diff --git a/compiler/rustc_abi/src/layout.rs b/compiler/rustc_abi/src/layout.rs
index 7bffeaf4cc9e2..42250aa173bbd 100644
--- a/compiler/rustc_abi/src/layout.rs
+++ b/compiler/rustc_abi/src/layout.rs
@@ -315,7 +315,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
         repr: &ReprOptions,
         variants: &IndexSlice<VariantIdx, IndexVec<FieldIdx, F>>,
         is_enum: bool,
-        is_unsafe_cell: bool,
+        is_special_no_niche: bool,
         scalar_valid_range: (Bound<u128>, Bound<u128>),
         discr_range_of_repr: impl Fn(i128, i128) -> (Integer, bool),
         discriminants: impl Iterator<Item = (VariantIdx, i128)>,
@@ -348,7 +348,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
                 repr,
                 variants,
                 is_enum,
-                is_unsafe_cell,
+                is_special_no_niche,
                 scalar_valid_range,
                 always_sized,
                 present_first,
@@ -505,7 +505,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
         repr: &ReprOptions,
         variants: &IndexSlice<VariantIdx, IndexVec<FieldIdx, F>>,
         is_enum: bool,
-        is_unsafe_cell: bool,
+        is_special_no_niche: bool,
         scalar_valid_range: (Bound<u128>, Bound<u128>),
         always_sized: bool,
         present_first: VariantIdx,
@@ -524,7 +524,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
         let mut st = self.univariant(&variants[v], repr, kind)?;
         st.variants = Variants::Single { index: v };
 
-        if is_unsafe_cell {
+        if is_special_no_niche {
             let hide_niches = |scalar: &mut _| match scalar {
                 Scalar::Initialized { value, valid_range } => {
                     *valid_range = WrappingRange::full(value.size(dl))
diff --git a/compiler/rustc_expand/src/mbe/macro_rules.rs b/compiler/rustc_expand/src/mbe/macro_rules.rs
index 77ec598e62a17..460a06f9c0604 100644
--- a/compiler/rustc_expand/src/mbe/macro_rules.rs
+++ b/compiler/rustc_expand/src/mbe/macro_rules.rs
@@ -12,7 +12,7 @@ use rustc_ast::{self as ast, DUMMY_NODE_ID, NodeId};
 use rustc_ast_pretty::pprust;
 use rustc_attr_parsing::{AttributeKind, find_attr};
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
-use rustc_errors::{Applicability, ErrorGuaranteed};
+use rustc_errors::{Applicability, Diag, ErrorGuaranteed};
 use rustc_feature::Features;
 use rustc_hir as hir;
 use rustc_lint_defs::BuiltinLintDiag;
@@ -27,19 +27,18 @@ use rustc_span::hygiene::Transparency;
 use rustc_span::{Ident, MacroRulesNormalizedIdent, Span, kw, sym};
 use tracing::{debug, instrument, trace, trace_span};
 
-use super::diagnostics;
 use super::macro_parser::{NamedMatches, NamedParseResult};
+use super::{SequenceRepetition, diagnostics};
 use crate::base::{
     DummyResult, ExpandResult, ExtCtxt, MacResult, MacroExpanderResult, SyntaxExtension,
     SyntaxExtensionKind, TTMacroExpander,
 };
 use crate::expand::{AstFragment, AstFragmentKind, ensure_complete_parse, parse_ast_fragment};
-use crate::mbe;
 use crate::mbe::diagnostics::{annotate_doc_comment, parse_failure_msg};
-use crate::mbe::macro_check;
 use crate::mbe::macro_parser::NamedMatch::*;
 use crate::mbe::macro_parser::{Error, ErrorReported, Failure, MatcherLoc, Success, TtParser};
 use crate::mbe::transcribe::transcribe;
+use crate::mbe::{self, KleeneOp, macro_check};
 
 pub(crate) struct ParserAnyMacro<'a> {
     parser: Parser<'a>,
@@ -640,6 +639,37 @@ fn is_empty_token_tree(sess: &Session, seq: &mbe::SequenceRepetition) -> bool {
     }
 }
 
+/// Checks if a `vis` nonterminal fragment is unnecessarily wrapped in an optional repetition.
+///
+/// When a `vis` fragment (which can already be empty) is wrapped in `$(...)?`,
+/// this suggests removing the redundant repetition syntax since it provides no additional benefit.
+fn check_redundant_vis_repetition(
+    err: &mut Diag<'_>,
+    sess: &Session,
+    seq: &SequenceRepetition,
+    span: &DelimSpan,
+) {
+    let is_zero_or_one: bool = seq.kleene.op == KleeneOp::ZeroOrOne;
+    let is_vis = seq.tts.first().map_or(false, |tt| {
+        matches!(tt, mbe::TokenTree::MetaVarDecl(_, _, Some(NonterminalKind::Vis)))
+    });
+
+    if is_vis && is_zero_or_one {
+        err.note("a `vis` fragment can already be empty");
+        err.multipart_suggestion(
+            "remove the `$(` and `)?`",
+            vec![
+                (
+                    sess.source_map().span_extend_to_prev_char_before(span.open, '$', true),
+                    "".to_string(),
+                ),
+                (span.close.with_hi(seq.kleene.span.hi()), "".to_string()),
+            ],
+            Applicability::MaybeIncorrect,
+        );
+    }
+}
+
 /// Checks that the lhs contains no repetition which could match an empty token
 /// tree, because then the matcher would hang indefinitely.
 fn check_lhs_no_empty_seq(sess: &Session, tts: &[mbe::TokenTree]) -> Result<(), ErrorGuaranteed> {
@@ -654,8 +684,10 @@ fn check_lhs_no_empty_seq(sess: &Session, tts: &[mbe::TokenTree]) -> Result<(),
             TokenTree::Sequence(span, seq) => {
                 if is_empty_token_tree(sess, seq) {
                     let sp = span.entire();
-                    let guar = sess.dcx().span_err(sp, "repetition matches empty token tree");
-                    return Err(guar);
+                    let mut err =
+                        sess.dcx().struct_span_err(sp, "repetition matches empty token tree");
+                    check_redundant_vis_repetition(&mut err, sess, seq, span);
+                    return Err(err.emit());
                 }
                 check_lhs_no_empty_seq(sess, &seq.tts)?
             }
diff --git a/compiler/rustc_expand/src/proc_macro_server.rs b/compiler/rustc_expand/src/proc_macro_server.rs
index ee6306e396103..0ab779945f21d 100644
--- a/compiler/rustc_expand/src/proc_macro_server.rs
+++ b/compiler/rustc_expand/src/proc_macro_server.rs
@@ -1,5 +1,4 @@
 use std::ops::{Bound, Range};
-use std::sync::Arc;
 
 use ast::token::IdentIsRaw;
 use pm::bridge::{
@@ -18,7 +17,7 @@ use rustc_parse::parser::Parser;
 use rustc_parse::{exp, new_parser_from_source_str, source_str_to_stream, unwrap_or_emit_fatal};
 use rustc_session::parse::ParseSess;
 use rustc_span::def_id::CrateNum;
-use rustc_span::{BytePos, FileName, Pos, SourceFile, Span, Symbol, sym};
+use rustc_span::{BytePos, FileName, Pos, Span, Symbol, sym};
 use smallvec::{SmallVec, smallvec};
 
 use crate::base::ExtCtxt;
@@ -467,7 +466,6 @@ impl<'a, 'b> Rustc<'a, 'b> {
 impl server::Types for Rustc<'_, '_> {
     type FreeFunctions = FreeFunctions;
     type TokenStream = TokenStream;
-    type SourceFile = Arc<SourceFile>;
     type Span = Span;
     type Symbol = Symbol;
 }
@@ -673,28 +671,6 @@ impl server::TokenStream for Rustc<'_, '_> {
     }
 }
 
-impl server::SourceFile for Rustc<'_, '_> {
-    fn eq(&mut self, file1: &Self::SourceFile, file2: &Self::SourceFile) -> bool {
-        Arc::ptr_eq(file1, file2)
-    }
-
-    fn path(&mut self, file: &Self::SourceFile) -> String {
-        match &file.name {
-            FileName::Real(name) => name
-                .local_path()
-                .expect("attempting to get a file path in an imported file in `proc_macro::SourceFile::path`")
-                .to_str()
-                .expect("non-UTF8 file path in `proc_macro::SourceFile::path`")
-                .to_string(),
-            _ => file.name.prefer_local().to_string(),
-        }
-    }
-
-    fn is_real(&mut self, file: &Self::SourceFile) -> bool {
-        file.is_real_file()
-    }
-}
-
 impl server::Span for Rustc<'_, '_> {
     fn debug(&mut self, span: Self::Span) -> String {
         if self.ecx.ecfg.span_debug {
@@ -704,8 +680,29 @@ impl server::Span for Rustc<'_, '_> {
         }
     }
 
-    fn source_file(&mut self, span: Self::Span) -> Self::SourceFile {
-        self.psess().source_map().lookup_char_pos(span.lo()).file
+    fn file(&mut self, span: Self::Span) -> String {
+        self.psess()
+            .source_map()
+            .lookup_char_pos(span.lo())
+            .file
+            .name
+            .prefer_remapped_unconditionaly()
+            .to_string()
+    }
+
+    fn local_file(&mut self, span: Self::Span) -> Option<String> {
+        self.psess()
+            .source_map()
+            .lookup_char_pos(span.lo())
+            .file
+            .name
+            .clone()
+            .into_local_path()
+            .map(|p| {
+                p.to_str()
+                    .expect("non-UTF8 file path in `proc_macro::SourceFile::path`")
+                    .to_string()
+            })
     }
 
     fn parent(&mut self, span: Self::Span) -> Option<Self::Span> {
diff --git a/compiler/rustc_feature/src/unstable.rs b/compiler/rustc_feature/src/unstable.rs
index 98213affc5bfc..36e375c778d3f 100644
--- a/compiler/rustc_feature/src/unstable.rs
+++ b/compiler/rustc_feature/src/unstable.rs
@@ -565,6 +565,8 @@ declare_features! (
     (incomplete, mut_ref, "1.79.0", Some(123076)),
     /// Allows using `#[naked]` on functions.
     (unstable, naked_functions, "1.9.0", Some(90957)),
+    /// Allows using `#[naked]` on `extern "Rust"` functions.
+    (unstable, naked_functions_rustic_abi, "CURRENT_RUSTC_VERSION", Some(138997)),
     /// Allows using `#[target_feature(enable = "...")]` on `#[naked]` on functions.
     (unstable, naked_functions_target_feature, "1.86.0", Some(138568)),
     /// Allows specifying the as-needed link modifier
diff --git a/compiler/rustc_fluent_macro/src/fluent.rs b/compiler/rustc_fluent_macro/src/fluent.rs
index b04fd1b48f7ad..c96bb48a0368c 100644
--- a/compiler/rustc_fluent_macro/src/fluent.rs
+++ b/compiler/rustc_fluent_macro/src/fluent.rs
@@ -25,7 +25,10 @@ fn invocation_relative_path_to_absolute(span: Span, path: &str) -> PathBuf {
         path.to_path_buf()
     } else {
         // `/a/b/c/foo/bar.rs` contains the current macro invocation
+        #[cfg(bootstrap)]
         let mut source_file_path = span.source_file().path();
+        #[cfg(not(bootstrap))]
+        let mut source_file_path = span.local_file().unwrap();
         // `/a/b/c/foo/`
         source_file_path.pop();
         // `/a/b/c/foo/../locales/en-US/example.ftl`
diff --git a/compiler/rustc_hir/src/lang_items.rs b/compiler/rustc_hir/src/lang_items.rs
index 90fab01ba2d45..d4488b4b65760 100644
--- a/compiler/rustc_hir/src/lang_items.rs
+++ b/compiler/rustc_hir/src/lang_items.rs
@@ -182,6 +182,7 @@ language_item_table! {
     DynMetadata,             sym::dyn_metadata,        dyn_metadata,               Target::Struct,         GenericRequirement::None;
 
     Freeze,                  sym::freeze,              freeze_trait,               Target::Trait,          GenericRequirement::Exact(0);
+    UnsafeUnpin,             sym::unsafe_unpin,        unsafe_unpin_trait,         Target::Trait,          GenericRequirement::Exact(0);
 
     FnPtrTrait,              sym::fn_ptr_trait,        fn_ptr_trait,               Target::Trait,          GenericRequirement::Exact(0);
     FnPtrAddr,               sym::fn_ptr_addr,         fn_ptr_addr,                Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;
@@ -235,6 +236,8 @@ language_item_table! {
     IndexMut,                sym::index_mut,           index_mut_trait,            Target::Trait,          GenericRequirement::Exact(1);
 
     UnsafeCell,              sym::unsafe_cell,         unsafe_cell_type,           Target::Struct,         GenericRequirement::None;
+    UnsafePinned,            sym::unsafe_pinned,       unsafe_pinned_type,         Target::Struct,         GenericRequirement::None;
+
     VaList,                  sym::va_list,             va_list,                    Target::Struct,         GenericRequirement::None;
 
     Deref,                   sym::deref,               deref_trait,                Target::Trait,          GenericRequirement::Exact(0);
diff --git a/compiler/rustc_hir_typeck/src/cast.rs b/compiler/rustc_hir_typeck/src/cast.rs
index 8f5fddd19d7f6..b19d9efe2c6f5 100644
--- a/compiler/rustc_hir_typeck/src/cast.rs
+++ b/compiler/rustc_hir_typeck/src/cast.rs
@@ -1042,30 +1042,31 @@ impl<'a, 'tcx> CastCheck<'tcx> {
         m_cast: ty::TypeAndMut<'tcx>,
     ) -> Result<CastKind, CastError<'tcx>> {
         // array-ptr-cast: allow mut-to-mut, mut-to-const, const-to-const
-        if m_expr.mutbl >= m_cast.mutbl {
-            if let ty::Array(ety, _) = m_expr.ty.kind() {
-                // Due to the limitations of LLVM global constants,
-                // region pointers end up pointing at copies of
-                // vector elements instead of the original values.
-                // To allow raw pointers to work correctly, we
-                // need to special-case obtaining a raw pointer
-                // from a region pointer to a vector.
-
-                // Coerce to a raw pointer so that we generate RawPtr in MIR.
-                let array_ptr_type = Ty::new_ptr(fcx.tcx, m_expr.ty, m_expr.mutbl);
-                fcx.coerce(self.expr, self.expr_ty, array_ptr_type, AllowTwoPhase::No, None)
-                    .unwrap_or_else(|_| {
-                        bug!(
+        if m_expr.mutbl >= m_cast.mutbl
+            && let ty::Array(ety, _) = m_expr.ty.kind()
+            && fcx.can_eq(fcx.param_env, *ety, m_cast.ty)
+        {
+            // Due to the limitations of LLVM global constants,
+            // region pointers end up pointing at copies of
+            // vector elements instead of the original values.
+            // To allow raw pointers to work correctly, we
+            // need to special-case obtaining a raw pointer
+            // from a region pointer to a vector.
+
+            // Coerce to a raw pointer so that we generate RawPtr in MIR.
+            let array_ptr_type = Ty::new_ptr(fcx.tcx, m_expr.ty, m_expr.mutbl);
+            fcx.coerce(self.expr, self.expr_ty, array_ptr_type, AllowTwoPhase::No, None)
+                .unwrap_or_else(|_| {
+                    bug!(
                         "could not cast from reference to array to pointer to array ({:?} to {:?})",
                         self.expr_ty,
                         array_ptr_type,
                     )
-                    });
+                });
 
-                // this will report a type mismatch if needed
-                fcx.demand_eqtype(self.span, *ety, m_cast.ty);
-                return Ok(CastKind::ArrayPtrCast);
-            }
+            // this will report a type mismatch if needed
+            fcx.demand_eqtype(self.span, *ety, m_cast.ty);
+            return Ok(CastKind::ArrayPtrCast);
         }
 
         Err(CastError::IllegalCast)
diff --git a/compiler/rustc_hir_typeck/src/coercion.rs b/compiler/rustc_hir_typeck/src/coercion.rs
index f1571cf4c8317..fd899425f62d2 100644
--- a/compiler/rustc_hir_typeck/src/coercion.rs
+++ b/compiler/rustc_hir_typeck/src/coercion.rs
@@ -103,15 +103,6 @@ fn coerce_mutbls<'tcx>(
     if from_mutbl >= to_mutbl { Ok(()) } else { Err(TypeError::Mutability) }
 }
 
-/// Do not require any adjustments, i.e. coerce `x -> x`.
-fn identity(_: Ty<'_>) -> Vec<Adjustment<'_>> {
-    vec![]
-}
-
-fn simple<'tcx>(kind: Adjust) -> impl FnOnce(Ty<'tcx>) -> Vec<Adjustment<'tcx>> {
-    move |target| vec![Adjustment { kind, target }]
-}
-
 /// This always returns `Ok(...)`.
 fn success<'tcx>(
     adj: Vec<Adjustment<'tcx>>,
@@ -131,7 +122,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
         Coerce { fcx, cause, allow_two_phase, use_lub: false, coerce_never }
     }
 
-    fn unify(&self, a: Ty<'tcx>, b: Ty<'tcx>) -> InferResult<'tcx, Ty<'tcx>> {
+    fn unify_raw(&self, a: Ty<'tcx>, b: Ty<'tcx>) -> InferResult<'tcx, Ty<'tcx>> {
         debug!("unify(a: {:?}, b: {:?}, use_lub: {})", a, b, self.use_lub);
         self.commit_if_ok(|_| {
             let at = self.at(&self.cause, self.fcx.param_env);
@@ -161,13 +152,30 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
         })
     }
 
+    /// Unify two types (using sub or lub).
+    fn unify(&self, a: Ty<'tcx>, b: Ty<'tcx>) -> CoerceResult<'tcx> {
+        self.unify_raw(a, b)
+            .and_then(|InferOk { value: ty, obligations }| success(vec![], ty, obligations))
+    }
+
     /// Unify two types (using sub or lub) and produce a specific coercion.
-    fn unify_and<F>(&self, a: Ty<'tcx>, b: Ty<'tcx>, f: F) -> CoerceResult<'tcx>
-    where
-        F: FnOnce(Ty<'tcx>) -> Vec<Adjustment<'tcx>>,
-    {
-        self.unify(a, b)
-            .and_then(|InferOk { value: ty, obligations }| success(f(ty), ty, obligations))
+    fn unify_and(
+        &self,
+        a: Ty<'tcx>,
+        b: Ty<'tcx>,
+        adjustments: impl IntoIterator<Item = Adjustment<'tcx>>,
+        final_adjustment: Adjust,
+    ) -> CoerceResult<'tcx> {
+        self.unify_raw(a, b).and_then(|InferOk { value: ty, obligations }| {
+            success(
+                adjustments
+                    .into_iter()
+                    .chain(std::iter::once(Adjustment { target: ty, kind: final_adjustment }))
+                    .collect(),
+                ty,
+                obligations,
+            )
+        })
     }
 
     #[instrument(skip(self))]
@@ -180,10 +188,14 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
         // Coercing from `!` to any type is allowed:
         if a.is_never() {
             if self.coerce_never {
-                return success(simple(Adjust::NeverToAny)(b), b, PredicateObligations::new());
+                return success(
+                    vec![Adjustment { kind: Adjust::NeverToAny, target: b }],
+                    b,
+                    PredicateObligations::new(),
+                );
             } else {
                 // Otherwise the only coercion we can do is unification.
-                return self.unify_and(a, b, identity);
+                return self.unify(a, b);
             }
         }
 
@@ -191,7 +203,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
         // we have no information about the source type. This will always
         // ultimately fall back to some form of subtyping.
         if a.is_ty_var() {
-            return self.coerce_from_inference_variable(a, b, identity);
+            return self.coerce_from_inference_variable(a, b);
         }
 
         // Consider coercing the subtype to a DST
@@ -247,7 +259,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
             ty::FnPtr(a_sig_tys, a_hdr) => {
                 // We permit coercion of fn pointers to drop the
                 // unsafe qualifier.
-                self.coerce_from_fn_pointer(a, a_sig_tys.with(a_hdr), b)
+                self.coerce_from_fn_pointer(a_sig_tys.with(a_hdr), b)
             }
             ty::Closure(closure_def_id_a, args_a) => {
                 // Non-capturing closures are coercible to
@@ -257,7 +269,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
             }
             _ => {
                 // Otherwise, just use unification rules.
-                self.unify_and(a, b, identity)
+                self.unify(a, b)
             }
         }
     }
@@ -265,12 +277,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
     /// Coercing *from* an inference variable. In this case, we have no information
     /// about the source type, so we can't really do a true coercion and we always
     /// fall back to subtyping (`unify_and`).
-    fn coerce_from_inference_variable(
-        &self,
-        a: Ty<'tcx>,
-        b: Ty<'tcx>,
-        make_adjustments: impl FnOnce(Ty<'tcx>) -> Vec<Adjustment<'tcx>>,
-    ) -> CoerceResult<'tcx> {
+    fn coerce_from_inference_variable(&self, a: Ty<'tcx>, b: Ty<'tcx>) -> CoerceResult<'tcx> {
         debug!("coerce_from_inference_variable(a={:?}, b={:?})", a, b);
         assert!(a.is_ty_var() && self.shallow_resolve(a) == a);
         assert!(self.shallow_resolve(b) == b);
@@ -298,12 +305,11 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
                 "coerce_from_inference_variable: two inference variables, target_ty={:?}, obligations={:?}",
                 target_ty, obligations
             );
-            let adjustments = make_adjustments(target_ty);
-            InferResult::Ok(InferOk { value: (adjustments, target_ty), obligations })
+            success(vec![], target_ty, obligations)
         } else {
             // One unresolved type variable: just apply subtyping, we may be able
             // to do something useful.
-            self.unify_and(a, b, make_adjustments)
+            self.unify(a, b)
         }
     }
 
@@ -331,7 +337,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
                 coerce_mutbls(mt_a.mutbl, mutbl_b)?;
                 (r_a, mt_a)
             }
-            _ => return self.unify_and(a, b, identity),
+            _ => return self.unify(a, b),
         };
 
         let span = self.cause.span;
@@ -437,7 +443,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
                 referent_ty,
                 mutbl_b, // [1] above
             );
-            match self.unify(derefd_ty_a, b) {
+            match self.unify_raw(derefd_ty_a, b) {
                 Ok(ok) => {
                     found = Some(ok);
                     break;
@@ -579,13 +585,13 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
         // We only have the latter, so we use an inference variable
         // for the former and let type inference do the rest.
         let coerce_target = self.next_ty_var(self.cause.span);
-        let mut coercion = self.unify_and(coerce_target, target, |target| {
-            let unsize = Adjustment { kind: Adjust::Pointer(PointerCoercion::Unsize), target };
-            match reborrow {
-                None => vec![unsize],
-                Some((ref deref, ref autoref)) => vec![deref.clone(), autoref.clone(), unsize],
-            }
-        })?;
+
+        let mut coercion = self.unify_and(
+            coerce_target,
+            target,
+            reborrow.into_iter().flat_map(|(deref, autoref)| [deref, autoref]),
+            Adjust::Pointer(PointerCoercion::Unsize),
+        )?;
 
         let mut selcx = traits::SelectionContext::new(self);
 
@@ -708,7 +714,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
             && let ty::Dynamic(b_data, _, ty::DynStar) = b.kind()
             && a_data.principal_def_id() == b_data.principal_def_id()
         {
-            return self.unify_and(a, b, |_| vec![]);
+            return self.unify(a, b);
         }
 
         // Check the obligations of the cast -- for example, when casting
@@ -808,23 +814,15 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
 
         // To complete the reborrow, we need to make sure we can unify the inner types, and if so we
         // add the adjustments.
-        self.unify_and(a, b, |_inner_ty| {
-            vec![Adjustment { kind: Adjust::ReborrowPin(mut_b), target: b }]
-        })
+        self.unify_and(a, b, [], Adjust::ReborrowPin(mut_b))
     }
 
-    fn coerce_from_safe_fn<F, G>(
+    fn coerce_from_safe_fn(
         &self,
-        a: Ty<'tcx>,
         fn_ty_a: ty::PolyFnSig<'tcx>,
         b: Ty<'tcx>,
-        to_unsafe: F,
-        normal: G,
-    ) -> CoerceResult<'tcx>
-    where
-        F: FnOnce(Ty<'tcx>) -> Vec<Adjustment<'tcx>>,
-        G: FnOnce(Ty<'tcx>) -> Vec<Adjustment<'tcx>>,
-    {
+        adjustment: Option<Adjust>,
+    ) -> CoerceResult<'tcx> {
         self.commit_if_ok(|snapshot| {
             let outer_universe = self.infcx.universe();
 
@@ -833,9 +831,19 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
                 && hdr_b.safety.is_unsafe()
             {
                 let unsafe_a = self.tcx.safe_to_unsafe_fn_ty(fn_ty_a);
-                self.unify_and(unsafe_a, b, to_unsafe)
+                self.unify_and(
+                    unsafe_a,
+                    b,
+                    adjustment
+                        .map(|kind| Adjustment { kind, target: Ty::new_fn_ptr(self.tcx, fn_ty_a) }),
+                    Adjust::Pointer(PointerCoercion::UnsafeFnPointer),
+                )
             } else {
-                self.unify_and(a, b, normal)
+                let a = Ty::new_fn_ptr(self.tcx, fn_ty_a);
+                match adjustment {
+                    Some(adjust) => self.unify_and(a, b, [], adjust),
+                    None => self.unify(a, b),
+                }
             };
 
             // FIXME(#73154): This is a hack. Currently LUB can generate
@@ -852,7 +860,6 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
 
     fn coerce_from_fn_pointer(
         &self,
-        a: Ty<'tcx>,
         fn_ty_a: ty::PolyFnSig<'tcx>,
         b: Ty<'tcx>,
     ) -> CoerceResult<'tcx> {
@@ -861,15 +868,9 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
         //!
 
         let b = self.shallow_resolve(b);
-        debug!("coerce_from_fn_pointer(a={:?}, b={:?})", a, b);
-
-        self.coerce_from_safe_fn(
-            a,
-            fn_ty_a,
-            b,
-            simple(Adjust::Pointer(PointerCoercion::UnsafeFnPointer)),
-            identity,
-        )
+        debug!(?fn_ty_a, ?b, "coerce_from_fn_pointer");
+
+        self.coerce_from_safe_fn(fn_ty_a, b, None)
     }
 
     fn coerce_from_fn_item(&self, a: Ty<'tcx>, b: Ty<'tcx>) -> CoerceResult<'tcx> {
@@ -916,30 +917,16 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
                     self.at(&self.cause, self.param_env).normalize(a_sig);
                 obligations.extend(o1);
 
-                let a_fn_pointer = Ty::new_fn_ptr(self.tcx, a_sig);
                 let InferOk { value, obligations: o2 } = self.coerce_from_safe_fn(
-                    a_fn_pointer,
                     a_sig,
                     b,
-                    |unsafe_ty| {
-                        vec![
-                            Adjustment {
-                                kind: Adjust::Pointer(PointerCoercion::ReifyFnPointer),
-                                target: a_fn_pointer,
-                            },
-                            Adjustment {
-                                kind: Adjust::Pointer(PointerCoercion::UnsafeFnPointer),
-                                target: unsafe_ty,
-                            },
-                        ]
-                    },
-                    simple(Adjust::Pointer(PointerCoercion::ReifyFnPointer)),
+                    Some(Adjust::Pointer(PointerCoercion::ReifyFnPointer)),
                 )?;
 
                 obligations.extend(o2);
                 Ok(InferOk { value, obligations })
             }
-            _ => self.unify_and(a, b, identity),
+            _ => self.unify(a, b),
         }
     }
 
@@ -983,10 +970,11 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
                 self.unify_and(
                     pointer_ty,
                     b,
-                    simple(Adjust::Pointer(PointerCoercion::ClosureFnPointer(safety))),
+                    [],
+                    Adjust::Pointer(PointerCoercion::ClosureFnPointer(safety)),
                 )
             }
-            _ => self.unify_and(a, b, identity),
+            _ => self.unify(a, b),
         }
     }
 
@@ -1001,7 +989,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
         let (is_ref, mt_a) = match *a.kind() {
             ty::Ref(_, ty, mutbl) => (true, ty::TypeAndMut { ty, mutbl }),
             ty::RawPtr(ty, mutbl) => (false, ty::TypeAndMut { ty, mutbl }),
-            _ => return self.unify_and(a, b, identity),
+            _ => return self.unify(a, b),
         };
         coerce_mutbls(mt_a.mutbl, mutbl_b)?;
 
@@ -1011,16 +999,16 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
         // representation, we still register an Adjust::DerefRef so that
         // regionck knows that the region for `a` must be valid here.
         if is_ref {
-            self.unify_and(a_raw, b, |target| {
-                vec![
-                    Adjustment { kind: Adjust::Deref(None), target: mt_a.ty },
-                    Adjustment { kind: Adjust::Borrow(AutoBorrow::RawPtr(mutbl_b)), target },
-                ]
-            })
+            self.unify_and(
+                a_raw,
+                b,
+                [Adjustment { kind: Adjust::Deref(None), target: mt_a.ty }],
+                Adjust::Borrow(AutoBorrow::RawPtr(mutbl_b)),
+            )
         } else if mt_a.mutbl != mutbl_b {
-            self.unify_and(a_raw, b, simple(Adjust::Pointer(PointerCoercion::MutToConstPointer)))
+            self.unify_and(a_raw, b, [], Adjust::Pointer(PointerCoercion::MutToConstPointer))
         } else {
-            self.unify_and(a_raw, b, identity)
+            self.unify(a_raw, b)
         }
     }
 }
@@ -1118,9 +1106,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let cause = self.cause(DUMMY_SP, ObligationCauseCode::ExprAssignable);
         // We don't ever need two-phase here since we throw out the result of the coercion.
         let coerce = Coerce::new(self, cause, AllowTwoPhase::No, true);
-        coerce
-            .autoderef(DUMMY_SP, expr_ty)
-            .find_map(|(ty, steps)| self.probe(|_| coerce.unify(ty, target)).ok().map(|_| steps))
+        coerce.autoderef(DUMMY_SP, expr_ty).find_map(|(ty, steps)| {
+            self.probe(|_| coerce.unify_raw(ty, target)).ok().map(|_| steps)
+        })
     }
 
     /// Given a type, this function will calculate and return the type given
diff --git a/compiler/rustc_index_macros/src/newtype.rs b/compiler/rustc_index_macros/src/newtype.rs
index f0b58eabbff9a..eedbe630cf2c4 100644
--- a/compiler/rustc_index_macros/src/newtype.rs
+++ b/compiler/rustc_index_macros/src/newtype.rs
@@ -257,6 +257,13 @@ impl Parse for Newtype {
                 }
             }
 
+            impl std::ops::AddAssign<usize> for #name {
+                #[inline]
+                fn add_assign(&mut self, other: usize) {
+                    *self = *self + other;
+                }
+            }
+
             impl rustc_index::Idx for #name {
                 #[inline]
                 fn new(value: usize) -> Self {
diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
index 9b5c564d3324b..12384690ff398 100644
--- a/compiler/rustc_lint/src/lib.rs
+++ b/compiler/rustc_lint/src/lib.rs
@@ -606,6 +606,11 @@ fn register_builtins(store: &mut LintStore) {
         "converted into hard error, see issue #127323 \
          <https://github.com/rust-lang/rust/issues/127323> for more information",
     );
+    store.register_removed(
+        "undefined_naked_function_abi",
+        "converted into hard error, see PR #139001 \
+         <https://github.com/rust-lang/rust/issues/139001> for more information",
+    );
 }
 
 fn register_internals(store: &mut LintStore) {
diff --git a/compiler/rustc_lint/src/types.rs b/compiler/rustc_lint/src/types.rs
index a6c82f574a1c7..a084dacfb5be8 100644
--- a/compiler/rustc_lint/src/types.rs
+++ b/compiler/rustc_lint/src/types.rs
@@ -864,8 +864,8 @@ fn ty_is_known_nonnull<'tcx>(
                 return true;
             }
 
-            // `UnsafeCell` has its niche hidden.
-            if def.is_unsafe_cell() {
+            // `UnsafeCell` and `UnsafePinned` have their niche hidden.
+            if def.is_unsafe_cell() || def.is_unsafe_pinned() {
                 return false;
             }
 
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index 8a761a0a0969b..b25d2a30681c0 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -110,7 +110,6 @@ declare_lint_pass! {
         UNCONDITIONAL_PANIC,
         UNCONDITIONAL_RECURSION,
         UNCOVERED_PARAM_IN_PROJECTION,
-        UNDEFINED_NAKED_FUNCTION_ABI,
         UNEXPECTED_CFGS,
         UNFULFILLED_LINT_EXPECTATIONS,
         UNINHABITED_STATIC,
@@ -2830,39 +2829,6 @@ declare_lint! {
     "detects deprecation attributes with no effect",
 }
 
-declare_lint! {
-    /// The `undefined_naked_function_abi` lint detects naked function definitions that
-    /// either do not specify an ABI or specify the Rust ABI.
-    ///
-    /// ### Example
-    ///
-    /// ```rust
-    /// #![feature(asm_experimental_arch, naked_functions)]
-    ///
-    /// use std::arch::naked_asm;
-    ///
-    /// #[naked]
-    /// pub fn default_abi() -> u32 {
-    ///     unsafe { naked_asm!(""); }
-    /// }
-    ///
-    /// #[naked]
-    /// pub extern "Rust" fn rust_abi() -> u32 {
-    ///     unsafe { naked_asm!(""); }
-    /// }
-    /// ```
-    ///
-    /// {{produces}}
-    ///
-    /// ### Explanation
-    ///
-    /// The Rust ABI is currently undefined. Therefore, naked functions should
-    /// specify a non-Rust ABI.
-    pub UNDEFINED_NAKED_FUNCTION_ABI,
-    Warn,
-    "undefined naked function ABI"
-}
-
 declare_lint! {
     /// The `ineffective_unstable_trait_impl` lint detects `#[unstable]` attributes which are not used.
     ///
diff --git a/compiler/rustc_middle/src/ty/adt.rs b/compiler/rustc_middle/src/ty/adt.rs
index 00fe5cb0c5d6c..66517c97a687e 100644
--- a/compiler/rustc_middle/src/ty/adt.rs
+++ b/compiler/rustc_middle/src/ty/adt.rs
@@ -53,6 +53,10 @@ bitflags::bitflags! {
         const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 8;
         /// Indicates whether the type is `UnsafeCell`.
         const IS_UNSAFE_CELL              = 1 << 9;
+        /// Indicates whether the type is `UnsafePinned`.
+        const IS_UNSAFE_PINNED              = 1 << 10;
+        /// Indicates whether the type is anonymous.
+        const IS_ANONYMOUS                = 1 << 11;
     }
 }
 rustc_data_structures::external_bitflags_debug! { AdtFlags }
@@ -302,6 +306,9 @@ impl AdtDefData {
         if tcx.is_lang_item(did, LangItem::UnsafeCell) {
             flags |= AdtFlags::IS_UNSAFE_CELL;
         }
+        if tcx.is_lang_item(did, LangItem::UnsafePinned) {
+            flags |= AdtFlags::IS_UNSAFE_PINNED;
+        }
 
         AdtDefData { did, variants, flags, repr }
     }
@@ -405,6 +412,12 @@ impl<'tcx> AdtDef<'tcx> {
         self.flags().contains(AdtFlags::IS_UNSAFE_CELL)
     }
 
+    /// Returns `true` if this is `UnsafePinned<T>`.
+    #[inline]
+    pub fn is_unsafe_pinned(self) -> bool {
+        self.flags().contains(AdtFlags::IS_UNSAFE_PINNED)
+    }
+
     /// Returns `true` if this is `ManuallyDrop<T>`.
     #[inline]
     pub fn is_manually_drop(self) -> bool {
diff --git a/compiler/rustc_mir_transform/src/coroutine.rs b/compiler/rustc_mir_transform/src/coroutine.rs
index 04d96f117072f..80c729d66b1ec 100644
--- a/compiler/rustc_mir_transform/src/coroutine.rs
+++ b/compiler/rustc_mir_transform/src/coroutine.rs
@@ -547,7 +547,7 @@ fn transform_async_context<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
 
     let get_context_def_id = tcx.require_lang_item(LangItem::GetContext, None);
 
-    for bb in START_BLOCK..body.basic_blocks.next_index() {
+    for bb in body.basic_blocks.indices() {
         let bb_data = &body[bb];
         if bb_data.is_cleanup {
             continue;
@@ -556,11 +556,11 @@ fn transform_async_context<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         match &bb_data.terminator().kind {
             TerminatorKind::Call { func, .. } => {
                 let func_ty = func.ty(body, tcx);
-                if let ty::FnDef(def_id, _) = *func_ty.kind() {
-                    if def_id == get_context_def_id {
-                        let local = eliminate_get_context_call(&mut body[bb]);
-                        replace_resume_ty_local(tcx, body, local, context_mut_ref);
-                    }
+                if let ty::FnDef(def_id, _) = *func_ty.kind()
+                    && def_id == get_context_def_id
+                {
+                    let local = eliminate_get_context_call(&mut body[bb]);
+                    replace_resume_ty_local(tcx, body, local, context_mut_ref);
                 }
             }
             TerminatorKind::Yield { resume_arg, .. } => {
@@ -1057,7 +1057,7 @@ fn insert_switch<'tcx>(
     let blocks = body.basic_blocks_mut().iter_mut();
 
     for target in blocks.flat_map(|b| b.terminator_mut().successors_mut()) {
-        *target = BasicBlock::new(target.index() + 1);
+        *target += 1;
     }
 }
 
@@ -1209,14 +1209,8 @@ fn can_return<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>, typing_env: ty::Typing
     }
 
     // If there's a return terminator the function may return.
-    for block in body.basic_blocks.iter() {
-        if let TerminatorKind::Return = block.terminator().kind {
-            return true;
-        }
-    }
-
+    body.basic_blocks.iter().any(|block| matches!(block.terminator().kind, TerminatorKind::Return))
     // Otherwise the function can't return.
-    false
 }
 
 fn can_unwind<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>) -> bool {
@@ -1293,12 +1287,12 @@ fn create_coroutine_resume_function<'tcx>(
                         kind: TerminatorKind::Goto { target: poison_block },
                     };
                 }
-            } else if !block.is_cleanup {
+            } else if !block.is_cleanup
                 // Any terminators that *can* unwind but don't have an unwind target set are also
                 // pointed at our poisoning block (unless they're part of the cleanup path).
-                if let Some(unwind @ UnwindAction::Continue) = block.terminator_mut().unwind_mut() {
-                    *unwind = UnwindAction::Cleanup(poison_block);
-                }
+                && let Some(unwind @ UnwindAction::Continue) = block.terminator_mut().unwind_mut()
+            {
+                *unwind = UnwindAction::Cleanup(poison_block);
             }
         }
     }
@@ -1340,12 +1334,14 @@ fn create_coroutine_resume_function<'tcx>(
     make_coroutine_state_argument_indirect(tcx, body);
 
     match transform.coroutine_kind {
+        CoroutineKind::Coroutine(_)
+        | CoroutineKind::Desugared(CoroutineDesugaring::Async | CoroutineDesugaring::AsyncGen, _) =>
+        {
+            make_coroutine_state_argument_pinned(tcx, body);
+        }
         // Iterator::next doesn't accept a pinned argument,
         // unlike for all other coroutine kinds.
         CoroutineKind::Desugared(CoroutineDesugaring::Gen, _) => {}
-        _ => {
-            make_coroutine_state_argument_pinned(tcx, body);
-        }
     }
 
     // Make sure we remove dead blocks to remove
@@ -1408,8 +1404,7 @@ fn create_cases<'tcx>(
                 let mut statements = Vec::new();
 
                 // Create StorageLive instructions for locals with live storage
-                for i in 0..(body.local_decls.len()) {
-                    let l = Local::new(i);
+                for l in body.local_decls.indices() {
                     let needs_storage_live = point.storage_liveness.contains(l)
                         && !transform.remap.contains(l)
                         && !transform.always_live_locals.contains(l);
@@ -1535,15 +1530,10 @@ impl<'tcx> crate::MirPass<'tcx> for StateTransform {
         let coroutine_kind = body.coroutine_kind().unwrap();
 
         // Get the discriminant type and args which typeck computed
-        let (discr_ty, movable) = match *coroutine_ty.kind() {
-            ty::Coroutine(_, args) => {
-                let args = args.as_coroutine();
-                (args.discr_ty(tcx), coroutine_kind.movability() == hir::Movability::Movable)
-            }
-            _ => {
-                tcx.dcx().span_bug(body.span, format!("unexpected coroutine type {coroutine_ty}"));
-            }
+        let ty::Coroutine(_, args) = coroutine_ty.kind() else {
+            tcx.dcx().span_bug(body.span, format!("unexpected coroutine type {coroutine_ty}"));
         };
+        let discr_ty = args.as_coroutine().discr_ty(tcx);
 
         let new_ret_ty = match coroutine_kind {
             CoroutineKind::Desugared(CoroutineDesugaring::Async, _) => {
@@ -1610,6 +1600,7 @@ impl<'tcx> crate::MirPass<'tcx> for StateTransform {
 
         let always_live_locals = always_storage_live_locals(body);
 
+        let movable = coroutine_kind.movability() == hir::Movability::Movable;
         let liveness_info =
             locals_live_across_suspend_points(tcx, body, &always_live_locals, movable);
 
diff --git a/compiler/rustc_mir_transform/src/early_otherwise_branch.rs b/compiler/rustc_mir_transform/src/early_otherwise_branch.rs
index 57f7893be1b8c..d49f5d9f9c385 100644
--- a/compiler/rustc_mir_transform/src/early_otherwise_branch.rs
+++ b/compiler/rustc_mir_transform/src/early_otherwise_branch.rs
@@ -103,9 +103,8 @@ impl<'tcx> crate::MirPass<'tcx> for EarlyOtherwiseBranch {
         let mut should_cleanup = false;
 
         // Also consider newly generated bbs in the same pass
-        for i in 0..body.basic_blocks.len() {
+        for parent in body.basic_blocks.indices() {
             let bbs = &*body.basic_blocks;
-            let parent = BasicBlock::from_usize(i);
             let Some(opt_data) = evaluate_candidate(tcx, body, parent) else { continue };
 
             trace!("SUCCESS: found optimization possibility to apply: {opt_data:?}");
diff --git a/compiler/rustc_mir_transform/src/elaborate_drop.rs b/compiler/rustc_mir_transform/src/elaborate_drop.rs
index 0d8cf524661c8..fa476f961235d 100644
--- a/compiler/rustc_mir_transform/src/elaborate_drop.rs
+++ b/compiler/rustc_mir_transform/src/elaborate_drop.rs
@@ -266,19 +266,16 @@ where
                 let tcx = self.tcx();
 
                 assert_eq!(self.elaborator.typing_env().typing_mode, ty::TypingMode::PostAnalysis);
-                // The type error for normalization may have been in dropck: see
-                // `compute_drop_data` in rustc_borrowck, in which case we wouldn't have
-                // deleted the MIR body and could have an error here as well.
                 let field_ty = match tcx
                     .try_normalize_erasing_regions(self.elaborator.typing_env(), f.ty(tcx, args))
                 {
                     Ok(t) => t,
                     Err(_) => Ty::new_error(
                         self.tcx(),
-                        self.elaborator
-                            .body()
-                            .tainted_by_errors
-                            .expect("Error in drop elaboration not found by dropck."),
+                        self.tcx().dcx().span_delayed_bug(
+                            self.elaborator.body().span,
+                            "Error normalizing in drop elaboration.",
+                        ),
                     ),
                 };
 
diff --git a/compiler/rustc_mir_transform/src/instsimplify.rs b/compiler/rustc_mir_transform/src/instsimplify.rs
index a8d6aaa50a294..5f0c55ddc092d 100644
--- a/compiler/rustc_mir_transform/src/instsimplify.rs
+++ b/compiler/rustc_mir_transform/src/instsimplify.rs
@@ -10,7 +10,6 @@ use rustc_middle::ty::{self, GenericArgsRef, Ty, TyCtxt, layout};
 use rustc_span::{DUMMY_SP, Symbol, sym};
 
 use crate::simplify::simplify_duplicate_switch_targets;
-use crate::take_array;
 
 pub(super) enum InstSimplify {
     BeforeInline,
@@ -214,7 +213,9 @@ impl<'tcx> InstSimplifyContext<'_, 'tcx> {
         terminator: &mut Terminator<'tcx>,
         statements: &mut Vec<Statement<'tcx>>,
     ) {
-        let TerminatorKind::Call { func, args, destination, target, .. } = &mut terminator.kind
+        let TerminatorKind::Call {
+            func, args, destination, target: Some(destination_block), ..
+        } = &terminator.kind
         else {
             return;
         };
@@ -222,15 +223,8 @@ impl<'tcx> InstSimplifyContext<'_, 'tcx> {
         // It's definitely not a clone if there are multiple arguments
         let [arg] = &args[..] else { return };
 
-        let Some(destination_block) = *target else { return };
-
         // Only bother looking more if it's easy to know what we're calling
-        let Some((fn_def_id, fn_args)) = func.const_fn_def() else { return };
-
-        // Clone needs one arg, so we can cheaply rule out other stuff
-        if fn_args.len() != 1 {
-            return;
-        }
+        let Some((fn_def_id, ..)) = func.const_fn_def() else { return };
 
         // These types are easily available from locals, so check that before
         // doing DefId lookups to figure out what we're actually calling.
@@ -238,15 +232,12 @@ impl<'tcx> InstSimplifyContext<'_, 'tcx> {
 
         let ty::Ref(_region, inner_ty, Mutability::Not) = *arg_ty.kind() else { return };
 
-        if !inner_ty.is_trivially_pure_clone_copy() {
-            return;
-        }
-
-        if !self.tcx.is_lang_item(fn_def_id, LangItem::CloneFn) {
+        if !self.tcx.is_lang_item(fn_def_id, LangItem::CloneFn)
+            || !inner_ty.is_trivially_pure_clone_copy()
+        {
             return;
         }
 
-        let Ok([arg]) = take_array(args) else { return };
         let Some(arg_place) = arg.node.place() else { return };
 
         statements.push(Statement {
@@ -258,7 +249,7 @@ impl<'tcx> InstSimplifyContext<'_, 'tcx> {
                 )),
             ))),
         });
-        terminator.kind = TerminatorKind::Goto { target: destination_block };
+        terminator.kind = TerminatorKind::Goto { target: *destination_block };
     }
 
     fn simplify_nounwind_call(&self, terminator: &mut Terminator<'tcx>) {
diff --git a/compiler/rustc_mir_transform/src/match_branches.rs b/compiler/rustc_mir_transform/src/match_branches.rs
index 0d9d0368d3729..5059837328e24 100644
--- a/compiler/rustc_mir_transform/src/match_branches.rs
+++ b/compiler/rustc_mir_transform/src/match_branches.rs
@@ -20,13 +20,11 @@ impl<'tcx> crate::MirPass<'tcx> for MatchBranchSimplification {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         let typing_env = body.typing_env(tcx);
         let mut should_cleanup = false;
-        for i in 0..body.basic_blocks.len() {
-            let bbs = &*body.basic_blocks;
-            let bb_idx = BasicBlock::from_usize(i);
-            match bbs[bb_idx].terminator().kind {
+        for bb_idx in body.basic_blocks.indices() {
+            match &body.basic_blocks[bb_idx].terminator().kind {
                 TerminatorKind::SwitchInt {
-                    discr: ref _discr @ (Operand::Copy(_) | Operand::Move(_)),
-                    ref targets,
+                    discr: Operand::Copy(_) | Operand::Move(_),
+                    targets,
                     ..
                     // We require that the possible target blocks don't contain this block.
                 } if !targets.all_targets().contains(&bb_idx) => {}
@@ -66,9 +64,10 @@ trait SimplifyMatch<'tcx> {
         typing_env: ty::TypingEnv<'tcx>,
     ) -> Option<()> {
         let bbs = &body.basic_blocks;
-        let (discr, targets) = match bbs[switch_bb_idx].terminator().kind {
-            TerminatorKind::SwitchInt { ref discr, ref targets, .. } => (discr, targets),
-            _ => unreachable!(),
+        let TerminatorKind::SwitchInt { discr, targets, .. } =
+            &bbs[switch_bb_idx].terminator().kind
+        else {
+            unreachable!();
         };
 
         let discr_ty = discr.ty(body.local_decls(), tcx);
diff --git a/compiler/rustc_mir_transform/src/multiple_return_terminators.rs b/compiler/rustc_mir_transform/src/multiple_return_terminators.rs
index c63bfdcee8559..f59b849e85c62 100644
--- a/compiler/rustc_mir_transform/src/multiple_return_terminators.rs
+++ b/compiler/rustc_mir_transform/src/multiple_return_terminators.rs
@@ -18,19 +18,17 @@ impl<'tcx> crate::MirPass<'tcx> for MultipleReturnTerminators {
         // find basic blocks with no statement and a return terminator
         let mut bbs_simple_returns = DenseBitSet::new_empty(body.basic_blocks.len());
         let bbs = body.basic_blocks_mut();
-        for idx in bbs.indices() {
-            if bbs[idx].statements.is_empty()
-                && bbs[idx].terminator().kind == TerminatorKind::Return
-            {
+        for (idx, bb) in bbs.iter_enumerated() {
+            if bb.statements.is_empty() && bb.terminator().kind == TerminatorKind::Return {
                 bbs_simple_returns.insert(idx);
             }
         }
 
         for bb in bbs {
-            if let TerminatorKind::Goto { target } = bb.terminator().kind {
-                if bbs_simple_returns.contains(target) {
-                    bb.terminator_mut().kind = TerminatorKind::Return;
-                }
+            if let TerminatorKind::Goto { target } = bb.terminator().kind
+                && bbs_simple_returns.contains(target)
+            {
+                bb.terminator_mut().kind = TerminatorKind::Return;
             }
         }
 
diff --git a/compiler/rustc_mir_transform/src/validate.rs b/compiler/rustc_mir_transform/src/validate.rs
index e7930f0a1e3f6..66fe3ef4141f5 100644
--- a/compiler/rustc_mir_transform/src/validate.rs
+++ b/compiler/rustc_mir_transform/src/validate.rs
@@ -221,12 +221,11 @@ impl<'a, 'tcx> CfgChecker<'a, 'tcx> {
 
         // Check for cycles
         let mut stack = FxHashSet::default();
-        for i in 0..parent.len() {
-            let mut bb = BasicBlock::from_usize(i);
+        for (mut bb, parent) in parent.iter_enumerated_mut() {
             stack.clear();
             stack.insert(bb);
             loop {
-                let Some(parent) = parent[bb].take() else { break };
+                let Some(parent) = parent.take() else { break };
                 let no_cycle = stack.insert(parent);
                 if !no_cycle {
                     self.fail(
diff --git a/compiler/rustc_passes/messages.ftl b/compiler/rustc_passes/messages.ftl
index bea86801ed753..6ee5e356435c8 100644
--- a/compiler/rustc_passes/messages.ftl
+++ b/compiler/rustc_passes/messages.ftl
@@ -742,9 +742,6 @@ passes_trait_impl_const_stable =
 passes_transparent_incompatible =
     transparent {$target} cannot have other repr hints
 
-passes_undefined_naked_function_abi =
-    Rust ABI is unsupported in naked functions
-
 passes_unknown_external_lang_item =
     unknown external lang item: `{$lang_item}`
 
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index c514250781222..42279258e8777 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -624,6 +624,21 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         match target {
             Target::Fn
             | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => {
+                let fn_sig = self.tcx.hir_node(hir_id).fn_sig().unwrap();
+                let abi = fn_sig.header.abi;
+                if abi.is_rustic_abi() && !self.tcx.features().naked_functions_rustic_abi() {
+                    feature_err(
+                        &self.tcx.sess,
+                        sym::naked_functions_rustic_abi,
+                        fn_sig.span,
+                        format!(
+                            "`#[naked]` is currently unstable on `extern \"{}\"` functions",
+                            abi.as_str()
+                        ),
+                    )
+                    .emit();
+                }
+
                 for other_attr in attrs {
                     // this covers "sugared doc comments" of the form `/// ...`
                     // it does not cover `#[doc = "..."]`, which is handled below
diff --git a/compiler/rustc_passes/src/errors.rs b/compiler/rustc_passes/src/errors.rs
index 4e3e0324205a4..85eddafefcd56 100644
--- a/compiler/rustc_passes/src/errors.rs
+++ b/compiler/rustc_passes/src/errors.rs
@@ -1197,10 +1197,6 @@ pub(crate) struct UnlabeledCfInWhileCondition<'a> {
     pub cf_type: &'a str,
 }
 
-#[derive(LintDiagnostic)]
-#[diag(passes_undefined_naked_function_abi)]
-pub(crate) struct UndefinedNakedFunctionAbi;
-
 #[derive(Diagnostic)]
 #[diag(passes_no_patterns)]
 pub(crate) struct NoPatterns {
diff --git a/compiler/rustc_passes/src/naked_functions.rs b/compiler/rustc_passes/src/naked_functions.rs
index d35aedf9a5647..3c9f8b72c3635 100644
--- a/compiler/rustc_passes/src/naked_functions.rs
+++ b/compiler/rustc_passes/src/naked_functions.rs
@@ -1,6 +1,5 @@
 //! Checks validity of naked functions.
 
-use rustc_abi::ExternAbi;
 use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{LocalDefId, LocalModDefId};
@@ -10,12 +9,11 @@ use rustc_middle::hir::nested_filter::OnlyBodies;
 use rustc_middle::query::Providers;
 use rustc_middle::span_bug;
 use rustc_middle::ty::TyCtxt;
-use rustc_session::lint::builtin::UNDEFINED_NAKED_FUNCTION_ABI;
 use rustc_span::{Span, sym};
 
 use crate::errors::{
     NakedAsmOutsideNakedFn, NakedFunctionsAsmBlock, NakedFunctionsMustNakedAsm, NoPatterns,
-    ParamsNotAllowed, UndefinedNakedFunctionAbi,
+    ParamsNotAllowed,
 };
 
 pub(crate) fn provide(providers: &mut Providers) {
@@ -29,26 +27,21 @@ fn check_mod_naked_functions(tcx: TyCtxt<'_>, module_def_id: LocalModDefId) {
             continue;
         }
 
-        let (fn_header, body_id) = match tcx.hir_node_by_def_id(def_id) {
+        let body = match tcx.hir_node_by_def_id(def_id) {
             hir::Node::Item(hir::Item {
-                kind: hir::ItemKind::Fn { sig, body: body_id, .. },
-                ..
+                kind: hir::ItemKind::Fn { body: body_id, .. }, ..
             })
             | hir::Node::TraitItem(hir::TraitItem {
-                kind: hir::TraitItemKind::Fn(sig, hir::TraitFn::Provided(body_id)),
+                kind: hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(body_id)),
                 ..
             })
             | hir::Node::ImplItem(hir::ImplItem {
-                kind: hir::ImplItemKind::Fn(sig, body_id),
-                ..
-            }) => (sig.header, *body_id),
+                kind: hir::ImplItemKind::Fn(_, body_id), ..
+            }) => tcx.hir_body(*body_id),
             _ => continue,
         };
 
-        let body = tcx.hir_body(body_id);
-
         if tcx.has_attr(def_id, sym::naked) {
-            check_abi(tcx, def_id, fn_header.abi);
             check_no_patterns(tcx, body.params);
             check_no_parameters_use(tcx, body);
             check_asm(tcx, def_id, body);
@@ -60,20 +53,6 @@ fn check_mod_naked_functions(tcx: TyCtxt<'_>, module_def_id: LocalModDefId) {
     }
 }
 
-/// Checks that function uses non-Rust ABI.
-fn check_abi(tcx: TyCtxt<'_>, def_id: LocalDefId, abi: ExternAbi) {
-    if abi == ExternAbi::Rust {
-        let hir_id = tcx.local_def_id_to_hir_id(def_id);
-        let span = tcx.def_span(def_id);
-        tcx.emit_node_span_lint(
-            UNDEFINED_NAKED_FUNCTION_ABI,
-            hir_id,
-            span,
-            UndefinedNakedFunctionAbi,
-        );
-    }
-}
-
 /// Checks that parameters don't use patterns. Mirrors the checks for function declarations.
 fn check_no_patterns(tcx: TyCtxt<'_>, params: &[hir::Param<'_>]) {
     for param in params {
diff --git a/compiler/rustc_smir/src/rustc_internal/mod.rs b/compiler/rustc_smir/src/rustc_internal/mod.rs
index a546a44c87004..146ba17d14fc8 100644
--- a/compiler/rustc_smir/src/rustc_internal/mod.rs
+++ b/compiler/rustc_smir/src/rustc_internal/mod.rs
@@ -244,6 +244,7 @@ where
 /// ```ignore(needs-extern-crate)
 /// # extern crate rustc_driver;
 /// # extern crate rustc_interface;
+/// # extern crate rustc_middle;
 /// # #[macro_use]
 /// # extern crate rustc_smir;
 /// # extern crate stable_mir;
@@ -264,6 +265,7 @@ where
 /// ```ignore(needs-extern-crate)
 /// # extern crate rustc_driver;
 /// # extern crate rustc_interface;
+/// # extern crate rustc_middle;
 /// # #[macro_use]
 /// # extern crate rustc_smir;
 /// # extern crate stable_mir;
@@ -328,6 +330,7 @@ macro_rules! run_driver {
         use rustc_driver::{Callbacks, Compilation, run_compiler};
         use rustc_middle::ty::TyCtxt;
         use rustc_interface::interface;
+        use rustc_smir::rustc_internal;
         use stable_mir::CompilerError;
         use std::ops::ControlFlow;
 
diff --git a/compiler/rustc_span/src/source_map.rs b/compiler/rustc_span/src/source_map.rs
index 6fdf8e46fec65..0273bb040f433 100644
--- a/compiler/rustc_span/src/source_map.rs
+++ b/compiler/rustc_span/src/source_map.rs
@@ -633,6 +633,24 @@ impl SourceMap {
         sp
     }
 
+    /// Extends the given `Span` to just before the previous occurrence of `c`. Return the same span
+    /// if an error occurred while retrieving the code snippet.
+    pub fn span_extend_to_prev_char_before(
+        &self,
+        sp: Span,
+        c: char,
+        accept_newlines: bool,
+    ) -> Span {
+        if let Ok(prev_source) = self.span_to_prev_source(sp) {
+            let prev_source = prev_source.rsplit(c).next().unwrap_or("");
+            if accept_newlines || !prev_source.contains('\n') {
+                return sp.with_lo(BytePos(sp.lo().0 - prev_source.len() as u32 - 1_u32));
+            }
+        }
+
+        sp
+    }
+
     /// Extends the given `Span` to just after the previous occurrence of `pat` when surrounded by
     /// whitespace. Returns None if the pattern could not be found or if an error occurred while
     /// retrieving the code snippet.
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 986370f501918..d1f3eb16e4e4a 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -1400,6 +1400,7 @@ symbols! {
         naked,
         naked_asm,
         naked_functions,
+        naked_functions_rustic_abi,
         naked_functions_target_feature,
         name,
         names,
@@ -2215,6 +2216,8 @@ symbols! {
         unsafe_fields,
         unsafe_no_drop_flag,
         unsafe_pin_internals,
+        unsafe_pinned,
+        unsafe_unpin,
         unsize,
         unsized_const_param_ty,
         unsized_const_params,
diff --git a/compiler/rustc_ty_utils/src/layout.rs b/compiler/rustc_ty_utils/src/layout.rs
index 0017186c1b082..1915ba623cb2f 100644
--- a/compiler/rustc_ty_utils/src/layout.rs
+++ b/compiler/rustc_ty_utils/src/layout.rs
@@ -514,6 +514,9 @@ fn layout_of_uncached<'tcx>(
                 return map_layout(cx.calc.layout_of_union(&def.repr(), &variants));
             }
 
+            // UnsafeCell and UnsafePinned both disable niche optimizations
+            let is_special_no_niche = def.is_unsafe_cell() || def.is_unsafe_pinned();
+
             let get_discriminant_type =
                 |min, max| abi::Integer::repr_discr(tcx, ty, &def.repr(), min, max);
 
@@ -542,7 +545,7 @@ fn layout_of_uncached<'tcx>(
                     &def.repr(),
                     &variants,
                     def.is_enum(),
-                    def.is_unsafe_cell(),
+                    is_special_no_niche,
                     tcx.layout_scalar_valid_range(def.did()),
                     get_discriminant_type,
                     discriminants_iter(),
@@ -568,7 +571,7 @@ fn layout_of_uncached<'tcx>(
                     &def.repr(),
                     &variants,
                     def.is_enum(),
-                    def.is_unsafe_cell(),
+                    is_special_no_niche,
                     tcx.layout_scalar_valid_range(def.did()),
                     get_discriminant_type,
                     discriminants_iter(),
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index dc06aa4c38d55..5f701921eb66f 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -127,6 +127,7 @@
 #![feature(ub_checks)]
 #![feature(unchecked_neg)]
 #![feature(unchecked_shifts)]
+#![feature(unsafe_pinned)]
 #![feature(utf16_extra)]
 #![feature(variant_count)]
 // tidy-alphabetical-end
diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs
index 68011310d2cad..9dc20beda6c64 100644
--- a/library/core/src/marker.rs
+++ b/library/core/src/marker.rs
@@ -17,6 +17,7 @@ use crate::cell::UnsafeCell;
 use crate::cmp;
 use crate::fmt::Debug;
 use crate::hash::{Hash, Hasher};
+use crate::pin::UnsafePinned;
 
 /// Implements a given marker trait for multiple types at the same time.
 ///
@@ -878,6 +879,23 @@ marker_impls! {
         {T: ?Sized} &mut T,
 }
 
+/// Used to determine whether a type contains any `UnsafePinned` (or `PhantomPinned`) internally,
+/// but not through an indirection. This affects, for example, whether we emit `noalias` metadata
+/// for `&mut T` or not.
+///
+/// This is part of [RFC 3467](https://rust-lang.github.io/rfcs/3467-unsafe-pinned.html), and is
+/// tracked by [#125735](https://github.com/rust-lang/rust/issues/125735).
+#[cfg_attr(not(bootstrap), lang = "unsafe_unpin")]
+#[cfg_attr(bootstrap, allow(dead_code))]
+pub(crate) unsafe auto trait UnsafeUnpin {}
+
+impl<T: ?Sized> !UnsafeUnpin for UnsafePinned<T> {}
+unsafe impl<T: ?Sized> UnsafeUnpin for PhantomData<T> {}
+unsafe impl<T: ?Sized> UnsafeUnpin for *const T {}
+unsafe impl<T: ?Sized> UnsafeUnpin for *mut T {}
+unsafe impl<T: ?Sized> UnsafeUnpin for &T {}
+unsafe impl<T: ?Sized> UnsafeUnpin for &mut T {}
+
 /// Types that do not require any pinning guarantees.
 ///
 /// For information on what "pinning" is, see the [`pin` module] documentation.
@@ -953,6 +971,11 @@ pub auto trait Unpin {}
 /// A marker type which does not implement `Unpin`.
 ///
 /// If a type contains a `PhantomPinned`, it will not implement `Unpin` by default.
+//
+// FIXME(unsafe_pinned): This is *not* a stable guarantee we want to make, at least not yet.
+// Note that for backwards compatibility with the new [`UnsafePinned`] wrapper type, placing this
+// marker in your struct acts as if you wrapped the entire struct in an `UnsafePinned`. This type
+// will likely eventually be deprecated, and all new code should be using `UnsafePinned` instead.
 #[stable(feature = "pin", since = "1.33.0")]
 #[derive(Debug, Default, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
 pub struct PhantomPinned;
@@ -960,6 +983,12 @@ pub struct PhantomPinned;
 #[stable(feature = "pin", since = "1.33.0")]
 impl !Unpin for PhantomPinned {}
 
+// This is a small hack to allow existing code which uses PhantomPinned to opt-out of noalias to
+// continue working. Ideally PhantomPinned could just wrap an `UnsafePinned<()>` to get the same
+// effect, but we can't add a new field to an already stable unit struct -- that would be a breaking
+// change.
+impl !UnsafeUnpin for PhantomPinned {}
+
 marker_impls! {
     #[stable(feature = "pin", since = "1.33.0")]
     Unpin for
diff --git a/library/core/src/pin.rs b/library/core/src/pin.rs
index 2ef1bbfd1fa70..48ed5ae451e40 100644
--- a/library/core/src/pin.rs
+++ b/library/core/src/pin.rs
@@ -931,6 +931,11 @@ use crate::{
 };
 use crate::{cmp, fmt};
 
+mod unsafe_pinned;
+
+#[unstable(feature = "unsafe_pinned", issue = "125735")]
+pub use self::unsafe_pinned::UnsafePinned;
+
 /// A pointer which pins its pointee in place.
 ///
 /// [`Pin`] is a wrapper around some kind of pointer `Ptr` which makes that pointer "pin" its
diff --git a/library/core/src/pin/unsafe_pinned.rs b/library/core/src/pin/unsafe_pinned.rs
new file mode 100644
index 0000000000000..5fb628c8adbc5
--- /dev/null
+++ b/library/core/src/pin/unsafe_pinned.rs
@@ -0,0 +1,197 @@
+use crate::marker::{PointerLike, Unpin};
+use crate::ops::{CoerceUnsized, DispatchFromDyn};
+use crate::pin::Pin;
+use crate::{fmt, ptr};
+
+/// This type provides a way to opt-out of typical aliasing rules;
+/// specifically, `&mut UnsafePinned<T>` is not guaranteed to be a unique pointer.
+///
+/// However, even if you define your type like `pub struct Wrapper(UnsafePinned<...>)`, it is still
+/// very risky to have an `&mut Wrapper` that aliases anything else. Many functions that work
+/// generically on `&mut T` assume that the memory that stores `T` is uniquely owned (such as
+/// `mem::swap`). In other words, while having aliasing with `&mut Wrapper` is not immediate
+/// Undefined Behavior, it is still unsound to expose such a mutable reference to code you do not
+/// control! Techniques such as pinning via [`Pin`] are needed to ensure soundness.
+///
+/// Similar to [`UnsafeCell`](crate::cell::UnsafeCell), `UnsafePinned` will not usually show up in
+/// the public API of a library. It is an internal implementation detail of libraries that need to
+/// support aliasing mutable references.
+///
+/// Further note that this does *not* lift the requirement that shared references must be read-only!
+/// Use `UnsafeCell` for that.
+///
+/// This type blocks niches the same way `UnsafeCell` does.
+#[cfg_attr(not(bootstrap), lang = "unsafe_pinned")]
+#[repr(transparent)]
+#[unstable(feature = "unsafe_pinned", issue = "125735")]
+pub struct UnsafePinned<T: ?Sized> {
+    value: T,
+}
+
+/// When this type is used, that almost certainly means safe APIs need to use pinning to avoid the
+/// aliases from becoming invalidated. Therefore let's mark this as `!Unpin`. You can always opt
+/// back in to `Unpin` with an `impl` block, provided your API is still sound while unpinned.
+#[unstable(feature = "unsafe_pinned", issue = "125735")]
+impl<T: ?Sized> !Unpin for UnsafePinned<T> {}
+
+/// The type is `Copy` when `T` is to avoid people assuming that `Copy` implies there is no
+/// `UnsafePinned` anywhere. (This is an issue with `UnsafeCell`: people use `Copy` bounds to mean
+/// `Freeze`.) Given that there is no `unsafe impl Copy for ...`, this is also the option that
+/// leaves the user more choices (as they can always wrap this in a `!Copy` type).
+// FIXME(unsafe_pinned): this may be unsound or a footgun?
+#[unstable(feature = "unsafe_pinned", issue = "125735")]
+impl<T: Copy> Copy for UnsafePinned<T> {}
+
+#[unstable(feature = "unsafe_pinned", issue = "125735")]
+impl<T: Copy> Clone for UnsafePinned<T> {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+// `Send` and `Sync` are inherited from `T`. This is similar to `SyncUnsafeCell`, since
+// we eventually concluded that `UnsafeCell` implicitly making things `!Sync` is sometimes
+// unergonomic. A type that needs to be `!Send`/`!Sync` should really have an explicit
+// opt-out itself, e.g. via an `PhantomData<*mut T>` or (one day) via `impl !Send`/`impl !Sync`.
+
+impl<T> UnsafePinned<T> {
+    /// Constructs a new instance of `UnsafePinned` which will wrap the specified value.
+    ///
+    /// All access to the inner value through `&UnsafePinned<T>` or `&mut UnsafePinned<T>` or
+    /// `Pin<&mut UnsafePinned<T>>` requires `unsafe` code.
+    #[inline(always)]
+    #[must_use]
+    #[unstable(feature = "unsafe_pinned", issue = "125735")]
+    pub const fn new(value: T) -> Self {
+        UnsafePinned { value }
+    }
+
+    /// Unwraps the value, consuming this `UnsafePinned`.
+    #[inline(always)]
+    #[must_use]
+    #[unstable(feature = "unsafe_pinned", issue = "125735")]
+    #[rustc_allow_const_fn_unstable(const_precise_live_drops)]
+    pub const fn into_inner(self) -> T {
+        self.value
+    }
+}
+
+impl<T: ?Sized> UnsafePinned<T> {
+    /// Get read-write access to the contents of a pinned `UnsafePinned`.
+    #[inline(always)]
+    #[must_use]
+    #[unstable(feature = "unsafe_pinned", issue = "125735")]
+    pub const fn get_mut_pinned(self: Pin<&mut Self>) -> *mut T {
+        // SAFETY: we're not using `get_unchecked_mut` to unpin anything
+        unsafe { self.get_unchecked_mut() }.get_mut_unchecked()
+    }
+
+    /// Get read-write access to the contents of an `UnsafePinned`.
+    ///
+    /// You should usually be using `get_mut_pinned` instead to explicitly track the fact that this
+    /// memory is "pinned" due to there being aliases.
+    #[inline(always)]
+    #[must_use]
+    #[unstable(feature = "unsafe_pinned", issue = "125735")]
+    pub const fn get_mut_unchecked(&mut self) -> *mut T {
+        ptr::from_mut(self) as *mut T
+    }
+
+    /// Get read-only access to the contents of a shared `UnsafePinned`.
+    ///
+    /// Note that `&UnsafePinned<T>` is read-only if `&T` is read-only. This means that if there is
+    /// mutation of the `T`, future reads from the `*const T` returned here are UB! Use
+    /// [`UnsafeCell`] if you also need interior mutability.
+    ///
+    /// [`UnsafeCell`]: crate::cell::UnsafeCell
+    ///
+    /// ```rust,no_run
+    /// #![feature(unsafe_pinned)]
+    /// use std::pin::UnsafePinned;
+    ///
+    /// unsafe {
+    ///     let mut x = UnsafePinned::new(0);
+    ///     let ptr = x.get(); // read-only pointer, assumes immutability
+    ///     x.get_mut_unchecked().write(1);
+    ///     ptr.read(); // UB!
+    /// }
+    /// ```
+    #[inline(always)]
+    #[must_use]
+    #[unstable(feature = "unsafe_pinned", issue = "125735")]
+    pub const fn get(&self) -> *const T {
+        ptr::from_ref(self) as *const T
+    }
+
+    /// Gets an immutable pointer to the wrapped value.
+    ///
+    /// The difference from [`get`] is that this function accepts a raw pointer, which is useful to
+    /// avoid the creation of temporary references.
+    ///
+    /// [`get`]: UnsafePinned::get
+    #[inline(always)]
+    #[must_use]
+    #[unstable(feature = "unsafe_pinned", issue = "125735")]
+    pub const fn raw_get(this: *const Self) -> *const T {
+        this as *const T
+    }
+
+    /// Gets a mutable pointer to the wrapped value.
+    ///
+    /// The difference from [`get_mut_pinned`] and [`get_mut_unchecked`] is that this function
+    /// accepts a raw pointer, which is useful to avoid the creation of temporary references.
+    ///
+    /// [`get_mut_pinned`]: UnsafePinned::get_mut_pinned
+    /// [`get_mut_unchecked`]: UnsafePinned::get_mut_unchecked
+    #[inline(always)]
+    #[must_use]
+    #[unstable(feature = "unsafe_pinned", issue = "125735")]
+    pub const fn raw_get_mut(this: *mut Self) -> *mut T {
+        this as *mut T
+    }
+}
+
+#[unstable(feature = "unsafe_pinned", issue = "125735")]
+impl<T: Default> Default for UnsafePinned<T> {
+    /// Creates an `UnsafePinned`, with the `Default` value for T.
+    fn default() -> Self {
+        UnsafePinned::new(T::default())
+    }
+}
+
+#[unstable(feature = "unsafe_pinned", issue = "125735")]
+impl<T> From<T> for UnsafePinned<T> {
+    /// Creates a new `UnsafePinned<T>` containing the given value.
+    fn from(value: T) -> Self {
+        UnsafePinned::new(value)
+    }
+}
+
+#[unstable(feature = "unsafe_pinned", issue = "125735")]
+impl<T: ?Sized> fmt::Debug for UnsafePinned<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("UnsafePinned").finish_non_exhaustive()
+    }
+}
+
+#[unstable(feature = "coerce_unsized", issue = "18598")]
+// #[unstable(feature = "unsafe_pinned", issue = "125735")]
+impl<T: CoerceUnsized<U>, U> CoerceUnsized<UnsafePinned<U>> for UnsafePinned<T> {}
+
+// Allow types that wrap `UnsafePinned` to also implement `DispatchFromDyn`
+// and become dyn-compatible method receivers.
+// Note that currently `UnsafePinned` itself cannot be a method receiver
+// because it does not implement Deref.
+// In other words:
+// `self: UnsafePinned<&Self>` won't work
+// `self: UnsafePinned<Self>` becomes possible
+// FIXME(unsafe_pinned) this logic is copied from UnsafeCell, is it still sound?
+#[unstable(feature = "dispatch_from_dyn", issue = "none")]
+// #[unstable(feature = "unsafe_pinned", issue = "125735")]
+impl<T: DispatchFromDyn<U>, U> DispatchFromDyn<UnsafePinned<U>> for UnsafePinned<T> {}
+
+#[unstable(feature = "pointer_like_trait", issue = "none")]
+// #[unstable(feature = "unsafe_pinned", issue = "125735")]
+impl<T: PointerLike> PointerLike for UnsafePinned<T> {}
+
+// FIXME(unsafe_pinned): impl PinCoerceUnsized for UnsafePinned<T>?
diff --git a/library/proc_macro/src/bridge/client.rs b/library/proc_macro/src/bridge/client.rs
index f6d4825c67b24..e7d547966a5d5 100644
--- a/library/proc_macro/src/bridge/client.rs
+++ b/library/proc_macro/src/bridge/client.rs
@@ -111,12 +111,6 @@ impl Clone for TokenStream {
     }
 }
 
-impl Clone for SourceFile {
-    fn clone(&self) -> Self {
-        self.clone()
-    }
-}
-
 impl Span {
     pub(crate) fn def_site() -> Span {
         Bridge::with(|bridge| bridge.globals.def_site)
diff --git a/library/proc_macro/src/bridge/mod.rs b/library/proc_macro/src/bridge/mod.rs
index 1b5c221425ec6..75d82d7465404 100644
--- a/library/proc_macro/src/bridge/mod.rs
+++ b/library/proc_macro/src/bridge/mod.rs
@@ -81,16 +81,8 @@ macro_rules! with_api {
                     $self: $S::TokenStream
                 ) -> Vec<TokenTree<$S::TokenStream, $S::Span, $S::Symbol>>;
             },
-            SourceFile {
-                fn drop($self: $S::SourceFile);
-                fn clone($self: &$S::SourceFile) -> $S::SourceFile;
-                fn eq($self: &$S::SourceFile, other: &$S::SourceFile) -> bool;
-                fn path($self: &$S::SourceFile) -> String;
-                fn is_real($self: &$S::SourceFile) -> bool;
-            },
             Span {
                 fn debug($self: $S::Span) -> String;
-                fn source_file($self: $S::Span) -> $S::SourceFile;
                 fn parent($self: $S::Span) -> Option<$S::Span>;
                 fn source($self: $S::Span) -> $S::Span;
                 fn byte_range($self: $S::Span) -> Range<usize>;
@@ -98,6 +90,8 @@ macro_rules! with_api {
                 fn end($self: $S::Span) -> $S::Span;
                 fn line($self: $S::Span) -> usize;
                 fn column($self: $S::Span) -> usize;
+                fn file($self: $S::Span) -> String;
+                fn local_file($self: $S::Span) -> Option<String>;
                 fn join($self: $S::Span, other: $S::Span) -> Option<$S::Span>;
                 fn subspan($self: $S::Span, start: Bound<usize>, end: Bound<usize>) -> Option<$S::Span>;
                 fn resolved_at($self: $S::Span, at: $S::Span) -> $S::Span;
@@ -120,7 +114,6 @@ macro_rules! with_api_handle_types {
             'owned:
             FreeFunctions,
             TokenStream,
-            SourceFile,
 
             'interned:
             Span,
diff --git a/library/proc_macro/src/bridge/server.rs b/library/proc_macro/src/bridge/server.rs
index 97e5a603c3ac9..5beda7c3c96e5 100644
--- a/library/proc_macro/src/bridge/server.rs
+++ b/library/proc_macro/src/bridge/server.rs
@@ -82,7 +82,6 @@ with_api_handle_types!(define_server_handles);
 pub trait Types {
     type FreeFunctions: 'static;
     type TokenStream: 'static + Clone;
-    type SourceFile: 'static + Clone;
     type Span: 'static + Copy + Eq + Hash;
     type Symbol: 'static;
 }
diff --git a/library/proc_macro/src/lib.rs b/library/proc_macro/src/lib.rs
index f1cf0c5a2db7c..c46dcebedcab8 100644
--- a/library/proc_macro/src/lib.rs
+++ b/library/proc_macro/src/lib.rs
@@ -491,12 +491,6 @@ impl Span {
         Span(bridge::client::Span::mixed_site())
     }
 
-    /// The original source file into which this span points.
-    #[unstable(feature = "proc_macro_span", issue = "54725")]
-    pub fn source_file(&self) -> SourceFile {
-        SourceFile(self.0.source_file())
-    }
-
     /// The `Span` for the tokens in the previous macro expansion from which
     /// `self` was generated from, if any.
     #[unstable(feature = "proc_macro_span", issue = "54725")]
@@ -546,6 +540,25 @@ impl Span {
         self.0.column()
     }
 
+    /// The path to the source file in which this span occurs, for display purposes.
+    ///
+    /// This might not correspond to a valid file system path.
+    /// It might be remapped, or might be an artificial path such as `"<macro expansion>"`.
+    #[unstable(feature = "proc_macro_span", issue = "54725")]
+    pub fn file(&self) -> String {
+        self.0.file()
+    }
+
+    /// The path to the source file in which this span occurs on disk.
+    ///
+    /// This is the actual path on disk. It is unaffected by path remapping.
+    ///
+    /// This path should not be embedded in the output of the macro; prefer `file()` instead.
+    #[unstable(feature = "proc_macro_span", issue = "54725")]
+    pub fn local_file(&self) -> Option<PathBuf> {
+        self.0.local_file().map(|s| PathBuf::from(s))
+    }
+
     /// Creates a new span encompassing `self` and `other`.
     ///
     /// Returns `None` if `self` and `other` are from different files.
@@ -614,58 +627,6 @@ impl fmt::Debug for Span {
     }
 }
 
-/// The source file of a given `Span`.
-#[unstable(feature = "proc_macro_span", issue = "54725")]
-#[derive(Clone)]
-pub struct SourceFile(bridge::client::SourceFile);
-
-impl SourceFile {
-    /// Gets the path to this source file.
-    ///
-    /// ### Note
-    /// If the code span associated with this `SourceFile` was generated by an external macro, this
-    /// macro, this might not be an actual path on the filesystem. Use [`is_real`] to check.
-    ///
-    /// Also note that even if `is_real` returns `true`, if `--remap-path-prefix` was passed on
-    /// the command line, the path as given might not actually be valid.
-    ///
-    /// [`is_real`]: Self::is_real
-    #[unstable(feature = "proc_macro_span", issue = "54725")]
-    pub fn path(&self) -> PathBuf {
-        PathBuf::from(self.0.path())
-    }
-
-    /// Returns `true` if this source file is a real source file, and not generated by an external
-    /// macro's expansion.
-    #[unstable(feature = "proc_macro_span", issue = "54725")]
-    pub fn is_real(&self) -> bool {
-        // This is a hack until intercrate spans are implemented and we can have real source files
-        // for spans generated in external macros.
-        // https://github.com/rust-lang/rust/pull/43604#issuecomment-333334368
-        self.0.is_real()
-    }
-}
-
-#[unstable(feature = "proc_macro_span", issue = "54725")]
-impl fmt::Debug for SourceFile {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("SourceFile")
-            .field("path", &self.path())
-            .field("is_real", &self.is_real())
-            .finish()
-    }
-}
-
-#[unstable(feature = "proc_macro_span", issue = "54725")]
-impl PartialEq for SourceFile {
-    fn eq(&self, other: &Self) -> bool {
-        self.0.eq(&other.0)
-    }
-}
-
-#[unstable(feature = "proc_macro_span", issue = "54725")]
-impl Eq for SourceFile {}
-
 /// A single token or a delimited sequence of token trees (e.g., `[1, (), ..]`).
 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
 #[derive(Clone)]
diff --git a/src/tools/rust-analyzer/crates/proc-macro-srv/src/server_impl/rust_analyzer_span.rs b/src/tools/rust-analyzer/crates/proc-macro-srv/src/server_impl/rust_analyzer_span.rs
index 59293ee3f9659..80f6d85a3d05c 100644
--- a/src/tools/rust-analyzer/crates/proc-macro-srv/src/server_impl/rust_analyzer_span.rs
+++ b/src/tools/rust-analyzer/crates/proc-macro-srv/src/server_impl/rust_analyzer_span.rs
@@ -11,7 +11,7 @@ use std::{
 
 use intern::Symbol;
 use proc_macro::bridge::{self, server};
-use span::{FileId, Span, FIXUP_ERASED_FILE_AST_ID_MARKER};
+use span::{Span, FIXUP_ERASED_FILE_AST_ID_MARKER};
 use tt::{TextRange, TextSize};
 
 use crate::server_impl::{literal_kind_to_internal, token_stream::TokenStreamBuilder, TopSubtree};
@@ -27,10 +27,6 @@ mod tt {
 
 type TokenStream = crate::server_impl::TokenStream<Span>;
 
-#[derive(Copy, Clone, PartialEq, Eq, Debug)]
-pub struct SourceFile {
-    file_id: FileId,
-}
 pub struct FreeFunctions;
 
 pub struct RaSpanServer {
@@ -46,7 +42,6 @@ pub struct RaSpanServer {
 impl server::Types for RaSpanServer {
     type FreeFunctions = FreeFunctions;
     type TokenStream = TokenStream;
-    type SourceFile = SourceFile;
     type Span = Span;
     type Symbol = Symbol;
 }
@@ -245,25 +240,17 @@ impl server::TokenStream for RaSpanServer {
     }
 }
 
-impl server::SourceFile for RaSpanServer {
-    fn eq(&mut self, file1: &Self::SourceFile, file2: &Self::SourceFile) -> bool {
-        file1 == file2
-    }
-    fn path(&mut self, _file: &Self::SourceFile) -> String {
-        // FIXME
-        String::new()
-    }
-    fn is_real(&mut self, _file: &Self::SourceFile) -> bool {
-        true
-    }
-}
-
 impl server::Span for RaSpanServer {
     fn debug(&mut self, span: Self::Span) -> String {
         format!("{:?}", span)
     }
-    fn source_file(&mut self, span: Self::Span) -> Self::SourceFile {
-        SourceFile { file_id: span.anchor.file_id.file_id() }
+    fn file(&mut self, _: Self::Span) -> String {
+        // FIXME
+        String::new()
+    }
+    fn local_file(&mut self, _: Self::Span) -> Option<String> {
+        // FIXME
+        None
     }
     fn save_span(&mut self, _span: Self::Span) -> usize {
         // FIXME, quote is incompatible with third-party tools
diff --git a/src/tools/rust-analyzer/crates/proc-macro-srv/src/server_impl/token_id.rs b/src/tools/rust-analyzer/crates/proc-macro-srv/src/server_impl/token_id.rs
index 409cf3cc78134..4d7c7c46766b0 100644
--- a/src/tools/rust-analyzer/crates/proc-macro-srv/src/server_impl/token_id.rs
+++ b/src/tools/rust-analyzer/crates/proc-macro-srv/src/server_impl/token_id.rs
@@ -24,8 +24,6 @@ type Literal = tt::Literal;
 type Span = tt::TokenId;
 type TokenStream = crate::server_impl::TokenStream<Span>;
 
-#[derive(Clone)]
-pub struct SourceFile;
 pub struct FreeFunctions;
 
 pub struct TokenIdServer {
@@ -37,7 +35,6 @@ pub struct TokenIdServer {
 impl server::Types for TokenIdServer {
     type FreeFunctions = FreeFunctions;
     type TokenStream = TokenStream;
-    type SourceFile = SourceFile;
     type Span = Span;
     type Symbol = Symbol;
 }
@@ -223,24 +220,15 @@ impl server::TokenStream for TokenIdServer {
     }
 }
 
-impl server::SourceFile for TokenIdServer {
-    fn eq(&mut self, _file1: &Self::SourceFile, _file2: &Self::SourceFile) -> bool {
-        true
-    }
-    fn path(&mut self, _file: &Self::SourceFile) -> String {
-        String::new()
-    }
-    fn is_real(&mut self, _file: &Self::SourceFile) -> bool {
-        true
-    }
-}
-
 impl server::Span for TokenIdServer {
     fn debug(&mut self, span: Self::Span) -> String {
         format!("{:?}", span.0)
     }
-    fn source_file(&mut self, _span: Self::Span) -> Self::SourceFile {
-        SourceFile {}
+    fn file(&mut self, _span: Self::Span) -> String {
+        String::new()
+    }
+    fn local_file(&mut self, _span: Self::Span) -> Option<String> {
+        None
     }
     fn save_span(&mut self, _span: Self::Span) -> usize {
         0
diff --git a/tests/ui-fulldeps/stable-mir/check_abi.rs b/tests/ui-fulldeps/stable-mir/check_abi.rs
index ef2d5b4854bef..ebf2e333f085a 100644
--- a/tests/ui-fulldeps/stable-mir/check_abi.rs
+++ b/tests/ui-fulldeps/stable-mir/check_abi.rs
@@ -17,7 +17,6 @@ extern crate rustc_driver;
 extern crate rustc_interface;
 extern crate stable_mir;
 
-use rustc_smir::rustc_internal;
 use stable_mir::abi::{
     ArgAbi, CallConvention, FieldsShape, IntegerLength, PassMode, Primitive, Scalar, ValueAbi,
     VariantsShape,
diff --git a/tests/ui-fulldeps/stable-mir/check_allocation.rs b/tests/ui-fulldeps/stable-mir/check_allocation.rs
index c102f86a2286b..ae2609bbc1221 100644
--- a/tests/ui-fulldeps/stable-mir/check_allocation.rs
+++ b/tests/ui-fulldeps/stable-mir/check_allocation.rs
@@ -19,7 +19,6 @@ extern crate rustc_driver;
 extern crate rustc_interface;
 extern crate stable_mir;
 
-use rustc_smir::rustc_internal;
 use stable_mir::crate_def::CrateDef;
 use stable_mir::mir::alloc::GlobalAlloc;
 use stable_mir::mir::mono::{Instance, InstanceKind, StaticDef};
diff --git a/tests/ui-fulldeps/stable-mir/check_assoc_items.rs b/tests/ui-fulldeps/stable-mir/check_assoc_items.rs
index f75113676750e..9d611543b5aa7 100644
--- a/tests/ui-fulldeps/stable-mir/check_assoc_items.rs
+++ b/tests/ui-fulldeps/stable-mir/check_assoc_items.rs
@@ -17,7 +17,6 @@ extern crate rustc_driver;
 extern crate rustc_interface;
 extern crate stable_mir;
 
-use rustc_smir::rustc_internal;
 use std::io::Write;
 use std::collections::HashSet;
 use stable_mir::CrateDef;
diff --git a/tests/ui-fulldeps/stable-mir/check_attribute.rs b/tests/ui-fulldeps/stable-mir/check_attribute.rs
index de5ba15f6ea4e..4148fc0cb6a07 100644
--- a/tests/ui-fulldeps/stable-mir/check_attribute.rs
+++ b/tests/ui-fulldeps/stable-mir/check_attribute.rs
@@ -15,7 +15,6 @@ extern crate rustc_driver;
 extern crate rustc_interface;
 extern crate stable_mir;
 
-use rustc_smir::rustc_internal;
 use stable_mir::{CrateDef, CrateItems};
 use std::io::Write;
 use std::ops::ControlFlow;
diff --git a/tests/ui-fulldeps/stable-mir/check_binop.rs b/tests/ui-fulldeps/stable-mir/check_binop.rs
index 65b3ffd27ab05..6a141e9c5775c 100644
--- a/tests/ui-fulldeps/stable-mir/check_binop.rs
+++ b/tests/ui-fulldeps/stable-mir/check_binop.rs
@@ -15,7 +15,6 @@ extern crate rustc_driver;
 extern crate rustc_interface;
 extern crate stable_mir;
 
-use rustc_smir::rustc_internal;
 use stable_mir::mir::mono::Instance;
 use stable_mir::mir::visit::{Location, MirVisitor};
 use stable_mir::mir::{LocalDecl, Rvalue, Statement, StatementKind, Terminator, TerminatorKind};
diff --git a/tests/ui-fulldeps/stable-mir/check_crate_defs.rs b/tests/ui-fulldeps/stable-mir/check_crate_defs.rs
index 71cca94c34f62..31c47192d090f 100644
--- a/tests/ui-fulldeps/stable-mir/check_crate_defs.rs
+++ b/tests/ui-fulldeps/stable-mir/check_crate_defs.rs
@@ -16,7 +16,6 @@ extern crate rustc_driver;
 extern crate rustc_interface;
 extern crate stable_mir;
 
-use rustc_smir::rustc_internal;
 use stable_mir::CrateDef;
 use std::collections::HashSet;
 use std::io::Write;
diff --git a/tests/ui-fulldeps/stable-mir/check_def_ty.rs b/tests/ui-fulldeps/stable-mir/check_def_ty.rs
index 37b9a83e33e76..00a34f138673b 100644
--- a/tests/ui-fulldeps/stable-mir/check_def_ty.rs
+++ b/tests/ui-fulldeps/stable-mir/check_def_ty.rs
@@ -17,7 +17,6 @@ extern crate rustc_driver;
 extern crate rustc_interface;
 extern crate stable_mir;
 
-use rustc_smir::rustc_internal;
 use stable_mir::ty::{Ty, ForeignItemKind};
 use stable_mir::*;
 use std::io::Write;
diff --git a/tests/ui-fulldeps/stable-mir/check_defs.rs b/tests/ui-fulldeps/stable-mir/check_defs.rs
index cd3d76d876012..1ba73377d6e9f 100644
--- a/tests/ui-fulldeps/stable-mir/check_defs.rs
+++ b/tests/ui-fulldeps/stable-mir/check_defs.rs
@@ -19,7 +19,6 @@ extern crate stable_mir;
 use std::assert_matches::assert_matches;
 use mir::{mono::Instance, TerminatorKind::*};
 use stable_mir::mir::mono::InstanceKind;
-use rustc_smir::rustc_internal;
 use stable_mir::ty::{RigidTy, TyKind, Ty, UintTy};
 use stable_mir::*;
 use std::io::Write;
diff --git a/tests/ui-fulldeps/stable-mir/check_foreign.rs b/tests/ui-fulldeps/stable-mir/check_foreign.rs
index bc3956b309088..4419050ceb2c1 100644
--- a/tests/ui-fulldeps/stable-mir/check_foreign.rs
+++ b/tests/ui-fulldeps/stable-mir/check_foreign.rs
@@ -17,7 +17,6 @@ extern crate rustc_interface;
 extern crate rustc_span;
 extern crate stable_mir;
 
-use rustc_smir::rustc_internal;
 use stable_mir::{
     ty::{Abi, ForeignItemKind},
     *,
diff --git a/tests/ui-fulldeps/stable-mir/check_instance.rs b/tests/ui-fulldeps/stable-mir/check_instance.rs
index 72a138f907e72..1510a622cdfdb 100644
--- a/tests/ui-fulldeps/stable-mir/check_instance.rs
+++ b/tests/ui-fulldeps/stable-mir/check_instance.rs
@@ -21,7 +21,6 @@ use std::ops::ControlFlow;
 
 use mir::mono::Instance;
 use mir::TerminatorKind::*;
-use rustc_smir::rustc_internal;
 use stable_mir::ty::{RigidTy, TyKind};
 use stable_mir::*;
 
diff --git a/tests/ui-fulldeps/stable-mir/check_intrinsics.rs b/tests/ui-fulldeps/stable-mir/check_intrinsics.rs
index 07a2a62e06687..3f04abbb9d76d 100644
--- a/tests/ui-fulldeps/stable-mir/check_intrinsics.rs
+++ b/tests/ui-fulldeps/stable-mir/check_intrinsics.rs
@@ -20,7 +20,6 @@ extern crate rustc_driver;
 extern crate rustc_interface;
 extern crate stable_mir;
 
-use rustc_smir::rustc_internal;
 use stable_mir::mir::mono::{Instance, InstanceKind};
 use stable_mir::mir::visit::{Location, MirVisitor};
 use stable_mir::mir::{LocalDecl, Terminator, TerminatorKind};
diff --git a/tests/ui-fulldeps/stable-mir/check_item_kind.rs b/tests/ui-fulldeps/stable-mir/check_item_kind.rs
index 647ce534589e1..bb8c00c64c955 100644
--- a/tests/ui-fulldeps/stable-mir/check_item_kind.rs
+++ b/tests/ui-fulldeps/stable-mir/check_item_kind.rs
@@ -16,7 +16,6 @@ extern crate rustc_driver;
 extern crate rustc_interface;
 extern crate stable_mir;
 
-use rustc_smir::rustc_internal;
 use stable_mir::*;
 use std::io::Write;
 use std::ops::ControlFlow;
diff --git a/tests/ui-fulldeps/stable-mir/check_normalization.rs b/tests/ui-fulldeps/stable-mir/check_normalization.rs
index de14202adb9c0..797cb4cd5d051 100644
--- a/tests/ui-fulldeps/stable-mir/check_normalization.rs
+++ b/tests/ui-fulldeps/stable-mir/check_normalization.rs
@@ -17,7 +17,6 @@ extern crate stable_mir;
 
 use mir::mono::Instance;
 use ty::{Ty, TyKind, RigidTy};
-use rustc_smir::rustc_internal;
 use stable_mir::*;
 use std::io::Write;
 use std::ops::ControlFlow;
diff --git a/tests/ui-fulldeps/stable-mir/check_trait_queries.rs b/tests/ui-fulldeps/stable-mir/check_trait_queries.rs
index 23c2844d3f166..d9170d0c40811 100644
--- a/tests/ui-fulldeps/stable-mir/check_trait_queries.rs
+++ b/tests/ui-fulldeps/stable-mir/check_trait_queries.rs
@@ -16,7 +16,6 @@ extern crate rustc_driver;
 extern crate rustc_interface;
 extern crate stable_mir;
 
-use rustc_smir::rustc_internal;
 use stable_mir::CrateDef;
 use std::collections::HashSet;
 use std::io::Write;
diff --git a/tests/ui-fulldeps/stable-mir/check_transform.rs b/tests/ui-fulldeps/stable-mir/check_transform.rs
index d9fc924933fa8..604cc72c3418e 100644
--- a/tests/ui-fulldeps/stable-mir/check_transform.rs
+++ b/tests/ui-fulldeps/stable-mir/check_transform.rs
@@ -17,7 +17,6 @@ extern crate rustc_driver;
 extern crate rustc_interface;
 extern crate stable_mir;
 
-use rustc_smir::rustc_internal;
 use stable_mir::mir::alloc::GlobalAlloc;
 use stable_mir::mir::mono::Instance;
 use stable_mir::mir::{Body, ConstOperand, Operand, Rvalue, StatementKind, TerminatorKind};
diff --git a/tests/ui-fulldeps/stable-mir/check_ty_fold.rs b/tests/ui-fulldeps/stable-mir/check_ty_fold.rs
index 9d71697178e58..23233f8406cf5 100644
--- a/tests/ui-fulldeps/stable-mir/check_ty_fold.rs
+++ b/tests/ui-fulldeps/stable-mir/check_ty_fold.rs
@@ -17,7 +17,6 @@ extern crate rustc_driver;
 extern crate rustc_interface;
 extern crate stable_mir;
 
-use rustc_smir::rustc_internal;
 use stable_mir::mir::{
     Body, FieldIdx, MirVisitor, Place, ProjectionElem,
     visit::{Location, PlaceContext},
diff --git a/tests/ui-fulldeps/stable-mir/compilation-result.rs b/tests/ui-fulldeps/stable-mir/compilation-result.rs
index b8a9e720e5465..39416636fd673 100644
--- a/tests/ui-fulldeps/stable-mir/compilation-result.rs
+++ b/tests/ui-fulldeps/stable-mir/compilation-result.rs
@@ -16,7 +16,6 @@ extern crate rustc_driver;
 extern crate rustc_interface;
 extern crate stable_mir;
 
-use rustc_smir::rustc_internal;
 use std::io::Write;
 
 /// This test will generate and analyze a dummy crate using the stable mir.
diff --git a/tests/ui-fulldeps/stable-mir/crate-info.rs b/tests/ui-fulldeps/stable-mir/crate-info.rs
index 4d2d7e26276b5..e2086d5e57907 100644
--- a/tests/ui-fulldeps/stable-mir/crate-info.rs
+++ b/tests/ui-fulldeps/stable-mir/crate-info.rs
@@ -18,7 +18,6 @@ extern crate rustc_interface;
 extern crate stable_mir;
 
 use rustc_hir::def::DefKind;
-use rustc_smir::rustc_internal;
 use stable_mir::ItemKind;
 use stable_mir::crate_def::CrateDef;
 use stable_mir::mir::mono::Instance;
diff --git a/tests/ui-fulldeps/stable-mir/projections.rs b/tests/ui-fulldeps/stable-mir/projections.rs
index 6f82eba61fcea..f3bd894ac6903 100644
--- a/tests/ui-fulldeps/stable-mir/projections.rs
+++ b/tests/ui-fulldeps/stable-mir/projections.rs
@@ -17,7 +17,6 @@ extern crate rustc_driver;
 extern crate rustc_interface;
 extern crate stable_mir;
 
-use rustc_smir::rustc_internal;
 use stable_mir::ItemKind;
 use stable_mir::crate_def::CrateDef;
 use stable_mir::mir::{ProjectionElem, Rvalue, StatementKind};
diff --git a/tests/ui-fulldeps/stable-mir/smir_serde.rs b/tests/ui-fulldeps/stable-mir/smir_serde.rs
index 9b3638a9f2f40..3b3d743ad3263 100644
--- a/tests/ui-fulldeps/stable-mir/smir_serde.rs
+++ b/tests/ui-fulldeps/stable-mir/smir_serde.rs
@@ -19,7 +19,6 @@ extern crate serde_json;
 extern crate stable_mir;
 
 use rustc_middle::ty::TyCtxt;
-use rustc_smir::rustc_internal;
 use serde_json::to_string;
 use stable_mir::mir::Body;
 use std::io::{BufWriter, Write};
diff --git a/tests/ui-fulldeps/stable-mir/smir_visitor.rs b/tests/ui-fulldeps/stable-mir/smir_visitor.rs
index 0a579a07cef16..d225d9773fe51 100644
--- a/tests/ui-fulldeps/stable-mir/smir_visitor.rs
+++ b/tests/ui-fulldeps/stable-mir/smir_visitor.rs
@@ -16,7 +16,6 @@ extern crate rustc_driver;
 extern crate rustc_interface;
 extern crate stable_mir;
 
-use rustc_smir::rustc_internal;
 use stable_mir::mir::MirVisitor;
 use stable_mir::mir::MutMirVisitor;
 use stable_mir::*;
diff --git a/tests/ui/asm/naked-functions-rustic-abi.rs b/tests/ui/asm/naked-functions-rustic-abi.rs
new file mode 100644
index 0000000000000..b654d38ccc1a6
--- /dev/null
+++ b/tests/ui/asm/naked-functions-rustic-abi.rs
@@ -0,0 +1,27 @@
+//@ revisions: x86_64 aarch64
+//
+//@[aarch64] only-aarch64
+//@[x86_64] only-x86_64
+//
+//@ build-pass
+//@ needs-asm-support
+
+#![feature(naked_functions, naked_functions_rustic_abi, rust_cold_cc)]
+#![crate_type = "lib"]
+
+use std::arch::{asm, naked_asm};
+
+#[naked]
+pub unsafe fn rust_implicit() {
+    naked_asm!("ret");
+}
+
+#[naked]
+pub unsafe extern "Rust" fn rust_explicit() {
+    naked_asm!("ret");
+}
+
+#[naked]
+pub unsafe extern "rust-cold" fn rust_cold() {
+    naked_asm!("ret");
+}
diff --git a/tests/ui/asm/naked-functions-testattrs.rs b/tests/ui/asm/naked-functions-testattrs.rs
index 7e373270e9fc6..ad31876a77a59 100644
--- a/tests/ui/asm/naked-functions-testattrs.rs
+++ b/tests/ui/asm/naked-functions-testattrs.rs
@@ -1,7 +1,6 @@
 //@ needs-asm-support
 //@ compile-flags: --test
 
-#![allow(undefined_naked_function_abi)]
 #![feature(naked_functions)]
 #![feature(test)]
 #![crate_type = "lib"]
@@ -11,7 +10,7 @@ use std::arch::naked_asm;
 #[test]
 #[naked]
 //~^ ERROR [E0736]
-fn test_naked() {
+extern "C" fn test_naked() {
     unsafe { naked_asm!("") };
 }
 
@@ -19,7 +18,7 @@ fn test_naked() {
 #[test]
 #[naked]
 //~^ ERROR [E0736]
-fn test_naked_should_panic() {
+extern "C" fn test_naked_should_panic() {
     unsafe { naked_asm!("") };
 }
 
@@ -27,13 +26,13 @@ fn test_naked_should_panic() {
 #[test]
 #[naked]
 //~^ ERROR [E0736]
-fn test_naked_ignore() {
+extern "C" fn test_naked_ignore() {
     unsafe { naked_asm!("") };
 }
 
 #[bench]
 #[naked]
 //~^ ERROR [E0736]
-fn bench_naked() {
+extern "C" fn bench_naked() {
     unsafe { naked_asm!("") };
 }
diff --git a/tests/ui/asm/naked-functions-testattrs.stderr b/tests/ui/asm/naked-functions-testattrs.stderr
index 4dabe41964a57..0f0bb91b95413 100644
--- a/tests/ui/asm/naked-functions-testattrs.stderr
+++ b/tests/ui/asm/naked-functions-testattrs.stderr
@@ -1,5 +1,5 @@
 error[E0736]: cannot use `#[naked]` with testing attributes
-  --> $DIR/naked-functions-testattrs.rs:12:1
+  --> $DIR/naked-functions-testattrs.rs:11:1
    |
 LL | #[test]
    | ------- function marked with testing attribute here
@@ -7,7 +7,7 @@ LL | #[naked]
    | ^^^^^^^^ `#[naked]` is incompatible with testing attributes
 
 error[E0736]: cannot use `#[naked]` with testing attributes
-  --> $DIR/naked-functions-testattrs.rs:20:1
+  --> $DIR/naked-functions-testattrs.rs:19:1
    |
 LL | #[test]
    | ------- function marked with testing attribute here
@@ -15,7 +15,7 @@ LL | #[naked]
    | ^^^^^^^^ `#[naked]` is incompatible with testing attributes
 
 error[E0736]: cannot use `#[naked]` with testing attributes
-  --> $DIR/naked-functions-testattrs.rs:28:1
+  --> $DIR/naked-functions-testattrs.rs:27:1
    |
 LL | #[test]
    | ------- function marked with testing attribute here
@@ -23,7 +23,7 @@ LL | #[naked]
    | ^^^^^^^^ `#[naked]` is incompatible with testing attributes
 
 error[E0736]: cannot use `#[naked]` with testing attributes
-  --> $DIR/naked-functions-testattrs.rs:35:1
+  --> $DIR/naked-functions-testattrs.rs:34:1
    |
 LL | #[bench]
    | -------- function marked with testing attribute here
diff --git a/tests/ui/asm/naked-functions.rs b/tests/ui/asm/naked-functions.rs
index 3d4d414539c16..5bf2e2a3abd06 100644
--- a/tests/ui/asm/naked-functions.rs
+++ b/tests/ui/asm/naked-functions.rs
@@ -122,18 +122,6 @@ unsafe extern "C" fn invalid_may_unwind() {
     //~^ ERROR the `may_unwind` option cannot be used with `naked_asm!`
 }
 
-#[naked]
-pub unsafe fn default_abi() {
-    //~^ WARN Rust ABI is unsupported in naked functions
-    naked_asm!("");
-}
-
-#[naked]
-pub unsafe fn rust_abi() {
-    //~^ WARN Rust ABI is unsupported in naked functions
-    naked_asm!("");
-}
-
 #[naked]
 pub extern "C" fn valid_a<T>() -> T {
     unsafe {
diff --git a/tests/ui/asm/naked-functions.stderr b/tests/ui/asm/naked-functions.stderr
index 0898f3620f24f..0a55bb9cd8370 100644
--- a/tests/ui/asm/naked-functions.stderr
+++ b/tests/ui/asm/naked-functions.stderr
@@ -53,19 +53,19 @@ LL |     naked_asm!("", options(may_unwind));
    |                            ^^^^^^^^^^ the `may_unwind` option is not meaningful for global-scoped inline assembly
 
 error: this is a user specified error
-  --> $DIR/naked-functions.rs:169:5
+  --> $DIR/naked-functions.rs:157:5
    |
 LL |     compile_error!("this is a user specified error")
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this is a user specified error
-  --> $DIR/naked-functions.rs:175:5
+  --> $DIR/naked-functions.rs:163:5
    |
 LL |     compile_error!("this is a user specified error");
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: asm template must be a string literal
-  --> $DIR/naked-functions.rs:182:16
+  --> $DIR/naked-functions.rs:170:16
    |
 LL |     naked_asm!(invalid_syntax)
    |                ^^^^^^^^^^^^^^
@@ -175,20 +175,6 @@ LL |
 LL |         *&y
    |         --- not allowed in naked functions
 
-warning: Rust ABI is unsupported in naked functions
-  --> $DIR/naked-functions.rs:126:1
-   |
-LL | pub unsafe fn default_abi() {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[warn(undefined_naked_function_abi)]` on by default
-
-warning: Rust ABI is unsupported in naked functions
-  --> $DIR/naked-functions.rs:132:1
-   |
-LL | pub unsafe fn rust_abi() {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: aborting due to 25 previous errors; 2 warnings emitted
+error: aborting due to 25 previous errors
 
 For more information about this error, try `rustc --explain E0787`.
diff --git a/tests/ui/cast/cast-array-issue-138836.rs b/tests/ui/cast/cast-array-issue-138836.rs
new file mode 100644
index 0000000000000..3f8098e76fd29
--- /dev/null
+++ b/tests/ui/cast/cast-array-issue-138836.rs
@@ -0,0 +1,5 @@
+fn main() {
+    let a: [u8; 3] = [1,2,3];
+    let b = &a;
+    let c = b as *const [u32; 3]; //~ ERROR casting `&[u8; 3]` as `*const [u32; 3]` is invalid
+}
diff --git a/tests/ui/cast/cast-array-issue-138836.stderr b/tests/ui/cast/cast-array-issue-138836.stderr
new file mode 100644
index 0000000000000..309474c29f933
--- /dev/null
+++ b/tests/ui/cast/cast-array-issue-138836.stderr
@@ -0,0 +1,9 @@
+error[E0606]: casting `&[u8; 3]` as `*const [u32; 3]` is invalid
+  --> $DIR/cast-array-issue-138836.rs:4:13
+   |
+LL |     let c = b as *const [u32; 3];
+   |             ^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0606`.
diff --git a/tests/ui/consts/const-cast-wrong-type.rs b/tests/ui/consts/const-cast-wrong-type.rs
index 6e055a2bcd340..9936a660936b0 100644
--- a/tests/ui/consts/const-cast-wrong-type.rs
+++ b/tests/ui/consts/const-cast-wrong-type.rs
@@ -1,5 +1,5 @@
 const a: [u8; 3] = ['h' as u8, 'i' as u8, 0 as u8];
-const b: *const i8 = &a as *const i8; //~ ERROR mismatched types
+const b: *const i8 = &a as *const i8; //~ ERROR casting `&[u8; 3]` as `*const i8` is invalid
 
 fn main() {
 }
diff --git a/tests/ui/consts/const-cast-wrong-type.stderr b/tests/ui/consts/const-cast-wrong-type.stderr
index 44361f15d8a98..0730bac22354d 100644
--- a/tests/ui/consts/const-cast-wrong-type.stderr
+++ b/tests/ui/consts/const-cast-wrong-type.stderr
@@ -1,9 +1,9 @@
-error[E0308]: mismatched types
+error[E0606]: casting `&[u8; 3]` as `*const i8` is invalid
   --> $DIR/const-cast-wrong-type.rs:2:22
    |
 LL | const b: *const i8 = &a as *const i8;
-   |                      ^^^^^^^^^^^^^^^ expected `u8`, found `i8`
+   |                      ^^^^^^^^^^^^^^^
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0308`.
+For more information about this error, try `rustc --explain E0606`.
diff --git a/tests/crashes/137287.rs b/tests/ui/drop/drop_elaboration_with_errors2.rs
similarity index 68%
rename from tests/crashes/137287.rs
rename to tests/ui/drop/drop_elaboration_with_errors2.rs
index 59fdf568d3680..946c253179cb8 100644
--- a/tests/crashes/137287.rs
+++ b/tests/ui/drop/drop_elaboration_with_errors2.rs
@@ -1,11 +1,14 @@
-//@ known-bug: #137287
+// Regression test for #137287
 
 mod defining_scope {
     use super::*;
     pub type Alias<T> = impl Sized;
+    //~^ ERROR unconstrained opaque type
+    //~| ERROR `impl Trait` in type aliases is unstable
 
     pub fn cast<T>(x: Container<Alias<T>, T>) -> Container<T, T> {
         x
+        //~^ ERROR mismatched types
     }
 }
 
@@ -21,6 +24,7 @@ impl<T> Trait<T> for T {
     type Assoc = Box<u32>;
 }
 impl<T> Trait<T> for defining_scope::Alias<T> {
+    //~^ ERROR conflicting implementations of trait `Trait<_>`
     type Assoc = usize;
 }
 
diff --git a/tests/ui/drop/drop_elaboration_with_errors2.stderr b/tests/ui/drop/drop_elaboration_with_errors2.stderr
new file mode 100644
index 0000000000000..15fe3f6ecc1f4
--- /dev/null
+++ b/tests/ui/drop/drop_elaboration_with_errors2.stderr
@@ -0,0 +1,47 @@
+error[E0658]: `impl Trait` in type aliases is unstable
+  --> $DIR/drop_elaboration_with_errors2.rs:5:25
+   |
+LL |     pub type Alias<T> = impl Sized;
+   |                         ^^^^^^^^^^
+   |
+   = note: see issue #63063 <https://github.com/rust-lang/rust/issues/63063> for more information
+   = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error[E0119]: conflicting implementations of trait `Trait<_>`
+  --> $DIR/drop_elaboration_with_errors2.rs:26:1
+   |
+LL | impl<T> Trait<T> for T {
+   | ---------------------- first implementation here
+...
+LL | impl<T> Trait<T> for defining_scope::Alias<T> {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation
+
+error: unconstrained opaque type
+  --> $DIR/drop_elaboration_with_errors2.rs:5:25
+   |
+LL |     pub type Alias<T> = impl Sized;
+   |                         ^^^^^^^^^^
+   |
+   = note: `Alias` must be used in combination with a concrete type within the same crate
+
+error[E0308]: mismatched types
+  --> $DIR/drop_elaboration_with_errors2.rs:10:9
+   |
+LL |     pub type Alias<T> = impl Sized;
+   |                         ---------- the found opaque type
+...
+LL |     pub fn cast<T>(x: Container<Alias<T>, T>) -> Container<T, T> {
+   |                 - expected this type parameter   --------------- expected `Container<T, T>` because of return type
+LL |         x
+   |         ^ expected `Container<T, T>`, found `Container<Alias<T>, T>`
+   |
+   = note: expected struct `Container<T, _>`
+              found struct `Container<Alias<T>, _>`
+   = help: type parameters must be constrained to match other types
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0119, E0308, E0658.
+For more information about an error, try `rustc --explain E0119`.
diff --git a/tests/crashes/135668.rs b/tests/ui/drop/drop_elaboration_with_errors3.rs
similarity index 87%
rename from tests/crashes/135668.rs
rename to tests/ui/drop/drop_elaboration_with_errors3.rs
index 00d7b5db0c679..c5ed63eb7ac2b 100644
--- a/tests/crashes/135668.rs
+++ b/tests/ui/drop/drop_elaboration_with_errors3.rs
@@ -1,5 +1,6 @@
-//@ known-bug: #135668
+// Regression test for #135668
 //@ edition: 2021
+
 use std::future::Future;
 
 pub async fn foo() {
@@ -11,7 +12,8 @@ async fn create_task() -> impl Sized {
 }
 
 async fn documentation() {
-    include_str!("nonexistent");
+    compile_error!("bonjour");
+    //~^ ERROR bonjour
 }
 
 fn bind<F>(_filter: F) -> impl Sized
@@ -36,3 +38,5 @@ where
 {
     type Assoc = F;
 }
+
+fn main() {}
diff --git a/tests/ui/drop/drop_elaboration_with_errors3.stderr b/tests/ui/drop/drop_elaboration_with_errors3.stderr
new file mode 100644
index 0000000000000..2d44e7c662597
--- /dev/null
+++ b/tests/ui/drop/drop_elaboration_with_errors3.stderr
@@ -0,0 +1,8 @@
+error: bonjour
+  --> $DIR/drop_elaboration_with_errors3.rs:15:5
+   |
+LL |     compile_error!("bonjour");
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
diff --git a/tests/ui/feature-gates/feature-gate-naked_functions_rustic_abi.rs b/tests/ui/feature-gates/feature-gate-naked_functions_rustic_abi.rs
new file mode 100644
index 0000000000000..c91d833994414
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-naked_functions_rustic_abi.rs
@@ -0,0 +1,26 @@
+//@ needs-asm-support
+//@ only-x86_64
+
+#![feature(naked_functions, rust_cold_cc)]
+
+use std::arch::naked_asm;
+
+#[naked]
+pub unsafe fn rust_implicit() {
+    //~^ ERROR `#[naked]` is currently unstable on `extern "Rust"` functions
+    naked_asm!("ret");
+}
+
+#[naked]
+pub unsafe extern "Rust" fn rust_explicit() {
+    //~^ ERROR `#[naked]` is currently unstable on `extern "Rust"` functions
+    naked_asm!("ret");
+}
+
+#[naked]
+pub unsafe extern "rust-cold" fn rust_cold() {
+    //~^ ERROR `#[naked]` is currently unstable on `extern "rust-cold"` functions
+    naked_asm!("ret");
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-naked_functions_rustic_abi.stderr b/tests/ui/feature-gates/feature-gate-naked_functions_rustic_abi.stderr
new file mode 100644
index 0000000000000..ba45e15ec86b6
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-naked_functions_rustic_abi.stderr
@@ -0,0 +1,33 @@
+error[E0658]: `#[naked]` is currently unstable on `extern "Rust"` functions
+  --> $DIR/feature-gate-naked_functions_rustic_abi.rs:9:1
+   |
+LL | pub unsafe fn rust_implicit() {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #138997 <https://github.com/rust-lang/rust/issues/138997> for more information
+   = help: add `#![feature(naked_functions_rustic_abi)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error[E0658]: `#[naked]` is currently unstable on `extern "Rust"` functions
+  --> $DIR/feature-gate-naked_functions_rustic_abi.rs:15:1
+   |
+LL | pub unsafe extern "Rust" fn rust_explicit() {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #138997 <https://github.com/rust-lang/rust/issues/138997> for more information
+   = help: add `#![feature(naked_functions_rustic_abi)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error[E0658]: `#[naked]` is currently unstable on `extern "rust-cold"` functions
+  --> $DIR/feature-gate-naked_functions_rustic_abi.rs:21:1
+   |
+LL | pub unsafe extern "rust-cold" fn rust_cold() {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #138997 <https://github.com/rust-lang/rust/issues/138997> for more information
+   = help: add `#![feature(naked_functions_rustic_abi)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/lint/dead-code/self-assign.rs b/tests/ui/lint/dead-code/self-assign.rs
index 072a899e1bdb1..357846baf2212 100644
--- a/tests/ui/lint/dead-code/self-assign.rs
+++ b/tests/ui/lint/dead-code/self-assign.rs
@@ -1,19 +1,29 @@
-// Test that dead code warnings are issued for superfluous assignments of
-// fields or variables to themselves (issue #75356).
-
-//@ ignore-test FIXME(81658, 83171)
+//! Test that dead code warnings are issued for superfluous assignments of fields or variables to
+//! themselves (issue #75356).
+//!
+//! # History of this test (to aid relanding of a fixed version of #81473)
+//!
+//! - Original lint request was about self-assignments not triggering sth like `dead_code`.
+//! - `dead_code` lint expansion for self-assignments was implemented in #87129.
+//! - Unfortunately implementation components of #87129 had to be disabled as part of reverts
+//!   #86212, #83171 (to revert #81473) to address regressions #81626 and #81658.
+//! - Consequently, none of the following warnings are emitted.
 
 //@ check-pass
+
+// Implementation of self-assignment `dead_code` lint expansions disabled due to reverts.
+//@ known-bug: #75356
+
 #![allow(unused_assignments)]
 #![warn(dead_code)]
 
 fn main() {
     let mut x = 0;
     x = x;
-    //~^ WARNING: useless assignment of variable of type `i32` to itself
+    // FIXME ~^ WARNING: useless assignment of variable of type `i32` to itself
 
     x = (x);
-    //~^ WARNING: useless assignment of variable of type `i32` to itself
+    // FIXME ~^ WARNING: useless assignment of variable of type `i32` to itself
 
     x = {x};
     // block expressions don't count as self-assignments
@@ -22,10 +32,10 @@ fn main() {
     struct S<'a> { f: &'a str }
     let mut s = S { f: "abc" };
     s = s;
-    //~^ WARNING: useless assignment of variable of type `S` to itself
+    // FIXME ~^ WARNING: useless assignment of variable of type `S` to itself
 
     s.f = s.f;
-    //~^ WARNING: useless assignment of field of type `&str` to itself
+    // FIXME ~^ WARNING: useless assignment of field of type `&str` to itself
 
 
     struct N0 { x: Box<i32> }
@@ -34,11 +44,11 @@ fn main() {
     struct N3 { n: N2 };
     let mut n3 = N3 { n: N2(N1 { n: N0 { x: Box::new(42) } }) };
     n3.n.0.n.x = n3.n.0.n.x;
-    //~^ WARNING: useless assignment of field of type `Box<i32>` to itself
+    // FIXME ~^ WARNING: useless assignment of field of type `Box<i32>` to itself
 
     let mut t = (1, ((2, 3, (4, 5)),));
     t.1.0.2.1 = t.1.0.2.1;
-    //~^ WARNING: useless assignment of field of type `i32` to itself
+    // FIXME ~^ WARNING: useless assignment of field of type `i32` to itself
 
 
     let mut y = 0;
diff --git a/tests/ui/lint/dead-code/self-assign.stderr b/tests/ui/lint/dead-code/self-assign.stderr
deleted file mode 100644
index bb79c0ec72a34..0000000000000
--- a/tests/ui/lint/dead-code/self-assign.stderr
+++ /dev/null
@@ -1,44 +0,0 @@
-warning: useless assignment of variable of type `i32` to itself
-  --> $DIR/self-assign.rs:10:5
-   |
-LL |     x = x;
-   |     ^^^^^
-   |
-note: the lint level is defined here
-  --> $DIR/self-assign.rs:6:9
-   |
-LL | #![warn(dead_code)]
-   |         ^^^^^^^^^
-
-warning: useless assignment of variable of type `i32` to itself
-  --> $DIR/self-assign.rs:13:5
-   |
-LL |     x = (x);
-   |     ^^^^^^^
-
-warning: useless assignment of variable of type `S` to itself
-  --> $DIR/self-assign.rs:22:5
-   |
-LL |     s = s;
-   |     ^^^^^
-
-warning: useless assignment of field of type `&str` to itself
-  --> $DIR/self-assign.rs:25:5
-   |
-LL |     s.f = s.f;
-   |     ^^^^^^^^^
-
-warning: useless assignment of field of type `Box<i32>` to itself
-  --> $DIR/self-assign.rs:34:5
-   |
-LL |     n3.n.0.n.x = n3.n.0.n.x;
-   |     ^^^^^^^^^^^^^^^^^^^^^^^
-
-warning: useless assignment of field of type `i32` to itself
-  --> $DIR/self-assign.rs:38:5
-   |
-LL |     t.1.0.2.1 = t.1.0.2.1;
-   |     ^^^^^^^^^^^^^^^^^^^^^
-
-warning: 6 warnings emitted
-
diff --git a/tests/ui/lint/removed-lints/undefined_naked_function_abi.rs b/tests/ui/lint/removed-lints/undefined_naked_function_abi.rs
new file mode 100644
index 0000000000000..cf3ac66ac86d4
--- /dev/null
+++ b/tests/ui/lint/removed-lints/undefined_naked_function_abi.rs
@@ -0,0 +1,5 @@
+//@ check-pass
+
+#![deny(undefined_naked_function_abi)]
+//~^ WARN  lint `undefined_naked_function_abi` has been removed
+fn main() {}
diff --git a/tests/ui/lint/removed-lints/undefined_naked_function_abi.stderr b/tests/ui/lint/removed-lints/undefined_naked_function_abi.stderr
new file mode 100644
index 0000000000000..5a546688beb5c
--- /dev/null
+++ b/tests/ui/lint/removed-lints/undefined_naked_function_abi.stderr
@@ -0,0 +1,10 @@
+warning: lint `undefined_naked_function_abi` has been removed: converted into hard error, see PR #139001 <https://github.com/rust-lang/rust/issues/139001> for more information
+  --> $DIR/undefined_naked_function_abi.rs:3:9
+   |
+LL | #![deny(undefined_naked_function_abi)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(renamed_and_removed_lints)]` on by default
+
+warning: 1 warning emitted
+
diff --git a/tests/ui/macros/remove-repetition-issue-139480.rs b/tests/ui/macros/remove-repetition-issue-139480.rs
new file mode 100644
index 0000000000000..1efb4306763e4
--- /dev/null
+++ b/tests/ui/macros/remove-repetition-issue-139480.rs
@@ -0,0 +1,28 @@
+macro_rules! ciallo {
+    ($($v: vis)? $name: ident) => {
+    //~^ error: repetition matches empty token tree
+    };
+}
+
+macro_rules! meow {
+    ($name: ident $($v: vis)?) => {
+    //~^ error: repetition matches empty token tree
+    };
+}
+
+macro_rules! gbc {
+    ($name: ident $/*
+        this comment gets removed by the suggestion
+        */
+        ($v: vis)?) => {
+    //~^ error: repetition matches empty token tree
+    };
+}
+
+ciallo!(hello);
+
+meow!(miaow, pub);
+
+gbc!(mygo,);
+
+fn main() {}
diff --git a/tests/ui/macros/remove-repetition-issue-139480.stderr b/tests/ui/macros/remove-repetition-issue-139480.stderr
new file mode 100644
index 0000000000000..c2475589ee9ad
--- /dev/null
+++ b/tests/ui/macros/remove-repetition-issue-139480.stderr
@@ -0,0 +1,44 @@
+error: repetition matches empty token tree
+  --> $DIR/remove-repetition-issue-139480.rs:2:7
+   |
+LL |     ($($v: vis)? $name: ident) => {
+   |       ^^^^^^^^^
+   |
+   = note: a `vis` fragment can already be empty
+help: remove the `$(` and `)?`
+   |
+LL -     ($($v: vis)? $name: ident) => {
+LL +     ($v: vis $name: ident) => {
+   |
+
+error: repetition matches empty token tree
+  --> $DIR/remove-repetition-issue-139480.rs:8:20
+   |
+LL |     ($name: ident $($v: vis)?) => {
+   |                    ^^^^^^^^^
+   |
+   = note: a `vis` fragment can already be empty
+help: remove the `$(` and `)?`
+   |
+LL -     ($name: ident $($v: vis)?) => {
+LL +     ($name: ident $v: vis) => {
+   |
+
+error: repetition matches empty token tree
+  --> $DIR/remove-repetition-issue-139480.rs:17:9
+   |
+LL |         ($v: vis)?) => {
+   |         ^^^^^^^^^
+   |
+   = note: a `vis` fragment can already be empty
+help: remove the `$(` and `)?`
+   |
+LL -     ($name: ident $/*
+LL -         this comment gets removed by the suggestion
+LL -         */
+LL -         ($v: vis)?) => {
+LL +     ($name: ident $v: vis) => {
+   |
+
+error: aborting due to 3 previous errors
+
diff --git a/tests/ui/proc-macro/auxiliary/expand-expr.rs b/tests/ui/proc-macro/auxiliary/expand-expr.rs
index 78c9fa75d9ff2..14efc3c6b9f17 100644
--- a/tests/ui/proc-macro/auxiliary/expand-expr.rs
+++ b/tests/ui/proc-macro/auxiliary/expand-expr.rs
@@ -3,9 +3,10 @@
 
 extern crate proc_macro;
 
-use proc_macro::*;
 use std::str::FromStr;
 
+use proc_macro::*;
+
 // Flatten the TokenStream, removing any toplevel `Delimiter::None`s for
 // comparison.
 fn flatten(ts: TokenStream) -> Vec<TokenTree> {
@@ -136,9 +137,8 @@ pub fn check_expand_expr_file(ts: TokenStream) -> TokenStream {
         .to_string();
     assert_eq!(input_t, parse_t);
 
-    // Check that the literal matches `Span::call_site().source_file().path()`
-    let expect_t =
-        Literal::string(&Span::call_site().source_file().path().to_string_lossy()).to_string();
+    // Check that the literal matches `Span::call_site().file()`
+    let expect_t = Literal::string(&Span::call_site().file()).to_string();
     assert_eq!(input_t, expect_t);
 
     TokenStream::new()
diff --git a/tests/ui/proc-macro/auxiliary/macro-only-syntax.rs b/tests/ui/proc-macro/auxiliary/macro-only-syntax.rs
index 4971de284b760..11e1910288eee 100644
--- a/tests/ui/proc-macro/auxiliary/macro-only-syntax.rs
+++ b/tests/ui/proc-macro/auxiliary/macro-only-syntax.rs
@@ -79,7 +79,7 @@ fn check_useful_span(token: TokenTree, expected_filename: &str) {
     let span = token.span();
     assert!(span.column() < span.end().column());
 
-    let source_path = span.source_file().path();
+    let source_path = span.local_file().unwrap();
     let filename = source_path.components().last().unwrap();
     assert_eq!(filename, Component::Normal(expected_filename.as_ref()));
 }
diff --git a/tests/ui/proc-macro/auxiliary/span-api-tests.rs b/tests/ui/proc-macro/auxiliary/span-api-tests.rs
index 99db66ed6a94c..036f2e3ac3f5e 100644
--- a/tests/ui/proc-macro/auxiliary/span-api-tests.rs
+++ b/tests/ui/proc-macro/auxiliary/span-api-tests.rs
@@ -11,20 +11,9 @@ pub fn reemit(input: TokenStream) -> TokenStream {
 }
 
 #[proc_macro]
-pub fn assert_fake_source_file(input: TokenStream) -> TokenStream {
+pub fn assert_local_file(input: TokenStream) -> TokenStream {
     for tk in input {
-        let source_file = tk.span().source_file();
-        assert!(!source_file.is_real(), "Source file is real: {:?}", source_file);
-    }
-
-    "".parse().unwrap()
-}
-
-#[proc_macro]
-pub fn assert_source_file(input: TokenStream) -> TokenStream {
-    for tk in input {
-        let source_file = tk.span().source_file();
-        assert!(source_file.is_real(), "Source file is not real: {:?}", source_file);
+        assert!(tk.span().local_file().is_some(), "No local file for span: {:?}", tk.span());
     }
 
     "".parse().unwrap()
diff --git a/tests/ui/proc-macro/span-api-tests.rs b/tests/ui/proc-macro/span-api-tests.rs
index ac42a7ea611ab..792859ed05b16 100644
--- a/tests/ui/proc-macro/span-api-tests.rs
+++ b/tests/ui/proc-macro/span-api-tests.rs
@@ -8,26 +8,24 @@ extern crate span_test_macros;
 
 extern crate span_api_tests;
 
-// FIXME(69775): Investigate `assert_fake_source_file`.
-
-use span_api_tests::{reemit, assert_source_file, macro_stringify};
+use span_api_tests::{reemit, assert_local_file, macro_stringify};
 
 macro_rules! say_hello {
     ($macname:ident) => ( $macname! { "Hello, world!" })
 }
 
-assert_source_file! { "Hello, world!" }
+assert_local_file! { "Hello, world!" }
 
-say_hello! { assert_source_file }
+say_hello! { assert_local_file }
 
 reemit_legacy! {
-    assert_source_file! { "Hello, world!" }
+    assert_local_file! { "Hello, world!" }
 }
 
-say_hello_extern! { assert_source_file }
+say_hello_extern! { assert_local_file }
 
 reemit! {
-    assert_source_file! { "Hello, world!" }
+    assert_local_file! { "Hello, world!" }
 }
 
 fn main() {
diff --git a/tests/ui/rfcs/rfc-3467-unsafe-pinned/unsafe-pinned-hides-niche.rs b/tests/ui/rfcs/rfc-3467-unsafe-pinned/unsafe-pinned-hides-niche.rs
new file mode 100644
index 0000000000000..a1ff9a1f69fd2
--- /dev/null
+++ b/tests/ui/rfcs/rfc-3467-unsafe-pinned/unsafe-pinned-hides-niche.rs
@@ -0,0 +1,29 @@
+//@ check-pass
+// this test ensures that UnsafePinned hides the niche of its inner type, just like UnsafeCell does
+
+#![crate_type = "lib"]
+#![feature(unsafe_pinned)]
+
+use std::num::NonZero;
+use std::pin::UnsafePinned;
+
+macro_rules! assert_size_is {
+    ($ty:ty = $size:expr) => {
+        const _: () = assert!(size_of::<$ty>() == $size);
+    };
+}
+
+assert_size_is!(UnsafePinned<()> = 0);
+assert_size_is!(UnsafePinned<u8> = 1);
+
+assert_size_is!(       UnsafePinned<               u32>    = 4);
+assert_size_is!(       UnsafePinned<       NonZero<u32>>   = 4);
+assert_size_is!(       UnsafePinned<Option<NonZero<u32>>>  = 4);
+assert_size_is!(Option<UnsafePinned<               u32>>   = 8);
+assert_size_is!(Option<UnsafePinned<       NonZero<u32>>>  = 8);
+assert_size_is!(Option<UnsafePinned<Option<NonZero<u32>>>> = 8);
+
+assert_size_is!(       UnsafePinned<       &()>   = size_of::<usize>());
+assert_size_is!(       UnsafePinned<Option<&()>>  = size_of::<usize>());
+assert_size_is!(Option<UnsafePinned<       &()>>  = size_of::<usize>() * 2);
+assert_size_is!(Option<UnsafePinned<Option<&()>>> = size_of::<usize>() * 2);