rustc_middle/ty/context/

impl_interner.rs

//! Implementation of [`rustc_type_ir::Interner`] for [`TyCtxt`].

use std::ops::ControlFlow;
use std::{debug_assert_matches, fmt};

use rustc_data_structures::Limit;
use rustc_data_structures::intern::Interned;
use rustc_errors::ErrorGuaranteed;
use rustc_hir as hir;
use rustc_hir::def::{CtorKind, DefKind, Namespace};
use rustc_hir::def_id::{DefId, LOCAL_CRATE, LocalDefId};
use rustc_hir::{CRATE_HIR_ID, LangItem};
use rustc_span::{DUMMY_SP, Span, Symbol};
use rustc_type_ir::lang_items::{SolverAdtLangItem, SolverProjectionLangItem, SolverTraitLangItem};
use rustc_type_ir::{
    BoundVar, CollectAndApply, DebruijnIndex, Interner, TypeFoldable, Unnormalized, VisitorResult,
    search_graph,
};

use crate::dep_graph::{DepKind, DepNodeIndex};
use crate::infer::canonical::CanonicalVarKinds;
use crate::traits::cache::WithDepNode;
use crate::traits::solve::{
    self, CanonicalInput, ExternalConstraints, ExternalConstraintsData, QueryResult, inspect,
};
use crate::ty::print::{FmtPrinter, Print};
use crate::ty::{
    self, BoundRegion, Clause, Const, List, ParamTy, Pattern, PolyExistentialPredicate, Predicate,
    Region, RegionKind, Ty, TyCtxt,
};

#[allow(rustc::usage_of_ty_tykind)]
impl<'tcx> Interner for TyCtxt<'tcx> {
    fn next_trait_solver_globally(self) -> bool {
        self.next_trait_solver_globally()
    }

    type DefId = DefId;
    type LocalDefId = LocalDefId;
    type TraitId = DefId;
    type ForeignId = DefId;
    type FunctionId = DefId;
    type ClosureId = DefId;
    type CoroutineClosureId = DefId;
    type CoroutineId = DefId;
    type AdtId = DefId;
    type ImplId = DefId;
    type AnonConstId = DefId;
    type TraitAssocTyId = DefId;
    type TraitAssocConstId = DefId;
    type TraitAssocTermId = DefId;
    type OpaqueTyId = DefId;
    type LocalOpaqueTyId = LocalDefId;
    type FreeTyAliasId = DefId;
    type FreeConstAliasId = DefId;
    type FreeTermAliasId = DefId;
    type ImplOrTraitAssocTyId = DefId;
    type ImplOrTraitAssocConstId = DefId;
    type ImplOrTraitAssocTermId = DefId;
    type InherentAssocTyId = DefId;
    type InherentAssocConstId = DefId;
    type InherentAssocTermId = DefId;
    type Span = Span;

    type GenericArgs = ty::GenericArgsRef<'tcx>;

    type GenericArgsSlice = &'tcx [ty::GenericArg<'tcx>];
    type GenericArg = ty::GenericArg<'tcx>;
    type Term = ty::Term<'tcx>;
    type BoundVarKinds = &'tcx List<ty::BoundVariableKind<'tcx>>;

    type PredefinedOpaques = solve::PredefinedOpaques<'tcx>;

    fn mk_predefined_opaques_in_body(
        self,
        data: &[(ty::OpaqueTypeKey<'tcx>, Ty<'tcx>)],
    ) -> Self::PredefinedOpaques {
        self.mk_predefined_opaques_in_body(data)
    }
    type LocalDefIds = &'tcx ty::List<LocalDefId>;
    type CanonicalVarKinds = CanonicalVarKinds<'tcx>;
    fn mk_canonical_var_kinds(
        self,
        kinds: &[ty::CanonicalVarKind<Self>],
    ) -> Self::CanonicalVarKinds {
        self.mk_canonical_var_kinds(kinds)
    }

    type ExternalConstraints = ExternalConstraints<'tcx>;
    fn mk_external_constraints(
        self,
        data: ExternalConstraintsData<Self>,
    ) -> ExternalConstraints<'tcx> {
        self.mk_external_constraints(data)
    }
    type DepNodeIndex = DepNodeIndex;
    fn with_cached_task<T>(self, task: impl FnOnce() -> T) -> (T, DepNodeIndex) {
        self.dep_graph.with_anon_task(self, DepKind::TraitSelect, task)
    }
    type Ty = Ty<'tcx>;
    type Tys = &'tcx List<Ty<'tcx>>;

    type FnInputTys = &'tcx [Ty<'tcx>];
    type ParamTy = ParamTy;
    type Symbol = Symbol;

    type ErrorGuaranteed = ErrorGuaranteed;
    type BoundExistentialPredicates = &'tcx List<PolyExistentialPredicate<'tcx>>;

    type AllocId = crate::mir::interpret::AllocId;
    type Pat = Pattern<'tcx>;
    type PatList = &'tcx List<Pattern<'tcx>>;
    type Safety = hir::Safety;
    type Const = ty::Const<'tcx>;
    type Consts = &'tcx List<Self::Const>;

    type ParamConst = ty::ParamConst;
    type ValueConst = ty::Value<'tcx>;
    type ExprConst = ty::Expr<'tcx>;
    type ValTree = ty::ValTree<'tcx>;
    type ScalarInt = ty::ScalarInt;
    type InternedRegionKind = Interned<'tcx, ty::RegionKind<'tcx>>;
    type EarlyParamRegion = ty::EarlyParamRegion;
    type LateParamRegion = ty::LateParamRegion;

    type RegionAssumptions = &'tcx ty::List<ty::ArgOutlivesPredicate<'tcx>>;

    type ParamEnv = ty::ParamEnv<'tcx>;
    type Predicate = Predicate<'tcx>;

    type Clause = Clause<'tcx>;
    type Clauses = ty::Clauses<'tcx>;

    type Tracked<T: fmt::Debug + Clone> = WithDepNode<T>;
    fn mk_tracked<T: fmt::Debug + Clone>(
        self,
        data: T,
        dep_node: DepNodeIndex,
    ) -> Self::Tracked<T> {
        WithDepNode::new(dep_node, data)
    }
    fn get_tracked<T: fmt::Debug + Clone>(self, tracked: &Self::Tracked<T>) -> T {
        tracked.get(self)
    }

    fn with_global_cache<R>(self, f: impl FnOnce(&mut search_graph::GlobalCache<Self>) -> R) -> R {
        f(&mut *self.new_solver_evaluation_cache.lock())
    }

    fn canonical_param_env_cache_get_or_insert<R>(
        self,
        param_env: ty::ParamEnv<'tcx>,
        f: impl FnOnce() -> ty::CanonicalParamEnvCacheEntry<Self>,
        from_entry: impl FnOnce(&ty::CanonicalParamEnvCacheEntry<Self>) -> R,
    ) -> R {
        let mut cache = self.new_solver_canonical_param_env_cache.lock();
        let entry = cache.entry(param_env).or_insert_with(f);
        from_entry(entry)
    }

    fn assert_evaluation_is_concurrent(&self) {
        // Turns out, the assumption for this function isn't perfect.
        // See trait-system-refactor-initiative#234.
    }

    fn expand_abstract_consts<T: TypeFoldable<TyCtxt<'tcx>>>(self, t: T) -> T {
        self.expand_abstract_consts(t)
    }

    type GenericsOf = &'tcx ty::Generics;

    fn generics_of(self, def_id: DefId) -> &'tcx ty::Generics {
        self.generics_of(def_id)
    }

    type VariancesOf = &'tcx [ty::Variance];

    fn variances_of(self, def_id: DefId) -> Self::VariancesOf {
        self.variances_of(def_id)
    }

    fn opt_alias_variances(
        self,
        kind: impl Into<ty::AliasTermKind<'tcx>>,
    ) -> Option<&'tcx [ty::Variance]> {
        self.opt_alias_variances(kind)
    }

    fn type_of(self, def_id: DefId) -> ty::EarlyBinder<'tcx, Ty<'tcx>> {
        self.type_of(def_id)
    }
    fn type_of_opaque_hir_typeck(self, def_id: LocalDefId) -> ty::EarlyBinder<'tcx, Ty<'tcx>> {
        self.type_of_opaque_hir_typeck(def_id)
    }
    fn is_type_const(self, def_id: DefId) -> bool {
        self.is_type_const(def_id)
    }
    fn const_of_item(self, def_id: DefId) -> ty::EarlyBinder<'tcx, Const<'tcx>> {
        self.const_of_item(def_id)
    }
    fn anon_const_kind(self, def_id: DefId) -> ty::AnonConstKind {
        self.anon_const_kind(def_id)
    }

    fn def_span(self, def_id: DefId) -> Span {
        self.def_span(def_id)
    }

    type AdtDef = ty::AdtDef<'tcx>;
    fn adt_def(self, adt_def_id: DefId) -> Self::AdtDef {
        self.adt_def(adt_def_id)
    }

    fn alias_const_kind_from_def_id(self, def_id: Self::DefId) -> ty::AliasConstKind<'tcx> {
        match self.def_kind(def_id) {
            DefKind::AssocConst { .. } => {
                if let DefKind::Impl { of_trait: false } = self.def_kind(self.parent(def_id)) {
                    ty::AliasConstKind::Inherent { def_id }
                } else {
                    ty::AliasConstKind::Projection { def_id }
                }
            }
            DefKind::Const { .. } => ty::AliasConstKind::Free { def_id },
            DefKind::AnonConst | DefKind::Ctor(_, CtorKind::Const) => {
                ty::AliasConstKind::Anon { def_id }
            }
            kind => bug!("unexpected DefKind in AliasConst: {kind:?}"),
        }
    }

    fn alias_term_kind_from_def_id(self, def_id: DefId) -> ty::AliasTermKind<'tcx> {
        match self.def_kind(def_id) {
            DefKind::AssocTy => {
                if let DefKind::Impl { of_trait: false } = self.def_kind(self.parent(def_id)) {
                    ty::AliasTermKind::InherentTy { def_id }
                } else {
                    ty::AliasTermKind::ProjectionTy { def_id }
                }
            }
            DefKind::AssocConst { .. } => {
                if let DefKind::Impl { of_trait: false } = self.def_kind(self.parent(def_id)) {
                    ty::AliasTermKind::InherentConst { def_id }
                } else {
                    ty::AliasTermKind::ProjectionConst { def_id }
                }
            }
            DefKind::OpaqueTy => ty::AliasTermKind::OpaqueTy { def_id },
            DefKind::TyAlias => ty::AliasTermKind::FreeTy { def_id },
            DefKind::Const { .. } => ty::AliasTermKind::FreeConst { def_id },
            DefKind::AnonConst | DefKind::Ctor(_, CtorKind::Const) => {
                ty::AliasTermKind::AnonConst { def_id }
            }
            kind => bug!("unexpected DefKind in AliasTy: {kind:?}"),
        }
    }

    fn trait_ref_and_own_args_for_alias(
        self,
        def_id: DefId,
        args: ty::GenericArgsRef<'tcx>,
    ) -> (ty::TraitRef<'tcx>, &'tcx [ty::GenericArg<'tcx>]) {
        debug_assert_matches!(self.def_kind(def_id), DefKind::AssocTy | DefKind::AssocConst { .. });
        let trait_def_id = self.parent(def_id);
        debug_assert_matches!(self.def_kind(trait_def_id), DefKind::Trait);
        let trait_ref = ty::TraitRef::from_assoc(self, trait_def_id, args);
        (trait_ref, &args[trait_ref.args.len()..])
    }

    fn mk_args(self, args: &[Self::GenericArg]) -> ty::GenericArgsRef<'tcx> {
        self.mk_args(args)
    }

    fn mk_args_from_iter<I, T>(self, args: I) -> T::Output
    where
        I: Iterator<Item = T>,
        T: CollectAndApply<Self::GenericArg, ty::GenericArgsRef<'tcx>>,
    {
        self.mk_args_from_iter(args)
    }

    fn check_args_compatible(self, def_id: DefId, args: ty::GenericArgsRef<'tcx>) -> bool {
        self.check_args_compatible(def_id, args)
    }

    fn debug_assert_args_compatible(self, def_id: DefId, args: ty::GenericArgsRef<'tcx>) {
        self.debug_assert_args_compatible(def_id, args);
    }

    /// Assert that the args from an `ExistentialTraitRef` or `ExistentialProjection`
    /// are compatible with the `DefId`. Since we're missing a `Self` type, stick on
    /// a dummy self type and forward to `debug_assert_args_compatible`.
    fn debug_assert_existential_args_compatible(
        self,
        def_id: Self::DefId,
        args: Self::GenericArgs,
    ) {
        // FIXME: We could perhaps add a `skip: usize` to `debug_assert_args_compatible`
        // to avoid needing to reintern the set of args...
        if cfg!(debug_assertions) {
            self.debug_assert_args_compatible(
                def_id,
                self.mk_args_from_iter(
                    [self.types.trait_object_dummy_self.into()].into_iter().chain(args.iter()),
                ),
            );
        }
    }

    fn mk_type_list_from_iter<I, T>(self, args: I) -> T::Output
    where
        I: Iterator<Item = T>,
        T: CollectAndApply<Ty<'tcx>, &'tcx List<Ty<'tcx>>>,
    {
        self.mk_type_list_from_iter(args)
    }

    fn projection_parent(self, def_id: Self::TraitAssocTermId) -> Self::TraitId {
        self.parent(def_id)
    }

    fn impl_or_trait_assoc_term_parent(self, def_id: Self::ImplOrTraitAssocTyId) -> DefId {
        self.parent(def_id)
    }

    fn inherent_alias_term_parent(self, def_id: Self::InherentAssocTermId) -> Self::ImplId {
        self.parent(def_id)
    }

    fn recursion_limit(self) -> usize {
        self.recursion_limit().0
    }

    type Features = &'tcx rustc_feature::Features;

    fn features(self) -> Self::Features {
        self.features()
    }

    fn assumptions_on_binders(self) -> bool {
        self.assumptions_on_binders()
    }

    fn renormalize_rigid_aliases(self) -> bool {
        self.renormalize_rigid_aliases()
    }

    fn coroutine_hidden_types(
        self,
        def_id: DefId,
    ) -> ty::EarlyBinder<'tcx, ty::Binder<'tcx, ty::CoroutineWitnessTypes<TyCtxt<'tcx>>>> {
        self.coroutine_hidden_types(def_id)
    }

    fn fn_sig(self, def_id: DefId) -> ty::EarlyBinder<'tcx, ty::PolyFnSig<'tcx>> {
        self.fn_sig(def_id)
    }

    fn coroutine_movability(self, def_id: DefId) -> rustc_ast::Movability {
        self.coroutine_movability(def_id)
    }

    fn coroutine_for_closure(self, def_id: DefId) -> DefId {
        self.coroutine_for_closure(def_id)
    }

    fn generics_require_sized_self(self, def_id: DefId) -> bool {
        self.generics_require_sized_self(def_id)
    }

    fn item_bounds(
        self,
        def_id: DefId,
    ) -> ty::EarlyBinder<'tcx, impl IntoIterator<Item = ty::Clause<'tcx>>> {
        self.item_bounds(def_id).map_bound(IntoIterator::into_iter)
    }

    fn item_self_bounds(
        self,
        def_id: DefId,
    ) -> ty::EarlyBinder<'tcx, impl IntoIterator<Item = ty::Clause<'tcx>>> {
        self.item_self_bounds(def_id).map_bound(IntoIterator::into_iter)
    }

    fn item_non_self_bounds(
        self,
        def_id: DefId,
    ) -> ty::EarlyBinder<'tcx, impl IntoIterator<Item = ty::Clause<'tcx>>> {
        self.item_non_self_bounds(def_id).map_bound(IntoIterator::into_iter)
    }

    fn clauses_of(
        self,
        def_id: DefId,
    ) -> ty::EarlyBinder<'tcx, impl IntoIterator<Item = ty::Clause<'tcx>>> {
        ty::EarlyBinder::bind_iter(
            self.clauses_of(def_id)
                .instantiate_identity(self)
                .clauses
                .into_iter()
                .map(Unnormalized::skip_normalization),
        )
    }

    fn own_clauses_of(
        self,
        def_id: DefId,
    ) -> ty::EarlyBinder<'tcx, impl IntoIterator<Item = ty::Clause<'tcx>>> {
        ty::EarlyBinder::bind_iter(
            self.clauses_of(def_id)
                .instantiate_own_identity()
                .map(|(clause, _)| clause.skip_normalization()),
        )
    }

    fn explicit_super_clauses_of(
        self,
        def_id: DefId,
    ) -> ty::EarlyBinder<'tcx, impl IntoIterator<Item = (ty::Clause<'tcx>, Span)>> {
        self.explicit_super_clauses_of(def_id).map_bound(|preds| preds.into_iter().copied())
    }

    fn explicit_implied_clauses_of(
        self,
        def_id: DefId,
    ) -> ty::EarlyBinder<'tcx, impl IntoIterator<Item = (ty::Clause<'tcx>, Span)>> {
        self.explicit_implied_clauses_of(def_id).map_bound(|preds| preds.into_iter().copied())
    }

    fn impl_super_outlives(
        self,
        impl_def_id: DefId,
    ) -> ty::EarlyBinder<'tcx, impl IntoIterator<Item = ty::Clause<'tcx>>> {
        self.impl_super_outlives(impl_def_id)
    }

    fn impl_is_const(self, def_id: DefId) -> bool {
        debug_assert_matches!(self.def_kind(def_id), DefKind::Impl { of_trait: true });
        self.is_conditionally_const(def_id)
    }

    fn fn_is_const(self, def_id: DefId) -> bool {
        debug_assert_matches!(
            self.def_kind(def_id),
            DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(_, CtorKind::Fn)
        );
        self.is_conditionally_const(def_id)
    }

    fn closure_is_const(self, def_id: DefId) -> bool {
        debug_assert_matches!(self.def_kind(def_id), DefKind::Closure);
        matches!(self.constness(def_id), hir::Constness::Const { always: false })
    }

    fn alias_has_const_conditions(self, def_id: DefId) -> bool {
        debug_assert_matches!(self.def_kind(def_id), DefKind::AssocTy | DefKind::OpaqueTy);
        self.is_conditionally_const(def_id)
    }

    fn const_conditions(
        self,
        def_id: DefId,
    ) -> ty::EarlyBinder<'tcx, impl IntoIterator<Item = ty::Binder<'tcx, ty::TraitRef<'tcx>>>> {
        ty::EarlyBinder::bind_iter(
            self.const_conditions(def_id)
                .instantiate_identity(self)
                .into_iter()
                .map(|(c, _)| c.skip_normalization()),
        )
    }

    fn explicit_implied_const_bounds(
        self,
        def_id: DefId,
    ) -> ty::EarlyBinder<'tcx, impl IntoIterator<Item = ty::Binder<'tcx, ty::TraitRef<'tcx>>>> {
        ty::EarlyBinder::bind_iter(
            self.explicit_implied_const_bounds(def_id)
                .iter_identity_copied()
                .map(Unnormalized::skip_normalization)
                .map(|(c, _)| c),
        )
    }

    fn impl_self_is_guaranteed_unsized(self, impl_def_id: DefId) -> bool {
        self.impl_self_is_guaranteed_unsized(impl_def_id)
    }

    fn has_target_features(self, def_id: DefId) -> bool {
        !self.codegen_fn_attrs(def_id).target_features.is_empty()
    }

    fn require_projection_lang_item(self, lang_item: SolverProjectionLangItem) -> DefId {
        self.require_lang_item(solver_lang_item_to_lang_item(lang_item), DUMMY_SP)
    }

    fn require_trait_lang_item(self, lang_item: SolverTraitLangItem) -> DefId {
        self.require_lang_item(solver_trait_lang_item_to_lang_item(lang_item), DUMMY_SP)
    }

    fn require_adt_lang_item(self, lang_item: SolverAdtLangItem) -> DefId {
        self.require_lang_item(solver_adt_lang_item_to_lang_item(lang_item), DUMMY_SP)
    }

    fn is_projection_lang_item(self, def_id: DefId, lang_item: SolverProjectionLangItem) -> bool {
        self.is_lang_item(def_id, solver_lang_item_to_lang_item(lang_item))
    }

    fn is_trait_lang_item(self, def_id: DefId, lang_item: SolverTraitLangItem) -> bool {
        self.is_lang_item(def_id, solver_trait_lang_item_to_lang_item(lang_item))
    }

    fn is_adt_lang_item(self, def_id: DefId, lang_item: SolverAdtLangItem) -> bool {
        self.is_lang_item(def_id, solver_adt_lang_item_to_lang_item(lang_item))
    }

    fn is_default_trait(self, def_id: DefId) -> bool {
        self.is_default_trait(def_id)
    }

    fn is_sizedness_trait(self, def_id: DefId) -> bool {
        self.is_sizedness_trait(def_id)
    }

    fn as_projection_lang_item(self, def_id: DefId) -> Option<SolverProjectionLangItem> {
        lang_item_to_solver_lang_item(self.lang_items().from_def_id(def_id)?)
    }

    fn as_trait_lang_item(self, def_id: DefId) -> Option<SolverTraitLangItem> {
        lang_item_to_solver_trait_lang_item(self.lang_items().from_def_id(def_id)?)
    }

    fn as_adt_lang_item(self, def_id: DefId) -> Option<SolverAdtLangItem> {
        lang_item_to_solver_adt_lang_item(self.lang_items().from_def_id(def_id)?)
    }

    fn associated_type_def_ids(self, def_id: DefId) -> impl IntoIterator<Item = DefId> {
        self.associated_items(def_id)
            .in_definition_order()
            .filter(|assoc_item| assoc_item.is_type())
            .map(|assoc_item| assoc_item.def_id)
    }

    // This implementation is a bit different from `TyCtxt::for_each_relevant_impl`,
    // since we want to skip over blanket impls for non-rigid aliases, and also we
    // only want to consider types that *actually* unify with float/int vars.
    fn for_each_relevant_impl<R: VisitorResult>(
        self,
        trait_ref: ty::TraitRef<'tcx>,
        mut f: impl FnMut(DefId) -> R,
    ) -> R {
        macro_rules! ret {
            ($e: expr) => {
                match $e.branch() {
                    ControlFlow::Break(b) => return R::from_residual(b),
                    ControlFlow::Continue(()) => {}
                }
            };
        }

        let trait_def_id = trait_ref.def_id;
        let self_ty = trait_ref.self_ty();
        let tcx = self;
        let trait_impls = tcx.trait_impls_of(trait_def_id);
        let mut consider_impls_for_simplified_type = |simp| {
            if let Some(impls_for_type) = trait_impls.non_blanket_impls().get(&simp) {
                for &impl_def_id in impls_for_type {
                    ret!(f(impl_def_id))
                }
            }

            R::output()
        };

        match self_ty.kind() {
            ty::Bool
            | ty::Char
            | ty::Int(_)
            | ty::Uint(_)
            | ty::Float(_)
            | ty::Adt(_, _)
            | ty::Foreign(_)
            | ty::Str
            | ty::Array(_, _)
            | ty::Pat(_, _)
            | ty::Slice(_)
            | ty::RawPtr(_, _)
            | ty::Ref(_, _, _)
            | ty::FnDef(_, _)
            | ty::FnPtr(..)
            | ty::Dynamic(_, _)
            | ty::Closure(..)
            | ty::CoroutineClosure(..)
            | ty::Coroutine(_, _)
            | ty::Never
            | ty::Tuple(_)
            | ty::UnsafeBinder(_) => {
                if let Some(simp) = ty::fast_reject::simplify_type(
                    tcx,
                    self_ty,
                    ty::fast_reject::TreatParams::AsRigid,
                ) {
                    ret!(consider_impls_for_simplified_type(simp));
                }
            }

            // HACK: For integer and float variables we have to manually look at all impls
            // which have some integer or float as a self type.
            ty::Infer(ty::IntVar(_)) => {
                use ty::IntTy::*;
                use ty::UintTy::*;
                // This causes a compiler error if any new integer kinds are added.
                let (I8 | I16 | I32 | I64 | I128 | Isize): ty::IntTy;
                let (U8 | U16 | U32 | U64 | U128 | Usize): ty::UintTy;
                let possible_integers = [
                    // signed integers
                    ty::SimplifiedType::Int(I8),
                    ty::SimplifiedType::Int(I16),
                    ty::SimplifiedType::Int(I32),
                    ty::SimplifiedType::Int(I64),
                    ty::SimplifiedType::Int(I128),
                    ty::SimplifiedType::Int(Isize),
                    // unsigned integers
                    ty::SimplifiedType::Uint(U8),
                    ty::SimplifiedType::Uint(U16),
                    ty::SimplifiedType::Uint(U32),
                    ty::SimplifiedType::Uint(U64),
                    ty::SimplifiedType::Uint(U128),
                    ty::SimplifiedType::Uint(Usize),
                ];
                for simp in possible_integers {
                    ret!(consider_impls_for_simplified_type(simp));
                }
            }

            ty::Infer(ty::FloatVar(_)) => {
                // This causes a compiler error if any new float kinds are added.
                let (ty::FloatTy::F16 | ty::FloatTy::F32 | ty::FloatTy::F64 | ty::FloatTy::F128);
                let possible_floats = [
                    ty::SimplifiedType::Float(ty::FloatTy::F16),
                    ty::SimplifiedType::Float(ty::FloatTy::F32),
                    ty::SimplifiedType::Float(ty::FloatTy::F64),
                    ty::SimplifiedType::Float(ty::FloatTy::F128),
                ];

                for simp in possible_floats {
                    ret!(consider_impls_for_simplified_type(simp));
                }
            }

            // The only traits applying to aliases and placeholders are blanket impls.
            //
            // Impls which apply to an alias after normalization are handled by
            // `assemble_candidates_after_normalizing_self_ty`.
            ty::Alias(ty::IsRigid::Yes, _) | ty::Placeholder(..) | ty::Error(_) => (),
            // FIXME(-Znext-solver=no): Need to support aliases not marked as
            // rigid for the old solver.
            ty::Alias(ty::IsRigid::No, _) => (),

            // FIXME: These should ideally not exist as a self type. It would be nice for
            // the builtin auto trait impls of coroutines to instead directly recurse
            // into the witness.
            ty::CoroutineWitness(..) => (),

            // These variants should not exist as a self type.
            ty::Infer(ty::TyVar(_) | ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_))
            | ty::Param(_)
            | ty::Bound(_, _) => bug!("unexpected self type: {self_ty}"),
        }

        #[allow(rustc::usage_of_type_ir_traits)]
        self.for_each_blanket_impl(trait_def_id, f)
    }
    fn for_each_blanket_impl<R: VisitorResult>(
        self,
        trait_def_id: DefId,
        mut f: impl FnMut(DefId) -> R,
    ) -> R {
        let trait_impls = self.trait_impls_of(trait_def_id);
        for &impl_def_id in trait_impls.blanket_impls() {
            match f(impl_def_id).branch() {
                ControlFlow::Break(b) => return R::from_residual(b),
                ControlFlow::Continue(()) => {}
            }
        }

        R::output()
    }

    fn has_item_definition(self, def_id: DefId) -> bool {
        self.defaultness(def_id).has_value()
    }

    fn impl_specializes(self, impl_def_id: Self::DefId, victim_def_id: Self::DefId) -> bool {
        self.specializes((impl_def_id, victim_def_id))
    }

    fn impl_is_default(self, impl_def_id: DefId) -> bool {
        self.defaultness(impl_def_id).is_default()
    }

    fn impl_trait_ref(self, impl_def_id: DefId) -> ty::EarlyBinder<'tcx, ty::TraitRef<'tcx>> {
        self.impl_trait_ref(impl_def_id)
    }

    fn impl_polarity(self, impl_def_id: DefId) -> ty::ImplPolarity {
        self.impl_polarity(impl_def_id)
    }

    fn is_fully_generic_for_reflection(self, impl_def_id: Self::ImplId) -> bool {
        self.impl_is_fully_generic_for_reflection(impl_def_id)
    }

    fn trait_is_auto(self, trait_def_id: DefId) -> bool {
        self.trait_is_auto(trait_def_id)
    }

    fn trait_is_coinductive(self, trait_def_id: DefId) -> bool {
        self.trait_is_coinductive(trait_def_id)
    }

    fn trait_is_alias(self, trait_def_id: DefId) -> bool {
        self.trait_is_alias(trait_def_id)
    }

    fn trait_is_dyn_compatible(self, trait_def_id: DefId) -> bool {
        self.is_dyn_compatible(trait_def_id)
    }

    fn trait_is_fundamental(self, def_id: DefId) -> bool {
        self.trait_def(def_id).is_fundamental
    }

    fn trait_is_unsafe(self, trait_def_id: Self::DefId) -> bool {
        self.trait_def(trait_def_id).safety.is_unsafe()
    }

    fn is_impl_trait_in_trait(self, def_id: DefId) -> bool {
        self.is_impl_trait_in_trait(def_id)
    }

    fn delay_bug(self, msg: impl ToString) -> ErrorGuaranteed {
        self.dcx().span_delayed_bug(DUMMY_SP, msg.to_string())
    }

    fn is_general_coroutine(self, coroutine_def_id: DefId) -> bool {
        self.is_general_coroutine(coroutine_def_id)
    }

    fn coroutine_is_async(self, coroutine_def_id: DefId) -> bool {
        self.coroutine_is_async(coroutine_def_id)
    }

    fn coroutine_is_gen(self, coroutine_def_id: DefId) -> bool {
        self.coroutine_is_gen(coroutine_def_id)
    }

    fn coroutine_is_async_gen(self, coroutine_def_id: DefId) -> bool {
        self.coroutine_is_async_gen(coroutine_def_id)
    }

    type UnsizingParams = &'tcx rustc_index::bit_set::DenseBitSet<u32>;
    fn unsizing_params_for_adt(self, adt_def_id: DefId) -> Self::UnsizingParams {
        self.unsizing_params_for_adt(adt_def_id)
    }

    fn anonymize_bound_vars<T: TypeFoldable<TyCtxt<'tcx>>>(
        self,
        binder: ty::Binder<'tcx, T>,
    ) -> ty::Binder<'tcx, T> {
        self.anonymize_bound_vars(binder)
    }

    fn opaque_types_defined_by(self, defining_anchor: LocalDefId) -> Self::LocalDefIds {
        self.opaque_types_defined_by(defining_anchor)
    }

    fn opaque_types_and_coroutines_defined_by(
        self,
        defining_anchor: Self::LocalDefId,
    ) -> Self::LocalDefIds {
        let coroutines_defined_by = self
            .nested_bodies_within(defining_anchor)
            .iter()
            .filter(|def_id| self.is_coroutine(def_id.to_def_id()));
        self.mk_local_def_ids_from_iter(
            self.opaque_types_defined_by(defining_anchor).iter().chain(coroutines_defined_by),
        )
    }

    type Probe = &'tcx inspect::Probe<TyCtxt<'tcx>>;
    fn mk_probe(self, probe: inspect::Probe<Self>) -> &'tcx inspect::Probe<TyCtxt<'tcx>> {
        self.arena.alloc(probe)
    }
    fn evaluate_root_goal_for_proof_tree_raw(
        self,
        canonical_goal: CanonicalInput<'tcx>,
        root_depth: usize,
    ) -> (QueryResult<'tcx>, &'tcx inspect::Probe<TyCtxt<'tcx>>) {
        self.evaluate_root_goal_for_proof_tree_raw((canonical_goal, root_depth))
    }

    fn emit_next_solver_overflow_fcw(self, predicate: ty::Predicate<'tcx>, span: Span) {
        self.emit_node_span_lint(
            rustc_session::lint::builtin::RECURSION_DEPTH_EXCEEDING_LIMIT,
            CRATE_HIR_ID,
            span,
            rustc_errors::DiagDecorator(|diag| {
                // FIXME: share this with overflow error in fulfillment instead of duplicating.
                let pred_str = {
                    let s = predicate.to_string();
                    if s.len() > 50 {
                        let mut p: FmtPrinter<'_, '_> =
                            FmtPrinter::new_with_limit(self, Namespace::TypeNS, Limit(6));
                        predicate.print(&mut p).unwrap();
                        p.into_buffer()
                    } else {
                        s
                    }
                };
                diag.primary_message(format!(
                    "overflow evaluating the requirement `{pred_str}`",
                ));
                diag.help(format!(
                    "consider increasing the recursion limit by adding a \
                     `#![recursion_limit = \"{}\"]` attribute to your crate (`{}`)",
                    self.recursion_limit() * 2,
                    self.crate_name(LOCAL_CRATE),
                ));
                diag.help(
                    "or consider adding a manual `impl` of auto traits like `Send` for intermediate types, if auto traits are involved",
                );
                diag.note("this lint is attached to the whole crate and can't be disabled on a per-function basis");
            }),
        )
    }

    fn item_name(self, id: DefId) -> Symbol {
        self.opt_item_name(id).unwrap_or_else(|| {
            bug!("item_name: no name for {:?}", self.def_path(id));
        })
    }

    fn get_anon_re_bounds_lifetime(self, idx: usize, var_idx: usize) -> Option<Region<'tcx>> {
        if let Some(inner) = self.lifetimes.anon_re_bounds.get(idx) {
            inner.get(var_idx).copied()
        } else {
            None
        }
    }

    fn get_anon_re_canonical_bounds_lifetime(self, idx: usize) -> Option<Region<'tcx>> {
        self.lifetimes.anon_re_canonical_bounds.get(idx).copied()
    }

    fn get_re_static_lifetime(self) -> Region<'tcx> {
        self.lifetimes.re_static
    }

    fn intern_region(self, region_kind: RegionKind<'tcx>) -> Region<'tcx> {
        self.intern_region(region_kind)
    }

    fn intern_bound_region(
        self,
        debruijn: DebruijnIndex,
        bound_region: BoundRegion<'tcx>,
    ) -> Region<'tcx> {
        // Use a pre-interned one when possible.
        if let ty::BoundRegion { var, kind: ty::BoundRegionKind::Anon } = bound_region
            && let Some(inner) = self.lifetimes.anon_re_bounds.get(debruijn.as_usize())
            && let Some(re) = inner.get(var.as_usize()).copied()
        {
            re
        } else {
            self.intern_region(ty::ReBound(ty::BoundVarIndexKind::Bound(debruijn), bound_region))
        }
    }

    fn intern_canonical_bound(self, var: BoundVar) -> Region<'tcx> {
        // Use a pre-interned one when possible.
        if let Some(re) = self.lifetimes.anon_re_canonical_bounds.get(var.as_usize()).copied() {
            re
        } else {
            self.intern_region(ty::ReBound(
                ty::BoundVarIndexKind::Canonical,
                BoundRegion { var, kind: ty::BoundRegionKind::Anon },
            ))
        }
    }
}

impl<'tcx, T: std::fmt::Debug + Clone + Copy> rustc_type_ir::intern::Interned<TyCtxt<'tcx>>
    for Interned<'tcx, T>
{
    type Value = T;
    fn get(self) -> T {
        *self.0
    }
}

/// Defines trivial conversion functions between the main [`LangItem`] enum,
/// and some other lang-item enum that is a subset of it.
macro_rules! bidirectional_lang_item_map {
    (
        $solver_ty:ident, fn $to_solver:ident, fn $from_solver:ident;
        $($name:ident),+ $(,)?
    ) => {
        fn $from_solver(lang_item: $solver_ty) -> LangItem {
            match lang_item {
                $($solver_ty::$name => LangItem::$name,)+
            }
        }

        fn $to_solver(lang_item: LangItem) -> Option<$solver_ty> {
            Some(match lang_item {
                $(LangItem::$name => $solver_ty::$name,)+
                _ => return None,
            })
        }
    }
}

bidirectional_lang_item_map! {
    SolverProjectionLangItem, fn lang_item_to_solver_lang_item, fn solver_lang_item_to_lang_item;

// tidy-alphabetical-start
    AsyncFnKindUpvars,
    AsyncFnOnceOutput,
    CallOnceFuture,
    CallRefFuture,
    CoroutineReturn,
    CoroutineYield,
    FieldBase,
    FieldType,
    FutureOutput,
    Metadata,
// tidy-alphabetical-end
}

bidirectional_lang_item_map! {
    SolverAdtLangItem, fn lang_item_to_solver_adt_lang_item, fn solver_adt_lang_item_to_lang_item;

// tidy-alphabetical-start
    DynMetadata,
    Option,
    Poll,
// tidy-alphabetical-end
}

bidirectional_lang_item_map! {
    SolverTraitLangItem, fn lang_item_to_solver_trait_lang_item, fn solver_trait_lang_item_to_lang_item;

// tidy-alphabetical-start
    AsyncFn,
    AsyncFnKindHelper,
    AsyncFnMut,
    AsyncFnOnce,
    AsyncIterator,
    BikeshedGuaranteedNoDrop,
    Clone,
    Copy,
    Coroutine,
    Destruct,
    DiscriminantKind,
    Drop,
    Field,
    Fn,
    FnMut,
    FnOnce,
    FnPtrTrait,
    FusedIterator,
    Future,
    Iterator,
    MetaSized,
    PointeeSized,
    PointeeTrait,
    Sized,
    TransmuteTrait,
    TrivialClone,
    TryAsDyn,
    Tuple,
    Unpin,
    Unsize,
// tidy-alphabetical-end
}