diff --git a/compiler/rustc_ast/src/util/parser.rs b/compiler/rustc_ast/src/util/parser.rs
index 500c97e65ef9c..742a7d1d2df70 100644
--- a/compiler/rustc_ast/src/util/parser.rs
+++ b/compiler/rustc_ast/src/util/parser.rs
@@ -212,7 +212,8 @@ impl AssocOp {
     /// parentheses while having a high degree of confidence on the correctness of the suggestion.
     pub fn can_continue_expr_unambiguously(&self) -> bool {
         use AssocOp::*;
-        match self {
+        matches!(
+            self,
             BitXor | // `{ 42 } ^ 3`
             Assign | // `{ 42 } = { 42 }`
             Divide | // `{ 42 } / 42`
@@ -225,9 +226,8 @@ impl AssocOp {
             As | // `{ 42 } as usize`
             // Equal | // `{ 42 } == { 42 }`    Accepting these here would regress incorrect
             // NotEqual | // `{ 42 } != { 42 }  struct literals parser recovery.
-            Colon => true, // `{ 42 }: usize`
-            _ => false,
-        }
+            Colon, // `{ 42 }: usize`
+        )
     }
 }
 
diff --git a/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs b/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
index d5de0801ac443..79973ab170cad 100644
--- a/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
@@ -53,10 +53,7 @@ pub(crate) enum LaterUseKind {
 
 impl BorrowExplanation {
     pub(crate) fn is_explained(&self) -> bool {
-        match self {
-            BorrowExplanation::Unexplained => false,
-            _ => true,
-        }
+        !matches!(self, BorrowExplanation::Unexplained)
     }
     pub(crate) fn add_explanation_to_diagnostic<'tcx>(
         &self,
diff --git a/compiler/rustc_borrowck/src/region_infer/mod.rs b/compiler/rustc_borrowck/src/region_infer/mod.rs
index 22bb3a29425ee..f4a5da1fe36fa 100644
--- a/compiler/rustc_borrowck/src/region_infer/mod.rs
+++ b/compiler/rustc_borrowck/src/region_infer/mod.rs
@@ -2110,14 +2110,14 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                     _ => constraint_sup_scc != target_scc,
                 }
             } else {
-                match categorized_path[*i].category {
+                !matches!(
+                    categorized_path[*i].category,
                     ConstraintCategory::OpaqueType
-                    | ConstraintCategory::Boring
-                    | ConstraintCategory::BoringNoLocation
-                    | ConstraintCategory::Internal
-                    | ConstraintCategory::Predicate(_) => false,
-                    _ => true,
-                }
+                        | ConstraintCategory::Boring
+                        | ConstraintCategory::BoringNoLocation
+                        | ConstraintCategory::Internal
+                        | ConstraintCategory::Predicate(_)
+                )
             }
         };
 
diff --git a/compiler/rustc_borrowck/src/universal_regions.rs b/compiler/rustc_borrowck/src/universal_regions.rs
index bebd19370299d..147e2aead648d 100644
--- a/compiler/rustc_borrowck/src/universal_regions.rs
+++ b/compiler/rustc_borrowck/src/universal_regions.rs
@@ -138,17 +138,11 @@ impl<'tcx> DefiningTy<'tcx> {
     }
 
     pub fn is_fn_def(&self) -> bool {
-        match *self {
-            DefiningTy::FnDef(..) => true,
-            _ => false,
-        }
+        matches!(*self, DefiningTy::FnDef(..))
     }
 
     pub fn is_const(&self) -> bool {
-        match *self {
-            DefiningTy::Const(..) => true,
-            _ => false,
-        }
+        matches!(*self, DefiningTy::Const(..))
     }
 
     pub fn def_id(&self) -> DefId {
diff --git a/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs b/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
index accb54e464553..ab119ae25f5e8 100644
--- a/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
+++ b/compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs
@@ -124,10 +124,7 @@ fn push_debuginfo_type_name<'tcx>(
             // info for MSVC debugger. However, wrapping these types' names in a synthetic type
             // causes the .natvis engine for WinDbg to fail to display their data, so we opt these
             // types out to aid debugging in MSVC.
-            let is_slice_or_str = match *inner_type.kind() {
-                ty::Slice(_) | ty::Str => true,
-                _ => false,
-            };
+            let is_slice_or_str = matches!(*inner_type.kind(), ty::Slice(_) | ty::Str);
 
             if !cpp_like_names {
                 output.push('&');
diff --git a/compiler/rustc_const_eval/src/const_eval/error.rs b/compiler/rustc_const_eval/src/const_eval/error.rs
index 5da1681662577..87298023980ed 100644
--- a/compiler/rustc_const_eval/src/const_eval/error.rs
+++ b/compiler/rustc_const_eval/src/const_eval/error.rs
@@ -25,10 +25,7 @@ pub enum ConstEvalErrKind {
 
 impl MachineStopType for ConstEvalErrKind {
     fn is_hard_err(&self) -> bool {
-        match self {
-            Self::Panic { .. } => true,
-            _ => false,
-        }
+        matches!(self, Self::Panic { .. })
     }
 }
 
diff --git a/compiler/rustc_const_eval/src/const_eval/fn_queries.rs b/compiler/rustc_const_eval/src/const_eval/fn_queries.rs
index 80551518d3c5d..821b048eb9bcf 100644
--- a/compiler/rustc_const_eval/src/const_eval/fn_queries.rs
+++ b/compiler/rustc_const_eval/src/const_eval/fn_queries.rs
@@ -51,10 +51,8 @@ fn is_const_fn_raw(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
         // If the function itself is not annotated with `const`, it may still be a `const fn`
         // if it resides in a const trait impl.
         is_parent_const_impl_raw(tcx, hir_id)
-    } else if let hir::Node::Ctor(_) = node {
-        true
     } else {
-        false
+        matches!(node, hir::Node::Ctor(_))
     }
 }
 
diff --git a/compiler/rustc_const_eval/src/interpret/intrinsics/type_name.rs b/compiler/rustc_const_eval/src/interpret/intrinsics/type_name.rs
index a7012cd63f313..5b4a5ac357722 100644
--- a/compiler/rustc_const_eval/src/interpret/intrinsics/type_name.rs
+++ b/compiler/rustc_const_eval/src/interpret/intrinsics/type_name.rs
@@ -138,10 +138,8 @@ impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
         args: &[GenericArg<'tcx>],
     ) -> Result<Self::Path, Self::Error> {
         self = print_prefix(self)?;
-        let args = args.iter().cloned().filter(|arg| match arg.unpack() {
-            GenericArgKind::Lifetime(_) => false,
-            _ => true,
-        });
+        let args =
+            args.iter().cloned().filter(|arg| !matches!(arg.unpack(), GenericArgKind::Lifetime(_)));
         if args.clone().next().is_some() {
             self.generic_delimiters(|cx| cx.comma_sep(args))
         } else {
diff --git a/compiler/rustc_const_eval/src/interpret/terminator.rs b/compiler/rustc_const_eval/src/interpret/terminator.rs
index 8d3544d434acf..00208574c555e 100644
--- a/compiler/rustc_const_eval/src/interpret/terminator.rs
+++ b/compiler/rustc_const_eval/src/interpret/terminator.rs
@@ -345,10 +345,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
 
                     // Figure out how to pass which arguments.
                     // The Rust ABI is special: ZST get skipped.
-                    let rust_abi = match caller_abi {
-                        Abi::Rust | Abi::RustCall => true,
-                        _ => false,
-                    };
+                    let rust_abi = matches!(caller_abi, Abi::Rust | Abi::RustCall);
+
                     // We have two iterators: Where the arguments come from,
                     // and where they go to.
 
diff --git a/compiler/rustc_const_eval/src/transform/check_consts/check.rs b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
index 3a5bc37b85ad6..3785c170f6b2b 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/check.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
@@ -131,10 +131,7 @@ impl Qualifs<'mir, 'tcx> {
             .body
             .basic_blocks()
             .iter_enumerated()
-            .find(|(_, block)| match block.terminator().kind {
-                TerminatorKind::Return => true,
-                _ => false,
-            })
+            .find(|(_, block)| matches!(block.terminator().kind, TerminatorKind::Return))
             .map(|(bb, _)| bb);
 
         let return_block = match return_block {
diff --git a/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs b/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
index 0fdb772c262dd..abc5a3c6a5206 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
@@ -170,11 +170,12 @@ impl Qualif for NeedsNonConstDrop {
             let mut selcx = SelectionContext::with_constness(&infcx, hir::Constness::Const);
             selcx.select(&obligation)
         });
-        match implsrc {
-            Ok(Some(ImplSource::ConstDrop(_)))
-            | Ok(Some(ImplSource::Param(_, ty::BoundConstness::ConstIfConst))) => false,
-            _ => true,
-        }
+        !matches!(
+            implsrc,
+            Ok(Some(
+                ImplSource::ConstDrop(_) | ImplSource::Param(_, ty::BoundConstness::ConstIfConst)
+            ))
+        )
     }
 
     fn in_adt_inherently(cx: &ConstCx<'_, 'tcx>, adt: &'tcx AdtDef, _: SubstsRef<'tcx>) -> bool {
diff --git a/compiler/rustc_lexer/src/unescape.rs b/compiler/rustc_lexer/src/unescape.rs
index b970c9e4911fa..d789237e692d2 100644
--- a/compiler/rustc_lexer/src/unescape.rs
+++ b/compiler/rustc_lexer/src/unescape.rs
@@ -68,11 +68,10 @@ pub enum EscapeError {
 impl EscapeError {
     /// Returns true for actual errors, as opposed to warnings.
     pub fn is_fatal(&self) -> bool {
-        match self {
-            EscapeError::UnskippedWhitespaceWarning => false,
-            EscapeError::MultipleSkippedLinesWarning => false,
-            _ => true,
-        }
+        !matches!(
+            self,
+            EscapeError::UnskippedWhitespaceWarning | EscapeError::MultipleSkippedLinesWarning
+        )
     }
 }
 
diff --git a/compiler/rustc_middle/src/mir/interpret/error.rs b/compiler/rustc_middle/src/mir/interpret/error.rs
index 9472a287e5a41..7a51bb4a1f32a 100644
--- a/compiler/rustc_middle/src/mir/interpret/error.rs
+++ b/compiler/rustc_middle/src/mir/interpret/error.rs
@@ -538,12 +538,12 @@ impl InterpError<'_> {
     /// To avoid performance issues, there are places where we want to be sure to never raise these formatting errors,
     /// so this method lets us detect them and `bug!` on unexpected errors.
     pub fn formatted_string(&self) -> bool {
-        match self {
+        matches!(
+            self,
             InterpError::Unsupported(UnsupportedOpInfo::Unsupported(_))
-            | InterpError::UndefinedBehavior(UndefinedBehaviorInfo::ValidationFailure { .. })
-            | InterpError::UndefinedBehavior(UndefinedBehaviorInfo::Ub(_)) => true,
-            _ => false,
-        }
+                | InterpError::UndefinedBehavior(UndefinedBehaviorInfo::ValidationFailure { .. })
+                | InterpError::UndefinedBehavior(UndefinedBehaviorInfo::Ub(_))
+        )
     }
 
     /// Should this error be reported as a hard error, preventing compilation, or a soft error,
diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
index 4ac93f7161923..6807d02519e2b 100644
--- a/compiler/rustc_mir_transform/src/coverage/mod.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mod.rs
@@ -485,7 +485,7 @@ fn inject_statement(
 
 // Non-code expressions are injected into the coverage map, without generating executable code.
 fn inject_intermediate_expression(mir_body: &mut mir::Body<'tcx>, expression: CoverageKind) {
-    debug_assert!(if let CoverageKind::Expression { .. } = expression { true } else { false });
+    debug_assert!(matches!(expression, CoverageKind::Expression { .. }));
     debug!("  injecting non-code expression {:?}", expression);
     let inject_in_bb = mir::START_BLOCK;
     let data = &mut mir_body[inject_in_bb];
diff --git a/compiler/rustc_mir_transform/src/coverage/spans.rs b/compiler/rustc_mir_transform/src/coverage/spans.rs
index cc525a4d6b91c..d13fa0729cd95 100644
--- a/compiler/rustc_mir_transform/src/coverage/spans.rs
+++ b/compiler/rustc_mir_transform/src/coverage/spans.rs
@@ -94,10 +94,9 @@ impl CoverageSpan {
         stmt_index: usize,
     ) -> Self {
         let is_closure = match statement.kind {
-            StatementKind::Assign(box (_, Rvalue::Aggregate(box ref kind, _))) => match kind {
-                AggregateKind::Closure(_, _) | AggregateKind::Generator(_, _, _) => true,
-                _ => false,
-            },
+            StatementKind::Assign(box (_, Rvalue::Aggregate(box ref kind, _))) => {
+                matches!(kind, AggregateKind::Closure(_, _) | AggregateKind::Generator(_, _, _))
+            }
             _ => false,
         };
 
diff --git a/compiler/rustc_mir_transform/src/reveal_all.rs b/compiler/rustc_mir_transform/src/reveal_all.rs
index 7b4eb4912cb36..6c423a2bb5756 100644
--- a/compiler/rustc_mir_transform/src/reveal_all.rs
+++ b/compiler/rustc_mir_transform/src/reveal_all.rs
@@ -11,7 +11,7 @@ impl<'tcx> MirPass<'tcx> for RevealAll {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         // This pass must run before inlining, since we insert callee bodies in RevealAll mode.
         // Do not apply this transformation to generators.
-        if (tcx.sess.mir_opt_level() >= 3 || !super::inline::is_enabled(tcx))
+        if (tcx.sess.mir_opt_level() >= 3 || super::inline::is_enabled(tcx))
             && body.generator.is_none()
         {
             let param_env = tcx.param_env_reveal_all_normalized(body.source.def_id());
diff --git a/compiler/rustc_mir_transform/src/unreachable_prop.rs b/compiler/rustc_mir_transform/src/unreachable_prop.rs
index baf381081ddab..64cd6f56a9ffa 100644
--- a/compiler/rustc_mir_transform/src/unreachable_prop.rs
+++ b/compiler/rustc_mir_transform/src/unreachable_prop.rs
@@ -27,9 +27,8 @@ impl MirPass<'_> for UnreachablePropagation {
             // This is a temporary solution that handles possibly diverging asm statements.
             // Accompanying testcases: mir-opt/unreachable_asm.rs and mir-opt/unreachable_asm_2.rs
             let asm_stmt_in_block = || {
-                bb_data.statements.iter().any(|stmt: &Statement<'_>| match stmt.kind {
-                    StatementKind::LlvmInlineAsm(..) => true,
-                    _ => false,
+                bb_data.statements.iter().any(|stmt: &Statement<'_>| {
+                    matches!(stmt.kind, StatementKind::LlvmInlineAsm(..))
                 })
             };
 
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index 60676ad3f4f60..481bfa4a26b36 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -320,10 +320,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     /// Returns `true` if the trait predicate is considerd `const` to this selection context.
     pub fn is_trait_predicate_const(&self, pred: ty::TraitPredicate<'_>) -> bool {
-        match pred.constness {
-            ty::BoundConstness::ConstIfConst if self.is_in_const_context => true,
-            _ => false,
-        }
+        matches!(pred.constness, ty::BoundConstness::ConstIfConst) && self.is_in_const_context
     }
 
     /// Returns `true` if the predicate is considered `const` to
diff --git a/compiler/rustc_typeck/src/check/cast.rs b/compiler/rustc_typeck/src/check/cast.rs
index 78849b276d6bf..511a2d7ddacf9 100644
--- a/compiler/rustc_typeck/src/check/cast.rs
+++ b/compiler/rustc_typeck/src/check/cast.rs
@@ -436,11 +436,8 @@ impl<'a, 'tcx> CastCheck<'tcx> {
                     // Very crude check to see whether the expression must be wrapped
                     // in parentheses for the suggestion to work (issue #89497).
                     // Can/should be extended in the future.
-                    let needs_parens = !has_parens
-                        && match self.expr.kind {
-                            hir::ExprKind::Cast(..) => true,
-                            _ => false,
-                        };
+                    let needs_parens =
+                        !has_parens && matches!(self.expr.kind, hir::ExprKind::Cast(..));
 
                     let mut suggestion = vec![(self.expr.span.shrink_to_lo(), sugg)];
                     if needs_parens {
diff --git a/compiler/rustc_typeck/src/check/demand.rs b/compiler/rustc_typeck/src/check/demand.rs
index 2b3672211e4f5..0cbbcdd107371 100644
--- a/compiler/rustc_typeck/src/check/demand.rs
+++ b/compiler/rustc_typeck/src/check/demand.rs
@@ -29,6 +29,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>,
     ) {
         self.annotate_expected_due_to_let_ty(err, expr);
+        self.suggest_box_deref(err, expr, expected, expr_ty);
         self.suggest_compatible_variants(err, expr, expected, expr_ty);
         self.suggest_deref_ref_or_into(err, expr, expected, expr_ty, expected_ty_expr);
         if self.suggest_calling_boxed_future_when_appropriate(err, expr, expected, expr_ty) {
@@ -167,6 +168,23 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
     }
 
+    fn suggest_box_deref(
+        &self,
+        err: &mut DiagnosticBuilder<'_>,
+        expr: &hir::Expr<'_>,
+        expected: Ty<'tcx>,
+        expr_ty: Ty<'tcx>,
+    ) {
+        if expr_ty.is_box() && expr_ty.boxed_ty() == expected {
+            err.span_suggestion_verbose(
+                expr.span.shrink_to_lo(),
+                "try dereferencing the `Box`",
+                "*".to_string(),
+                Applicability::MachineApplicable,
+            );
+        }
+    }
+
     /// If the expected type is an enum (Issue #55250) with any variants whose
     /// sole field is of the found type, suggest such variants. (Issue #42764)
     fn suggest_compatible_variants(
diff --git a/compiler/rustc_typeck/src/check/expr.rs b/compiler/rustc_typeck/src/check/expr.rs
index 3846aad2cfc10..2d0a4068fbbe3 100644
--- a/compiler/rustc_typeck/src/check/expr.rs
+++ b/compiler/rustc_typeck/src/check/expr.rs
@@ -1698,15 +1698,15 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         // Save the index of all fields regardless of their visibility in case
                         // of error recovery.
                         self.write_field_index(expr.hir_id, index);
+                        let adjustments = self.adjust_steps(&autoderef);
                         if field.vis.is_accessible_from(def_scope, self.tcx) {
-                            let adjustments = self.adjust_steps(&autoderef);
                             self.apply_adjustments(base, adjustments);
                             self.register_predicates(autoderef.into_obligations());
 
                             self.tcx.check_stability(field.did, Some(expr.hir_id), expr.span, None);
                             return field_ty;
                         }
-                        private_candidate = Some((base_def.did, field_ty));
+                        private_candidate = Some((adjustments, base_def.did, field_ty));
                     }
                 }
                 ty::Tuple(tys) => {
@@ -1729,7 +1729,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
         self.structurally_resolved_type(autoderef.span(), autoderef.final_ty(false));
 
-        if let Some((did, field_ty)) = private_candidate {
+        if let Some((adjustments, did, field_ty)) = private_candidate {
+            // (#90483) apply adjustments to avoid ExprUseVisitor from
+            // creating erroneous projection.
+            self.apply_adjustments(base, adjustments);
             self.ban_private_field_access(expr, expr_t, field, did);
             return field_ty;
         }
diff --git a/compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs b/compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs
index 8d3862ffc8f01..a1c2945770920 100644
--- a/compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs
+++ b/compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs
@@ -300,7 +300,7 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> {
                     hir::TyKind::Path(hir::QPath::Resolved(
                         None,
                         hir::Path { res: hir::def::Res::Def(_, id), .. },
-                    )) if *id == def_id => true,
+                    )) => *id == def_id,
                     _ => false,
                 })
             })
diff --git a/library/std/src/net/ip.rs b/library/std/src/net/ip.rs
index 140647128a937..da95fe21ac9af 100644
--- a/library/std/src/net/ip.rs
+++ b/library/std/src/net/ip.rs
@@ -878,12 +878,7 @@ impl Ipv4Addr {
     #[must_use]
     #[inline]
     pub const fn is_documentation(&self) -> bool {
-        match self.octets() {
-            [192, 0, 2, _] => true,
-            [198, 51, 100, _] => true,
-            [203, 0, 113, _] => true,
-            _ => false,
-        }
+        matches!(self.octets(), [192, 0, 2, _] | [198, 51, 100, _] | [203, 0, 113, _])
     }
 
     /// Converts this address to an [IPv4-compatible] [`IPv6` address].
diff --git a/library/std/src/os/unix/net/addr.rs b/library/std/src/os/unix/net/addr.rs
index 887f605993918..f450e41bfea1e 100644
--- a/library/std/src/os/unix/net/addr.rs
+++ b/library/std/src/os/unix/net/addr.rs
@@ -159,7 +159,7 @@ impl SocketAddr {
     #[must_use]
     #[stable(feature = "unix_socket", since = "1.10.0")]
     pub fn is_unnamed(&self) -> bool {
-        if let AddressKind::Unnamed = self.address() { true } else { false }
+        matches!(self.address(), AddressKind::Unnamed)
     }
 
     /// Returns the contents of this address if it is a `pathname` address.
diff --git a/src/doc/rustdoc/src/SUMMARY.md b/src/doc/rustdoc/src/SUMMARY.md
index 3fa91bb51f02f..eb18185945387 100644
--- a/src/doc/rustdoc/src/SUMMARY.md
+++ b/src/doc/rustdoc/src/SUMMARY.md
@@ -1,6 +1,7 @@
 # The Rustdoc Book
 
 - [What is rustdoc?](what-is-rustdoc.md)
+- [How to read rustdoc output](how-to-read-rustdoc.md)
 - [How to write documentation](how-to-write-documentation.md)
 - [What to include (and exclude)](what-to-include.md)
 - [Command-line arguments](command-line-arguments.md)
diff --git a/src/doc/rustdoc/src/how-to-read-rustdoc.md b/src/doc/rustdoc/src/how-to-read-rustdoc.md
new file mode 100644
index 0000000000000..99724d859ee75
--- /dev/null
+++ b/src/doc/rustdoc/src/how-to-read-rustdoc.md
@@ -0,0 +1,107 @@
+# How to read rustdoc output
+
+Rustdoc's HTML output includes a friendly and useful navigation interface which
+makes it easier for users to navigate and understand your code.
+This chapter covers the major features of that interface,
+and is a great starting point for documentation authors and users alike.
+
+## Structure
+
+The `rustdoc` output is divided into three sections.
+Along the left side of each page is a quick navigation bar,
+which shows contextual information about the current entry.
+The rest of the page is taken up by the search interface at the top
+and the documentation for the current item below that.
+
+## The Item Documentation
+
+The majority of the screen is taken up with the documentation text for the item
+currently being viewed.
+At the top is some at-a-glance info and controls:
+
+- the type and name of the item,
+  such as "Struct `std::time::Duration`",
+- a button to copy the item's path to the clipboard,
+  which is a clipboard item
+- a button to collapse or expand the top-level documentation for that item
+  (`[+]` or `[-]`),
+- a link to the source code (`[src]`),
+  if [configured](the-doc-attribute.html#html_no_source),
+  and present (the source may not be available if
+  the documentation was created with `cargo doc --no-deps`),
+- and the version in which the item became stable,
+  if it's a stable item in the standard library.
+
+Below this is the main documentation for the item,
+including a definition or function signature if appropriate,
+followed by a list of fields or variants for Rust types.
+Finally, the page lists associated functions and trait implementations,
+including automatic and blanket implementations that `rustdoc` knows about.
+
+### Navigation
+
+Subheadings, variants, fields, and many other things in this documentation
+are anchors and can be clicked on and deep-linked to,
+which is a great way to communicate exactly what you're talking about.
+The typograpical character "§" appears next to lines with anchors on them
+when hovered or given keyboard focus.
+
+## The Navigation Bar
+
+For example, when looking at documentation for the crate root,
+it shows all the crates documented in the documentation bundle,
+and quick links to the modules, structs, traits, functions, and macros available
+from the current crate.
+At the top, it displays a [configurable logo](the-doc-attribute.html#html_logo_url)
+alongside the current crate's name and version,
+or the current item whose documentation is being displayed.
+
+## The Theme Picker and Search Interface
+
+When viewing `rustdoc`'s output in a browser with JavaScript enabled,
+a dynamic interface appears at the top of the page.
+To the left is the theme picker, denoted with a paint-brush icon,
+and the search interface, help screen, and options appear to the right of that.
+
+### The Theme Picker
+
+Clicking on the theme picker provides a list of themes -
+by default `ayu`, `light`, and `dark` -
+which are available for viewing.
+
+### The Search Interface
+
+Typing in the search bar instantly searches the available documentation for
+the string entered with a fuzzy matching algorithm that is tolerant of minor
+typos.
+
+By default, the search results give are "In Names",
+meaning that the fuzzy match is made against the names of items.
+Matching names are shown on the left, and the first few words of their
+descriptions are given on the right.
+By clicking an item, you will navigate to its particular documentation.
+
+There are two other sets of results, shown as tabs in the search results pane.
+"In Parameters" shows matches for the string in the types of parameters to
+functions, and "In Return Types" shows matches in the return types of functions.
+Both are very useful when looking for a function whose name you can't quite
+bring to mind when you know the type you have or want.
+
+When typing in the search bar, you can prefix your search term with a type
+followed by a colon (such as `mod:`) to restrict the results to just that
+kind of item. (The available items are listed in the help popup.)
+
+### Shortcuts
+
+Pressing `S` while focused elsewhere on the page will move focus to the
+search bar, and pressing `?` shows the help screen,
+which includes all these shortcuts and more.
+Pressing `T` focuses the theme picker.
+
+When the search results are focused,
+the left and right arrows move between tabs and the up and down arrows move
+among the results.
+Pressing the enter or return key opens the highlighted result.
+
+When looking at the documentation for an item, the plus and minus keys expand
+and collapse all sections in the document.
diff --git a/src/test/mir-opt/issue-78192.rs b/src/test/mir-opt/issue-78192.rs
index 906d094f72b4a..39f665402b025 100644
--- a/src/test/mir-opt/issue-78192.rs
+++ b/src/test/mir-opt/issue-78192.rs
@@ -1,4 +1,4 @@
-// EMIT_MIR issue_78192.f.InstCombine.diff
+// compile-flags: -Zmir-opt-level=1 -Zinline-mir
 pub fn f<T>(a: &T) -> *const T {
     let b: &*const T = &(a as *const T);
     *b
@@ -7,3 +7,5 @@ pub fn f<T>(a: &T) -> *const T {
 fn main() {
     f(&2);
 }
+
+// EMIT_MIR issue_78192.f.InstCombine.diff
diff --git a/src/test/ui/suggestions/boxed-variant-field.rs b/src/test/ui/suggestions/boxed-variant-field.rs
new file mode 100644
index 0000000000000..d8f7fac151356
--- /dev/null
+++ b/src/test/ui/suggestions/boxed-variant-field.rs
@@ -0,0 +1,16 @@
+enum Ty {
+    Unit,
+    List(Box<Ty>),
+}
+
+fn foo(x: Ty) -> Ty {
+    match x {
+        Ty::Unit => Ty::Unit,
+        Ty::List(elem) => foo(elem),
+        //~^ ERROR mismatched types
+        //~| HELP try dereferencing the `Box`
+        //~| HELP try using a variant of the expected enum
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/suggestions/boxed-variant-field.stderr b/src/test/ui/suggestions/boxed-variant-field.stderr
new file mode 100644
index 0000000000000..d4ccb2ca490bc
--- /dev/null
+++ b/src/test/ui/suggestions/boxed-variant-field.stderr
@@ -0,0 +1,20 @@
+error[E0308]: mismatched types
+  --> $DIR/boxed-variant-field.rs:9:31
+   |
+LL |         Ty::List(elem) => foo(elem),
+   |                               ^^^^ expected enum `Ty`, found struct `Box`
+   |
+   = note: expected enum `Ty`
+            found struct `Box<Ty>`
+help: try dereferencing the `Box`
+   |
+LL |         Ty::List(elem) => foo(*elem),
+   |                               +
+help: try using a variant of the expected enum
+   |
+LL |         Ty::List(elem) => foo(Ty::List(elem)),
+   |                               ~~~~~~~~~~~~~~
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/terr-sorts.stderr b/src/test/ui/terr-sorts.stderr
index 869b372965966..65d90678040d5 100644
--- a/src/test/ui/terr-sorts.stderr
+++ b/src/test/ui/terr-sorts.stderr
@@ -6,6 +6,10 @@ LL |     want_foo(b);
    |
    = note: expected struct `Foo`
               found struct `Box<Foo>`
+help: try dereferencing the `Box`
+   |
+LL |     want_foo(*b);
+   |              +
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/typeck/issue-90483-inaccessible-field-adjustment.rs b/src/test/ui/typeck/issue-90483-inaccessible-field-adjustment.rs
new file mode 100644
index 0000000000000..74e50d46e8dcf
--- /dev/null
+++ b/src/test/ui/typeck/issue-90483-inaccessible-field-adjustment.rs
@@ -0,0 +1,14 @@
+// edition:2021
+
+mod m {
+  pub struct S { foo: i32 }
+  impl S {
+    pub fn foo(&self) -> i32 { 42 }
+  }
+}
+
+fn bar(s: &m::S) {
+  || s.foo() + s.foo; //~ ERROR E0616
+}
+
+fn main() {}
diff --git a/src/test/ui/typeck/issue-90483-inaccessible-field-adjustment.stderr b/src/test/ui/typeck/issue-90483-inaccessible-field-adjustment.stderr
new file mode 100644
index 0000000000000..02cdc102c15ba
--- /dev/null
+++ b/src/test/ui/typeck/issue-90483-inaccessible-field-adjustment.stderr
@@ -0,0 +1,14 @@
+error[E0616]: field `foo` of struct `S` is private
+  --> $DIR/issue-90483-inaccessible-field-adjustment.rs:11:18
+   |
+LL |   || s.foo() + s.foo;
+   |                  ^^^ private field
+   |
+help: a method `foo` also exists, call it with parentheses
+   |
+LL |   || s.foo() + s.foo();
+   |                     ++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0616`.