compiler/rustc_traits/src/chalk/db.rs

   1 //! Provides the `RustIrDatabase` implementation for `chalk-solve`
   2 //!
   3 //! The purpose of the `chalk_solve::RustIrDatabase` is to get data about
   4 //! specific types, such as bounds, where clauses, or fields. This file contains
   5 //! the minimal logic to assemble the types for `chalk-solve` by calling out to
   6 //! either the `TyCtxt` (for information about types) or
   7 //! `crate::chalk::lowering` (to lower rustc types into Chalk types).
   8
   9 use rustc_middle::traits::ChalkRustInterner as RustInterner;
  10 use rustc_middle::ty::subst::{InternalSubsts, Subst, SubstsRef};
  11 use rustc_middle::ty::{self, AssocItemContainer, AssocKind, TyCtxt, TypeFoldable};
  12
  13 use rustc_ast::ast;
  14 use rustc_attr as attr;
  15
  16 use rustc_hir::def_id::DefId;
  17
  18 use rustc_span::symbol::sym;
  19
  20 use std::fmt;
  21 use std::sync::Arc;
  22
  23 use crate::chalk::lowering::{self, LowerInto};
  24
  25 pub struct RustIrDatabase<'tcx> {
  26     pub(crate) interner: RustInterner<'tcx>,
  27     pub(crate) reempty_placeholder: ty::Region<'tcx>,
  28 }
  29
  30 impl fmt::Debug for RustIrDatabase<'_> {
  31     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  32         write!(f, "RustIrDatabase")
  33     }
  34 }
  35
  36 impl<'tcx> RustIrDatabase<'tcx> {
  37     fn where_clauses_for(
  38         &self,
  39         def_id: DefId,
  40         bound_vars: SubstsRef<'tcx>,
  41     ) -> Vec<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>> {
  42         let predicates = self.interner.tcx.predicates_defined_on(def_id).predicates;
  43         let mut regions_substitutor =
  44             lowering::RegionsSubstitutor::new(self.interner.tcx, self.reempty_placeholder);
  45         predicates
  46             .iter()
  47             .map(|(wc, _)| wc.subst(self.interner.tcx, bound_vars))
  48             .map(|wc| wc.fold_with(&mut regions_substitutor))
  49             .filter_map(|wc| LowerInto::<Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>>::lower_into(wc, &self.interner)).collect()
  50     }
  51
  52     fn bounds_for<T>(&self, def_id: DefId, bound_vars: SubstsRef<'tcx>) -> Vec<T>
  53     where
  54         ty::Predicate<'tcx>: LowerInto<'tcx, std::option::Option<T>>,
  55     {
  56         self.interner
  57             .tcx
  58             .explicit_item_bounds(def_id)
  59             .iter()
  60             .map(|(bound, _)| bound.subst(self.interner.tcx, &bound_vars))
  61             .filter_map(|bound| LowerInto::<Option<_>>::lower_into(bound, &self.interner))
  62             .collect()
  63     }
  64 }
  65
  66 impl<'tcx> chalk_solve::RustIrDatabase<RustInterner<'tcx>> for RustIrDatabase<'tcx> {
  67     fn interner(&self) -> &RustInterner<'tcx> {
  68         &self.interner
  69     }
  70
  71     fn associated_ty_data(
  72         &self,
  73         assoc_type_id: chalk_ir::AssocTypeId<RustInterner<'tcx>>,
  74     ) -> Arc<chalk_solve::rust_ir::AssociatedTyDatum<RustInterner<'tcx>>> {
  75         let def_id = assoc_type_id.0;
  76         let assoc_item = self.interner.tcx.associated_item(def_id);
  77         let trait_def_id = match assoc_item.container {
  78             AssocItemContainer::TraitContainer(def_id) => def_id,
  79             _ => unimplemented!("Not possible??"),
  80         };
  81         match assoc_item.kind {
  82             AssocKind::Type => {}
  83             _ => unimplemented!("Not possible??"),
  84         }
  85         let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
  86         let binders = binders_for(&self.interner, bound_vars);
  87
  88         let where_clauses = self.where_clauses_for(def_id, bound_vars);
  89         let bounds = self.bounds_for(def_id, bound_vars);
  90
  91         Arc::new(chalk_solve::rust_ir::AssociatedTyDatum {
  92             trait_id: chalk_ir::TraitId(trait_def_id),
  93             id: assoc_type_id,
  94             name: (),
  95             binders: chalk_ir::Binders::new(
  96                 binders,
  97                 chalk_solve::rust_ir::AssociatedTyDatumBound { bounds, where_clauses },
  98             ),
  99         })
 100     }
 101
 102     fn trait_datum(
 103         &self,
 104         trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
 105     ) -> Arc<chalk_solve::rust_ir::TraitDatum<RustInterner<'tcx>>> {
 106         let def_id = trait_id.0;
 107         let trait_def = self.interner.tcx.trait_def(def_id);
 108
 109         let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
 110         let binders = binders_for(&self.interner, bound_vars);
 111
 112         let where_clauses = self.where_clauses_for(def_id, bound_vars);
 113
 114         let associated_ty_ids: Vec<_> = self
 115             .interner
 116             .tcx
 117             .associated_items(def_id)
 118             .in_definition_order()
 119             .filter(|i| i.kind == AssocKind::Type)
 120             .map(|i| chalk_ir::AssocTypeId(i.def_id))
 121             .collect();
 122
 123         let lang_items = self.interner.tcx.lang_items();
 124         let well_known = if lang_items.sized_trait() == Some(def_id) {
 125             Some(chalk_solve::rust_ir::WellKnownTrait::Sized)
 126         } else if lang_items.copy_trait() == Some(def_id) {
 127             Some(chalk_solve::rust_ir::WellKnownTrait::Copy)
 128         } else if lang_items.clone_trait() == Some(def_id) {
 129             Some(chalk_solve::rust_ir::WellKnownTrait::Clone)
 130         } else if lang_items.drop_trait() == Some(def_id) {
 131             Some(chalk_solve::rust_ir::WellKnownTrait::Drop)
 132         } else if lang_items.fn_trait() == Some(def_id) {
 133             Some(chalk_solve::rust_ir::WellKnownTrait::Fn)
 134         } else if lang_items.fn_once_trait() == Some(def_id) {
 135             Some(chalk_solve::rust_ir::WellKnownTrait::FnOnce)
 136         } else if lang_items.fn_mut_trait() == Some(def_id) {
 137             Some(chalk_solve::rust_ir::WellKnownTrait::FnMut)
 138         } else if lang_items.unsize_trait() == Some(def_id) {
 139             Some(chalk_solve::rust_ir::WellKnownTrait::Unsize)
 140         } else if lang_items.unpin_trait() == Some(def_id) {
 141             Some(chalk_solve::rust_ir::WellKnownTrait::Unpin)
 142         } else if lang_items.coerce_unsized_trait() == Some(def_id) {
 143             Some(chalk_solve::rust_ir::WellKnownTrait::CoerceUnsized)
 144         } else {
 145             None
 146         };
 147         Arc::new(chalk_solve::rust_ir::TraitDatum {
 148             id: trait_id,
 149             binders: chalk_ir::Binders::new(
 150                 binders,
 151                 chalk_solve::rust_ir::TraitDatumBound { where_clauses },
 152             ),
 153             flags: chalk_solve::rust_ir::TraitFlags {
 154                 auto: trait_def.has_auto_impl,
 155                 marker: trait_def.is_marker,
 156                 upstream: !def_id.is_local(),
 157                 fundamental: self.interner.tcx.has_attr(def_id, sym::fundamental),
 158                 non_enumerable: true,
 159                 coinductive: false,
 160             },
 161             associated_ty_ids,
 162             well_known,
 163         })
 164     }
 165
 166     fn adt_datum(
 167         &self,
 168         adt_id: chalk_ir::AdtId<RustInterner<'tcx>>,
 169     ) -> Arc<chalk_solve::rust_ir::AdtDatum<RustInterner<'tcx>>> {
 170         let adt_def = adt_id.0;
 171
 172         let bound_vars = bound_vars_for_item(self.interner.tcx, adt_def.did);
 173         let binders = binders_for(&self.interner, bound_vars);
 174
 175         let where_clauses = self.where_clauses_for(adt_def.did, bound_vars);
 176
 177         let variants: Vec<_> = adt_def
 178             .variants
 179             .iter()
 180             .map(|variant| chalk_solve::rust_ir::AdtVariantDatum {
 181                 fields: variant
 182                     .fields
 183                     .iter()
 184                     .map(|field| field.ty(self.interner.tcx, bound_vars).lower_into(&self.interner))
 185                     .collect(),
 186             })
 187             .collect();
 188         Arc::new(chalk_solve::rust_ir::AdtDatum {
 189             id: adt_id,
 190             binders: chalk_ir::Binders::new(
 191                 binders,
 192                 chalk_solve::rust_ir::AdtDatumBound { variants, where_clauses },
 193             ),
 194             flags: chalk_solve::rust_ir::AdtFlags {
 195                 upstream: !adt_def.did.is_local(),
 196                 fundamental: adt_def.is_fundamental(),
 197                 phantom_data: adt_def.is_phantom_data(),
 198             },
 199             kind: match adt_def.adt_kind() {
 200                 ty::AdtKind::Struct => chalk_solve::rust_ir::AdtKind::Struct,
 201                 ty::AdtKind::Union => chalk_solve::rust_ir::AdtKind::Union,
 202                 ty::AdtKind::Enum => chalk_solve::rust_ir::AdtKind::Enum,
 203             },
 204         })
 205     }
 206
 207     fn adt_repr(
 208         &self,
 209         adt_id: chalk_ir::AdtId<RustInterner<'tcx>>,
 210     ) -> Arc<chalk_solve::rust_ir::AdtRepr<RustInterner<'tcx>>> {
 211         let adt_def = adt_id.0;
 212         let int = |i| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Int(i)).intern(&self.interner);
 213         let uint = |i| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Uint(i)).intern(&self.interner);
 214         Arc::new(chalk_solve::rust_ir::AdtRepr {
 215             c: adt_def.repr.c(),
 216             packed: adt_def.repr.packed(),
 217             int: adt_def.repr.int.map(|i| match i {
 218                 attr::IntType::SignedInt(ty) => match ty {
 219                     ast::IntTy::Isize => int(chalk_ir::IntTy::Isize),
 220                     ast::IntTy::I8 => int(chalk_ir::IntTy::I8),
 221                     ast::IntTy::I16 => int(chalk_ir::IntTy::I16),
 222                     ast::IntTy::I32 => int(chalk_ir::IntTy::I32),
 223                     ast::IntTy::I64 => int(chalk_ir::IntTy::I64),
 224                     ast::IntTy::I128 => int(chalk_ir::IntTy::I128),
 225                 },
 226                 attr::IntType::UnsignedInt(ty) => match ty {
 227                     ast::UintTy::Usize => uint(chalk_ir::UintTy::Usize),
 228                     ast::UintTy::U8 => uint(chalk_ir::UintTy::U8),
 229                     ast::UintTy::U16 => uint(chalk_ir::UintTy::U16),
 230                     ast::UintTy::U32 => uint(chalk_ir::UintTy::U32),
 231                     ast::UintTy::U64 => uint(chalk_ir::UintTy::U64),
 232                     ast::UintTy::U128 => uint(chalk_ir::UintTy::U128),
 233                 },
 234             }),
 235         })
 236     }
 237
 238     fn fn_def_datum(
 239         &self,
 240         fn_def_id: chalk_ir::FnDefId<RustInterner<'tcx>>,
 241     ) -> Arc<chalk_solve::rust_ir::FnDefDatum<RustInterner<'tcx>>> {
 242         let def_id = fn_def_id.0;
 243         let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
 244         let binders = binders_for(&self.interner, bound_vars);
 245
 246         let where_clauses = self.where_clauses_for(def_id, bound_vars);
 247
 248         let sig = self.interner.tcx.fn_sig(def_id);
 249         let (inputs_and_output, iobinders, _) = crate::chalk::lowering::collect_bound_vars(
 250             &self.interner,
 251             self.interner.tcx,
 252             sig.inputs_and_output().subst(self.interner.tcx, bound_vars),
 253         );
 254
 255         let argument_types = inputs_and_output[..inputs_and_output.len() - 1]
 256             .iter()
 257             .map(|t| t.subst(self.interner.tcx, &bound_vars).lower_into(&self.interner))
 258             .collect();
 259
 260         let return_type = inputs_and_output[inputs_and_output.len() - 1]
 261             .subst(self.interner.tcx, &bound_vars)
 262             .lower_into(&self.interner);
 263
 264         let bound = chalk_solve::rust_ir::FnDefDatumBound {
 265             inputs_and_output: chalk_ir::Binders::new(
 266                 iobinders,
 267                 chalk_solve::rust_ir::FnDefInputsAndOutputDatum { argument_types, return_type },
 268             ),
 269             where_clauses,
 270         };
 271         Arc::new(chalk_solve::rust_ir::FnDefDatum {
 272             id: fn_def_id,
 273             sig: sig.lower_into(&self.interner),
 274             binders: chalk_ir::Binders::new(binders, bound),
 275         })
 276     }
 277
 278     fn impl_datum(
 279         &self,
 280         impl_id: chalk_ir::ImplId<RustInterner<'tcx>>,
 281     ) -> Arc<chalk_solve::rust_ir::ImplDatum<RustInterner<'tcx>>> {
 282         let def_id = impl_id.0;
 283         let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
 284         let binders = binders_for(&self.interner, bound_vars);
 285
 286         let trait_ref = self.interner.tcx.impl_trait_ref(def_id).expect("not an impl");
 287         let trait_ref = trait_ref.subst(self.interner.tcx, bound_vars);
 288         let mut regions_substitutor =
 289             lowering::RegionsSubstitutor::new(self.interner.tcx, self.reempty_placeholder);
 290         let trait_ref = trait_ref.fold_with(&mut regions_substitutor);
 291
 292         let where_clauses = self.where_clauses_for(def_id, bound_vars);
 293
 294         let value = chalk_solve::rust_ir::ImplDatumBound {
 295             trait_ref: trait_ref.lower_into(&self.interner),
 296             where_clauses,
 297         };
 298
 299         let associated_ty_value_ids: Vec<_> = self
 300             .interner
 301             .tcx
 302             .associated_items(def_id)
 303             .in_definition_order()
 304             .filter(|i| i.kind == AssocKind::Type)
 305             .map(|i| chalk_solve::rust_ir::AssociatedTyValueId(i.def_id))
 306             .collect();
 307
 308         Arc::new(chalk_solve::rust_ir::ImplDatum {
 309             polarity: self.interner.tcx.impl_polarity(def_id).lower_into(&self.interner),
 310             binders: chalk_ir::Binders::new(binders, value),
 311             impl_type: chalk_solve::rust_ir::ImplType::Local,
 312             associated_ty_value_ids,
 313         })
 314     }
 315
 316     fn impls_for_trait(
 317         &self,
 318         trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
 319         parameters: &[chalk_ir::GenericArg<RustInterner<'tcx>>],
 320         _binders: &chalk_ir::CanonicalVarKinds<RustInterner<'tcx>>,
 321     ) -> Vec<chalk_ir::ImplId<RustInterner<'tcx>>> {
 322         let def_id = trait_id.0;
 323
 324         // FIXME(chalk): use TraitDef::for_each_relevant_impl, but that will
 325         // require us to be able to interconvert `Ty<'tcx>`, and we're
 326         // not there yet.
 327
 328         let all_impls = self.interner.tcx.all_impls(def_id);
 329         let matched_impls = all_impls.filter(|impl_def_id| {
 330             use chalk_ir::could_match::CouldMatch;
 331             let trait_ref = self.interner.tcx.impl_trait_ref(*impl_def_id).unwrap();
 332             let bound_vars = bound_vars_for_item(self.interner.tcx, *impl_def_id);
 333
 334             let self_ty = trait_ref.self_ty();
 335             let self_ty = self_ty.subst(self.interner.tcx, bound_vars);
 336             let mut regions_substitutor =
 337                 lowering::RegionsSubstitutor::new(self.interner.tcx, self.reempty_placeholder);
 338             let self_ty = self_ty.fold_with(&mut regions_substitutor);
 339             let lowered_ty = self_ty.lower_into(&self.interner);
 340
 341             parameters[0].assert_ty_ref(&self.interner).could_match(
 342                 &self.interner,
 343                 self.unification_database(),
 344                 &lowered_ty,
 345             )
 346         });
 347
 348         let impls = matched_impls.map(chalk_ir::ImplId).collect();
 349         impls
 350     }
 351
 352     fn impl_provided_for(
 353         &self,
 354         auto_trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
 355         chalk_ty: &chalk_ir::TyKind<RustInterner<'tcx>>,
 356     ) -> bool {
 357         use chalk_ir::Scalar::*;
 358         use chalk_ir::TyKind::*;
 359
 360         let trait_def_id = auto_trait_id.0;
 361         let all_impls = self.interner.tcx.all_impls(trait_def_id);
 362         for impl_def_id in all_impls {
 363             let trait_ref = self.interner.tcx.impl_trait_ref(impl_def_id).unwrap();
 364             let self_ty = trait_ref.self_ty();
 365             let provides = match (self_ty.kind(), chalk_ty) {
 366                 (&ty::Adt(impl_adt_def, ..), Adt(id, ..)) => impl_adt_def.did == id.0.did,
 367                 (_, AssociatedType(_ty_id, ..)) => {
 368                     // FIXME(chalk): See https://github.com/rust-lang/rust/pull/77152#discussion_r494484774
 369                     false
 370                 }
 371                 (ty::Bool, Scalar(Bool)) => true,
 372                 (ty::Char, Scalar(Char)) => true,
 373                 (ty::Int(ty1), Scalar(Int(ty2))) => matches!(
 374                     (ty1, ty2),
 375                     (ty::IntTy::Isize, chalk_ir::IntTy::Isize)
 376                         | (ty::IntTy::I8, chalk_ir::IntTy::I8)
 377                         | (ty::IntTy::I16, chalk_ir::IntTy::I16)
 378                         | (ty::IntTy::I32, chalk_ir::IntTy::I32)
 379                         | (ty::IntTy::I64, chalk_ir::IntTy::I64)
 380                         | (ty::IntTy::I128, chalk_ir::IntTy::I128)
 381                 ),
 382                 (ty::Uint(ty1), Scalar(Uint(ty2))) => matches!(
 383                     (ty1, ty2),
 384                     (ty::UintTy::Usize, chalk_ir::UintTy::Usize)
 385                         | (ty::UintTy::U8, chalk_ir::UintTy::U8)
 386                         | (ty::UintTy::U16, chalk_ir::UintTy::U16)
 387                         | (ty::UintTy::U32, chalk_ir::UintTy::U32)
 388                         | (ty::UintTy::U64, chalk_ir::UintTy::U64)
 389                         | (ty::UintTy::U128, chalk_ir::UintTy::U128)
 390                 ),
 391                 (ty::Float(ty1), Scalar(Float(ty2))) => matches!(
 392                     (ty1, ty2),
 393                     (ty::FloatTy::F32, chalk_ir::FloatTy::F32)
 394                         | (ty::FloatTy::F64, chalk_ir::FloatTy::F64)
 395                 ),
 396                 (&ty::Tuple(substs), Tuple(len, _)) => substs.len() == *len,
 397                 (&ty::Array(..), Array(..)) => true,
 398                 (&ty::Slice(..), Slice(..)) => true,
 399                 (&ty::RawPtr(type_and_mut), Raw(mutability, _)) => {
 400                     match (type_and_mut.mutbl, mutability) {
 401                         (ast::Mutability::Mut, chalk_ir::Mutability::Mut) => true,
 402                         (ast::Mutability::Mut, chalk_ir::Mutability::Not) => false,
 403                         (ast::Mutability::Not, chalk_ir::Mutability::Mut) => false,
 404                         (ast::Mutability::Not, chalk_ir::Mutability::Not) => true,
 405                     }
 406                 }
 407                 (&ty::Ref(.., mutability1), Ref(mutability2, ..)) => {
 408                     match (mutability1, mutability2) {
 409                         (ast::Mutability::Mut, chalk_ir::Mutability::Mut) => true,
 410                         (ast::Mutability::Mut, chalk_ir::Mutability::Not) => false,
 411                         (ast::Mutability::Not, chalk_ir::Mutability::Mut) => false,
 412                         (ast::Mutability::Not, chalk_ir::Mutability::Not) => true,
 413                     }
 414                 }
 415                 (&ty::Opaque(def_id, ..), OpaqueType(opaque_ty_id, ..)) => def_id == opaque_ty_id.0,
 416                 (&ty::FnDef(def_id, ..), FnDef(fn_def_id, ..)) => def_id == fn_def_id.0,
 417                 (&ty::Str, Str) => true,
 418                 (&ty::Never, Never) => true,
 419                 (&ty::Closure(def_id, ..), Closure(closure_id, _)) => def_id == closure_id.0,
 420                 (&ty::Foreign(def_id), Foreign(foreign_def_id)) => def_id == foreign_def_id.0,
 421                 (&ty::Error(..), Error) => false,
 422                 _ => false,
 423             };
 424             if provides {
 425                 return true;
 426             }
 427         }
 428         false
 429     }
 430
 431     fn associated_ty_value(
 432         &self,
 433         associated_ty_id: chalk_solve::rust_ir::AssociatedTyValueId<RustInterner<'tcx>>,
 434     ) -> Arc<chalk_solve::rust_ir::AssociatedTyValue<RustInterner<'tcx>>> {
 435         let def_id = associated_ty_id.0;
 436         let assoc_item = self.interner.tcx.associated_item(def_id);
 437         let (impl_id, trait_id) = match assoc_item.container {
 438             AssocItemContainer::TraitContainer(def_id) => (def_id, def_id),
 439             AssocItemContainer::ImplContainer(def_id) => {
 440                 (def_id, self.interner.tcx.impl_trait_ref(def_id).unwrap().def_id)
 441             }
 442         };
 443         match assoc_item.kind {
 444             AssocKind::Type => {}
 445             _ => unimplemented!("Not possible??"),
 446         }
 447
 448         let trait_item = self
 449             .interner
 450             .tcx
 451             .associated_items(trait_id)
 452             .find_by_name_and_kind(self.interner.tcx, assoc_item.ident, assoc_item.kind, trait_id)
 453             .unwrap();
 454         let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
 455         let binders = binders_for(&self.interner, bound_vars);
 456         let ty = self
 457             .interner
 458             .tcx
 459             .type_of(def_id)
 460             .subst(self.interner.tcx, bound_vars)
 461             .lower_into(&self.interner);
 462
 463         Arc::new(chalk_solve::rust_ir::AssociatedTyValue {
 464             impl_id: chalk_ir::ImplId(impl_id),
 465             associated_ty_id: chalk_ir::AssocTypeId(trait_item.def_id),
 466             value: chalk_ir::Binders::new(
 467                 binders,
 468                 chalk_solve::rust_ir::AssociatedTyValueBound { ty },
 469             ),
 470         })
 471     }
 472
 473     fn custom_clauses(&self) -> Vec<chalk_ir::ProgramClause<RustInterner<'tcx>>> {
 474         vec![]
 475     }
 476
 477     fn local_impls_to_coherence_check(
 478         &self,
 479         _trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
 480     ) -> Vec<chalk_ir::ImplId<RustInterner<'tcx>>> {
 481         unimplemented!()
 482     }
 483
 484     fn opaque_ty_data(
 485         &self,
 486         opaque_ty_id: chalk_ir::OpaqueTyId<RustInterner<'tcx>>,
 487     ) -> Arc<chalk_solve::rust_ir::OpaqueTyDatum<RustInterner<'tcx>>> {
 488         let bound_vars = ty::fold::shift_vars(
 489             self.interner.tcx,
 490             bound_vars_for_item(self.interner.tcx, opaque_ty_id.0),
 491             1,
 492         );
 493         let where_clauses = self.where_clauses_for(opaque_ty_id.0, bound_vars);
 494
 495         let identity_substs = InternalSubsts::identity_for_item(self.interner.tcx, opaque_ty_id.0);
 496
 497         let bounds =
 498             self.interner
 499                 .tcx
 500                 .explicit_item_bounds(opaque_ty_id.0)
 501                 .iter()
 502                 .map(|(bound, _)| bound.subst(self.interner.tcx, &bound_vars))
 503                 .map(|bound| {
 504                     bound.fold_with(&mut ty::fold::BottomUpFolder {
 505                         tcx: self.interner.tcx,
 506                         ty_op: |ty| {
 507                             if let ty::Opaque(def_id, substs) = *ty.kind() {
 508                                 if def_id == opaque_ty_id.0 && substs == identity_substs {
 509                                     return self.interner.tcx.mk_ty(ty::Bound(
 510                                         ty::INNERMOST,
 511                                         ty::BoundTy::from(ty::BoundVar::from_u32(0)),
 512                                     ));
 513                                 }
 514                             }
 515                             ty
 516                         },
 517                         lt_op: |lt| lt,
 518                         ct_op: |ct| ct,
 519                     })
 520                 })
 521                 .filter_map(|bound| {
 522                     LowerInto::<
 523                     Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>
 524                 >::lower_into(bound, &self.interner)
 525                 })
 526                 .collect();
 527
 528         // Binder for the bound variable representing the concrete impl Trait type.
 529         let existential_binder = chalk_ir::VariableKinds::from1(
 530             &self.interner,
 531             chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General),
 532         );
 533
 534         let value = chalk_solve::rust_ir::OpaqueTyDatumBound {
 535             bounds: chalk_ir::Binders::new(existential_binder.clone(), bounds),
 536             where_clauses: chalk_ir::Binders::new(existential_binder, where_clauses),
 537         };
 538
 539         let binders = binders_for(&self.interner, bound_vars);
 540         Arc::new(chalk_solve::rust_ir::OpaqueTyDatum {
 541             opaque_ty_id,
 542             bound: chalk_ir::Binders::new(binders, value),
 543         })
 544     }
 545
 546     fn program_clauses_for_env(
 547         &self,
 548         environment: &chalk_ir::Environment<RustInterner<'tcx>>,
 549     ) -> chalk_ir::ProgramClauses<RustInterner<'tcx>> {
 550         chalk_solve::program_clauses_for_env(self, environment)
 551     }
 552
 553     fn well_known_trait_id(
 554         &self,
 555         well_known_trait: chalk_solve::rust_ir::WellKnownTrait,
 556     ) -> Option<chalk_ir::TraitId<RustInterner<'tcx>>> {
 557         use chalk_solve::rust_ir::WellKnownTrait::*;
 558         let lang_items = self.interner.tcx.lang_items();
 559         let def_id = match well_known_trait {
 560             Sized => lang_items.sized_trait(),
 561             Copy => lang_items.copy_trait(),
 562             Clone => lang_items.clone_trait(),
 563             Drop => lang_items.drop_trait(),
 564             Fn => lang_items.fn_trait(),
 565             FnMut => lang_items.fn_mut_trait(),
 566             FnOnce => lang_items.fn_once_trait(),
 567             Unsize => lang_items.unsize_trait(),
 568             Unpin => lang_items.unpin_trait(),
 569             CoerceUnsized => lang_items.coerce_unsized_trait(),
 570             DiscriminantKind => lang_items.discriminant_kind_trait(),
 571         };
 572         def_id.map(chalk_ir::TraitId)
 573     }
 574
 575     fn is_object_safe(&self, trait_id: chalk_ir::TraitId<RustInterner<'tcx>>) -> bool {
 576         self.interner.tcx.is_object_safe(trait_id.0)
 577     }
 578
 579     fn hidden_opaque_type(
 580         &self,
 581         _id: chalk_ir::OpaqueTyId<RustInterner<'tcx>>,
 582     ) -> chalk_ir::Ty<RustInterner<'tcx>> {
 583         // FIXME(chalk): actually get hidden ty
 584         self.interner
 585             .tcx
 586             .mk_ty(ty::Tuple(self.interner.tcx.intern_substs(&[])))
 587             .lower_into(&self.interner)
 588     }
 589
 590     fn closure_kind(
 591         &self,
 592         _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
 593         substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
 594     ) -> chalk_solve::rust_ir::ClosureKind {
 595         let kind = &substs.as_slice(&self.interner)[substs.len(&self.interner) - 3];
 596         match kind.assert_ty_ref(&self.interner).kind(&self.interner) {
 597             chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Int(int_ty)) => match int_ty {
 598                 chalk_ir::IntTy::I8 => chalk_solve::rust_ir::ClosureKind::Fn,
 599                 chalk_ir::IntTy::I16 => chalk_solve::rust_ir::ClosureKind::FnMut,
 600                 chalk_ir::IntTy::I32 => chalk_solve::rust_ir::ClosureKind::FnOnce,
 601                 _ => bug!("bad closure kind"),
 602             },
 603             _ => bug!("bad closure kind"),
 604         }
 605     }
 606
 607     fn closure_inputs_and_output(
 608         &self,
 609         _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
 610         substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
 611     ) -> chalk_ir::Binders<chalk_solve::rust_ir::FnDefInputsAndOutputDatum<RustInterner<'tcx>>>
 612     {
 613         let sig = &substs.as_slice(&self.interner)[substs.len(&self.interner) - 2];
 614         match sig.assert_ty_ref(&self.interner).kind(&self.interner) {
 615             chalk_ir::TyKind::Function(f) => {
 616                 let substitution = f.substitution.0.as_slice(&self.interner);
 617                 let return_type =
 618                     substitution.last().unwrap().assert_ty_ref(&self.interner).clone();
 619                 // Closure arguments are tupled
 620                 let argument_tuple = substitution[0].assert_ty_ref(&self.interner);
 621                 let argument_types = match argument_tuple.kind(&self.interner) {
 622                     chalk_ir::TyKind::Tuple(_len, substitution) => substitution
 623                         .iter(&self.interner)
 624                         .map(|arg| arg.assert_ty_ref(&self.interner))
 625                         .cloned()
 626                         .collect(),
 627                     _ => bug!("Expecting closure FnSig args to be tupled."),
 628                 };
 629
 630                 chalk_ir::Binders::new(
 631                     chalk_ir::VariableKinds::from_iter(
 632                         &self.interner,
 633                         (0..f.num_binders).map(|_| chalk_ir::VariableKind::Lifetime),
 634                     ),
 635                     chalk_solve::rust_ir::FnDefInputsAndOutputDatum { argument_types, return_type },
 636                 )
 637             }
 638             _ => panic!("Invalid sig."),
 639         }
 640     }
 641
 642     fn closure_upvars(
 643         &self,
 644         _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
 645         substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
 646     ) -> chalk_ir::Binders<chalk_ir::Ty<RustInterner<'tcx>>> {
 647         let inputs_and_output = self.closure_inputs_and_output(_closure_id, substs);
 648         let tuple = substs.as_slice(&self.interner).last().unwrap().assert_ty_ref(&self.interner);
 649         inputs_and_output.map_ref(|_| tuple.clone())
 650     }
 651
 652     fn closure_fn_substitution(
 653         &self,
 654         _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
 655         substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
 656     ) -> chalk_ir::Substitution<RustInterner<'tcx>> {
 657         let substitution = &substs.as_slice(&self.interner)[0..substs.len(&self.interner) - 3];
 658         chalk_ir::Substitution::from_iter(&self.interner, substitution)
 659     }
 660
 661     fn generator_datum(
 662         &self,
 663         _generator_id: chalk_ir::GeneratorId<RustInterner<'tcx>>,
 664     ) -> Arc<chalk_solve::rust_ir::GeneratorDatum<RustInterner<'tcx>>> {
 665         unimplemented!()
 666     }
 667
 668     fn generator_witness_datum(
 669         &self,
 670         _generator_id: chalk_ir::GeneratorId<RustInterner<'tcx>>,
 671     ) -> Arc<chalk_solve::rust_ir::GeneratorWitnessDatum<RustInterner<'tcx>>> {
 672         unimplemented!()
 673     }
 674
 675     fn unification_database(&self) -> &dyn chalk_ir::UnificationDatabase<RustInterner<'tcx>> {
 676         self
 677     }
 678
 679     fn discriminant_type(
 680         &self,
 681         _: chalk_ir::Ty<RustInterner<'tcx>>,
 682     ) -> chalk_ir::Ty<RustInterner<'tcx>> {
 683         unimplemented!()
 684     }
 685 }
 686
 687 impl<'tcx> chalk_ir::UnificationDatabase<RustInterner<'tcx>> for RustIrDatabase<'tcx> {
 688     fn fn_def_variance(
 689         &self,
 690         def_id: chalk_ir::FnDefId<RustInterner<'tcx>>,
 691     ) -> chalk_ir::Variances<RustInterner<'tcx>> {
 692         let variances = self.interner.tcx.variances_of(def_id.0);
 693         chalk_ir::Variances::from_iter(
 694             &self.interner,
 695             variances.iter().map(|v| match v {
 696                 ty::Variance::Invariant => chalk_ir::Variance::Invariant,
 697                 ty::Variance::Covariant => chalk_ir::Variance::Covariant,
 698                 ty::Variance::Contravariant => chalk_ir::Variance::Contravariant,
 699                 ty::Variance::Bivariant => unimplemented!(),
 700             }),
 701         )
 702     }
 703
 704     fn adt_variance(
 705         &self,
 706         def_id: chalk_ir::AdtId<RustInterner<'tcx>>,
 707     ) -> chalk_ir::Variances<RustInterner<'tcx>> {
 708         let variances = self.interner.tcx.variances_of(def_id.0.did);
 709         chalk_ir::Variances::from_iter(
 710             &self.interner,
 711             variances.iter().map(|v| match v {
 712                 ty::Variance::Invariant => chalk_ir::Variance::Invariant,
 713                 ty::Variance::Covariant => chalk_ir::Variance::Covariant,
 714                 ty::Variance::Contravariant => chalk_ir::Variance::Contravariant,
 715                 ty::Variance::Bivariant => unimplemented!(),
 716             }),
 717         )
 718     }
 719 }
 720
 721 /// Creates a `InternalSubsts` that maps each generic parameter to a higher-ranked
 722 /// var bound at index `0`. For types, we use a `BoundVar` index equal to
 723 /// the type parameter index. For regions, we use the `BoundRegionKind::BrNamed`
 724 /// variant (which has a `DefId`).
 725 fn bound_vars_for_item(tcx: TyCtxt<'tcx>, def_id: DefId) -> SubstsRef<'tcx> {
 726     InternalSubsts::for_item(tcx, def_id, |param, substs| match param.kind {
 727         ty::GenericParamDefKind::Type { .. } => tcx
 728             .mk_ty(ty::Bound(
 729                 ty::INNERMOST,
 730                 ty::BoundTy {
 731                     var: ty::BoundVar::from(param.index),
 732                     kind: ty::BoundTyKind::Param(param.name),
 733                 },
 734             ))
 735             .into(),
 736
 737         ty::GenericParamDefKind::Lifetime => {
 738             let br = ty::BoundRegion { kind: ty::BrAnon(substs.len() as u32) };
 739             tcx.mk_region(ty::RegionKind::ReLateBound(ty::INNERMOST, br)).into()
 740         }
 741
 742         ty::GenericParamDefKind::Const { .. } => tcx
 743             .mk_const(ty::Const {
 744                 val: ty::ConstKind::Bound(ty::INNERMOST, ty::BoundVar::from(param.index)),
 745                 ty: tcx.type_of(param.def_id),
 746             })
 747             .into(),
 748     })
 749 }
 750
 751 fn binders_for<'tcx>(
 752     interner: &RustInterner<'tcx>,
 753     bound_vars: SubstsRef<'tcx>,
 754 ) -> chalk_ir::VariableKinds<RustInterner<'tcx>> {
 755     chalk_ir::VariableKinds::from_iter(
 756         interner,
 757         bound_vars.iter().map(|arg| match arg.unpack() {
 758             ty::subst::GenericArgKind::Lifetime(_re) => chalk_ir::VariableKind::Lifetime,
 759             ty::subst::GenericArgKind::Type(_ty) => {
 760                 chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General)
 761             }
 762             ty::subst::GenericArgKind::Const(c) => {
 763                 chalk_ir::VariableKind::Const(c.ty.lower_into(interner))
 764             }
 765         }),
 766     )
 767 }