Auto merge of #107143 - compiler-errors:rollup-zabvmo5, r=compiler-errors

Rollup of 9 pull requests

Successful merges:

 - #104154 (Change `bindings_with_variant_name` to deny-by-default)
 - #104347 (diagnostics: suggest changing `s@self::{macro}`@::macro`` for exported)
 - #104672 (Unify stable and unstable sort implementations in same core module)
 - #107048 (check for x version updates)
 - #107061 (Implement some more new solver candidates and fix some bugs)
 - #107095 (rustdoc: remove redundant CSS selector `.sidebar .current`)
 - #107112 (Fix typo in opaque_types.rs)
 - #107124 (fix check macro expansion)
 - #107131 (rustdoc: use CSS inline layout for radio line instead of flexbox)

Failed merges:

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

Cargo.lock

@@ -5608,6 +5608,7 @@ dependencies = [
  "lazy_static",
  "miropt-test-tools",
  "regex",
+ "semver",
  "termcolor",
  "walkdir",
 ]

compiler/rustc_index/src/vec.rs

@@ -207,7 +207,12 @@ pub fn drain_enumerated<'a, R: RangeBounds<usize>>(
         &'a mut self,
         range: R,
     ) -> impl Iterator<Item = (I, T)> + 'a {
-        self.raw.drain(range).enumerate().map(|(n, t)| (I::new(n), t))
+        let begin = match range.start_bound() {
+            std::ops::Bound::Included(i) => *i,
+            std::ops::Bound::Excluded(i) => i.checked_add(1).unwrap(),
+            std::ops::Bound::Unbounded => 0,
+        };
+        self.raw.drain(range).enumerate().map(move |(n, t)| (I::new(begin + n), t))
     }
 
     #[inline]

compiler/rustc_infer/src/infer/opaque_types.rs

@@ -479,7 +479,7 @@ fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
             }
 
             ty::Alias(ty::Opaque, ty::AliasTy { def_id, ref substs, .. }) => {
-                // Skip lifetime paramters that are not captures.
+                // Skip lifetime parameters that are not captures.
                 let variances = self.tcx.variances_of(*def_id);
 
                 for (v, s) in std::iter::zip(variances, substs.iter()) {
@@ -492,7 +492,7 @@ fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
             ty::Alias(ty::Projection, proj)
                 if self.tcx.def_kind(proj.def_id) == DefKind::ImplTraitPlaceholder =>
             {
-                // Skip lifetime paramters that are not captures.
+                // Skip lifetime parameters that are not captures.
                 let variances = self.tcx.variances_of(proj.def_id);
 
                 for (v, s) in std::iter::zip(variances, proj.substs.iter()) {

compiler/rustc_lint_defs/src/builtin.rs

@@ -708,7 +708,7 @@
     ///
     /// ### Example
     ///
-    /// ```rust
+    /// ```rust,compile_fail
     /// pub enum Enum {
     ///     Foo,
     ///     Bar,
@@ -743,7 +743,7 @@
     /// [identifier pattern]: https://doc.rust-lang.org/reference/patterns.html#identifier-patterns
     /// [path pattern]: https://doc.rust-lang.org/reference/patterns.html#path-patterns
     pub BINDINGS_WITH_VARIANT_NAME,
-    Warn,
+    Deny,
     "detects pattern bindings with the same name as one of the matched variants"
 }
 

compiler/rustc_resolve/src/diagnostics.rs

@@ -2125,9 +2125,15 @@ pub(crate) fn check_for_module_export_macro(
 
                 let source_map = self.r.session.source_map();
 
+                // Make sure this is actually crate-relative.
+                let is_definitely_crate = import
+                    .module_path
+                    .first()
+                    .map_or(false, |f| f.ident.name != kw::SelfLower && f.ident.name != kw::Super);
+
                 // Add the import to the start, with a `{` if required.
                 let start_point = source_map.start_point(after_crate_name);
-                if let Ok(start_snippet) = source_map.span_to_snippet(start_point) {
+                if is_definitely_crate && let Ok(start_snippet) = source_map.span_to_snippet(start_point) {
                     corrections.push((
                         start_point,
                         if has_nested {
@@ -2139,11 +2145,17 @@ pub(crate) fn check_for_module_export_macro(
                             format!("{{{}, {}", import_snippet, start_snippet)
                         },
                     ));
-                }
 
-                // Add a `};` to the end if nested, matching the `{` added at the start.
+                    // Add a `};` to the end if nested, matching the `{` added at the start.
-                if !has_nested {
+                    if !has_nested {
-                    corrections.push((source_map.end_point(after_crate_name), "};".to_string()));
+                        corrections.push((source_map.end_point(after_crate_name), "};".to_string()));
+                    }
+                } else {
+                    // If the root import is module-relative, add the import separately
+                    corrections.push((
+                        import.use_span.shrink_to_lo(),
+                        format!("use {module_name}::{import_snippet};\n"),
+                    ));
                 }
             }
 

compiler/rustc_trait_selection/src/solve/assembly.rs

@@ -1,7 +1,7 @@
 //! Code shared by trait and projection goals for candidate assembly.
 
 use super::infcx_ext::InferCtxtExt;
-use super::{CanonicalResponse, EvalCtxt, Goal, QueryResult};
+use super::{CanonicalResponse, Certainty, EvalCtxt, Goal, MaybeCause, QueryResult};
 use rustc_hir::def_id::DefId;
 use rustc_infer::traits::query::NoSolution;
 use rustc_infer::traits::util::elaborate_predicates;
@@ -79,7 +79,7 @@ pub(super) enum CandidateSource {
     AliasBound(usize),
 }
 
-pub(super) trait GoalKind<'tcx>: TypeFoldable<'tcx> + Copy {
+pub(super) trait GoalKind<'tcx>: TypeFoldable<'tcx> + Copy + Eq {
     fn self_ty(self) -> Ty<'tcx>;
 
     fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self;
@@ -117,6 +117,22 @@ fn consider_builtin_copy_clone_candidate(
         ecx: &mut EvalCtxt<'_, 'tcx>,
         goal: Goal<'tcx, Self>,
     ) -> QueryResult<'tcx>;
+
+    fn consider_builtin_pointer_sized_candidate(
+        ecx: &mut EvalCtxt<'_, 'tcx>,
+        goal: Goal<'tcx, Self>,
+    ) -> QueryResult<'tcx>;
+
+    fn consider_builtin_fn_trait_candidates(
+        ecx: &mut EvalCtxt<'_, 'tcx>,
+        goal: Goal<'tcx, Self>,
+        kind: ty::ClosureKind,
+    ) -> QueryResult<'tcx>;
+
+    fn consider_builtin_tuple_candidate(
+        ecx: &mut EvalCtxt<'_, 'tcx>,
+        goal: Goal<'tcx, Self>,
+    ) -> QueryResult<'tcx>;
 }
 
 impl<'tcx> EvalCtxt<'_, 'tcx> {
@@ -124,6 +140,20 @@ pub(super) fn assemble_and_evaluate_candidates<G: GoalKind<'tcx>>(
         &mut self,
         goal: Goal<'tcx, G>,
     ) -> Vec<Candidate<'tcx>> {
+        debug_assert_eq!(goal, self.infcx.resolve_vars_if_possible(goal));
+
+        // HACK: `_: Trait` is ambiguous, because it may be satisfied via a builtin rule,
+        // object bound, alias bound, etc. We are unable to determine this until we can at
+        // least structually resolve the type one layer.
+        if goal.predicate.self_ty().is_ty_var() {
+            return vec![Candidate {
+                source: CandidateSource::BuiltinImpl,
+                result: self
+                    .make_canonical_response(Certainty::Maybe(MaybeCause::Ambiguity))
+                    .unwrap(),
+            }];
+        }
+
         let mut candidates = Vec::new();
 
         self.assemble_candidates_after_normalizing_self_ty(goal, &mut candidates);
@@ -169,6 +199,7 @@ fn assemble_candidates_after_normalizing_self_ty<G: GoalKind<'tcx>>(
                 Ok((_, certainty)) => certainty,
                 Err(NoSolution) => return,
             };
+            let normalized_ty = self.infcx.resolve_vars_if_possible(normalized_ty);
 
             // NOTE: Alternatively we could call `evaluate_goal` here and only have a `Normalized` candidate.
             // This doesn't work as long as we use `CandidateSource` in winnowing.
@@ -224,6 +255,12 @@ fn assemble_builtin_impl_candidates<G: GoalKind<'tcx>>(
             || lang_items.clone_trait() == Some(trait_def_id)
         {
             G::consider_builtin_copy_clone_candidate(self, goal)
+        } else if lang_items.pointer_sized() == Some(trait_def_id) {
+            G::consider_builtin_pointer_sized_candidate(self, goal)
+        } else if let Some(kind) = self.tcx().fn_trait_kind_from_def_id(trait_def_id) {
+            G::consider_builtin_fn_trait_candidates(self, goal, kind)
+        } else if lang_items.tuple_trait() == Some(trait_def_id) {
+            G::consider_builtin_tuple_candidate(self, goal)
         } else {
             Err(NoSolution)
         };

compiler/rustc_trait_selection/src/solve/fulfill.rs

@@ -52,7 +52,7 @@ fn select_all_or_error(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<FulfillmentErr
             .drain(..)
             .map(|obligation| FulfillmentError {
                 obligation: obligation.clone(),
-                code: FulfillmentErrorCode::CodeSelectionError(SelectionError::Unimplemented),
+                code: FulfillmentErrorCode::CodeAmbiguity,
                 root_obligation: obligation,
             })
             .collect()
@@ -75,7 +75,9 @@ fn select_where_possible(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<FulfillmentE
                     Err(NoSolution) => {
                         errors.push(FulfillmentError {
                             obligation: obligation.clone(),
-                            code: FulfillmentErrorCode::CodeAmbiguity,
+                            code: FulfillmentErrorCode::CodeSelectionError(
+                                SelectionError::Unimplemented,
+                            ),
                             root_obligation: obligation,
                         });
                         continue;

compiler/rustc_trait_selection/src/solve/project_goals.rs

@@ -2,6 +2,7 @@
 
 use super::assembly::{self, Candidate, CandidateSource};
 use super::infcx_ext::InferCtxtExt;
+use super::trait_goals::structural_traits;
 use super::{Certainty, EvalCtxt, Goal, MaybeCause, QueryResult};
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def::DefKind;
@@ -11,9 +12,9 @@
 use rustc_infer::traits::specialization_graph::LeafDef;
 use rustc_infer::traits::Reveal;
 use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams};
-use rustc_middle::ty::TypeVisitable;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_middle::ty::{ProjectionPredicate, TypeSuperVisitable, TypeVisitor};
+use rustc_middle::ty::{ToPredicate, TypeVisitable};
 use rustc_span::DUMMY_SP;
 use std::iter;
 use std::ops::ControlFlow;
@@ -351,6 +352,46 @@ fn consider_builtin_copy_clone_candidate(
     ) -> QueryResult<'tcx> {
         bug!("`Copy`/`Clone` does not have an associated type: {:?}", goal);
     }
+
+    fn consider_builtin_pointer_sized_candidate(
+        _ecx: &mut EvalCtxt<'_, 'tcx>,
+        goal: Goal<'tcx, Self>,
+    ) -> QueryResult<'tcx> {
+        bug!("`PointerSized` does not have an associated type: {:?}", goal);
+    }
+
+    fn consider_builtin_fn_trait_candidates(
+        ecx: &mut EvalCtxt<'_, 'tcx>,
+        goal: Goal<'tcx, Self>,
+        goal_kind: ty::ClosureKind,
+    ) -> QueryResult<'tcx> {
+        if let Some(tupled_inputs_and_output) =
+            structural_traits::extract_tupled_inputs_and_output_from_callable(
+                ecx.tcx(),
+                goal.predicate.self_ty(),
+                goal_kind,
+            )?
+        {
+            let pred = tupled_inputs_and_output
+                .map_bound(|(inputs, output)| ty::ProjectionPredicate {
+                    projection_ty: ecx
+                        .tcx()
+                        .mk_alias_ty(goal.predicate.def_id(), [goal.predicate.self_ty(), inputs]),
+                    term: output.into(),
+                })
+                .to_predicate(ecx.tcx());
+            Self::consider_assumption(ecx, goal, pred)
+        } else {
+            ecx.make_canonical_response(Certainty::Maybe(MaybeCause::Ambiguity))
+        }
+    }
+
+    fn consider_builtin_tuple_candidate(
+        _ecx: &mut EvalCtxt<'_, 'tcx>,
+        goal: Goal<'tcx, Self>,
+    ) -> QueryResult<'tcx> {
+        bug!("`Tuple` does not have an associated type: {:?}", goal);
+    }
 }
 
 /// This behavior is also implemented in `rustc_ty_utils` and in the old `project` code.

compiler/rustc_trait_selection/src/solve/trait_goals.rs

@@ -4,16 +4,16 @@
 
 use super::assembly::{self, Candidate, CandidateSource};
 use super::infcx_ext::InferCtxtExt;
-use super::{EvalCtxt, Goal, QueryResult};
+use super::{Certainty, EvalCtxt, Goal, MaybeCause, QueryResult};
 use rustc_hir::def_id::DefId;
 use rustc_infer::infer::InferCtxt;
 use rustc_infer::traits::query::NoSolution;
 use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams};
-use rustc_middle::ty::TraitPredicate;
+use rustc_middle::ty::{self, ToPredicate, Ty, TyCtxt};
-use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_middle::ty::{TraitPredicate, TypeVisitable};
 use rustc_span::DUMMY_SP;
 
-mod structural_traits;
+pub mod structural_traits;
 
 impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
     fn self_ty(self) -> Ty<'tcx> {
@@ -127,6 +127,64 @@ fn consider_builtin_copy_clone_candidate(
             structural_traits::instantiate_constituent_tys_for_copy_clone_trait,
         )
     }
+
+    fn consider_builtin_pointer_sized_candidate(
+        ecx: &mut EvalCtxt<'_, 'tcx>,
+        goal: Goal<'tcx, Self>,
+    ) -> QueryResult<'tcx> {
+        if goal.predicate.self_ty().has_non_region_infer() {
+            return ecx.make_canonical_response(Certainty::Maybe(MaybeCause::Ambiguity));
+        }
+
+        let tcx = ecx.tcx();
+        let self_ty = tcx.erase_regions(goal.predicate.self_ty());
+
+        if let Ok(layout) = tcx.layout_of(goal.param_env.and(self_ty))
+            &&  let usize_layout = tcx.layout_of(ty::ParamEnv::empty().and(tcx.types.usize)).unwrap().layout
+            && layout.layout.size() == usize_layout.size()
+            && layout.layout.align().abi == usize_layout.align().abi
+        {
+            // FIXME: We could make this faster by making a no-constraints response
+            ecx.make_canonical_response(Certainty::Yes)
+        } else {
+            Err(NoSolution)
+        }
+    }
+
+    fn consider_builtin_fn_trait_candidates(
+        ecx: &mut EvalCtxt<'_, 'tcx>,
+        goal: Goal<'tcx, Self>,
+        goal_kind: ty::ClosureKind,
+    ) -> QueryResult<'tcx> {
+        if let Some(tupled_inputs_and_output) =
+            structural_traits::extract_tupled_inputs_and_output_from_callable(
+                ecx.tcx(),
+                goal.predicate.self_ty(),
+                goal_kind,
+            )?
+        {
+            let pred = tupled_inputs_and_output
+                .map_bound(|(inputs, _)| {
+                    ecx.tcx()
+                        .mk_trait_ref(goal.predicate.def_id(), [goal.predicate.self_ty(), inputs])
+                })
+                .to_predicate(ecx.tcx());
+            Self::consider_assumption(ecx, goal, pred)
+        } else {
+            ecx.make_canonical_response(Certainty::Maybe(MaybeCause::Ambiguity))
+        }
+    }
+
+    fn consider_builtin_tuple_candidate(
+        ecx: &mut EvalCtxt<'_, 'tcx>,
+        goal: Goal<'tcx, Self>,
+    ) -> QueryResult<'tcx> {
+        if let ty::Tuple(..) = goal.predicate.self_ty().kind() {
+            ecx.make_canonical_response(Certainty::Yes)
+        } else {
+            Err(NoSolution)
+        }
+    }
 }
 
 impl<'tcx> EvalCtxt<'_, 'tcx> {

compiler/rustc_trait_selection/src/solve/trait_goals/structural_traits.rs

@@ -1,6 +1,6 @@
 use rustc_hir::{Movability, Mutability};
 use rustc_infer::{infer::InferCtxt, traits::query::NoSolution};
-use rustc_middle::ty::{self, Ty};
+use rustc_middle::ty::{self, Ty, TyCtxt};
 
 // Calculates the constituent types of a type for `auto trait` purposes.
 //
@@ -30,10 +30,7 @@ pub(super) fn instantiate_constituent_tys_for_auto_trait<'tcx>(
         | ty::Foreign(..)
         | ty::Alias(ty::Projection, ..)
         | ty::Bound(..)
-        | ty::Infer(ty::TyVar(_)) => {
+        | ty::Infer(ty::TyVar(_)) => Err(NoSolution),
-            // FIXME: Do we need to mark anything as ambiguous here? Yeah?
-            Err(NoSolution)
-        }
 
         ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => bug!(),
 
@@ -101,9 +98,8 @@ pub(super) fn instantiate_constituent_tys_for_sized_trait<'tcx>(
         | ty::Dynamic(..)
         | ty::Foreign(..)
         | ty::Alias(..)
-        | ty::Param(_) => Err(NoSolution),
+        | ty::Param(_)
-
+        | ty::Infer(ty::TyVar(_)) => Err(NoSolution),
-        ty::Infer(ty::TyVar(_)) => bug!("FIXME: ambiguous"),
 
         ty::Placeholder(..)
         | ty::Bound(..)
@@ -151,9 +147,8 @@ pub(super) fn instantiate_constituent_tys_for_copy_clone_trait<'tcx>(
         | ty::Ref(_, _, Mutability::Mut)
         | ty::Adt(_, _)
         | ty::Alias(_, _)
-        | ty::Param(_) => Err(NoSolution),
+        | ty::Param(_)
-
+        | ty::Infer(ty::TyVar(_)) => Err(NoSolution),
-        ty::Infer(ty::TyVar(_)) => bug!("FIXME: ambiguous"),
 
         ty::Placeholder(..)
         | ty::Bound(..)
@@ -177,3 +172,52 @@ pub(super) fn instantiate_constituent_tys_for_copy_clone_trait<'tcx>(
         }
     }
 }
+
+pub(crate) fn extract_tupled_inputs_and_output_from_callable<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    self_ty: Ty<'tcx>,
+    goal_kind: ty::ClosureKind,
+) -> Result<Option<ty::Binder<'tcx, (Ty<'tcx>, Ty<'tcx>)>>, NoSolution> {
+    match *self_ty.kind() {
+        ty::FnDef(def_id, substs) => Ok(Some(
+            tcx.bound_fn_sig(def_id)
+                .subst(tcx, substs)
+                .map_bound(|sig| (tcx.mk_tup(sig.inputs().iter()), sig.output())),
+        )),
+        ty::FnPtr(sig) => {
+            Ok(Some(sig.map_bound(|sig| (tcx.mk_tup(sig.inputs().iter()), sig.output()))))
+        }
+        ty::Closure(_, substs) => {
+            let closure_substs = substs.as_closure();
+            match closure_substs.kind_ty().to_opt_closure_kind() {
+                Some(closure_kind) if closure_kind.extends(goal_kind) => {}
+                None => return Ok(None),
+                _ => return Err(NoSolution),
+            }
+            Ok(Some(closure_substs.sig().map_bound(|sig| (sig.inputs()[0], sig.output()))))
+        }
+        ty::Bool
+        | ty::Char
+        | ty::Int(_)
+        | ty::Uint(_)
+        | ty::Float(_)
+        | ty::Adt(_, _)
+        | ty::Foreign(_)
+        | ty::Str
+        | ty::Array(_, _)
+        | ty::Slice(_)
+        | ty::RawPtr(_)
+        | ty::Ref(_, _, _)
+        | ty::Dynamic(_, _, _)
+        | ty::Generator(_, _, _)
+        | ty::GeneratorWitness(_)
+        | ty::Never
+        | ty::Tuple(_)
+        | ty::Alias(_, _)
+        | ty::Param(_)
+        | ty::Placeholder(_)
+        | ty::Bound(_, _)
+        | ty::Infer(_)
+        | ty::Error(_) => Err(NoSolution),
+    }
+}

library/alloc/src/slice.rs

@@ -19,10 +19,12 @@
 use core::mem::{self, SizedTypeProperties};
 #[cfg(not(no_global_oom_handling))]
 use core::ptr;
+#[cfg(not(no_global_oom_handling))]
+use core::slice::sort;
 
 use crate::alloc::Allocator;
 #[cfg(not(no_global_oom_handling))]
-use crate::alloc::Global;
+use crate::alloc::{self, Global};
 #[cfg(not(no_global_oom_handling))]
 use crate::borrow::ToOwned;
 use crate::boxed::Box;
@@ -206,7 +208,7 @@ pub fn sort(&mut self)
     where
         T: Ord,
     {
-        merge_sort(self, T::lt);
+        stable_sort(self, T::lt);
     }
 
     /// Sorts the slice with a comparator function.
@@ -262,7 +264,7 @@ pub fn sort_by<F>(&mut self, mut compare: F)
     where
         F: FnMut(&T, &T) -> Ordering,
     {
-        merge_sort(self, |a, b| compare(a, b) == Less);
+        stable_sort(self, |a, b| compare(a, b) == Less);
     }
 
     /// Sorts the slice with a key extraction function.
@@ -305,7 +307,7 @@ pub fn sort_by_key<K, F>(&mut self, mut f: F)
         F: FnMut(&T) -> K,
         K: Ord,
     {
-        merge_sort(self, |a, b| f(a).lt(&f(b)));
+        stable_sort(self, |a, b| f(a).lt(&f(b)));
     }
 
     /// Sorts the slice with a key extraction function.
@@ -812,324 +814,52 @@ fn clone_into(&self, target: &mut Vec<T>) {
 // Sorting
 ////////////////////////////////////////////////////////////////////////////////
 
-/// Inserts `v[0]` into pre-sorted sequence `v[1..]` so that whole `v[..]` becomes sorted.
+#[inline]
-///
-/// This is the integral subroutine of insertion sort.
 #[cfg(not(no_global_oom_handling))]
-fn insert_head<T, F>(v: &mut [T], is_less: &mut F)
+fn stable_sort<T, F>(v: &mut [T], mut is_less: F)
 where
     F: FnMut(&T, &T) -> bool,
 {
-    if v.len() >= 2 && is_less(&v[1], &v[0]) {
-        unsafe {
-            // There are three ways to implement insertion here:
-            //
-            // 1. Swap adjacent elements until the first one gets to its final destination.
-            //    However, this way we copy data around more than is necessary. If elements are big
-            //    structures (costly to copy), this method will be slow.
-            //
-            // 2. Iterate until the right place for the first element is found. Then shift the
-            //    elements succeeding it to make room for it and finally place it into the
-            //    remaining hole. This is a good method.
-            //
-            // 3. Copy the first element into a temporary variable. Iterate until the right place
-            //    for it is found. As we go along, copy every traversed element into the slot
-            //    preceding it. Finally, copy data from the temporary variable into the remaining
-            //    hole. This method is very good. Benchmarks demonstrated slightly better
-            //    performance than with the 2nd method.
-            //
-            // All methods were benchmarked, and the 3rd showed best results. So we chose that one.
-            let tmp = mem::ManuallyDrop::new(ptr::read(&v[0]));
-
-            // Intermediate state of the insertion process is always tracked by `hole`, which
-            // serves two purposes:
-            // 1. Protects integrity of `v` from panics in `is_less`.
-            // 2. Fills the remaining hole in `v` in the end.
-            //
-            // Panic safety:
-            //
-            // If `is_less` panics at any point during the process, `hole` will get dropped and
-            // fill the hole in `v` with `tmp`, thus ensuring that `v` still holds every object it
-            // initially held exactly once.
-            let mut hole = InsertionHole { src: &*tmp, dest: &mut v[1] };
-            ptr::copy_nonoverlapping(&v[1], &mut v[0], 1);
-
-            for i in 2..v.len() {
-                if !is_less(&v[i], &*tmp) {
-                    break;
-                }
-                ptr::copy_nonoverlapping(&v[i], &mut v[i - 1], 1);
-                hole.dest = &mut v[i];
-            }
-            // `hole` gets dropped and thus copies `tmp` into the remaining hole in `v`.
-        }
-    }
-
-    // When dropped, copies from `src` into `dest`.
-    struct InsertionHole<T> {
-        src: *const T,
-        dest: *mut T,
-    }
-
-    impl<T> Drop for InsertionHole<T> {
-        fn drop(&mut self) {
-            unsafe {
-                ptr::copy_nonoverlapping(self.src, self.dest, 1);
-            }
-        }
-    }
-}
-
-/// Merges non-decreasing runs `v[..mid]` and `v[mid..]` using `buf` as temporary storage, and
-/// stores the result into `v[..]`.
-///
-/// # Safety
-///
-/// The two slices must be non-empty and `mid` must be in bounds. Buffer `buf` must be long enough
-/// to hold a copy of the shorter slice. Also, `T` must not be a zero-sized type.
-#[cfg(not(no_global_oom_handling))]
-unsafe fn merge<T, F>(v: &mut [T], mid: usize, buf: *mut T, is_less: &mut F)
-where
-    F: FnMut(&T, &T) -> bool,
-{
-    let len = v.len();
-    let v = v.as_mut_ptr();
-    let (v_mid, v_end) = unsafe { (v.add(mid), v.add(len)) };
-
-    // The merge process first copies the shorter run into `buf`. Then it traces the newly copied
-    // run and the longer run forwards (or backwards), comparing their next unconsumed elements and
-    // copying the lesser (or greater) one into `v`.
-    //
-    // As soon as the shorter run is fully consumed, the process is done. If the longer run gets
-    // consumed first, then we must copy whatever is left of the shorter run into the remaining
-    // hole in `v`.
-    //
-    // Intermediate state of the process is always tracked by `hole`, which serves two purposes:
-    // 1. Protects integrity of `v` from panics in `is_less`.
-    // 2. Fills the remaining hole in `v` if the longer run gets consumed first.
-    //
-    // Panic safety:
-    //
-    // If `is_less` panics at any point during the process, `hole` will get dropped and fill the
-    // hole in `v` with the unconsumed range in `buf`, thus ensuring that `v` still holds every
-    // object it initially held exactly once.
-    let mut hole;
-
-    if mid <= len - mid {
-        // The left run is shorter.
-        unsafe {
-            ptr::copy_nonoverlapping(v, buf, mid);
-            hole = MergeHole { start: buf, end: buf.add(mid), dest: v };
-        }
-
-        // Initially, these pointers point to the beginnings of their arrays.
-        let left = &mut hole.start;
-        let mut right = v_mid;
-        let out = &mut hole.dest;
-
-        while *left < hole.end && right < v_end {
-            // Consume the lesser side.
-            // If equal, prefer the left run to maintain stability.
-            unsafe {
-                let to_copy = if is_less(&*right, &**left) {
-                    get_and_increment(&mut right)
-                } else {
-                    get_and_increment(left)
-                };
-                ptr::copy_nonoverlapping(to_copy, get_and_increment(out), 1);
-            }
-        }
-    } else {
-        // The right run is shorter.
-        unsafe {
-            ptr::copy_nonoverlapping(v_mid, buf, len - mid);
-            hole = MergeHole { start: buf, end: buf.add(len - mid), dest: v_mid };
-        }
-
-        // Initially, these pointers point past the ends of their arrays.
-        let left = &mut hole.dest;
-        let right = &mut hole.end;
-        let mut out = v_end;
-
-        while v < *left && buf < *right {
-            // Consume the greater side.
-            // If equal, prefer the right run to maintain stability.
-            unsafe {
-                let to_copy = if is_less(&*right.sub(1), &*left.sub(1)) {
-                    decrement_and_get(left)
-                } else {
-                    decrement_and_get(right)
-                };
-                ptr::copy_nonoverlapping(to_copy, decrement_and_get(&mut out), 1);
-            }
-        }
-    }
-    // Finally, `hole` gets dropped. If the shorter run was not fully consumed, whatever remains of
-    // it will now be copied into the hole in `v`.
-
-    unsafe fn get_and_increment<T>(ptr: &mut *mut T) -> *mut T {
-        let old = *ptr;
-        *ptr = unsafe { ptr.add(1) };
-        old
-    }
-
-    unsafe fn decrement_and_get<T>(ptr: &mut *mut T) -> *mut T {
-        *ptr = unsafe { ptr.sub(1) };
-        *ptr
-    }
-
-    // When dropped, copies the range `start..end` into `dest..`.
-    struct MergeHole<T> {
-        start: *mut T,
-        end: *mut T,
-        dest: *mut T,
-    }
-
-    impl<T> Drop for MergeHole<T> {
-        fn drop(&mut self) {
-            // `T` is not a zero-sized type, and these are pointers into a slice's elements.
-            unsafe {
-                let len = self.end.sub_ptr(self.start);
-                ptr::copy_nonoverlapping(self.start, self.dest, len);
-            }
-        }
-    }
-}
-
-/// This merge sort borrows some (but not all) ideas from TimSort, which is described in detail
-/// [here](https://github.com/python/cpython/blob/main/Objects/listsort.txt).
-///
-/// The algorithm identifies strictly descending and non-descending subsequences, which are called
-/// natural runs. There is a stack of pending runs yet to be merged. Each newly found run is pushed
-/// onto the stack, and then some pairs of adjacent runs are merged until these two invariants are
-/// satisfied:
-///
-/// 1. for every `i` in `1..runs.len()`: `runs[i - 1].len > runs[i].len`
-/// 2. for every `i` in `2..runs.len()`: `runs[i - 2].len > runs[i - 1].len + runs[i].len`
-///
-/// The invariants ensure that the total running time is *O*(*n* \* log(*n*)) worst-case.
-#[cfg(not(no_global_oom_handling))]
-fn merge_sort<T, F>(v: &mut [T], mut is_less: F)
-where
-    F: FnMut(&T, &T) -> bool,
-{
-    // Slices of up to this length get sorted using insertion sort.
-    const MAX_INSERTION: usize = 20;
-    // Very short runs are extended using insertion sort to span at least this many elements.
-    const MIN_RUN: usize = 10;
-
-    // Sorting has no meaningful behavior on zero-sized types.
     if T::IS_ZST {
+        // Sorting has no meaningful behavior on zero-sized types. Do nothing.
         return;
     }
 
-    let len = v.len();
+    let elem_alloc_fn = |len: usize| -> *mut T {
+        // SAFETY: Creating the layout is safe as long as merge_sort never calls this with len >
+        // v.len(). Alloc in general will only be used as 'shadow-region' to store temporary swap
+        // elements.
+        unsafe { alloc::alloc(alloc::Layout::array::<T>(len).unwrap_unchecked()) as *mut T }
+    };
 
-    // Short arrays get sorted in-place via insertion sort to avoid allocations.
+    let elem_dealloc_fn = |buf_ptr: *mut T, len: usize| {
-    if len <= MAX_INSERTION {
+        // SAFETY: Creating the layout is safe as long as merge_sort never calls this with len >
-        if len >= 2 {
+        // v.len(). The caller must ensure that buf_ptr was created by elem_alloc_fn with the same
-            for i in (0..len - 1).rev() {
+        // len.
-                insert_head(&mut v[i..], &mut is_less);
+        unsafe {
-            }
+            alloc::dealloc(buf_ptr as *mut u8, alloc::Layout::array::<T>(len).unwrap_unchecked());
         }
-        return;
+    };
-    }
 
-    // Allocate a buffer to use as scratch memory. We keep the length 0 so we can keep in it
+    let run_alloc_fn = |len: usize| -> *mut sort::TimSortRun {
-    // shallow copies of the contents of `v` without risking the dtors running on copies if
+        // SAFETY: Creating the layout is safe as long as merge_sort never calls this with an
-    // `is_less` panics. When merging two sorted runs, this buffer holds a copy of the shorter run,
+        // obscene length or 0.
-    // which will always have length at most `len / 2`.
+        unsafe {
-    let mut buf = Vec::with_capacity(len / 2);
+            alloc::alloc(alloc::Layout::array::<sort::TimSortRun>(len).unwrap_unchecked())
-
+                as *mut sort::TimSortRun
-    // In order to identify natural runs in `v`, we traverse it backwards. That might seem like a
-    // strange decision, but consider the fact that merges more often go in the opposite direction
-    // (forwards). According to benchmarks, merging forwards is slightly faster than merging
-    // backwards. To conclude, identifying runs by traversing backwards improves performance.
-    let mut runs = vec![];
-    let mut end = len;
-    while end > 0 {
-        // Find the next natural run, and reverse it if it's strictly descending.
-        let mut start = end - 1;
-        if start > 0 {
-            start -= 1;
-            unsafe {
-                if is_less(v.get_unchecked(start + 1), v.get_unchecked(start)) {
-                    while start > 0 && is_less(v.get_unchecked(start), v.get_unchecked(start - 1)) {
-                        start -= 1;
-                    }
-                    v[start..end].reverse();
-                } else {
-                    while start > 0 && !is_less(v.get_unchecked(start), v.get_unchecked(start - 1))
-                    {
-                        start -= 1;
-                    }
-                }
-            }
         }
+    };
 
-        // Insert some more elements into the run if it's too short. Insertion sort is faster than
+    let run_dealloc_fn = |buf_ptr: *mut sort::TimSortRun, len: usize| {
-        // merge sort on short sequences, so this significantly improves performance.
+        // SAFETY: The caller must ensure that buf_ptr was created by elem_alloc_fn with the same
-        while start > 0 && end - start < MIN_RUN {
+        // len.
-            start -= 1;
+        unsafe {
-            insert_head(&mut v[start..end], &mut is_less);
+            alloc::dealloc(
+                buf_ptr as *mut u8,
+                alloc::Layout::array::<sort::TimSortRun>(len).unwrap_unchecked(),
+            );
         }
+    };
 
-        // Push this run onto the stack.
+    sort::merge_sort(v, &mut is_less, elem_alloc_fn, elem_dealloc_fn, run_alloc_fn, run_dealloc_fn);
-        runs.push(Run { start, len: end - start });
-        end = start;
-
-        // Merge some pairs of adjacent runs to satisfy the invariants.
-        while let Some(r) = collapse(&runs) {
-            let left = runs[r + 1];
-            let right = runs[r];
-            unsafe {
-                merge(
-                    &mut v[left.start..right.start + right.len],
-                    left.len,
-                    buf.as_mut_ptr(),
-                    &mut is_less,
-                );
-            }
-            runs[r] = Run { start: left.start, len: left.len + right.len };
-            runs.remove(r + 1);
-        }
-    }
-
-    // Finally, exactly one run must remain in the stack.
-    debug_assert!(runs.len() == 1 && runs[0].start == 0 && runs[0].len == len);
-
-    // Examines the stack of runs and identifies the next pair of runs to merge. More specifically,
-    // if `Some(r)` is returned, that means `runs[r]` and `runs[r + 1]` must be merged next. If the
-    // algorithm should continue building a new run instead, `None` is returned.
-    //
-    // TimSort is infamous for its buggy implementations, as described here:
-    // http://envisage-project.eu/timsort-specification-and-verification/
-    //
-    // The gist of the story is: we must enforce the invariants on the top four runs on the stack.
-    // Enforcing them on just top three is not sufficient to ensure that the invariants will still
-    // hold for *all* runs in the stack.
-    //
-    // This function correctly checks invariants for the top four runs. Additionally, if the top
-    // run starts at index 0, it will always demand a merge operation until the stack is fully
-    // collapsed, in order to complete the sort.
-    #[inline]
-    fn collapse(runs: &[Run]) -> Option<usize> {
-        let n = runs.len();
-        if n >= 2
-            && (runs[n - 1].start == 0
-                || runs[n - 2].len <= runs[n - 1].len
-                || (n >= 3 && runs[n - 3].len <= runs[n - 2].len + runs[n - 1].len)
-                || (n >= 4 && runs[n - 4].len <= runs[n - 3].len + runs[n - 2].len))
-        {
-            if n >= 3 && runs[n - 3].len < runs[n - 1].len { Some(n - 3) } else { Some(n - 2) }
-        } else {
-            None
-        }
-    }
-
-    #[derive(Clone, Copy)]
-    struct Run {
-        start: usize,
-        len: usize,
-    }
 }

library/core/src/slice/mod.rs

@@ -29,13 +29,19 @@
 /// Pure rust memchr implementation, taken from rust-memchr
 pub mod memchr;
 
+#[unstable(
+    feature = "slice_internals",
+    issue = "none",
+    reason = "exposed from core to be reused in std;"
+)]
+pub mod sort;
+
 mod ascii;
 mod cmp;
 mod index;
 mod iter;
 mod raw;
 mod rotate;
-mod sort;
 mod specialize;
 
 #[stable(feature = "rust1", since = "1.0.0")]

library/core/src/slice/sort.rs

@@ -5,6 +5,9 @@
 //!
 //! Unstable sorting is compatible with core because it doesn't allocate memory, unlike our
 //! stable sorting implementation.
+//!
+//! In addition it also contains the core logic of the stable sort used by `slice::sort` based on
+//! TimSort.
 
 use crate::cmp;
 use crate::mem::{self, MaybeUninit, SizedTypeProperties};
@@ -905,6 +908,7 @@ fn partition_at_index_loop<'a, T, F>(
     }
 }
 
+/// Reorder the slice such that the element at `index` is at its final sorted position.
 pub fn partition_at_index<T, F>(
     v: &mut [T],
     index: usize,
@@ -949,3 +953,513 @@ pub fn partition_at_index<T, F>(
     let pivot = &mut pivot[0];
     (left, pivot, right)
 }
+
+/// Inserts `v[0]` into pre-sorted sequence `v[1..]` so that whole `v[..]` becomes sorted.
+///
+/// This is the integral subroutine of insertion sort.
+fn insert_head<T, F>(v: &mut [T], is_less: &mut F)
+where
+    F: FnMut(&T, &T) -> bool,
+{
+    if v.len() >= 2 && is_less(&v[1], &v[0]) {
+        // SAFETY: Copy tmp back even if panic, and ensure unique observation.
+        unsafe {
+            // There are three ways to implement insertion here:
+            //
+            // 1. Swap adjacent elements until the first one gets to its final destination.
+            //    However, this way we copy data around more than is necessary. If elements are big
+            //    structures (costly to copy), this method will be slow.
+            //
+            // 2. Iterate until the right place for the first element is found. Then shift the
+            //    elements succeeding it to make room for it and finally place it into the
+            //    remaining hole. This is a good method.
+            //
+            // 3. Copy the first element into a temporary variable. Iterate until the right place
+            //    for it is found. As we go along, copy every traversed element into the slot
+            //    preceding it. Finally, copy data from the temporary variable into the remaining
+            //    hole. This method is very good. Benchmarks demonstrated slightly better
+            //    performance than with the 2nd method.
+            //
+            // All methods were benchmarked, and the 3rd showed best results. So we chose that one.
+            let tmp = mem::ManuallyDrop::new(ptr::read(&v[0]));
+
+            // Intermediate state of the insertion process is always tracked by `hole`, which
+            // serves two purposes:
+            // 1. Protects integrity of `v` from panics in `is_less`.
+            // 2. Fills the remaining hole in `v` in the end.
+            //
+            // Panic safety:
+            //
+            // If `is_less` panics at any point during the process, `hole` will get dropped and
+            // fill the hole in `v` with `tmp`, thus ensuring that `v` still holds every object it
+            // initially held exactly once.
+            let mut hole = InsertionHole { src: &*tmp, dest: &mut v[1] };
+            ptr::copy_nonoverlapping(&v[1], &mut v[0], 1);
+
+            for i in 2..v.len() {
+                if !is_less(&v[i], &*tmp) {
+                    break;
+                }
+                ptr::copy_nonoverlapping(&v[i], &mut v[i - 1], 1);
+                hole.dest = &mut v[i];
+            }
+            // `hole` gets dropped and thus copies `tmp` into the remaining hole in `v`.
+        }
+    }
+
+    // When dropped, copies from `src` into `dest`.
+    struct InsertionHole<T> {
+        src: *const T,
+        dest: *mut T,
+    }
+
+    impl<T> Drop for InsertionHole<T> {
+        fn drop(&mut self) {
+            // SAFETY: The caller must ensure that src and dest are correctly set.
+            unsafe {
+                ptr::copy_nonoverlapping(self.src, self.dest, 1);
+            }
+        }
+    }
+}
+
+/// Merges non-decreasing runs `v[..mid]` and `v[mid..]` using `buf` as temporary storage, and
+/// stores the result into `v[..]`.
+///
+/// # Safety
+///
+/// The two slices must be non-empty and `mid` must be in bounds. Buffer `buf` must be long enough
+/// to hold a copy of the shorter slice. Also, `T` must not be a zero-sized type.
+unsafe fn merge<T, F>(v: &mut [T], mid: usize, buf: *mut T, is_less: &mut F)
+where
+    F: FnMut(&T, &T) -> bool,
+{
+    let len = v.len();
+    let v = v.as_mut_ptr();
+
+    // SAFETY: mid and len must be in-bounds of v.
+    let (v_mid, v_end) = unsafe { (v.add(mid), v.add(len)) };
+
+    // The merge process first copies the shorter run into `buf`. Then it traces the newly copied
+    // run and the longer run forwards (or backwards), comparing their next unconsumed elements and
+    // copying the lesser (or greater) one into `v`.
+    //
+    // As soon as the shorter run is fully consumed, the process is done. If the longer run gets
+    // consumed first, then we must copy whatever is left of the shorter run into the remaining
+    // hole in `v`.
+    //
+    // Intermediate state of the process is always tracked by `hole`, which serves two purposes:
+    // 1. Protects integrity of `v` from panics in `is_less`.
+    // 2. Fills the remaining hole in `v` if the longer run gets consumed first.
+    //
+    // Panic safety:
+    //
+    // If `is_less` panics at any point during the process, `hole` will get dropped and fill the
+    // hole in `v` with the unconsumed range in `buf`, thus ensuring that `v` still holds every
+    // object it initially held exactly once.
+    let mut hole;
+
+    if mid <= len - mid {
+        // The left run is shorter.
+
+        // SAFETY: buf must have enough capacity for `v[..mid]`.
+        unsafe {
+            ptr::copy_nonoverlapping(v, buf, mid);
+            hole = MergeHole { start: buf, end: buf.add(mid), dest: v };
+        }
+
+        // Initially, these pointers point to the beginnings of their arrays.
+        let left = &mut hole.start;
+        let mut right = v_mid;
+        let out = &mut hole.dest;
+
+        while *left < hole.end && right < v_end {
+            // Consume the lesser side.
+            // If equal, prefer the left run to maintain stability.
+
+            // SAFETY: left and right must be valid and part of v same for out.
+            unsafe {
+                let to_copy = if is_less(&*right, &**left) {
+                    get_and_increment(&mut right)
+                } else {
+                    get_and_increment(left)
+                };
+                ptr::copy_nonoverlapping(to_copy, get_and_increment(out), 1);
+            }
+        }
+    } else {
+        // The right run is shorter.
+
+        // SAFETY: buf must have enough capacity for `v[mid..]`.
+        unsafe {
+            ptr::copy_nonoverlapping(v_mid, buf, len - mid);
+            hole = MergeHole { start: buf, end: buf.add(len - mid), dest: v_mid };
+        }
+
+        // Initially, these pointers point past the ends of their arrays.
+        let left = &mut hole.dest;
+        let right = &mut hole.end;
+        let mut out = v_end;
+
+        while v < *left && buf < *right {
+            // Consume the greater side.
+            // If equal, prefer the right run to maintain stability.
+
+            // SAFETY: left and right must be valid and part of v same for out.
+            unsafe {
+                let to_copy = if is_less(&*right.sub(1), &*left.sub(1)) {
+                    decrement_and_get(left)
+                } else {
+                    decrement_and_get(right)
+                };
+                ptr::copy_nonoverlapping(to_copy, decrement_and_get(&mut out), 1);
+            }
+        }
+    }
+    // Finally, `hole` gets dropped. If the shorter run was not fully consumed, whatever remains of
+    // it will now be copied into the hole in `v`.
+
+    unsafe fn get_and_increment<T>(ptr: &mut *mut T) -> *mut T {
+        let old = *ptr;
+
+        // SAFETY: ptr.add(1) must still be a valid pointer and part of `v`.
+        *ptr = unsafe { ptr.add(1) };
+        old
+    }
+
+    unsafe fn decrement_and_get<T>(ptr: &mut *mut T) -> *mut T {
+        // SAFETY: ptr.sub(1) must still be a valid pointer and part of `v`.
+        *ptr = unsafe { ptr.sub(1) };
+        *ptr
+    }
+
+    // When dropped, copies the range `start..end` into `dest..`.
+    struct MergeHole<T> {
+        start: *mut T,
+        end: *mut T,
+        dest: *mut T,
+    }
+
+    impl<T> Drop for MergeHole<T> {
+        fn drop(&mut self) {
+            // SAFETY: `T` is not a zero-sized type, and these are pointers into a slice's elements.
+            unsafe {
+                let len = self.end.sub_ptr(self.start);
+                ptr::copy_nonoverlapping(self.start, self.dest, len);
+            }
+        }
+    }
+}
+
+/// This merge sort borrows some (but not all) ideas from TimSort, which used to be described in
+/// detail [here](https://github.com/python/cpython/blob/main/Objects/listsort.txt). However Python
+/// has switched to a Powersort based implementation.
+///
+/// The algorithm identifies strictly descending and non-descending subsequences, which are called
+/// natural runs. There is a stack of pending runs yet to be merged. Each newly found run is pushed
+/// onto the stack, and then some pairs of adjacent runs are merged until these two invariants are
+/// satisfied:
+///
+/// 1. for every `i` in `1..runs.len()`: `runs[i - 1].len > runs[i].len`
+/// 2. for every `i` in `2..runs.len()`: `runs[i - 2].len > runs[i - 1].len + runs[i].len`
+///
+/// The invariants ensure that the total running time is *O*(*n* \* log(*n*)) worst-case.
+pub fn merge_sort<T, CmpF, ElemAllocF, ElemDeallocF, RunAllocF, RunDeallocF>(
+    v: &mut [T],
+    is_less: &mut CmpF,
+    elem_alloc_fn: ElemAllocF,
+    elem_dealloc_fn: ElemDeallocF,
+    run_alloc_fn: RunAllocF,
+    run_dealloc_fn: RunDeallocF,
+) where
+    CmpF: FnMut(&T, &T) -> bool,
+    ElemAllocF: Fn(usize) -> *mut T,
+    ElemDeallocF: Fn(*mut T, usize),
+    RunAllocF: Fn(usize) -> *mut TimSortRun,
+    RunDeallocF: Fn(*mut TimSortRun, usize),
+{
+    // Slices of up to this length get sorted using insertion sort.
+    const MAX_INSERTION: usize = 20;
+    // Very short runs are extended using insertion sort to span at least this many elements.
+    const MIN_RUN: usize = 10;
+
+    // The caller should have already checked that.
+    debug_assert!(!T::IS_ZST);
+
+    let len = v.len();
+
+    // Short arrays get sorted in-place via insertion sort to avoid allocations.
+    if len <= MAX_INSERTION {
+        if len >= 2 {
+            for i in (0..len - 1).rev() {
+                insert_head(&mut v[i..], is_less);
+            }
+        }
+        return;
+    }
+
+    // Allocate a buffer to use as scratch memory. We keep the length 0 so we can keep in it
+    // shallow copies of the contents of `v` without risking the dtors running on copies if
+    // `is_less` panics. When merging two sorted runs, this buffer holds a copy of the shorter run,
+    // which will always have length at most `len / 2`.
+    let buf = BufGuard::new(len / 2, elem_alloc_fn, elem_dealloc_fn);
+    let buf_ptr = buf.buf_ptr;
+
+    let mut runs = RunVec::new(run_alloc_fn, run_dealloc_fn);
+
+    // In order to identify natural runs in `v`, we traverse it backwards. That might seem like a
+    // strange decision, but consider the fact that merges more often go in the opposite direction
+    // (forwards). According to benchmarks, merging forwards is slightly faster than merging
+    // backwards. To conclude, identifying runs by traversing backwards improves performance.
+    let mut end = len;
+    while end > 0 {
+        // Find the next natural run, and reverse it if it's strictly descending.
+        let mut start = end - 1;
+        if start > 0 {
+            start -= 1;
+
+            // SAFETY: The v.get_unchecked must be fed with correct inbound indicies.
+            unsafe {
+                if is_less(v.get_unchecked(start + 1), v.get_unchecked(start)) {
+                    while start > 0 && is_less(v.get_unchecked(start), v.get_unchecked(start - 1)) {
+                        start -= 1;
+                    }
+                    v[start..end].reverse();
+                } else {
+                    while start > 0 && !is_less(v.get_unchecked(start), v.get_unchecked(start - 1))
+                    {
+                        start -= 1;
+                    }
+                }
+            }
+        }
+
+        // Insert some more elements into the run if it's too short. Insertion sort is faster than
+        // merge sort on short sequences, so this significantly improves performance.
+        while start > 0 && end - start < MIN_RUN {
+            start -= 1;
+            insert_head(&mut v[start..end], is_less);
+        }
+
+        // Push this run onto the stack.
+        runs.push(TimSortRun { start, len: end - start });
+        end = start;
+
+        // Merge some pairs of adjacent runs to satisfy the invariants.
+        while let Some(r) = collapse(runs.as_slice()) {
+            let left = runs[r + 1];
+            let right = runs[r];
+            // SAFETY: `buf_ptr` must hold enough capacity for the shorter of the two sides, and
+            // neither side may be on length 0.
+            unsafe {
+                merge(&mut v[left.start..right.start + right.len], left.len, buf_ptr, is_less);
+            }
+            runs[r] = TimSortRun { start: left.start, len: left.len + right.len };
+            runs.remove(r + 1);
+        }
+    }
+
+    // Finally, exactly one run must remain in the stack.
+    debug_assert!(runs.len() == 1 && runs[0].start == 0 && runs[0].len == len);
+
+    // Examines the stack of runs and identifies the next pair of runs to merge. More specifically,
+    // if `Some(r)` is returned, that means `runs[r]` and `runs[r + 1]` must be merged next. If the
+    // algorithm should continue building a new run instead, `None` is returned.
+    //
+    // TimSort is infamous for its buggy implementations, as described here:
+    // http://envisage-project.eu/timsort-specification-and-verification/
+    //
+    // The gist of the story is: we must enforce the invariants on the top four runs on the stack.
+    // Enforcing them on just top three is not sufficient to ensure that the invariants will still
+    // hold for *all* runs in the stack.
+    //
+    // This function correctly checks invariants for the top four runs. Additionally, if the top
+    // run starts at index 0, it will always demand a merge operation until the stack is fully
+    // collapsed, in order to complete the sort.
+    #[inline]
+    fn collapse(runs: &[TimSortRun]) -> Option<usize> {
+        let n = runs.len();
+        if n >= 2
+            && (runs[n - 1].start == 0
+                || runs[n - 2].len <= runs[n - 1].len
+                || (n >= 3 && runs[n - 3].len <= runs[n - 2].len + runs[n - 1].len)
+                || (n >= 4 && runs[n - 4].len <= runs[n - 3].len + runs[n - 2].len))
+        {
+            if n >= 3 && runs[n - 3].len < runs[n - 1].len { Some(n - 3) } else { Some(n - 2) }
+        } else {
+            None
+        }
+    }
+
+    // Extremely basic versions of Vec.
+    // Their use is super limited and by having the code here, it allows reuse between the sort
+    // implementations.
+    struct BufGuard<T, ElemDeallocF>
+    where
+        ElemDeallocF: Fn(*mut T, usize),
+    {
+        buf_ptr: *mut T,
+        capacity: usize,
+        elem_dealloc_fn: ElemDeallocF,
+    }
+
+    impl<T, ElemDeallocF> BufGuard<T, ElemDeallocF>
+    where
+        ElemDeallocF: Fn(*mut T, usize),
+    {
+        fn new<ElemAllocF>(
+            len: usize,
+            elem_alloc_fn: ElemAllocF,
+            elem_dealloc_fn: ElemDeallocF,
+        ) -> Self
+        where
+            ElemAllocF: Fn(usize) -> *mut T,
+        {
+            Self { buf_ptr: elem_alloc_fn(len), capacity: len, elem_dealloc_fn }
+        }
+    }
+
+    impl<T, ElemDeallocF> Drop for BufGuard<T, ElemDeallocF>
+    where
+        ElemDeallocF: Fn(*mut T, usize),
+    {
+        fn drop(&mut self) {
+            (self.elem_dealloc_fn)(self.buf_ptr, self.capacity);
+        }
+    }
+
+    struct RunVec<RunAllocF, RunDeallocF>
+    where
+        RunAllocF: Fn(usize) -> *mut TimSortRun,
+        RunDeallocF: Fn(*mut TimSortRun, usize),
+    {
+        buf_ptr: *mut TimSortRun,
+        capacity: usize,
+        len: usize,
+        run_alloc_fn: RunAllocF,
+        run_dealloc_fn: RunDeallocF,
+    }
+
+    impl<RunAllocF, RunDeallocF> RunVec<RunAllocF, RunDeallocF>
+    where
+        RunAllocF: Fn(usize) -> *mut TimSortRun,
+        RunDeallocF: Fn(*mut TimSortRun, usize),
+    {
+        fn new(run_alloc_fn: RunAllocF, run_dealloc_fn: RunDeallocF) -> Self {
+            // Most slices can be sorted with at most 16 runs in-flight.
+            const START_RUN_CAPACITY: usize = 16;
+
+            Self {
+                buf_ptr: run_alloc_fn(START_RUN_CAPACITY),
+                capacity: START_RUN_CAPACITY,
+                len: 0,
+                run_alloc_fn,
+                run_dealloc_fn,
+            }
+        }
+
+        fn push(&mut self, val: TimSortRun) {
+            if self.len == self.capacity {
+                let old_capacity = self.capacity;
+                let old_buf_ptr = self.buf_ptr;
+
+                self.capacity = self.capacity * 2;
+                self.buf_ptr = (self.run_alloc_fn)(self.capacity);
+
+                // SAFETY: buf_ptr new and old were correctly allocated and old_buf_ptr has
+                // old_capacity valid elements.
+                unsafe {
+                    ptr::copy_nonoverlapping(old_buf_ptr, self.buf_ptr, old_capacity);
+                }
+
+                (self.run_dealloc_fn)(old_buf_ptr, old_capacity);
+            }
+
+            // SAFETY: The invariant was just checked.
+            unsafe {
+                self.buf_ptr.add(self.len).write(val);
+            }
+            self.len += 1;
+        }
+
+        fn remove(&mut self, index: usize) {
+            if index >= self.len {
+                panic!("Index out of bounds");
+            }
+
+            // SAFETY: buf_ptr needs to be valid and len invariant upheld.
+            unsafe {
+                // the place we are taking from.
+                let ptr = self.buf_ptr.add(index);
+
+                // Shift everything down to fill in that spot.
+                ptr::copy(ptr.add(1), ptr, self.len - index - 1);
+            }
+            self.len -= 1;
+        }
+
+        fn as_slice(&self) -> &[TimSortRun] {
+            // SAFETY: Safe as long as buf_ptr is valid and len invariant was upheld.
+            unsafe { &*ptr::slice_from_raw_parts(self.buf_ptr, self.len) }
+        }
+
+        fn len(&self) -> usize {
+            self.len
+        }
+    }
+
+    impl<RunAllocF, RunDeallocF> core::ops::Index<usize> for RunVec<RunAllocF, RunDeallocF>
+    where
+        RunAllocF: Fn(usize) -> *mut TimSortRun,
+        RunDeallocF: Fn(*mut TimSortRun, usize),
+    {
+        type Output = TimSortRun;
+
+        fn index(&self, index: usize) -> &Self::Output {
+            if index < self.len {
+                // SAFETY: buf_ptr and len invariant must be upheld.
+                unsafe {
+                    return &*(self.buf_ptr.add(index));
+                }
+            }
+
+            panic!("Index out of bounds");
+        }
+    }
+
+    impl<RunAllocF, RunDeallocF> core::ops::IndexMut<usize> for RunVec<RunAllocF, RunDeallocF>
+    where
+        RunAllocF: Fn(usize) -> *mut TimSortRun,
+        RunDeallocF: Fn(*mut TimSortRun, usize),
+    {
+        fn index_mut(&mut self, index: usize) -> &mut Self::Output {
+            if index < self.len {
+                // SAFETY: buf_ptr and len invariant must be upheld.
+                unsafe {
+                    return &mut *(self.buf_ptr.add(index));
+                }
+            }
+
+            panic!("Index out of bounds");
+        }
+    }
+
+    impl<RunAllocF, RunDeallocF> Drop for RunVec<RunAllocF, RunDeallocF>
+    where
+        RunAllocF: Fn(usize) -> *mut TimSortRun,
+        RunDeallocF: Fn(*mut TimSortRun, usize),
+    {
+        fn drop(&mut self) {
+            // As long as TimSortRun is Copy we don't need to drop them individually but just the
+            // whole allocation.
+            (self.run_dealloc_fn)(self.buf_ptr, self.capacity);
+        }
+    }
+}
+
+/// Internal type used by merge_sort.
+#[derive(Clone, Copy, Debug)]
+pub struct TimSortRun {
+    len: usize,
+    start: usize,
+}

src/librustdoc/html/static/css/rustdoc.css

@@ -497,7 +497,7 @@ ul.block, .block li {
 	padding-left: 24px;
 }
 
-.sidebar a, .sidebar .current {
+.sidebar a {
 	color: var(--sidebar-link-color);
 }
 .sidebar .current,

src/librustdoc/html/static/css/settings.css

@@ -3,11 +3,6 @@
 	position: relative;
 }
 
-.setting-line .choices {
-	display: flex;
-	flex-wrap: wrap;
-}
-
 .setting-line .radio-line input,
 .setting-line .settings-toggle input {
 	margin-right: 0.3em;
@@ -38,7 +33,7 @@
 	margin-bottom: 0.1em;
 	min-width: 3.8em;
 	padding: 0.3em;
-	display: flex;
+	display: inline-flex;
 	align-items: center;
 	cursor: pointer;
 }

src/tools/tidy/Cargo.toml

@@ -12,6 +12,7 @@ miropt-test-tools = { path = "../miropt-test-tools" }
 lazy_static = "1"
 walkdir = "2"
 ignore = "0.4.18"
+semver = "1.0"
 termcolor = "1.1.3"
 
 [[bin]]

src/tools/tidy/src/lib.rs

@@ -70,3 +70,4 @@ fn tidy_error(bad: &mut bool, args: impl Display) -> std::io::Result<()> {
 pub mod unit_tests;
 pub mod unstable_book;
 pub mod walk;
+pub mod x_version;

src/tools/tidy/src/main.rs

@@ -60,7 +60,7 @@ macro_rules! check {
 
                 let handle = s.spawn(|| {
                     let mut flag = false;
-                    $p::check($($args),* , &mut flag);
+                    $p::check($($args, )* &mut flag);
                     if (flag) {
                         bad.store(true, Ordering::Relaxed);
                     }
@@ -114,6 +114,8 @@ macro_rules! check {
         check!(alphabetical, &compiler_path);
         check!(alphabetical, &library_path);
 
+        check!(x_version, &root_path, &cargo);
+
         let collected = {
             drain_handles(&mut handles);
 

src/tools/tidy/src/x_version.rs

@@ -0,0 +1,68 @@
+use semver::Version;
+use std::path::Path;
+use std::process::{Command, Stdio};
+
+pub fn check(root: &Path, cargo: &Path, bad: &mut bool) {
+    let cargo_list = Command::new(cargo).args(["install", "--list"]).stdout(Stdio::piped()).spawn();
+
+    let child = match cargo_list {
+        Ok(child) => child,
+        Err(e) => return tidy_error!(bad, "failed to run `cargo`: {}", e),
+    };
+
+    let cargo_list = child.wait_with_output().unwrap();
+
+    if cargo_list.status.success() {
+        let exe_list = String::from_utf8_lossy(&cargo_list.stdout);
+        let exe_list = exe_list.lines();
+
+        let mut installed: Option<Version> = None;
+
+        for line in exe_list {
+            let mut iter = line.split_whitespace();
+            if iter.next() == Some("x") {
+                if let Some(version) = iter.next() {
+                    // Check this is the rust-lang/rust x tool installation since it should be
+                    // installed at a path containing `src/tools/x`.
+                    if let Some(path) = iter.next() {
+                        if path.contains(&"src/tools/x") {
+                            let version = version.strip_prefix("v").unwrap();
+                            installed = Some(Version::parse(version).unwrap());
+                            break;
+                        }
+                    };
+                }
+            } else {
+                continue;
+            }
+        }
+        // Unwrap the some if x is installed, otherwise return because it's fine if x isn't installed.
+        let installed = if let Some(i) = installed { i } else { return };
+
+        if let Some(expected) = get_x_wrapper_version(root, cargo) {
+            if installed < expected {
+                return println!(
+                    "Current version of x is {installed}, but the latest version is {expected}\nConsider updating to the newer version of x by running `cargo install --path src/tools/x`"
+                );
+            }
+        } else {
+            return tidy_error!(
+                bad,
+                "Unable to parse the latest version of `x` at `src/tools/x/Cargo.toml`"
+            );
+        }
+    } else {
+        return tidy_error!(bad, "failed to check version of `x`: {}", cargo_list.status);
+    }
+}
+
+// Parse latest version out of `x` Cargo.toml
+fn get_x_wrapper_version(root: &Path, cargo: &Path) -> Option<Version> {
+    let mut cmd = cargo_metadata::MetadataCommand::new();
+    cmd.cargo_path(cargo)
+        .manifest_path(root.join("src/tools/x/Cargo.toml"))
+        .no_deps()
+        .features(cargo_metadata::CargoOpt::AllFeatures);
+    let mut metadata = t!(cmd.exec());
+    metadata.packages.pop().map(|x| x.version)
+}

tests/ui/imports/issue-99695-b.fixed

@@ -0,0 +1,20 @@
+// run-rustfix
+#![allow(unused, nonstandard_style)]
+mod m {
+
+    mod p {
+        #[macro_export]
+        macro_rules! nu {
+            {} => {};
+        }
+
+        pub struct other_item;
+    }
+
+    use ::nu;
+pub use self::p::{other_item as _};
+    //~^ ERROR unresolved import `self::p::nu` [E0432]
+    //~| HELP a macro with this name exists at the root of the crate
+}
+
+fn main() {}

tests/ui/imports/issue-99695-b.rs

@@ -0,0 +1,19 @@
+// run-rustfix
+#![allow(unused, nonstandard_style)]
+mod m {
+
+    mod p {
+        #[macro_export]
+        macro_rules! nu {
+            {} => {};
+        }
+
+        pub struct other_item;
+    }
+
+    pub use self::p::{nu, other_item as _};
+    //~^ ERROR unresolved import `self::p::nu` [E0432]
+    //~| HELP a macro with this name exists at the root of the crate
+}
+
+fn main() {}

tests/ui/imports/issue-99695-b.stderr

@@ -0,0 +1,16 @@
+error[E0432]: unresolved import `self::p::nu`
+  --> $DIR/issue-99695-b.rs:14:23
+   |
+LL |     pub use self::p::{nu, other_item as _};
+   |                       ^^ no `nu` in `m::p`
+   |
+   = note: this could be because a macro annotated with `#[macro_export]` will be exported at the root of the crate instead of the module where it is defined
+help: a macro with this name exists at the root of the crate
+   |
+LL ~     use ::nu;
+LL ~ pub use self::p::{other_item as _};
+   |
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0432`.

tests/ui/imports/issue-99695.fixed

@@ -0,0 +1,17 @@
+// run-rustfix
+#![allow(unused, nonstandard_style)]
+mod m {
+    #[macro_export]
+    macro_rules! nu {
+        {} => {};
+    }
+
+    pub struct other_item;
+
+    use ::nu;
+pub use self::{other_item as _};
+    //~^ ERROR unresolved import `self::nu` [E0432]
+    //~| HELP a macro with this name exists at the root of the crate
+}
+
+fn main() {}

tests/ui/imports/issue-99695.rs

@@ -0,0 +1,16 @@
+// run-rustfix
+#![allow(unused, nonstandard_style)]
+mod m {
+    #[macro_export]
+    macro_rules! nu {
+        {} => {};
+    }
+
+    pub struct other_item;
+
+    pub use self::{nu, other_item as _};
+    //~^ ERROR unresolved import `self::nu` [E0432]
+    //~| HELP a macro with this name exists at the root of the crate
+}
+
+fn main() {}

tests/ui/imports/issue-99695.stderr

@@ -0,0 +1,16 @@
+error[E0432]: unresolved import `self::nu`
+  --> $DIR/issue-99695.rs:11:20
+   |
+LL |     pub use self::{nu, other_item as _};
+   |                    ^^ no `nu` in `m`
+   |
+   = note: this could be because a macro annotated with `#[macro_export]` will be exported at the root of the crate instead of the module where it is defined
+help: a macro with this name exists at the root of the crate
+   |
+LL ~     use ::nu;
+LL ~ pub use self::{other_item as _};
+   |
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0432`.

tests/ui/issues/issue-19100.fixed

@@ -1,4 +1,3 @@
-// run-pass
 // run-rustfix
 
 #![allow(non_snake_case)]
@@ -16,11 +15,11 @@ impl Foo {
         match self {
             &
 Foo::Bar if true
-//~^ WARN pattern binding `Bar` is named the same as one of the variants of the type `Foo`
+//~^ ERROR pattern binding `Bar` is named the same as one of the variants of the type `Foo`
 => println!("bar"),
             &
 Foo::Baz if false
-//~^ WARN pattern binding `Baz` is named the same as one of the variants of the type `Foo`
+//~^ ERROR pattern binding `Baz` is named the same as one of the variants of the type `Foo`
 => println!("baz"),
 _ => ()
         }

tests/ui/issues/issue-19100.rs

@@ -1,4 +1,3 @@
-// run-pass
 // run-rustfix
 
 #![allow(non_snake_case)]
@@ -16,11 +15,11 @@ fn foo(&self) {
         match self {
             &
 Bar if true
-//~^ WARN pattern binding `Bar` is named the same as one of the variants of the type `Foo`
+//~^ ERROR pattern binding `Bar` is named the same as one of the variants of the type `Foo`
 => println!("bar"),
             &
 Baz if false
-//~^ WARN pattern binding `Baz` is named the same as one of the variants of the type `Foo`
+//~^ ERROR pattern binding `Baz` is named the same as one of the variants of the type `Foo`
 => println!("baz"),
 _ => ()
         }

tests/ui/issues/issue-19100.stderr

@@ -1,17 +1,17 @@
-warning[E0170]: pattern binding `Bar` is named the same as one of the variants of the type `Foo`
+error[E0170]: pattern binding `Bar` is named the same as one of the variants of the type `Foo`
-  --> $DIR/issue-19100.rs:18:1
+  --> $DIR/issue-19100.rs:17:1
    |
 LL | Bar if true
    | ^^^ help: to match on the variant, qualify the path: `Foo::Bar`
    |
-   = note: `#[warn(bindings_with_variant_name)]` on by default
+   = note: `#[deny(bindings_with_variant_name)]` on by default
 
-warning[E0170]: pattern binding `Baz` is named the same as one of the variants of the type `Foo`
+error[E0170]: pattern binding `Baz` is named the same as one of the variants of the type `Foo`
-  --> $DIR/issue-19100.rs:22:1
+  --> $DIR/issue-19100.rs:21:1
    |
 LL | Baz if false
    | ^^^ help: to match on the variant, qualify the path: `Foo::Baz`
 
-warning: 2 warnings emitted
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0170`.

tests/ui/lint/issue-30302.rs

@@ -11,7 +11,7 @@ enum Stack<T> {
 fn is_empty<T>(s: Stack<T>) -> bool {
     match s {
         Nil => true,
-//~^ WARN pattern binding `Nil` is named the same as one of the variants of the type `Stack`
+//~^ ERROR pattern binding `Nil` is named the same as one of the variants of the type `Stack`
         _ => false
 //~^ ERROR unreachable pattern
     }

tests/ui/lint/issue-30302.stderr

@@ -1,10 +1,10 @@
-warning[E0170]: pattern binding `Nil` is named the same as one of the variants of the type `Stack`
+error[E0170]: pattern binding `Nil` is named the same as one of the variants of the type `Stack`
   --> $DIR/issue-30302.rs:13:9
    |
 LL |         Nil => true,
    |         ^^^ help: to match on the variant, qualify the path: `Stack::Nil`
    |
-   = note: `#[warn(bindings_with_variant_name)]` on by default
+   = note: `#[deny(bindings_with_variant_name)]` on by default
 
 error: unreachable pattern
   --> $DIR/issue-30302.rs:15:9
@@ -21,6 +21,6 @@ note: the lint level is defined here
 LL | #![deny(unreachable_patterns)]
    |         ^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to previous error; 1 warning emitted
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0170`.

tests/ui/lint/lint-uppercase-variables.rs

@@ -21,18 +21,18 @@ fn main() {
     match foo::Foo::Foo {
         Foo => {}
     //~^ ERROR variable `Foo` should have a snake case name
-    //~^^ WARN `Foo` is named the same as one of the variants of the type `foo::Foo`
+    //~^^ ERROR `Foo` is named the same as one of the variants of the type `foo::Foo`
     //~^^^ WARN unused variable: `Foo`
     }
 
     let Foo = foo::Foo::Foo;
     //~^ ERROR variable `Foo` should have a snake case name
-    //~^^ WARN `Foo` is named the same as one of the variants of the type `foo::Foo`
+    //~^^ ERROR `Foo` is named the same as one of the variants of the type `foo::Foo`
     //~^^^ WARN unused variable: `Foo`
 
     fn in_param(Foo: foo::Foo) {}
     //~^ ERROR variable `Foo` should have a snake case name
-    //~^^ WARN `Foo` is named the same as one of the variants of the type `foo::Foo`
+    //~^^ ERROR `Foo` is named the same as one of the variants of the type `foo::Foo`
     //~^^^ WARN unused variable: `Foo`
 
     test(1);

tests/ui/lint/lint-uppercase-variables.stderr

@@ -1,18 +1,18 @@
-warning[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `foo::Foo`
+error[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `foo::Foo`
   --> $DIR/lint-uppercase-variables.rs:22:9
    |
 LL |         Foo => {}
    |         ^^^ help: to match on the variant, qualify the path: `foo::Foo::Foo`
    |
-   = note: `#[warn(bindings_with_variant_name)]` on by default
+   = note: `#[deny(bindings_with_variant_name)]` on by default
 
-warning[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `foo::Foo`
+error[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `foo::Foo`
   --> $DIR/lint-uppercase-variables.rs:28:9
    |
 LL |     let Foo = foo::Foo::Foo;
    |         ^^^ help: to match on the variant, qualify the path: `foo::Foo::Foo`
 
-warning[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `foo::Foo`
+error[E0170]: pattern binding `Foo` is named the same as one of the variants of the type `foo::Foo`
   --> $DIR/lint-uppercase-variables.rs:33:17
    |
 LL |     fn in_param(Foo: foo::Foo) {}
@@ -85,6 +85,6 @@ error: variable `Foo` should have a snake case name
 LL |     fn in_param(Foo: foo::Foo) {}
    |                 ^^^ help: convert the identifier to snake case (notice the capitalization): `foo`
 
-error: aborting due to 6 previous errors; 6 warnings emitted
+error: aborting due to 9 previous errors; 3 warnings emitted
 
 For more information about this error, try `rustc --explain E0170`.

tests/ui/pattern/issue-14221.rs

@@ -11,9 +11,9 @@ pub mod b {
     pub fn key(e: ::E) -> &'static str {
         match e {
             A => "A",
-//~^ WARN pattern binding `A` is named the same as one of the variants of the type `E`
+//~^ ERROR pattern binding `A` is named the same as one of the variants of the type `E`
             B => "B", //~ ERROR: unreachable pattern
-//~^ WARN pattern binding `B` is named the same as one of the variants of the type `E`
+//~^ ERROR pattern binding `B` is named the same as one of the variants of the type `E`
         }
     }
 }

tests/ui/pattern/issue-14221.stderr

@@ -1,12 +1,12 @@
-warning[E0170]: pattern binding `A` is named the same as one of the variants of the type `E`
+error[E0170]: pattern binding `A` is named the same as one of the variants of the type `E`
   --> $DIR/issue-14221.rs:13:13
    |
 LL |             A => "A",
    |             ^ help: to match on the variant, qualify the path: `E::A`
    |
-   = note: `#[warn(bindings_with_variant_name)]` on by default
+   = note: `#[deny(bindings_with_variant_name)]` on by default
 
-warning[E0170]: pattern binding `B` is named the same as one of the variants of the type `E`
+error[E0170]: pattern binding `B` is named the same as one of the variants of the type `E`
   --> $DIR/issue-14221.rs:15:13
    |
 LL |             B => "B",
@@ -27,6 +27,6 @@ note: the lint level is defined here
 LL | #![deny(unreachable_patterns)]
    |         ^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to previous error; 2 warnings emitted
+error: aborting due to 3 previous errors
 
 For more information about this error, try `rustc --explain E0170`.

tests/ui/pattern/issue-67776-match-same-name-enum-variant-refs.rs

@@ -1,7 +1,5 @@
 // Test for issue #67776: binding named the same as enum variant
-// should report a warning even when matching against a reference type
+// should report an error even when matching against a reference type
-
-// check-pass
 
 #![allow(unused_variables)]
 #![allow(non_snake_case)]
@@ -15,27 +13,27 @@ enum Foo {
 fn fn1(e: Foo) {
     match e {
         Bar => {},
-        //~^ WARNING named the same as one of the variants of the type `Foo`
+        //~^ ERROR named the same as one of the variants of the type `Foo`
         Baz => {},
-        //~^ WARNING named the same as one of the variants of the type `Foo`
+        //~^ ERROR named the same as one of the variants of the type `Foo`
     }
 }
 
 fn fn2(e: &Foo) {
     match e {
         Bar => {},
-        //~^ WARNING named the same as one of the variants of the type `Foo`
+        //~^ ERROR named the same as one of the variants of the type `Foo`
         Baz => {},
-        //~^ WARNING named the same as one of the variants of the type `Foo`
+        //~^ ERROR named the same as one of the variants of the type `Foo`
     }
 }
 
 fn fn3(e: &mut &&mut Foo) {
     match e {
         Bar => {},
-        //~^ WARNING named the same as one of the variants of the type `Foo`
+        //~^ ERROR named the same as one of the variants of the type `Foo`
         Baz => {},
-        //~^ WARNING named the same as one of the variants of the type `Foo`
+        //~^ ERROR named the same as one of the variants of the type `Foo`
     }
 }
 

tests/ui/pattern/issue-67776-match-same-name-enum-variant-refs.stderr

@@ -1,41 +1,41 @@
-warning[E0170]: pattern binding `Bar` is named the same as one of the variants of the type `Foo`
+error[E0170]: pattern binding `Bar` is named the same as one of the variants of the type `Foo`
+  --> $DIR/issue-67776-match-same-name-enum-variant-refs.rs:15:9
+   |
+LL |         Bar => {},
+   |         ^^^ help: to match on the variant, qualify the path: `Foo::Bar`
+   |
+   = note: `#[deny(bindings_with_variant_name)]` on by default
+
+error[E0170]: pattern binding `Baz` is named the same as one of the variants of the type `Foo`
   --> $DIR/issue-67776-match-same-name-enum-variant-refs.rs:17:9
    |
-LL |         Bar => {},
-   |         ^^^ help: to match on the variant, qualify the path: `Foo::Bar`
-   |
-   = note: `#[warn(bindings_with_variant_name)]` on by default
-
-warning[E0170]: pattern binding `Baz` is named the same as one of the variants of the type `Foo`
-  --> $DIR/issue-67776-match-same-name-enum-variant-refs.rs:19:9
-   |
 LL |         Baz => {},
    |         ^^^ help: to match on the variant, qualify the path: `Foo::Baz`
 
-warning[E0170]: pattern binding `Bar` is named the same as one of the variants of the type `Foo`
+error[E0170]: pattern binding `Bar` is named the same as one of the variants of the type `Foo`
+  --> $DIR/issue-67776-match-same-name-enum-variant-refs.rs:24:9
+   |
+LL |         Bar => {},
+   |         ^^^ help: to match on the variant, qualify the path: `Foo::Bar`
+
+error[E0170]: pattern binding `Baz` is named the same as one of the variants of the type `Foo`
   --> $DIR/issue-67776-match-same-name-enum-variant-refs.rs:26:9
    |
-LL |         Bar => {},
-   |         ^^^ help: to match on the variant, qualify the path: `Foo::Bar`
-
-warning[E0170]: pattern binding `Baz` is named the same as one of the variants of the type `Foo`
-  --> $DIR/issue-67776-match-same-name-enum-variant-refs.rs:28:9
-   |
 LL |         Baz => {},
    |         ^^^ help: to match on the variant, qualify the path: `Foo::Baz`
 
-warning[E0170]: pattern binding `Bar` is named the same as one of the variants of the type `Foo`
+error[E0170]: pattern binding `Bar` is named the same as one of the variants of the type `Foo`
+  --> $DIR/issue-67776-match-same-name-enum-variant-refs.rs:33:9
+   |
+LL |         Bar => {},
+   |         ^^^ help: to match on the variant, qualify the path: `Foo::Bar`
+
+error[E0170]: pattern binding `Baz` is named the same as one of the variants of the type `Foo`
   --> $DIR/issue-67776-match-same-name-enum-variant-refs.rs:35:9
    |
-LL |         Bar => {},
-   |         ^^^ help: to match on the variant, qualify the path: `Foo::Bar`
-
-warning[E0170]: pattern binding `Baz` is named the same as one of the variants of the type `Foo`
-  --> $DIR/issue-67776-match-same-name-enum-variant-refs.rs:37:9
-   |
 LL |         Baz => {},
    |         ^^^ help: to match on the variant, qualify the path: `Foo::Baz`
 
-warning: 6 warnings emitted
+error: aborting due to 6 previous errors
 
 For more information about this error, try `rustc --explain E0170`.

tests/ui/suggestions/issue-88730.rs

@@ -1,9 +1,8 @@
 #![allow(unused, nonstandard_style)]
-#![deny(bindings_with_variant_name)]
 
 // If an enum has two different variants,
 // then it cannot be matched upon in a function argument.
-// It still gets a warning, but no suggestions.
+// It still gets an error, but no suggestions.
 enum Foo {
     C,
     D,

tests/ui/suggestions/issue-88730.stderr

@@ -1,17 +1,13 @@
 error[E0170]: pattern binding `C` is named the same as one of the variants of the type `Foo`
-  --> $DIR/issue-88730.rs:12:8
+  --> $DIR/issue-88730.rs:11:8
    |
 LL | fn foo(C: Foo) {}
    |        ^
    |
-note: the lint level is defined here
+   = note: `#[deny(bindings_with_variant_name)]` on by default
-  --> $DIR/issue-88730.rs:2:9
-   |
-LL | #![deny(bindings_with_variant_name)]
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0170]: pattern binding `C` is named the same as one of the variants of the type `Foo`
-  --> $DIR/issue-88730.rs:15:9
+  --> $DIR/issue-88730.rs:14:9
    |
 LL |     let C = Foo::D;
    |         ^

tests/ui/traits/new-solver/fn-trait-closure.rs

@@ -0,0 +1,15 @@
+// compile-flags: -Ztrait-solver=next
+// known-bug: unknown
+// failure-status: 101
+// dont-check-compiler-stderr
+
+// This test will fail until we fix `FulfillmentCtxt::relationships`. That's
+// because we create a type variable for closure upvar types, which is not
+// constrained until after we try to do fallback on diverging type variables.
+// Thus, we will call that function, which is unimplemented.
+
+fn require_fn(_: impl Fn() -> i32) {}
+
+fn main() {
+    require_fn(|| -> i32 { 1i32 });
+}

tests/ui/traits/new-solver/fn-trait.rs

@@ -0,0 +1,13 @@
+// compile-flags: -Ztrait-solver=next
+// check-pass
+
+fn require_fn(_: impl Fn() -> i32) {}
+
+fn f() -> i32 {
+    1i32
+}
+
+fn main() {
+    require_fn(f);
+    require_fn(f as fn() -> i32);
+}

tests/ui/traits/new-solver/pointer-sized.rs

@@ -0,0 +1,12 @@
+#![feature(pointer_sized_trait)]
+
+use std::marker::PointerSized;
+
+fn require_pointer_sized(_: impl PointerSized) {}
+
+fn main() {
+    require_pointer_sized(1usize);
+    require_pointer_sized(1u16);
+    //~^ ERROR `u16` needs to be a pointer-sized type
+    require_pointer_sized(&1i16);
+}

tests/ui/traits/new-solver/pointer-sized.stderr

@@ -0,0 +1,24 @@
+error[E0277]: `u16` needs to be a pointer-sized type
+  --> $DIR/pointer-sized.rs:9:27
+   |
+LL |     require_pointer_sized(1u16);
+   |     --------------------- ^^^^ the trait `PointerSized` is not implemented for `u16`
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = note: the trait bound `u16: PointerSized` is not satisfied
+note: required by a bound in `require_pointer_sized`
+  --> $DIR/pointer-sized.rs:5:34
+   |
+LL | fn require_pointer_sized(_: impl PointerSized) {}
+   |                                  ^^^^^^^^^^^^ required by this bound in `require_pointer_sized`
+help: consider borrowing here
+   |
+LL |     require_pointer_sized(&1u16);
+   |                           +
+LL |     require_pointer_sized(&mut 1u16);
+   |                           ++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.