Merging upstream version 1.70.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

17 files changed, 256 insertions, 201 deletions

diff --git a/compiler/rustc_lint/locales/en-US.ftl b/compiler/rustc_lint/messages.ftl
index 68e62c978..db15b176d 100644
--- a/compiler/rustc_lint/locales/en-US.ftl
+++ b/compiler/rustc_lint/messages.ftl
@@ -91,7 +91,7 @@ lint_ty_qualified = usage of qualified `ty::{$ty}`
 lint_lintpass_by_hand = implementing `LintPass` by hand
     .help = try using `declare_lint_pass!` or `impl_lint_pass!` instead
 
-lint_non_existant_doc_keyword = found non-existing keyword `{$keyword}` used in `#[doc(keyword = \"...\")]`
+lint_non_existent_doc_keyword = found non-existing keyword `{$keyword}` used in `#[doc(keyword = "...")]`
     .help = only existing keywords are allowed in core/std
 
 lint_diag_out_of_impl =
@@ -107,7 +107,7 @@ lint_cstring_ptr = getting the inner pointer of a temporary `CString`
     .note = pointers do not have a lifetime; when calling `as_ptr` the `CString` will be deallocated at the end of the statement because nothing is referencing it as far as the type system is concerned
     .help = for more information, see https://doc.rust-lang.org/reference/destructors.html
 
-lint_multple_supertrait_upcastable = `{$ident}` is object-safe and has multiple supertraits
+lint_multiple_supertrait_upcastable = `{$ident}` is object-safe and has multiple supertraits
 
 lint_identifier_non_ascii_char = identifier contains non-ASCII characters
 
@@ -197,7 +197,9 @@ lint_drop_glue =
     types that do not implement `Drop` can still have drop glue, consider instead using `{$needs_drop}` to detect whether a type is trivially dropped
 
 lint_range_endpoint_out_of_range = range endpoint is out of range for `{$ty}`
-    .suggestion = use an inclusive range instead
+
+lint_range_use_inclusive_range = use an inclusive range instead
+
 
 lint_overflowing_bin_hex = literal out of range for `{$ty}`
     .negative_note = the literal `{$lit}` (decimal `{$dec}`) does not fit into the type `{$ty}`
diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index 5b2100b5d..6b387df78 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -58,7 +58,6 @@ use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{DefId, LocalDefId, LocalDefIdSet, CRATE_DEF_ID};
 use rustc_hir::intravisit::FnKind as HirFnKind;
 use rustc_hir::{Body, FnDecl, ForeignItemKind, GenericParamKind, Node, PatKind, PredicateOrigin};
-use rustc_index::vec::Idx;
 use rustc_middle::lint::in_external_macro;
 use rustc_middle::ty::layout::{LayoutError, LayoutOf};
 use rustc_middle::ty::print::with_no_trimmed_paths;
@@ -69,7 +68,7 @@ use rustc_span::edition::Edition;
 use rustc_span::source_map::Spanned;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{BytePos, InnerSpan, Span};
-use rustc_target::abi::{Abi, VariantIdx};
+use rustc_target::abi::{Abi, FIRST_VARIANT};
 use rustc_trait_selection::infer::{InferCtxtExt, TyCtxtInferExt};
 use rustc_trait_selection::traits::{self, misc::type_allowed_to_implement_copy};
 
@@ -358,29 +357,29 @@ impl EarlyLintPass for UnsafeCode {
             }
 
             ast::ItemKind::Fn(..) => {
-                if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::no_mangle) {
+                if let Some(attr) = attr::find_by_name(&it.attrs, sym::no_mangle) {
                     self.report_unsafe(cx, attr.span, BuiltinUnsafe::NoMangleFn);
                 }
 
-                if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::export_name) {
+                if let Some(attr) = attr::find_by_name(&it.attrs, sym::export_name) {
                     self.report_unsafe(cx, attr.span, BuiltinUnsafe::ExportNameFn);
                 }
 
-                if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::link_section) {
+                if let Some(attr) = attr::find_by_name(&it.attrs, sym::link_section) {
                     self.report_unsafe(cx, attr.span, BuiltinUnsafe::LinkSectionFn);
                 }
             }
 
             ast::ItemKind::Static(..) => {
-                if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::no_mangle) {
+                if let Some(attr) = attr::find_by_name(&it.attrs, sym::no_mangle) {
                     self.report_unsafe(cx, attr.span, BuiltinUnsafe::NoMangleStatic);
                 }
 
-                if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::export_name) {
+                if let Some(attr) = attr::find_by_name(&it.attrs, sym::export_name) {
                     self.report_unsafe(cx, attr.span, BuiltinUnsafe::ExportNameStatic);
                 }
 
-                if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::link_section) {
+                if let Some(attr) = attr::find_by_name(&it.attrs, sym::link_section) {
                     self.report_unsafe(cx, attr.span, BuiltinUnsafe::LinkSectionStatic);
                 }
             }
@@ -391,10 +390,10 @@ impl EarlyLintPass for UnsafeCode {
 
     fn check_impl_item(&mut self, cx: &EarlyContext<'_>, it: &ast::AssocItem) {
         if let ast::AssocItemKind::Fn(..) = it.kind {
-            if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::no_mangle) {
+            if let Some(attr) = attr::find_by_name(&it.attrs, sym::no_mangle) {
                 self.report_unsafe(cx, attr.span, BuiltinUnsafe::NoMangleMethod);
             }
-            if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::export_name) {
+            if let Some(attr) = attr::find_by_name(&it.attrs, sym::export_name) {
                 self.report_unsafe(cx, attr.span, BuiltinUnsafe::ExportNameMethod);
             }
         }
@@ -1123,12 +1122,12 @@ impl<'tcx> LateLintPass<'tcx> for InvalidNoMangleItems {
         };
         match it.kind {
             hir::ItemKind::Fn(.., ref generics, _) => {
-                if let Some(no_mangle_attr) = cx.sess().find_by_name(attrs, sym::no_mangle) {
+                if let Some(no_mangle_attr) = attr::find_by_name(attrs, sym::no_mangle) {
                     check_no_mangle_on_generic_fn(no_mangle_attr, None, generics, it.span);
                 }
             }
             hir::ItemKind::Const(..) => {
-                if cx.sess().contains_name(attrs, sym::no_mangle) {
+                if attr::contains_name(attrs, sym::no_mangle) {
                     // account for "pub const" (#45562)
                     let start = cx
                         .tcx
@@ -1152,9 +1151,8 @@ impl<'tcx> LateLintPass<'tcx> for InvalidNoMangleItems {
             hir::ItemKind::Impl(hir::Impl { generics, items, .. }) => {
                 for it in *items {
                     if let hir::AssocItemKind::Fn { .. } = it.kind {
-                        if let Some(no_mangle_attr) = cx
-                            .sess()
-                            .find_by_name(cx.tcx.hir().attrs(it.id.hir_id()), sym::no_mangle)
+                        if let Some(no_mangle_attr) =
+                            attr::find_by_name(cx.tcx.hir().attrs(it.id.hir_id()), sym::no_mangle)
                         {
                             check_no_mangle_on_generic_fn(
                                 no_mangle_attr,
@@ -1306,7 +1304,7 @@ impl<'tcx> LateLintPass<'tcx> for UngatedAsyncFnTrackCaller {
         if fn_kind.asyncness() == IsAsync::Async
             && !cx.tcx.features().closure_track_caller
             // Now, check if the function has the `#[track_caller]` attribute
-            && let Some(attr) = cx.tcx.get_attr(def_id.to_def_id(), sym::track_caller)
+            && let Some(attr) = cx.tcx.get_attr(def_id, sym::track_caller)
         {
             cx.emit_spanned_lint(UNGATED_ASYNC_FN_TRACK_CALLER, attr.span, BuiltinUngatedAsyncFnTrackCaller {
                 label: span,
@@ -1601,7 +1599,7 @@ impl<'tcx> LateLintPass<'tcx> for TrivialConstraints {
                     // Ignore projections, as they can only be global
                     // if the trait bound is global
                     Clause(Clause::Projection(..)) |
-                    AliasEq(..) |
+                    AliasRelate(..) |
                     // Ignore bounds that a user can't type
                     WellFormed(..) |
                     ObjectSafe(..) |
@@ -1836,7 +1834,7 @@ impl<'tcx> LateLintPass<'tcx> for UnnameableTestItems {
         }
 
         let attrs = cx.tcx.hir().attrs(it.hir_id());
-        if let Some(attr) = cx.sess().find_by_name(attrs, sym::rustc_test_marker) {
+        if let Some(attr) = attr::find_by_name(attrs, sym::rustc_test_marker) {
             cx.emit_spanned_lint(UNNAMEABLE_TEST_ITEMS, attr.span, BuiltinUnnameableTestItems);
         }
     }
@@ -1949,7 +1947,7 @@ impl KeywordIdents {
         };
 
         // Don't lint `r#foo`.
-        if cx.sess().parse_sess.raw_identifier_spans.borrow().contains(&ident.span) {
+        if cx.sess().parse_sess.raw_identifier_spans.contains(ident.span) {
             return;
         }
 
@@ -2748,10 +2746,7 @@ impl ClashingExternDeclarations {
                 // information, we could have codegen_fn_attrs also give span information back for
                 // where the attribute was defined. However, until this is found to be a
                 // bottleneck, this does just fine.
-                (
-                    overridden_link_name,
-                    tcx.get_attr(fi.owner_id.to_def_id(), sym::link_name).unwrap().span,
-                )
+                (overridden_link_name, tcx.get_attr(fi.owner_id, sym::link_name).unwrap().span)
             })
         {
             SymbolName::Link(overridden_link_name, overridden_link_name_span)
@@ -2781,8 +2776,7 @@ impl ClashingExternDeclarations {
 
             // Given a transparent newtype, reach through and grab the inner
             // type unless the newtype makes the type non-null.
-            let non_transparent_ty = |ty: Ty<'tcx>| -> Ty<'tcx> {
-                let mut ty = ty;
+            let non_transparent_ty = |mut ty: Ty<'tcx>| -> Ty<'tcx> {
                 loop {
                     if let ty::Adt(def, substs) = *ty.kind() {
                         let is_transparent = def.repr().transparent();
@@ -2792,14 +2786,14 @@ impl ClashingExternDeclarations {
                             ty, is_transparent, is_non_null
                         );
                         if is_transparent && !is_non_null {
-                            debug_assert!(def.variants().len() == 1);
-                            let v = &def.variant(VariantIdx::new(0));
-                            ty = transparent_newtype_field(tcx, v)
-                                .expect(
-                                    "single-variant transparent structure with zero-sized field",
-                                )
-                                .ty(tcx, substs);
-                            continue;
+                            debug_assert_eq!(def.variants().len(), 1);
+                            let v = &def.variant(FIRST_VARIANT);
+                            // continue with `ty`'s non-ZST field,
+                            // otherwise `ty` is a ZST and we can return
+                            if let Some(field) = transparent_newtype_field(tcx, v) {
+                                ty = field.ty(tcx, substs);
+                                continue;
+                            }
                         }
                     }
                     debug!("non_transparent_ty -> {:?}", ty);
@@ -2813,10 +2807,8 @@ impl ClashingExternDeclarations {
             if !seen_types.insert((a, b)) {
                 // We've encountered a cycle. There's no point going any further -- the types are
                 // structurally the same.
-                return true;
-            }
-            let tcx = cx.tcx;
-            if a == b {
+                true
+            } else if a == b {
                 // All nominally-same types are structurally same, too.
                 true
             } else {
diff --git a/compiler/rustc_lint/src/context.rs b/compiler/rustc_lint/src/context.rs
index f5a711315..626c09fea 100644
--- a/compiler/rustc_lint/src/context.rs
+++ b/compiler/rustc_lint/src/context.rs
@@ -910,6 +910,10 @@ pub trait LintContext: Sized {
                         Applicability::MachineApplicable,
                     );
                 }
+                BuiltinLintDiagnostics::AmbiguousGlobReexports { name, namespace, first_reexport_span, duplicate_reexport_span } => {
+                    db.span_label(first_reexport_span, format!("the name `{}` in the {} namespace is first re-exported here", name, namespace));
+                    db.span_label(duplicate_reexport_span, format!("but the name `{}` in the {} namespace is also re-exported here", name, namespace));
+                }
             }
             // Rewrap `db`, and pass control to the user.
             decorate(db)
diff --git a/compiler/rustc_lint/src/early.rs b/compiler/rustc_lint/src/early.rs
index 337a19dd0..65607d718 100644
--- a/compiler/rustc_lint/src/early.rs
+++ b/compiler/rustc_lint/src/early.rs
@@ -224,8 +224,7 @@ impl<'a, T: EarlyLintPass> ast_visit::Visitor<'a> for EarlyContextAndPass<'a, T>
             ast::ExprKind::Closure(box ast::Closure {
                 asyncness: ast::Async::Yes { closure_id, .. },
                 ..
-            })
-            | ast::ExprKind::Async(_, closure_id, ..) => self.check_id(closure_id),
+            }) => self.check_id(closure_id),
             _ => {}
         }
     }
@@ -341,7 +340,7 @@ pub trait EarlyCheckNode<'a>: Copy {
         'a: 'b;
 }
 
-impl<'a> EarlyCheckNode<'a> for &'a ast::Crate {
+impl<'a> EarlyCheckNode<'a> for (&'a ast::Crate, &'a [ast::Attribute]) {
     fn id(self) -> ast::NodeId {
         ast::CRATE_NODE_ID
     }
@@ -349,15 +348,15 @@ impl<'a> EarlyCheckNode<'a> for &'a ast::Crate {
     where
         'a: 'b,
     {
-        &self.attrs
+        &self.1
     }
     fn check<'b, T: EarlyLintPass>(self, cx: &mut EarlyContextAndPass<'b, T>)
     where
         'a: 'b,
     {
-        lint_callback!(cx, check_crate, self);
-        ast_visit::walk_crate(cx, self);
-        lint_callback!(cx, check_crate_post, self);
+        lint_callback!(cx, check_crate, self.0);
+        ast_visit::walk_crate(cx, self.0);
+        lint_callback!(cx, check_crate_post, self.0);
     }
 }
 
diff --git a/compiler/rustc_lint/src/for_loops_over_fallibles.rs b/compiler/rustc_lint/src/for_loops_over_fallibles.rs
index a3367ae4a..7b58bf03b 100644
--- a/compiler/rustc_lint/src/for_loops_over_fallibles.rs
+++ b/compiler/rustc_lint/src/for_loops_over_fallibles.rs
@@ -11,6 +11,7 @@ use rustc_hir as hir;
 use rustc_infer::{infer::TyCtxtInferExt, traits::ObligationCause};
 use rustc_middle::ty::{self, List};
 use rustc_span::{sym, Span};
+use rustc_trait_selection::traits::ObligationCtxt;
 
 declare_lint! {
     /// The `for_loops_over_fallibles` lint checks for `for` loops over `Option` or `Result` values.
@@ -136,20 +137,22 @@ fn suggest_question_mark<'tcx>(
 
     let ty = substs.type_at(0);
     let infcx = cx.tcx.infer_ctxt().build();
+    let ocx = ObligationCtxt::new(&infcx);
+
     let body_def_id = cx.tcx.hir().body_owner_def_id(body_id);
     let cause = ObligationCause::new(
         span,
         body_def_id,
         rustc_infer::traits::ObligationCauseCode::MiscObligation,
     );
-    let errors = rustc_trait_selection::traits::fully_solve_bound(
-        &infcx,
+
+    ocx.register_bound(
         cause,
-        ty::ParamEnv::empty(),
+        cx.param_env,
         // Erase any region vids from the type, which may not be resolved
         infcx.tcx.erase_regions(ty),
         into_iterator_did,
     );
 
-    errors.is_empty()
+    ocx.select_all_or_error().is_empty()
 }
diff --git a/compiler/rustc_lint/src/internal.rs b/compiler/rustc_lint/src/internal.rs
index 2fd0ef3cd..4ac589c2e 100644
--- a/compiler/rustc_lint/src/internal.rs
+++ b/compiler/rustc_lint/src/internal.rs
@@ -2,7 +2,7 @@
 //! Clippy.
 
 use crate::lints::{
-    BadOptAccessDiag, DefaultHashTypesDiag, DiagOutOfImpl, LintPassByHand, NonExistantDocKeyword,
+    BadOptAccessDiag, DefaultHashTypesDiag, DiagOutOfImpl, LintPassByHand, NonExistentDocKeyword,
     QueryInstability, TyQualified, TykindDiag, TykindKind, UntranslatableDiag,
 };
 use crate::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
@@ -17,6 +17,11 @@ use rustc_span::symbol::{kw, sym, Symbol};
 use rustc_span::Span;
 
 declare_tool_lint! {
+    /// The `default_hash_type` lint detects use of [`std::collections::HashMap`]/[`std::collections::HashSet`],
+    /// suggesting the use of `FxHashMap`/`FxHashSet`.
+    ///
+    /// This can help as `FxHasher` can perform better than the default hasher. DOS protection is not
+    /// required as input is assumed to be trusted.
     pub rustc::DEFAULT_HASH_TYPES,
     Allow,
     "forbid HashMap and HashSet and suggest the FxHash* variants",
@@ -67,6 +72,12 @@ fn typeck_results_of_method_fn<'tcx>(
 }
 
 declare_tool_lint! {
+    /// The `potential_query_instability` lint detects use of methods which can lead to
+    /// potential query instability, such as iterating over a `HashMap`.
+    ///
+    /// Due to the [incremental compilation](https://rustc-dev-guide.rust-lang.org/queries/incremental-compilation.html) model,
+    /// queries must return deterministic, stable results. `HashMap` iteration order can change between compilations,
+    /// and will introduce instability if query results expose the order.
     pub rustc::POTENTIAL_QUERY_INSTABILITY,
     Allow,
     "require explicit opt-in when using potentially unstable methods or functions",
@@ -92,6 +103,8 @@ impl LateLintPass<'_> for QueryStability {
 }
 
 declare_tool_lint! {
+    /// The `usage_of_ty_tykind` lint detects usages of `ty::TyKind::<kind>`,
+    /// where `ty::<kind>` would suffice.
     pub rustc::USAGE_OF_TY_TYKIND,
     Allow,
     "usage of `ty::TyKind` outside of the `ty::sty` module",
@@ -99,6 +112,8 @@ declare_tool_lint! {
 }
 
 declare_tool_lint! {
+    /// The `usage_of_qualified_ty` lint detects usages of `ty::TyKind`,
+    /// where `Ty` should be used instead.
     pub rustc::USAGE_OF_QUALIFIED_TY,
     Allow,
     "using `ty::{Ty,TyCtxt}` instead of importing it",
@@ -254,6 +269,8 @@ fn gen_args(segment: &PathSegment<'_>) -> String {
 }
 
 declare_tool_lint! {
+    /// The `lint_pass_impl_without_macro` detects manual implementations of a lint
+    /// pass, without using [`declare_lint_pass`] or [`impl_lint_pass`].
     pub rustc::LINT_PASS_IMPL_WITHOUT_MACRO,
     Allow,
     "`impl LintPass` without the `declare_lint_pass!` or `impl_lint_pass!` macros"
@@ -285,6 +302,8 @@ impl EarlyLintPass for LintPassImpl {
 }
 
 declare_tool_lint! {
+    /// The `existing_doc_keyword` lint detects use `#[doc()]` keywords
+    /// that don't exist, e.g. `#[doc(keyword = "..")]`.
     pub rustc::EXISTING_DOC_KEYWORD,
     Allow,
     "Check that documented keywords in std and core actually exist",
@@ -315,7 +334,7 @@ impl<'tcx> LateLintPass<'tcx> for ExistingDocKeyword {
                         cx.emit_spanned_lint(
                             EXISTING_DOC_KEYWORD,
                             attr.span,
-                            NonExistantDocKeyword { keyword },
+                            NonExistentDocKeyword { keyword },
                         );
                     }
                 }
@@ -325,6 +344,10 @@ impl<'tcx> LateLintPass<'tcx> for ExistingDocKeyword {
 }
 
 declare_tool_lint! {
+    /// The `untranslatable_diagnostic` lint detects diagnostics created
+    /// without using translatable Fluent strings.
+    ///
+    /// More details on translatable diagnostics can be found [here](https://rustc-dev-guide.rust-lang.org/diagnostics/translation.html).
     pub rustc::UNTRANSLATABLE_DIAGNOSTIC,
     Allow,
     "prevent creation of diagnostics which cannot be translated",
@@ -332,6 +355,11 @@ declare_tool_lint! {
 }
 
 declare_tool_lint! {
+    /// The `diagnostic_outside_of_impl` lint detects diagnostics created manually,
+    /// and inside an `IntoDiagnostic`/`AddToDiagnostic` implementation,
+    /// or a `#[derive(Diagnostic)]`/`#[derive(Subdiagnostic)]` expansion.
+    ///
+    /// More details on diagnostics implementations can be found [here](https://rustc-dev-guide.rust-lang.org/diagnostics/diagnostic-structs.html).
     pub rustc::DIAGNOSTIC_OUTSIDE_OF_IMPL,
     Allow,
     "prevent creation of diagnostics outside of `IntoDiagnostic`/`AddToDiagnostic` impls",
@@ -358,7 +386,7 @@ impl LateLintPass<'_> for Diagnostics {
         for (hir_id, parent) in cx.tcx.hir().parent_iter(expr.hir_id) {
             if let Some(owner_did) = hir_id.as_owner() {
                 found_parent_with_attr = found_parent_with_attr
-                    || cx.tcx.has_attr(owner_did.to_def_id(), sym::rustc_lint_diagnostics);
+                    || cx.tcx.has_attr(owner_did, sym::rustc_lint_diagnostics);
             }
 
             debug!(?parent);
@@ -396,6 +424,8 @@ impl LateLintPass<'_> for Diagnostics {
 }
 
 declare_tool_lint! {
+    /// The `bad_opt_access` lint detects accessing options by field instead of
+    /// the wrapper function.
     pub rustc::BAD_OPT_ACCESS,
     Deny,
     "prevent using options by field access when there is a wrapper function",
diff --git a/compiler/rustc_lint/src/let_underscore.rs b/compiler/rustc_lint/src/let_underscore.rs
index b83a9665f..3eefd1b0e 100644
--- a/compiler/rustc_lint/src/let_underscore.rs
+++ b/compiler/rustc_lint/src/let_underscore.rs
@@ -25,7 +25,7 @@ declare_lint! {
     ///
     /// fn main() {
     ///    #[warn(let_underscore_drop)]
-    ///     // SomeStuct is dropped immediately instead of at end of scope,
+    ///     // SomeStruct is dropped immediately instead of at end of scope,
     ///     // so "Dropping SomeStruct" is printed before "end of main".
     ///     // The order of prints would be reversed if SomeStruct was bound to
     ///     // a name (such as "_foo").
diff --git a/compiler/rustc_lint/src/levels.rs b/compiler/rustc_lint/src/levels.rs
index bc7488fab..bb863f095 100644
--- a/compiler/rustc_lint/src/levels.rs
+++ b/compiler/rustc_lint/src/levels.rs
@@ -3,7 +3,7 @@ use crate::{
     fluent_generated as fluent,
     late::unerased_lint_store,
     lints::{
-        DeprecatedLintName, IgnoredUnlessCrateSpecified, OverruledAtributeLint,
+        DeprecatedLintName, IgnoredUnlessCrateSpecified, OverruledAttributeLint,
         RenamedOrRemovedLint, RenamedOrRemovedLintSuggestion, UnknownLint, UnknownLintSuggestion,
     },
 };
@@ -128,7 +128,7 @@ fn lint_expectations(tcx: TyCtxt<'_>, (): ()) -> Vec<(LintExpectationId, LintExp
         },
         warn_about_weird_lints: false,
         store,
-        registered_tools: &tcx.resolutions(()).registered_tools,
+        registered_tools: &tcx.registered_tools(()),
     };
 
     builder.add_command_line();
@@ -156,7 +156,7 @@ fn shallow_lint_levels_on(tcx: TyCtxt<'_>, owner: hir::OwnerId) -> ShallowLintLe
         },
         warn_about_weird_lints: false,
         store,
-        registered_tools: &tcx.resolutions(()).registered_tools,
+        registered_tools: &tcx.registered_tools(()),
     };
 
     if owner == hir::CRATE_OWNER_ID {
@@ -266,12 +266,12 @@ impl LintLevelsProvider for QueryMapExpectationsWrapper<'_> {
         let LintExpectationId::Stable { attr_id: Some(attr_id), hir_id, attr_index, .. } = id else { bug!("unstable expectation id should already be mapped") };
         let key = LintExpectationId::Unstable { attr_id, lint_index: None };
 
-        if !self.unstable_to_stable_ids.contains_key(&key) {
-            self.unstable_to_stable_ids.insert(
-                key,
-                LintExpectationId::Stable { hir_id, attr_index, lint_index: None, attr_id: None },
-            );
-        }
+        self.unstable_to_stable_ids.entry(key).or_insert(LintExpectationId::Stable {
+            hir_id,
+            attr_index,
+            lint_index: None,
+            attr_id: None,
+        });
 
         self.expectations.push((id.normalize(), expectation));
     }
@@ -612,7 +612,7 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
                     self.emit_spanned_lint(
                         FORBIDDEN_LINT_GROUPS,
                         src.span().into(),
-                        OverruledAtributeLint {
+                        OverruledAttributeLint {
                             overruled: src.span(),
                             lint_level: level.as_str(),
                             lint_source: src.name(),
diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
index 35dc533e5..b35785405 100644
--- a/compiler/rustc_lint/src/lib.rs
+++ b/compiler/rustc_lint/src/lib.rs
@@ -126,7 +126,7 @@ pub use rustc_session::lint::Level::{self, *};
 pub use rustc_session::lint::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId};
 pub use rustc_session::lint::{LintArray, LintPass};
 
-fluent_messages! { "../locales/en-US.ftl" }
+fluent_messages! { "../messages.ftl" }
 
 pub fn provide(providers: &mut Providers) {
     levels::provide(providers);
diff --git a/compiler/rustc_lint/src/lints.rs b/compiler/rustc_lint/src/lints.rs
index 20ab0af58..1d5e02369 100644
--- a/compiler/rustc_lint/src/lints.rs
+++ b/compiler/rustc_lint/src/lints.rs
@@ -806,9 +806,9 @@ pub struct TyQualified {
 pub struct LintPassByHand;
 
 #[derive(LintDiagnostic)]
-#[diag(lint_non_existant_doc_keyword)]
+#[diag(lint_non_existent_doc_keyword)]
 #[help]
-pub struct NonExistantDocKeyword {
+pub struct NonExistentDocKeyword {
     pub keyword: Symbol,
 }
 
@@ -875,7 +875,7 @@ impl AddToDiagnostic for NonBindingLetSub {
 // levels.rs
 #[derive(LintDiagnostic)]
 #[diag(lint_overruled_attribute)]
-pub struct OverruledAtributeLint<'a> {
+pub struct OverruledAttributeLint<'a> {
     #[label]
     pub overruled: Span,
     pub lint_level: &'a str,
@@ -947,7 +947,7 @@ pub struct CStringPtr {
 
 // multiple_supertrait_upcastable.rs
 #[derive(LintDiagnostic)]
-#[diag(lint_multple_supertrait_upcastable)]
+#[diag(lint_multiple_supertrait_upcastable)]
 pub struct MultipleSupertraitUpcastable {
     pub ident: Ident,
 }
@@ -1210,11 +1210,33 @@ impl<'a> DecorateLint<'a, ()> for DropGlue<'_> {
 #[diag(lint_range_endpoint_out_of_range)]
 pub struct RangeEndpointOutOfRange<'a> {
     pub ty: &'a str,
-    #[suggestion(code = "{start}..={literal}{suffix}", applicability = "machine-applicable")]
-    pub suggestion: Span,
-    pub start: String,
-    pub literal: u128,
-    pub suffix: &'a str,
+    #[subdiagnostic]
+    pub sub: UseInclusiveRange<'a>,
+}
+
+#[derive(Subdiagnostic)]
+pub enum UseInclusiveRange<'a> {
+    #[suggestion(
+        lint_range_use_inclusive_range,
+        code = "{start}..={literal}{suffix}",
+        applicability = "machine-applicable"
+    )]
+    WithoutParen {
+        #[primary_span]
+        sugg: Span,
+        start: String,
+        literal: u128,
+        suffix: &'a str,
+    },
+    #[multipart_suggestion(lint_range_use_inclusive_range, applicability = "machine-applicable")]
+    WithParen {
+        #[suggestion_part(code = "=")]
+        eq_sugg: Span,
+        #[suggestion_part(code = "{literal}{suffix}")]
+        lit_sugg: Span,
+        literal: u128,
+        suffix: &'a str,
+    },
 }
 
 #[derive(LintDiagnostic)]
@@ -1390,7 +1412,7 @@ pub struct UnusedOp<'a> {
     pub op: &'a str,
     #[label]
     pub label: Span,
-    #[suggestion(style = "verbose", code = "let _ = ", applicability = "machine-applicable")]
+    #[suggestion(style = "verbose", code = "let _ = ", applicability = "maybe-incorrect")]
     pub suggestion: Span,
 }
 
@@ -1400,7 +1422,7 @@ pub struct UnusedResult<'a> {
     pub ty: Ty<'a>,
 }
 
-// FIXME(davidtwco): this isn't properly translatable becauses of the
+// FIXME(davidtwco): this isn't properly translatable because of the
 // pre/post strings
 #[derive(LintDiagnostic)]
 #[diag(lint_unused_closure)]
@@ -1411,7 +1433,7 @@ pub struct UnusedClosure<'a> {
     pub post: &'a str,
 }
 
-// FIXME(davidtwco): this isn't properly translatable becauses of the
+// FIXME(davidtwco): this isn't properly translatable because of the
 // pre/post strings
 #[derive(LintDiagnostic)]
 #[diag(lint_unused_generator)]
@@ -1422,7 +1444,7 @@ pub struct UnusedGenerator<'a> {
     pub post: &'a str,
 }
 
-// FIXME(davidtwco): this isn't properly translatable becauses of the pre/post
+// FIXME(davidtwco): this isn't properly translatable because of the pre/post
 // strings
 pub struct UnusedDef<'a, 'b> {
     pub pre: &'a str,
@@ -1434,17 +1456,15 @@ pub struct UnusedDef<'a, 'b> {
 }
 
 #[derive(Subdiagnostic)]
-pub enum UnusedDefSuggestion {
-    #[suggestion(
-        lint_suggestion,
-        style = "verbose",
-        code = "let _ = ",
-        applicability = "machine-applicable"
-    )]
-    Default {
-        #[primary_span]
-        span: Span,
-    },
+#[suggestion(
+    lint_suggestion,
+    style = "verbose",
+    code = "let _ = ",
+    applicability = "maybe-incorrect"
+)]
+pub struct UnusedDefSuggestion {
+    #[primary_span]
+    pub span: Span,
 }
 
 // Needed because of def_path_str
diff --git a/compiler/rustc_lint/src/map_unit_fn.rs b/compiler/rustc_lint/src/map_unit_fn.rs
index 62e8b4fe9..7c692fee3 100644
--- a/compiler/rustc_lint/src/map_unit_fn.rs
+++ b/compiler/rustc_lint/src/map_unit_fn.rs
@@ -56,6 +56,7 @@ impl<'tcx> LateLintPass<'tcx> for MapUnitFn {
                         return;
                     }
                     let arg_ty = cx.typeck_results().expr_ty(&args[0]);
+                    let default_span = args[0].span;
                     if let ty::FnDef(id, _) = arg_ty.kind() {
                         let fn_ty = cx.tcx.fn_sig(id).skip_binder();
                         let ret_ty = fn_ty.output().skip_binder();
@@ -64,7 +65,10 @@ impl<'tcx> LateLintPass<'tcx> for MapUnitFn {
                                 MAP_UNIT_FN,
                                 span,
                                 MappingToUnit {
-                                    function_label: cx.tcx.span_of_impl(*id).unwrap(),
+                                    function_label: cx
+                                        .tcx
+                                        .span_of_impl(*id)
+                                        .unwrap_or(default_span),
                                     argument_label: args[0].span,
                                     map_label: arg_ty.default_span(cx.tcx),
                                     suggestion: path.ident.span,
@@ -80,7 +84,10 @@ impl<'tcx> LateLintPass<'tcx> for MapUnitFn {
                                 MAP_UNIT_FN,
                                 span,
                                 MappingToUnit {
-                                    function_label: cx.tcx.span_of_impl(*id).unwrap(),
+                                    function_label: cx
+                                        .tcx
+                                        .span_of_impl(*id)
+                                        .unwrap_or(default_span),
                                     argument_label: args[0].span,
                                     map_label: arg_ty.default_span(cx.tcx),
                                     suggestion: path.ident.span,
diff --git a/compiler/rustc_lint/src/methods.rs b/compiler/rustc_lint/src/methods.rs
index 3045fc1a4..4c25d94a1 100644
--- a/compiler/rustc_lint/src/methods.rs
+++ b/compiler/rustc_lint/src/methods.rs
@@ -2,9 +2,9 @@ use crate::lints::CStringPtr;
 use crate::LateContext;
 use crate::LateLintPass;
 use crate::LintContext;
-use rustc_hir::{Expr, ExprKind, PathSegment};
+use rustc_hir::{Expr, ExprKind};
 use rustc_middle::ty;
-use rustc_span::{symbol::sym, ExpnKind, Span};
+use rustc_span::{symbol::sym, Span};
 
 declare_lint! {
     /// The `temporary_cstring_as_ptr` lint detects getting the inner pointer of
@@ -34,47 +34,14 @@ declare_lint! {
 
 declare_lint_pass!(TemporaryCStringAsPtr => [TEMPORARY_CSTRING_AS_PTR]);
 
-fn in_macro(span: Span) -> bool {
-    if span.from_expansion() {
-        !matches!(span.ctxt().outer_expn_data().kind, ExpnKind::Desugaring(..))
-    } else {
-        false
-    }
-}
-
-fn first_method_call<'tcx>(
-    expr: &'tcx Expr<'tcx>,
-) -> Option<(&'tcx PathSegment<'tcx>, &'tcx Expr<'tcx>)> {
-    if let ExprKind::MethodCall(path, receiver, args, ..) = &expr.kind {
-        if args.iter().any(|e| e.span.from_expansion()) || receiver.span.from_expansion() {
-            None
-        } else {
-            Some((path, *receiver))
-        }
-    } else {
-        None
-    }
-}
-
 impl<'tcx> LateLintPass<'tcx> for TemporaryCStringAsPtr {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
-        if in_macro(expr.span) {
-            return;
-        }
-
-        match first_method_call(expr) {
-            Some((path, unwrap_arg)) if path.ident.name == sym::as_ptr => {
-                let as_ptr_span = path.ident.span;
-                match first_method_call(unwrap_arg) {
-                    Some((path, receiver))
-                        if path.ident.name == sym::unwrap || path.ident.name == sym::expect =>
-                    {
-                        lint_cstring_as_ptr(cx, as_ptr_span, receiver, unwrap_arg);
-                    }
-                    _ => return,
-                }
-            }
-            _ => return,
+        if let ExprKind::MethodCall(as_ptr_path, as_ptr_receiver, ..) = expr.kind
+            && as_ptr_path.ident.name == sym::as_ptr
+            && let ExprKind::MethodCall(unwrap_path, unwrap_receiver, ..) = as_ptr_receiver.kind
+            && (unwrap_path.ident.name == sym::unwrap || unwrap_path.ident.name == sym::expect)
+        {
+            lint_cstring_as_ptr(cx, as_ptr_path.ident.span, unwrap_receiver, as_ptr_receiver);
         }
     }
 }
diff --git a/compiler/rustc_lint/src/non_ascii_idents.rs b/compiler/rustc_lint/src/non_ascii_idents.rs
index f130a9818..4af879b4e 100644
--- a/compiler/rustc_lint/src/non_ascii_idents.rs
+++ b/compiler/rustc_lint/src/non_ascii_idents.rs
@@ -250,7 +250,7 @@ impl EarlyLintPass for NonAsciiIdents {
             let latin_augmented_script_set = AugmentedScriptSet::for_char('A');
             script_states.insert(latin_augmented_script_set, ScriptSetUsage::Verified);
 
-            let mut has_suspicous = false;
+            let mut has_suspicious = false;
             for (symbol, &sp) in symbols.iter() {
                 let symbol_str = symbol.as_str();
                 for ch in symbol_str.chars() {
@@ -278,14 +278,14 @@ impl EarlyLintPass for NonAsciiIdents {
                             if !is_potential_mixed_script_confusable_char(ch) {
                                 ScriptSetUsage::Verified
                             } else {
-                                has_suspicous = true;
+                                has_suspicious = true;
                                 ScriptSetUsage::Suspicious(vec![ch], sp)
                             }
                         });
                 }
             }
 
-            if has_suspicous {
+            if has_suspicious {
                 let verified_augmented_script_sets = script_states
                     .iter()
                     .flat_map(|(k, v)| match v {
diff --git a/compiler/rustc_lint/src/nonstandard_style.rs b/compiler/rustc_lint/src/nonstandard_style.rs
index 71e2e66bd..9efc14849 100644
--- a/compiler/rustc_lint/src/nonstandard_style.rs
+++ b/compiler/rustc_lint/src/nonstandard_style.rs
@@ -328,8 +328,7 @@ impl<'tcx> LateLintPass<'tcx> for NonSnakeCase {
         let crate_ident = if let Some(name) = &cx.tcx.sess.opts.crate_name {
             Some(Ident::from_str(name))
         } else {
-            cx.sess()
-                .find_by_name(&cx.tcx.hir().attrs(hir::CRATE_HIR_ID), sym::crate_name)
+            attr::find_by_name(&cx.tcx.hir().attrs(hir::CRATE_HIR_ID), sym::crate_name)
                 .and_then(|attr| attr.meta())
                 .and_then(|meta| {
                     meta.name_value_literal().and_then(|lit| {
@@ -384,9 +383,7 @@ impl<'tcx> LateLintPass<'tcx> for NonSnakeCase {
         match &fk {
             FnKind::Method(ident, sig, ..) => match method_context(cx, id) {
                 MethodLateContext::PlainImpl => {
-                    if sig.header.abi != Abi::Rust
-                        && cx.tcx.has_attr(id.to_def_id(), sym::no_mangle)
-                    {
+                    if sig.header.abi != Abi::Rust && cx.tcx.has_attr(id, sym::no_mangle) {
                         return;
                     }
                     self.check_snake_case(cx, "method", ident);
@@ -398,7 +395,7 @@ impl<'tcx> LateLintPass<'tcx> for NonSnakeCase {
             },
             FnKind::ItemFn(ident, _, header) => {
                 // Skip foreign-ABI #[no_mangle] functions (Issue #31924)
-                if header.abi != Abi::Rust && cx.tcx.has_attr(id.to_def_id(), sym::no_mangle) {
+                if header.abi != Abi::Rust && cx.tcx.has_attr(id, sym::no_mangle) {
                     return;
                 }
                 self.check_snake_case(cx, "function", ident);
@@ -491,7 +488,7 @@ impl<'tcx> LateLintPass<'tcx> for NonUpperCaseGlobals {
     fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
         let attrs = cx.tcx.hir().attrs(it.hir_id());
         match it.kind {
-            hir::ItemKind::Static(..) if !cx.sess().contains_name(attrs, sym::no_mangle) => {
+            hir::ItemKind::Static(..) if !attr::contains_name(attrs, sym::no_mangle) => {
                 NonUpperCaseGlobals::check_upper_case(cx, "static variable", &it.ident);
             }
             hir::ItemKind::Const(..) => {
diff --git a/compiler/rustc_lint/src/opaque_hidden_inferred_bound.rs b/compiler/rustc_lint/src/opaque_hidden_inferred_bound.rs
index 883a56cb3..f9d43fe22 100644
--- a/compiler/rustc_lint/src/opaque_hidden_inferred_bound.rs
+++ b/compiler/rustc_lint/src/opaque_hidden_inferred_bound.rs
@@ -27,6 +27,8 @@ declare_lint! {
     /// ### Example
     ///
     /// ```rust
+    /// #![feature(type_alias_impl_trait)]
+    ///
     /// trait Duh {}
     ///
     /// impl Duh for i32 {}
@@ -41,7 +43,9 @@ declare_lint! {
     ///     type Assoc = F;
     /// }
     ///
-    /// fn test() -> impl Trait<Assoc = impl Sized> {
+    /// type Tait = impl Sized;
+    ///
+    /// fn test() -> impl Trait<Assoc = Tait> {
     ///     42
     /// }
     /// ```
@@ -54,7 +58,7 @@ declare_lint! {
     ///
     /// Although the hidden type, `i32` does satisfy this bound, we do not
     /// consider the return type to be well-formed with this lint. It can be
-    /// fixed by changing `impl Sized` into `impl Sized + Send`.
+    /// fixed by changing `Tait = impl Sized` into `Tait = impl Sized + Send`.
     pub OPAQUE_HIDDEN_INFERRED_BOUND,
     Warn,
     "detects the use of nested `impl Trait` types in associated type bounds that are not general enough"
@@ -64,7 +68,7 @@ declare_lint_pass!(OpaqueHiddenInferredBound => [OPAQUE_HIDDEN_INFERRED_BOUND]);
 
 impl<'tcx> LateLintPass<'tcx> for OpaqueHiddenInferredBound {
     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'tcx>) {
-        let hir::ItemKind::OpaqueTy(_) = &item.kind else { return; };
+        let hir::ItemKind::OpaqueTy(opaque) = &item.kind else { return; };
         let def_id = item.owner_id.def_id.to_def_id();
         let infcx = &cx.tcx.infer_ctxt().build();
         // For every projection predicate in the opaque type's explicit bounds,
@@ -81,6 +85,17 @@ impl<'tcx> LateLintPass<'tcx> for OpaqueHiddenInferredBound {
             // have opaques in them anyways.
             let Some(proj_term) = proj.term.ty() else { continue };
 
+            // HACK: `impl Trait<Assoc = impl Trait2>` from an RPIT is "ok"...
+            if let ty::Alias(ty::Opaque, opaque_ty) = *proj_term.kind()
+                && cx.tcx.parent(opaque_ty.def_id) == def_id
+                && matches!(
+                    opaque.origin,
+                    hir::OpaqueTyOrigin::FnReturn(_) | hir::OpaqueTyOrigin::AsyncFn(_)
+                )
+            {
+                continue;
+            }
+
             let proj_ty =
                 cx.tcx.mk_projection(proj.projection_ty.def_id, proj.projection_ty.substs);
             // For every instance of the projection type in the bounds,
diff --git a/compiler/rustc_lint/src/types.rs b/compiler/rustc_lint/src/types.rs
index 85958c417..a6ba74220 100644
--- a/compiler/rustc_lint/src/types.rs
+++ b/compiler/rustc_lint/src/types.rs
@@ -4,7 +4,8 @@ use crate::{
         AtomicOrderingFence, AtomicOrderingLoad, AtomicOrderingStore, ImproperCTypes,
         InvalidAtomicOrderingDiag, OnlyCastu8ToChar, OverflowingBinHex, OverflowingBinHexSign,
         OverflowingBinHexSub, OverflowingInt, OverflowingIntHelp, OverflowingLiteral,
-        OverflowingUInt, RangeEndpointOutOfRange, UnusedComparisons, VariantSizeDifferencesDiag,
+        OverflowingUInt, RangeEndpointOutOfRange, UnusedComparisons, UseInclusiveRange,
+        VariantSizeDifferencesDiag,
     },
 };
 use crate::{LateContext, LateLintPass, LintContext};
@@ -17,7 +18,7 @@ use rustc_hir::{is_range_literal, Expr, ExprKind, Node};
 use rustc_middle::ty::layout::{IntegerExt, LayoutOf, SizeSkeleton};
 use rustc_middle::ty::subst::SubstsRef;
 use rustc_middle::ty::{
-    self, AdtKind, DefIdTree, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitableExt,
+    self, AdtKind, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitableExt,
 };
 use rustc_span::def_id::LocalDefId;
 use rustc_span::source_map;
@@ -136,6 +137,14 @@ fn lint_overflowing_range_endpoint<'tcx>(
     expr: &'tcx hir::Expr<'tcx>,
     ty: &str,
 ) -> bool {
+    // Look past casts to support cases like `0..256 as u8`
+    let (expr, lit_span) = if let Node::Expr(par_expr) = cx.tcx.hir().get(cx.tcx.hir().parent_id(expr.hir_id))
+      && let ExprKind::Cast(_, _) = par_expr.kind {
+        (par_expr, expr.span)
+    } else {
+        (expr, expr.span)
+    };
+
     // We only want to handle exclusive (`..`) ranges,
     // which are represented as `ExprKind::Struct`.
     let par_id = cx.tcx.hir().parent_id(expr.hir_id);
@@ -155,7 +164,6 @@ fn lint_overflowing_range_endpoint<'tcx>(
     if !(eps[1].expr.hir_id == expr.hir_id && lit_val - 1 == max) {
         return false;
     };
-    let Ok(start) = cx.sess().source_map().span_to_snippet(eps[0].span) else { return false };
 
     use rustc_ast::{LitIntType, LitKind};
     let suffix = match lit.node {
@@ -164,16 +172,28 @@ fn lint_overflowing_range_endpoint<'tcx>(
         LitKind::Int(_, LitIntType::Unsuffixed) => "",
         _ => bug!(),
     };
-    cx.emit_spanned_lint(
-        OVERFLOWING_LITERALS,
-        struct_expr.span,
-        RangeEndpointOutOfRange {
-            ty,
-            suggestion: struct_expr.span,
+
+    let sub_sugg = if expr.span.lo() == lit_span.lo() {
+        let Ok(start) = cx.sess().source_map().span_to_snippet(eps[0].span) else { return false };
+        UseInclusiveRange::WithoutParen {
+            sugg: struct_expr.span.shrink_to_lo().to(lit_span.shrink_to_hi()),
             start,
             literal: lit_val - 1,
             suffix,
-        },
+        }
+    } else {
+        UseInclusiveRange::WithParen {
+            eq_sugg: expr.span.shrink_to_lo(),
+            lit_sugg: lit_span,
+            literal: lit_val - 1,
+            suffix,
+        }
+    };
+
+    cx.emit_spanned_lint(
+        OVERFLOWING_LITERALS,
+        struct_expr.span,
+        RangeEndpointOutOfRange { ty, sub: sub_sugg },
     );
 
     // We've just emitted a lint, special cased for `(...)..MAX+1` ranges,
@@ -750,7 +770,7 @@ pub(crate) fn repr_nullable_ptr<'tcx>(
     debug!("is_repr_nullable_ptr(cx, ty = {:?})", ty);
     if let ty::Adt(ty_def, substs) = ty.kind() {
         let field_ty = match &ty_def.variants().raw[..] {
-            [var_one, var_two] => match (&var_one.fields[..], &var_two.fields[..]) {
+            [var_one, var_two] => match (&var_one.fields.raw[..], &var_two.fields.raw[..]) {
                 ([], [field]) | ([field], []) => field.ty(cx.tcx, substs),
                 _ => return None,
             },
diff --git a/compiler/rustc_lint/src/unused.rs b/compiler/rustc_lint/src/unused.rs
index 3a92f5806..28cc63198 100644
--- a/compiler/rustc_lint/src/unused.rs
+++ b/compiler/rustc_lint/src/unused.rs
@@ -12,9 +12,9 @@ use rustc_errors::{pluralize, MultiSpan};
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::DefId;
-use rustc_infer::traits::util::elaborate_predicates_with_span;
+use rustc_infer::traits::util::elaborate;
 use rustc_middle::ty::adjustment;
-use rustc_middle::ty::{self, DefIdTree, Ty};
+use rustc_middle::ty::{self, Ty};
 use rustc_span::symbol::Symbol;
 use rustc_span::symbol::{kw, sym};
 use rustc_span::{BytePos, Span};
@@ -103,8 +103,10 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
             && let ty = cx.typeck_results().expr_ty(&await_expr)
             && let ty::Alias(ty::Opaque, ty::AliasTy { def_id: future_def_id, .. }) = ty.kind()
             && cx.tcx.ty_is_opaque_future(ty)
-            // FIXME: This also includes non-async fns that return `impl Future`.
             && let async_fn_def_id = cx.tcx.parent(*future_def_id)
+            && matches!(cx.tcx.def_kind(async_fn_def_id), DefKind::Fn | DefKind::AssocFn)
+            // Check that this `impl Future` actually comes from an `async fn`
+            && cx.tcx.asyncness(async_fn_def_id).is_async()
             && check_must_use_def(
                 cx,
                 async_fn_def_id,
@@ -123,7 +125,7 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
         let must_use_result = is_ty_must_use(cx, ty, &expr, expr.span);
         let type_lint_emitted_or_suppressed = match must_use_result {
             Some(path) => {
-                emit_must_use_untranslated(cx, &path, "", "", 1);
+                emit_must_use_untranslated(cx, &path, "", "", 1, false);
                 true
             }
             None => false,
@@ -254,24 +256,23 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
                 }
                 ty::Adt(def, _) => is_def_must_use(cx, def.did(), span),
                 ty::Alias(ty::Opaque, ty::AliasTy { def_id: def, .. }) => {
-                    elaborate_predicates_with_span(
-                        cx.tcx,
-                        cx.tcx.explicit_item_bounds(def).iter().cloned(),
-                    )
-                    .find_map(|obligation| {
-                        // We only look at the `DefId`, so it is safe to skip the binder here.
-                        if let ty::PredicateKind::Clause(ty::Clause::Trait(
-                            ref poly_trait_predicate,
-                        )) = obligation.predicate.kind().skip_binder()
-                        {
-                            let def_id = poly_trait_predicate.trait_ref.def_id;
-
-                            is_def_must_use(cx, def_id, span)
-                        } else {
-                            None
-                        }
-                    })
-                    .map(|inner| MustUsePath::Opaque(Box::new(inner)))
+                    elaborate(cx.tcx, cx.tcx.explicit_item_bounds(def).iter().cloned())
+                        // We only care about self bounds for the impl-trait
+                        .filter_only_self()
+                        .find_map(|(pred, _span)| {
+                            // We only look at the `DefId`, so it is safe to skip the binder here.
+                            if let ty::PredicateKind::Clause(ty::Clause::Trait(
+                                ref poly_trait_predicate,
+                            )) = pred.kind().skip_binder()
+                            {
+                                let def_id = poly_trait_predicate.trait_ref.def_id;
+
+                                is_def_must_use(cx, def_id, span)
+                            } else {
+                                None
+                            }
+                        })
+                        .map(|inner| MustUsePath::Opaque(Box::new(inner)))
                 }
                 ty::Dynamic(binders, _, _) => binders.iter().find_map(|predicate| {
                     if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate.skip_binder()
@@ -358,6 +359,7 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
                         descr_pre_path,
                         descr_post_path,
                         1,
+                        false,
                     )
                 })
                 .is_some()
@@ -370,6 +372,7 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
             descr_pre: &str,
             descr_post: &str,
             plural_len: usize,
+            is_inner: bool,
         ) {
             let plural_suffix = pluralize!(plural_len);
 
@@ -377,20 +380,22 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
                 MustUsePath::Suppressed => {}
                 MustUsePath::Boxed(path) => {
                     let descr_pre = &format!("{}boxed ", descr_pre);
-                    emit_must_use_untranslated(cx, path, descr_pre, descr_post, plural_len);
+                    emit_must_use_untranslated(cx, path, descr_pre, descr_post, plural_len, true);
                 }
                 MustUsePath::Opaque(path) => {
                     let descr_pre = &format!("{}implementer{} of ", descr_pre, plural_suffix);
-                    emit_must_use_untranslated(cx, path, descr_pre, descr_post, plural_len);
+                    emit_must_use_untranslated(cx, path, descr_pre, descr_post, plural_len, true);
                 }
                 MustUsePath::TraitObject(path) => {
                     let descr_post = &format!(" trait object{}{}", plural_suffix, descr_post);
-                    emit_must_use_untranslated(cx, path, descr_pre, descr_post, plural_len);
+                    emit_must_use_untranslated(cx, path, descr_pre, descr_post, plural_len, true);
                 }
                 MustUsePath::TupleElement(elems) => {
                     for (index, path) in elems {
                         let descr_post = &format!(" in tuple element {}", index);
-                        emit_must_use_untranslated(cx, path, descr_pre, descr_post, plural_len);
+                        emit_must_use_untranslated(
+                            cx, path, descr_pre, descr_post, plural_len, true,
+                        );
                     }
                 }
                 MustUsePath::Array(path, len) => {
@@ -401,6 +406,7 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
                         descr_pre,
                         descr_post,
                         plural_len.saturating_add(usize::try_from(*len).unwrap_or(usize::MAX)),
+                        true,
                     );
                 }
                 MustUsePath::Closure(span) => {
@@ -418,19 +424,6 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
                     );
                 }
                 MustUsePath::Def(span, def_id, reason) => {
-                    let suggestion = if matches!(
-                        cx.tcx.get_diagnostic_name(*def_id),
-                        Some(sym::add)
-                            | Some(sym::sub)
-                            | Some(sym::mul)
-                            | Some(sym::div)
-                            | Some(sym::rem)
-                            | Some(sym::neg),
-                    ) {
-                        Some(UnusedDefSuggestion::Default { span: span.shrink_to_lo() })
-                    } else {
-                        None
-                    };
                     cx.emit_spanned_lint(
                         UNUSED_MUST_USE,
                         *span,
@@ -440,7 +433,8 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
                             cx,
                             def_id: *def_id,
                             note: *reason,
-                            suggestion,
+                            suggestion: (!is_inner)
+                                .then_some(UnusedDefSuggestion { span: span.shrink_to_lo() }),
                         },
                     );
                 }
@@ -812,7 +806,9 @@ trait UnusedDelimLint {
     fn check_item(&mut self, cx: &EarlyContext<'_>, item: &ast::Item) {
         use ast::ItemKind::*;
 
-        if let Const(.., Some(expr)) | Static(.., Some(expr)) = &item.kind {
+        if let Const(box ast::ConstItem { expr: Some(expr), .. })
+        | Static(box ast::StaticItem { expr: Some(expr), .. }) = &item.kind
+        {
             self.check_unused_delims_expr(
                 cx,
                 expr,
@@ -1349,9 +1345,8 @@ declare_lint! {
     /// ### Example
     ///
     /// ```rust
-    /// #![feature(box_syntax)]
     /// fn main() {
-    ///     let a = (box [1, 2, 3]).len();
+    ///     let a = Box::new([1, 2, 3]).len();
     /// }
     /// ```
     ///
@@ -1372,7 +1367,11 @@ declare_lint_pass!(UnusedAllocation => [UNUSED_ALLOCATION]);
 impl<'tcx> LateLintPass<'tcx> for UnusedAllocation {
     fn check_expr(&mut self, cx: &LateContext<'_>, e: &hir::Expr<'_>) {
         match e.kind {
-            hir::ExprKind::Box(_) => {}
+            hir::ExprKind::Call(path_expr, [_])
+                if let hir::ExprKind::Path(qpath) = &path_expr.kind
+                && let Some(did) = cx.qpath_res(qpath, path_expr.hir_id).opt_def_id()
+                && cx.tcx.is_diagnostic_item(sym::box_new, did)
+                => {}
             _ => return,
         }