5: std::ptr::NonNull<T>;
+                    let mut _6: *mut T;
+                    let mut _7: *mut T;
                     scope 9 (inlined NonNull::<T>::as_ptr) {
-                        let mut _6: *const T;
                     }
                     scope 10 (inlined NonNull::<T>::as_ptr) {
-                        let mut _7: *const T;
                     }
                 }
             }
@@ -48,13 +48,13 @@ fn slice_iter_generic_is_empty(_1: &std::slice::Iter<'_, T>) -> bool {
         _4 = copy (*_3);
         StorageDead(_3);
         StorageLive(_6);
-        StorageLive(_7);
         StorageLive(_5);
         _5 = copy ((*_1).0: std::ptr::NonNull<T>);
-        _6 = copy (_5.0: *const T);
+        _6 = copy _5 as *mut T (Transmute);
         StorageDead(_5);
-        _7 = copy (_4.0: *const T);
-        _0 = Eq(copy _6, copy _7);
+        StorageLive(_7);
+        _7 = copy _4 as *mut T (Transmute);
+        _0 = Eq(move _6, move _7);
         StorageDead(_7);
         StorageDead(_6);
         goto -> bb3;
diff --git a/tests/mir-opt/pre-codegen/slice_iter.slice_iter_generic_is_empty.PreCodegen.after.panic-unwind.mir b/tests/mir-opt/pre-codegen/slice_iter.slice_iter_generic_is_empty.PreCodegen.after.panic-unwind.mir
index f8b0e749bfc..22be48c47b2 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.slice_iter_generic_is_empty.PreCodegen.after.panic-unwind.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.slice_iter_generic_is_empty.PreCodegen.after.panic-unwind.mir
@@ -15,11 +15,11 @@ fn slice_iter_generic_is_empty(_1: &std::slice::Iter<'_, T>) -> bool {
             scope 4 {
                 scope 8 (inlined <NonNull<T> as PartialEq>::eq) {
                     let mut _5: std::ptr::NonNull<T>;
+                    let mut _6: *mut T;
+                    let mut _7: *mut T;
                     scope 9 (inlined NonNull::<T>::as_ptr) {
-                        let mut _6: *const T;
                     }
                     scope 10 (inlined NonNull::<T>::as_ptr) {
-                        let mut _7: *const T;
                     }
                 }
             }
@@ -48,13 +48,13 @@ fn slice_iter_generic_is_empty(_1: &std::slice::Iter<'_, T>) -> bool {
         _4 = copy (*_3);
         StorageDead(_3);
         StorageLive(_6);
-        StorageLive(_7);
         StorageLive(_5);
         _5 = copy ((*_1).0: std::ptr::NonNull<T>);
-        _6 = copy (_5.0: *const T);
+        _6 = copy _5 as *mut T (Transmute);
         StorageDead(_5);
-        _7 = copy (_4.0: *const T);
-        _0 = Eq(copy _6, copy _7);
+        StorageLive(_7);
+        _7 = copy _4 as *mut T (Transmute);
+        _0 = Eq(move _6, move _7);
         StorageDead(_7);
         StorageDead(_6);
         goto -> bb3;
diff --git a/tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-abort.mir b/tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-abort.mir
index c3091bd4395..2efbb6d9904 100644
--- a/tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-abort.mir
+++ b/tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-abort.mir
@@ -7,16 +7,18 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
         debug self => _1;
         scope 2 (inlined Vec::<u8>::as_slice) {
             debug self => _1;
-            let mut _7: usize;
+            let mut _9: *const u8;
+            let mut _10: usize;
             scope 3 (inlined Vec::<u8>::as_ptr) {
                 debug self => _1;
                 let mut _2: &alloc::raw_vec::RawVec<u8>;
+                let mut _8: *mut u8;
                 scope 4 (inlined alloc::raw_vec::RawVec::<u8>::ptr) {
                     debug self => _2;
                     let mut _3: &alloc::raw_vec::RawVecInner;
                     scope 5 (inlined alloc::raw_vec::RawVecInner::ptr::<u8>) {
                         debug self => _3;
-                        let mut _6: std::ptr::NonNull<u8>;
+                        let mut _7: std::ptr::NonNull<u8>;
                         scope 6 (inlined alloc::raw_vec::RawVecInner::non_null::<u8>) {
                             debug self => _3;
                             let mut _4: std::ptr::NonNull<u8>;
@@ -25,27 +27,28 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
                                 debug ((self: Unique<u8>).1: std::marker::PhantomData<u8>) => const PhantomData::<u8>;
                                 scope 8 (inlined NonNull::<u8>::cast::<u8>) {
                                     debug self => _4;
+                                    let mut _5: *mut u8;
+                                    let mut _6: *const u8;
                                     scope 9 (inlined NonNull::<u8>::as_ptr) {
                                         debug self => _4;
-                                        let mut _5: *const u8;
                                     }
                                 }
                             }
                             scope 10 (inlined Unique::<u8>::as_non_null_ptr) {
-                                debug ((self: Unique<u8>).0: std::ptr::NonNull<u8>) => _6;
+                                debug ((self: Unique<u8>).0: std::ptr::NonNull<u8>) => _7;
                                 debug ((self: Unique<u8>).1: std::marker::PhantomData<u8>) => const PhantomData::<u8>;
                             }
                         }
                         scope 11 (inlined NonNull::<u8>::as_ptr) {
-                            debug self => _6;
+                            debug self => _7;
                         }
                     }
                 }
             }
             scope 12 (inlined std::slice::from_raw_parts::<'_, u8>) {
-                debug data => _5;
-                debug len => _7;
-                let _8: *const [u8];
+                debug data => _9;
+                debug len => _10;
+                let _11: *const [u8];
                 scope 13 (inlined core::ub_checks::check_language_ub) {
                     scope 14 (inlined core::ub_checks::check_language_ub::runtime) {
                     }
@@ -55,11 +58,11 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
                 scope 16 (inlined align_of::<u8>) {
                 }
                 scope 17 (inlined slice_from_raw_parts::<u8>) {
-                    debug data => _5;
-                    debug len => _7;
+                    debug data => _9;
+                    debug len => _10;
                     scope 18 (inlined std::ptr::from_raw_parts::<[u8], u8>) {
-                        debug data_pointer => _5;
-                        debug metadata => _7;
+                        debug data_pointer => _9;
+                        debug metadata => _10;
                     }
                 }
             }
@@ -67,26 +70,37 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
     }
 
     bb0: {
+        StorageLive(_8);
+        StorageLive(_9);
         StorageLive(_2);
         _2 = &((*_1).0: alloc::raw_vec::RawVec<u8>);
         StorageLive(_3);
         _3 = &(((*_1).0: alloc::raw_vec::RawVec<u8>).0: alloc::raw_vec::RawVecInner);
-        StorageLive(_6);
+        StorageLive(_7);
         StorageLive(_4);
         _4 = copy (((((*_1).0: alloc::raw_vec::RawVec<u8>).0: alloc::raw_vec::RawVecInner).0: std::ptr::Unique<u8>).0: std::ptr::NonNull<u8>);
-        _5 = copy (_4.0: *const u8);
-        _6 = NonNull::<u8> { pointer: copy _5 };
-        StorageDead(_4);
+        StorageLive(_5);
+        StorageLive(_6);
+        _5 = copy _4 as *mut u8 (Transmute);
+        _6 = copy _5 as *const u8 (PtrToPtr);
+        _7 = NonNull::<u8> { pointer: move _6 };
         StorageDead(_6);
+        StorageDead(_5);
+        StorageDead(_4);
+        _8 = copy _7 as *mut u8 (Transmute);
+        StorageDead(_7);
         StorageDead(_3);
+        _9 = copy _8 as *const u8 (PtrToPtr);
         StorageDead(_2);
-        StorageLive(_7);
-        _7 = copy ((*_1).1: usize);
-        StorageLive(_8);
-        _8 = *const [u8] from (copy _5, copy _7);
-        _0 = &(*_8);
+        StorageLive(_10);
+        _10 = copy ((*_1).1: usize);
+        StorageLive(_11);
+        _11 = *const [u8] from (copy _9, copy _10);
+        _0 = &(*_11);
+        StorageDead(_11);
+        StorageDead(_10);
+        StorageDead(_9);
         StorageDead(_8);
-        StorageDead(_7);
         return;
     }
 }
diff --git a/tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-unwind.mir b/tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-unwind.mir
index c3091bd4395..2efbb6d9904 100644
--- a/tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-unwind.mir
+++ b/tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-unwind.mir
@@ -7,16 +7,18 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
         debug self => _1;
         scope 2 (inlined Vec::<u8>::as_slice) {
             debug self => _1;
-            let mut _7: usize;
+            let mut _9: *const u8;
+            let mut _10: usize;
             scope 3 (inlined Vec::<u8>::as_ptr) {
                 debug self => _1;
                 let mut _2: &alloc::raw_vec::RawVec<u8>;
+                let mut _8: *mut u8;
                 scope 4 (inlined alloc::raw_vec::RawVec::<u8>::ptr) {
                     debug self => _2;
                     let mut _3: &alloc::raw_vec::RawVecInner;
                     scope 5 (inlined alloc::raw_vec::RawVecInner::ptr::<u8>) {
                         debug self => _3;
-                        let mut _6: std::ptr::NonNull<u8>;
+                        let mut _7: std::ptr::NonNull<u8>;
                         scope 6 (inlined alloc::raw_vec::RawVecInner::non_null::<u8>) {
                             debug self => _3;
                             let mut _4: std::ptr::NonNull<u8>;
@@ -25,27 +27,28 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
                                 debug ((self: Unique<u8>).1: std::marker::PhantomData<u8>) => const PhantomData::<u8>;
                                 scope 8 (inlined NonNull::<u8>::cast::<u8>) {
                                     debug self => _4;
+                                    let mut _5: *mut u8;
+                                    let mut _6: *const u8;
                                     scope 9 (inlined NonNull::<u8>::as_ptr) {
                                         debug self => _4;
-                                        let mut _5: *const u8;
                                     }
                                 }
                             }
                             scope 10 (inlined Unique::<u8>::as_non_null_ptr) {
-                                debug ((self: Unique<u8>).0: std::ptr::NonNull<u8>) => _6;
+                                debug ((self: Unique<u8>).0: std::ptr::NonNull<u8>) => _7;
                                 debug ((self: Unique<u8>).1: std::marker::PhantomData<u8>) => const PhantomData::<u8>;
                             }
                         }
                         scope 11 (inlined NonNull::<u8>::as_ptr) {
-                            debug self => _6;
+                            debug self => _7;
                         }
                     }
                 }
             }
             scope 12 (inlined std::slice::from_raw_parts::<'_, u8>) {
-                debug data => _5;
-                debug len => _7;
-                let _8: *const [u8];
+                debug data => _9;
+                debug len => _10;
+                let _11: *const [u8];
                 scope 13 (inlined core::ub_checks::check_language_ub) {
                     scope 14 (inlined core::ub_checks::check_language_ub::runtime) {
                     }
@@ -55,11 +58,11 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
                 scope 16 (inlined align_of::<u8>) {
                 }
                 scope 17 (inlined slice_from_raw_parts::<u8>) {
-                    debug data => _5;
-                    debug len => _7;
+                    debug data => _9;
+                    debug len => _10;
                     scope 18 (inlined std::ptr::from_raw_parts::<[u8], u8>) {
-                        debug data_pointer => _5;
-                        debug metadata => _7;
+                        debug data_pointer => _9;
+                        debug metadata => _10;
                     }
                 }
             }
@@ -67,26 +70,37 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
     }
 
     bb0: {
+        StorageLive(_8);
+        StorageLive(_9);
         StorageLive(_2);
         _2 = &((*_1).0: alloc::raw_vec::RawVec<u8>);
         StorageLive(_3);
         _3 = &(((*_1).0: alloc::raw_vec::RawVec<u8>).0: alloc::raw_vec::RawVecInner);
-        StorageLive(_6);
+        StorageLive(_7);
         StorageLive(_4);
         _4 = copy (((((*_1).0: alloc::raw_vec::RawVec<u8>).0: alloc::raw_vec::RawVecInner).0: std::ptr::Unique<u8>).0: std::ptr::NonNull<u8>);
-        _5 = copy (_4.0: *const u8);
-        _6 = NonNull::<u8> { pointer: copy _5 };
-        StorageDead(_4);
+        StorageLive(_5);
+        StorageLive(_6);
+        _5 = copy _4 as *mut u8 (Transmute);
+        _6 = copy _5 as *const u8 (PtrToPtr);
+        _7 = NonNull::<u8> { pointer: move _6 };
         StorageDead(_6);
+        StorageDead(_5);
+        StorageDead(_4);
+        _8 = copy _7 as *mut u8 (Transmute);
+        StorageDead(_7);
         StorageDead(_3);
+        _9 = copy _8 as *const u8 (PtrToPtr);
         StorageDead(_2);
-        StorageLive(_7);
-        _7 = copy ((*_1).1: usize);
-        StorageLive(_8);
-        _8 = *const [u8] from (copy _5, copy _7);
-        _0 = &(*_8);
+        StorageLive(_10);
+        _10 = copy ((*_1).1: usize);
+        StorageLive(_11);
+        _11 = *const [u8] from (copy _9, copy _10);
+        _0 = &(*_11);
+        StorageDead(_11);
+        StorageDead(_10);
+        StorageDead(_9);
         StorageDead(_8);
-        StorageDead(_7);
         return;
     }
 }
diff --git a/tests/ui-fulldeps/pprust-parenthesis-insertion.rs b/tests/ui-fulldeps/pprust-parenthesis-insertion.rs
index fd6644d73c1..b83e576076d 100644
--- a/tests/ui-fulldeps/pprust-parenthesis-insertion.rs
+++ b/tests/ui-fulldeps/pprust-parenthesis-insertion.rs
@@ -36,12 +36,11 @@ extern crate rustc_errors;
 extern crate rustc_parse;
 extern crate rustc_session;
 extern crate rustc_span;
-extern crate smallvec;
 
 use std::mem;
 use std::process::ExitCode;
 
-use rustc_ast::ast::{DUMMY_NODE_ID, Expr, ExprKind, Stmt};
+use rustc_ast::ast::{DUMMY_NODE_ID, Expr, ExprKind};
 use rustc_ast::mut_visit::{self, DummyAstNode as _, MutVisitor};
 use rustc_ast::node_id::NodeId;
 use rustc_ast::ptr::P;
@@ -50,7 +49,6 @@ use rustc_errors::Diag;
 use rustc_parse::parser::Recovery;
 use rustc_session::parse::ParseSess;
 use rustc_span::{DUMMY_SP, FileName, Span};
-use smallvec::SmallVec;
 
 // Every parenthesis in the following expressions is re-inserted by the
 // pretty-printer.
@@ -164,18 +162,6 @@ impl MutVisitor for Normalize {
     fn visit_span(&mut self, span: &mut Span) {
         *span = DUMMY_SP;
     }
-
-    fn visit_expr(&mut self, expr: &mut P<Expr>) {
-        if let ExprKind::Binary(binop, _left, _right) = &mut expr.kind {
-            self.visit_span(&mut binop.span);
-        }
-        mut_visit::walk_expr(self, expr);
-    }
-
-    fn flat_map_stmt(&mut self, mut stmt: Stmt) -> SmallVec<[Stmt; 1]> {
-        self.visit_span(&mut stmt.span);
-        mut_visit::walk_flat_map_stmt(self, stmt)
-    }
 }
 
 fn parse_expr(psess: &ParseSess, source_code: &str) -> Option<P<Expr>> {
diff --git a/tests/ui/nll/closure-requirements/thread_scope_correct_implied_bound.rs b/tests/ui/nll/closure-requirements/thread_scope_correct_implied_bound.rs
new file mode 100644
index 00000000000..e2b3b051ea8
--- /dev/null
+++ b/tests/ui/nll/closure-requirements/thread_scope_correct_implied_bound.rs
@@ -0,0 +1,23 @@
+// This example broke while refactoring the way closure
+// requirements are handled. The setup here matches
+// `thread::scope`.
+
+//@ check-pass
+
+struct Outlives<'hr, 'scope: 'hr>(*mut (&'scope (), &'hr ()));
+impl<'hr, 'scope> Outlives<'hr, 'scope> {
+    fn outlives_hr<T: 'hr>(self) {}
+}
+
+fn takes_closure_implied_bound<'scope>(f: impl for<'hr> FnOnce(Outlives<'hr, 'scope>)) {}
+
+fn requires_external_outlives_hr<T>() {
+    // implied bounds:
+    // - `T: 'scope` as `'scope` is local to this function
+    // - `'scope: 'hr` as it's an implied bound of `Outlives`
+    //
+    // need to prove `T: 'hr` :>
+    takes_closure_implied_bound(|proof| proof.outlives_hr::<T>());
+}
+
+fn main() {}
diff --git a/tests/ui/nll/closure-requirements/thread_scope_incorrect_implied_bound.rs b/tests/ui/nll/closure-requirements/thread_scope_incorrect_implied_bound.rs
new file mode 100644
index 00000000000..cfc8980410a
--- /dev/null
+++ b/tests/ui/nll/closure-requirements/thread_scope_incorrect_implied_bound.rs
@@ -0,0 +1,21 @@
+// This example incorrectly compiled while refactoring the way
+// closure requirements are handled.
+
+struct Outlives<'hr: 'scope, 'scope>(*mut (&'scope (), &'hr ()));
+impl<'hr, 'scope> Outlives<'hr, 'scope> {
+    fn outlives_hr<T: 'hr>(self) {}
+}
+
+fn takes_closure_implied_bound<'scope>(f: impl for<'hr> FnOnce(Outlives<'hr, 'scope>)) {}
+
+fn requires_external_outlives_hr<T>() {
+    // implied bounds:
+    // - `T: 'scope` as `'scope` is local to this function
+    // - `'hr: 'scope` as it's an implied bound of `Outlives`
+    //
+    // need to prove `T: 'hr` :<
+    takes_closure_implied_bound(|proof| proof.outlives_hr::<T>());
+    //~^ ERROR the parameter type `T` may not live long enough
+}
+
+fn main() {}
diff --git a/tests/ui/nll/closure-requirements/thread_scope_incorrect_implied_bound.stderr b/tests/ui/nll/closure-requirements/thread_scope_incorrect_implied_bound.stderr
new file mode 100644
index 00000000000..e22673c249f
--- /dev/null
+++ b/tests/ui/nll/closure-requirements/thread_scope_incorrect_implied_bound.stderr
@@ -0,0 +1,17 @@
+error[E0310]: the parameter type `T` may not live long enough
+  --> $DIR/thread_scope_incorrect_implied_bound.rs:17:47
+   |
+LL |     takes_closure_implied_bound(|proof| proof.outlives_hr::<T>());
+   |                                               ^^^^^^^^^^^
+   |                                               |
+   |                                               the parameter type `T` must be valid for the static lifetime...
+   |                                               ...so that the type `T` will meet its required lifetime bounds
+   |
+help: consider adding an explicit lifetime bound
+   |
+LL | fn requires_external_outlives_hr<T: 'static>() {
+   |                                   +++++++++
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0310`.
diff --git a/tests/ui/nll/ty-outlives/projection-implied-bounds.rs b/tests/ui/nll/ty-outlives/projection-implied-bounds.rs
index 7d983adfe88..c6572d60bb0 100644
--- a/tests/ui/nll/ty-outlives/projection-implied-bounds.rs
+++ b/tests/ui/nll/ty-outlives/projection-implied-bounds.rs
@@ -1,8 +1,6 @@
 // Test that we can deduce when projections like `T::Item` outlive the
 // function body. Test that this does not imply that `T: 'a` holds.
 
-//@ compile-flags:-Zverbose-internals
-
 use std::cell::Cell;
 
 fn twice<F, T>(mut value: T, mut f: F)
diff --git a/tests/ui/nll/ty-outlives/projection-implied-bounds.stderr b/tests/ui/nll/ty-outlives/projection-implied-bounds.stderr
index 2aab03ee7b7..5d5b890151d 100644
--- a/tests/ui/nll/ty-outlives/projection-implied-bounds.stderr
+++ b/tests/ui/nll/ty-outlives/projection-implied-bounds.stderr
@@ -1,5 +1,5 @@
 error[E0310]: the parameter type `T` may not live long enough
-  --> $DIR/projection-implied-bounds.rs:30:36
+  --> $DIR/projection-implied-bounds.rs:28:36
    |
 LL |     twice(value, |value_ref, item| invoke2(value_ref, item));
    |                                    ^^^^^^^^^^^^^^^^^^^^^^^^