diff options
Diffstat (limited to 'compiler/rustc_traits/src')
| -rw-r--r-- | compiler/rustc_traits/src/chalk/db.rs | 796 | ||||
| -rw-r--r-- | compiler/rustc_traits/src/chalk/lowering.rs | 1172 | ||||
| -rw-r--r-- | compiler/rustc_traits/src/chalk/mod.rs | 176 | ||||
| -rw-r--r-- | compiler/rustc_traits/src/dropck_outlives.rs | 348 | ||||
| -rw-r--r-- | compiler/rustc_traits/src/evaluate_obligation.rs | 34 | ||||
| -rw-r--r-- | compiler/rustc_traits/src/implied_outlives_bounds.rs | 172 | ||||
| -rw-r--r-- | compiler/rustc_traits/src/lib.rs | 32 | ||||
| -rw-r--r-- | compiler/rustc_traits/src/normalize_erasing_regions.rs | 73 | ||||
| -rw-r--r-- | compiler/rustc_traits/src/normalize_projection_ty.rs | 45 | ||||
| -rw-r--r-- | compiler/rustc_traits/src/type_op.rs | 283 |
10 files changed, 3131 insertions, 0 deletions
diff --git a/compiler/rustc_traits/src/chalk/db.rs b/compiler/rustc_traits/src/chalk/db.rs new file mode 100644 index 000000000..ff5ca0cbc --- /dev/null +++ b/compiler/rustc_traits/src/chalk/db.rs @@ -0,0 +1,796 @@ +//! Provides the `RustIrDatabase` implementation for `chalk-solve` +//! +//! The purpose of the `chalk_solve::RustIrDatabase` is to get data about +//! specific types, such as bounds, where clauses, or fields. This file contains +//! the minimal logic to assemble the types for `chalk-solve` by calling out to +//! either the `TyCtxt` (for information about types) or +//! `crate::chalk::lowering` (to lower rustc types into Chalk types). + +use rustc_middle::traits::ChalkRustInterner as RustInterner; +use rustc_middle::ty::subst::{InternalSubsts, Subst, SubstsRef}; +use rustc_middle::ty::{self, AssocKind, EarlyBinder, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable}; + +use rustc_ast::ast; +use rustc_attr as attr; + +use rustc_hir::def_id::DefId; + +use rustc_span::symbol::sym; + +use std::fmt; +use std::sync::Arc; + +use crate::chalk::lowering::LowerInto; + +pub struct RustIrDatabase<'tcx> { + pub(crate) interner: RustInterner<'tcx>, +} + +impl fmt::Debug for RustIrDatabase<'_> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!(f, "RustIrDatabase") + } +} + +impl<'tcx> RustIrDatabase<'tcx> { + fn where_clauses_for( + &self, + def_id: DefId, + bound_vars: SubstsRef<'tcx>, + ) -> Vec<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>> { + let predicates = self.interner.tcx.predicates_defined_on(def_id).predicates; + predicates + .iter() + .map(|(wc, _)| EarlyBinder(*wc).subst(self.interner.tcx, bound_vars)) + .filter_map(|wc| LowerInto::< + Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>> + >::lower_into(wc, self.interner)).collect() + } + + fn bounds_for<T>(&self, def_id: DefId, bound_vars: SubstsRef<'tcx>) -> Vec<T> + where + ty::Predicate<'tcx>: LowerInto<'tcx, std::option::Option<T>>, + { + let bounds = self.interner.tcx.bound_explicit_item_bounds(def_id); + bounds + .0 + .iter() + .map(|(bound, _)| bounds.rebind(*bound).subst(self.interner.tcx, &bound_vars)) + .filter_map(|bound| LowerInto::<Option<_>>::lower_into(bound, self.interner)) + .collect() + } +} + +impl<'tcx> chalk_solve::RustIrDatabase<RustInterner<'tcx>> for RustIrDatabase<'tcx> { + fn interner(&self) -> RustInterner<'tcx> { + self.interner + } + + fn associated_ty_data( + &self, + assoc_type_id: chalk_ir::AssocTypeId<RustInterner<'tcx>>, + ) -> Arc<chalk_solve::rust_ir::AssociatedTyDatum<RustInterner<'tcx>>> { + let def_id = assoc_type_id.0; + let assoc_item = self.interner.tcx.associated_item(def_id); + let Some(trait_def_id) = assoc_item.trait_container(self.interner.tcx) else { + unimplemented!("Not possible??"); + }; + match assoc_item.kind { + AssocKind::Type => {} + _ => unimplemented!("Not possible??"), + } + let bound_vars = bound_vars_for_item(self.interner.tcx, def_id); + let binders = binders_for(self.interner, bound_vars); + + let where_clauses = self.where_clauses_for(def_id, bound_vars); + let bounds = self.bounds_for(def_id, bound_vars); + + Arc::new(chalk_solve::rust_ir::AssociatedTyDatum { + trait_id: chalk_ir::TraitId(trait_def_id), + id: assoc_type_id, + name: (), + binders: chalk_ir::Binders::new( + binders, + chalk_solve::rust_ir::AssociatedTyDatumBound { bounds, where_clauses }, + ), + }) + } + + fn trait_datum( + &self, + trait_id: chalk_ir::TraitId<RustInterner<'tcx>>, + ) -> Arc<chalk_solve::rust_ir::TraitDatum<RustInterner<'tcx>>> { + use chalk_solve::rust_ir::WellKnownTrait::*; + + let def_id = trait_id.0; + let trait_def = self.interner.tcx.trait_def(def_id); + + let bound_vars = bound_vars_for_item(self.interner.tcx, def_id); + let binders = binders_for(self.interner, bound_vars); + + let where_clauses = self.where_clauses_for(def_id, bound_vars); + + let associated_ty_ids: Vec<_> = self + .interner + .tcx + .associated_items(def_id) + .in_definition_order() + .filter(|i| i.kind == AssocKind::Type) + .map(|i| chalk_ir::AssocTypeId(i.def_id)) + .collect(); + + let lang_items = self.interner.tcx.lang_items(); + let well_known = if lang_items.sized_trait() == Some(def_id) { + Some(Sized) + } else if lang_items.copy_trait() == Some(def_id) { + Some(Copy) + } else if lang_items.clone_trait() == Some(def_id) { + Some(Clone) + } else if lang_items.drop_trait() == Some(def_id) { + Some(Drop) + } else if lang_items.fn_trait() == Some(def_id) { + Some(Fn) + } else if lang_items.fn_once_trait() == Some(def_id) { + Some(FnOnce) + } else if lang_items.fn_mut_trait() == Some(def_id) { + Some(FnMut) + } else if lang_items.unsize_trait() == Some(def_id) { + Some(Unsize) + } else if lang_items.unpin_trait() == Some(def_id) { + Some(Unpin) + } else if lang_items.coerce_unsized_trait() == Some(def_id) { + Some(CoerceUnsized) + } else if lang_items.dispatch_from_dyn_trait() == Some(def_id) { + Some(DispatchFromDyn) + } else { + None + }; + Arc::new(chalk_solve::rust_ir::TraitDatum { + id: trait_id, + binders: chalk_ir::Binders::new( + binders, + chalk_solve::rust_ir::TraitDatumBound { where_clauses }, + ), + flags: chalk_solve::rust_ir::TraitFlags { + auto: trait_def.has_auto_impl, + marker: trait_def.is_marker, + upstream: !def_id.is_local(), + fundamental: self.interner.tcx.has_attr(def_id, sym::fundamental), + non_enumerable: true, + coinductive: false, + }, + associated_ty_ids, + well_known, + }) + } + + fn adt_datum( + &self, + adt_id: chalk_ir::AdtId<RustInterner<'tcx>>, + ) -> Arc<chalk_solve::rust_ir::AdtDatum<RustInterner<'tcx>>> { + let adt_def = adt_id.0; + + let bound_vars = bound_vars_for_item(self.interner.tcx, adt_def.did()); + let binders = binders_for(self.interner, bound_vars); + + let where_clauses = self.where_clauses_for(adt_def.did(), bound_vars); + + let variants: Vec<_> = adt_def + .variants() + .iter() + .map(|variant| chalk_solve::rust_ir::AdtVariantDatum { + fields: variant + .fields + .iter() + .map(|field| field.ty(self.interner.tcx, bound_vars).lower_into(self.interner)) + .collect(), + }) + .collect(); + Arc::new(chalk_solve::rust_ir::AdtDatum { + id: adt_id, + binders: chalk_ir::Binders::new( + binders, + chalk_solve::rust_ir::AdtDatumBound { variants, where_clauses }, + ), + flags: chalk_solve::rust_ir::AdtFlags { + upstream: !adt_def.did().is_local(), + fundamental: adt_def.is_fundamental(), + phantom_data: adt_def.is_phantom_data(), + }, + kind: match adt_def.adt_kind() { + ty::AdtKind::Struct => chalk_solve::rust_ir::AdtKind::Struct, + ty::AdtKind::Union => chalk_solve::rust_ir::AdtKind::Union, + ty::AdtKind::Enum => chalk_solve::rust_ir::AdtKind::Enum, + }, + }) + } + + fn adt_repr( + &self, + adt_id: chalk_ir::AdtId<RustInterner<'tcx>>, + ) -> Arc<chalk_solve::rust_ir::AdtRepr<RustInterner<'tcx>>> { + let adt_def = adt_id.0; + let int = |i| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Int(i)).intern(self.interner); + let uint = |i| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Uint(i)).intern(self.interner); + Arc::new(chalk_solve::rust_ir::AdtRepr { + c: adt_def.repr().c(), + packed: adt_def.repr().packed(), + int: adt_def.repr().int.map(|i| match i { + attr::IntType::SignedInt(ty) => match ty { + ast::IntTy::Isize => int(chalk_ir::IntTy::Isize), + ast::IntTy::I8 => int(chalk_ir::IntTy::I8), + ast::IntTy::I16 => int(chalk_ir::IntTy::I16), + ast::IntTy::I32 => int(chalk_ir::IntTy::I32), + ast::IntTy::I64 => int(chalk_ir::IntTy::I64), + ast::IntTy::I128 => int(chalk_ir::IntTy::I128), + }, + attr::IntType::UnsignedInt(ty) => match ty { + ast::UintTy::Usize => uint(chalk_ir::UintTy::Usize), + ast::UintTy::U8 => uint(chalk_ir::UintTy::U8), + ast::UintTy::U16 => uint(chalk_ir::UintTy::U16), + ast::UintTy::U32 => uint(chalk_ir::UintTy::U32), + ast::UintTy::U64 => uint(chalk_ir::UintTy::U64), + ast::UintTy::U128 => uint(chalk_ir::UintTy::U128), + }, + }), + }) + } + + fn adt_size_align( + &self, + adt_id: chalk_ir::AdtId<RustInterner<'tcx>>, + ) -> Arc<chalk_solve::rust_ir::AdtSizeAlign> { + let tcx = self.interner.tcx; + let did = adt_id.0.did(); + + // Grab the ADT and the param we might need to calculate its layout + let param_env = tcx.param_env(did); + let adt_ty = tcx.type_of(did); + + // The ADT is a 1-zst if it's a ZST and its alignment is 1. + // Mark the ADT as _not_ a 1-zst if there was a layout error. + let one_zst = if let Ok(layout) = tcx.layout_of(param_env.and(adt_ty)) { + layout.is_zst() && layout.align.abi.bytes() == 1 + } else { + false + }; + + Arc::new(chalk_solve::rust_ir::AdtSizeAlign::from_one_zst(one_zst)) + } + + fn fn_def_datum( + &self, + fn_def_id: chalk_ir::FnDefId<RustInterner<'tcx>>, + ) -> Arc<chalk_solve::rust_ir::FnDefDatum<RustInterner<'tcx>>> { + let def_id = fn_def_id.0; + let bound_vars = bound_vars_for_item(self.interner.tcx, def_id); + let binders = binders_for(self.interner, bound_vars); + + let where_clauses = self.where_clauses_for(def_id, bound_vars); + + let sig = self.interner.tcx.bound_fn_sig(def_id); + let (inputs_and_output, iobinders, _) = crate::chalk::lowering::collect_bound_vars( + self.interner, + self.interner.tcx, + sig.map_bound(|s| s.inputs_and_output()).subst(self.interner.tcx, bound_vars), + ); + + let argument_types = inputs_and_output[..inputs_and_output.len() - 1] + .iter() + .map(|t| sig.rebind(*t).subst(self.interner.tcx, &bound_vars).lower_into(self.interner)) + .collect(); + + let return_type = sig + .rebind(inputs_and_output[inputs_and_output.len() - 1]) + .subst(self.interner.tcx, &bound_vars) + .lower_into(self.interner); + + let bound = chalk_solve::rust_ir::FnDefDatumBound { + inputs_and_output: chalk_ir::Binders::new( + iobinders, + chalk_solve::rust_ir::FnDefInputsAndOutputDatum { argument_types, return_type }, + ), + where_clauses, + }; + Arc::new(chalk_solve::rust_ir::FnDefDatum { + id: fn_def_id, + sig: sig.0.lower_into(self.interner), + binders: chalk_ir::Binders::new(binders, bound), + }) + } + + fn impl_datum( + &self, + impl_id: chalk_ir::ImplId<RustInterner<'tcx>>, + ) -> Arc<chalk_solve::rust_ir::ImplDatum<RustInterner<'tcx>>> { + let def_id = impl_id.0; + let bound_vars = bound_vars_for_item(self.interner.tcx, def_id); + let binders = binders_for(self.interner, bound_vars); + + let trait_ref = self.interner.tcx.bound_impl_trait_ref(def_id).expect("not an impl"); + let trait_ref = trait_ref.subst(self.interner.tcx, bound_vars); + + let where_clauses = self.where_clauses_for(def_id, bound_vars); + + let value = chalk_solve::rust_ir::ImplDatumBound { + trait_ref: trait_ref.lower_into(self.interner), + where_clauses, + }; + + let associated_ty_value_ids: Vec<_> = self + .interner + .tcx + .associated_items(def_id) + .in_definition_order() + .filter(|i| i.kind == AssocKind::Type) + .map(|i| chalk_solve::rust_ir::AssociatedTyValueId(i.def_id)) + .collect(); + + Arc::new(chalk_solve::rust_ir::ImplDatum { + polarity: self.interner.tcx.impl_polarity(def_id).lower_into(self.interner), + binders: chalk_ir::Binders::new(binders, value), + impl_type: chalk_solve::rust_ir::ImplType::Local, + associated_ty_value_ids, + }) + } + + fn impls_for_trait( + &self, + trait_id: chalk_ir::TraitId<RustInterner<'tcx>>, + parameters: &[chalk_ir::GenericArg<RustInterner<'tcx>>], + _binders: &chalk_ir::CanonicalVarKinds<RustInterner<'tcx>>, + ) -> Vec<chalk_ir::ImplId<RustInterner<'tcx>>> { + let def_id = trait_id.0; + + // FIXME(chalk): use TraitDef::for_each_relevant_impl, but that will + // require us to be able to interconvert `Ty<'tcx>`, and we're + // not there yet. + + let all_impls = self.interner.tcx.all_impls(def_id); + let matched_impls = all_impls.filter(|impl_def_id| { + use chalk_ir::could_match::CouldMatch; + let trait_ref = self.interner.tcx.bound_impl_trait_ref(*impl_def_id).unwrap(); + let bound_vars = bound_vars_for_item(self.interner.tcx, *impl_def_id); + + let self_ty = trait_ref.map_bound(|t| t.self_ty()); + let self_ty = self_ty.subst(self.interner.tcx, bound_vars); + let lowered_ty = self_ty.lower_into(self.interner); + + parameters[0].assert_ty_ref(self.interner).could_match( + self.interner, + self.unification_database(), + &lowered_ty, + ) + }); + + let impls = matched_impls.map(chalk_ir::ImplId).collect(); + impls + } + + fn impl_provided_for( + &self, + auto_trait_id: chalk_ir::TraitId<RustInterner<'tcx>>, + chalk_ty: &chalk_ir::TyKind<RustInterner<'tcx>>, + ) -> bool { + use chalk_ir::Scalar::*; + use chalk_ir::TyKind::*; + + let trait_def_id = auto_trait_id.0; + let all_impls = self.interner.tcx.all_impls(trait_def_id); + for impl_def_id in all_impls { + let trait_ref = self.interner.tcx.impl_trait_ref(impl_def_id).unwrap(); + let self_ty = trait_ref.self_ty(); + let provides = match (self_ty.kind(), chalk_ty) { + (&ty::Adt(impl_adt_def, ..), Adt(id, ..)) => impl_adt_def.did() == id.0.did(), + (_, AssociatedType(_ty_id, ..)) => { + // FIXME(chalk): See https://github.com/rust-lang/rust/pull/77152#discussion_r494484774 + false + } + (ty::Bool, Scalar(Bool)) => true, + (ty::Char, Scalar(Char)) => true, + (ty::Int(ty1), Scalar(Int(ty2))) => matches!( + (ty1, ty2), + (ty::IntTy::Isize, chalk_ir::IntTy::Isize) + | (ty::IntTy::I8, chalk_ir::IntTy::I8) + | (ty::IntTy::I16, chalk_ir::IntTy::I16) + | (ty::IntTy::I32, chalk_ir::IntTy::I32) + | (ty::IntTy::I64, chalk_ir::IntTy::I64) + | (ty::IntTy::I128, chalk_ir::IntTy::I128) + ), + (ty::Uint(ty1), Scalar(Uint(ty2))) => matches!( + (ty1, ty2), + (ty::UintTy::Usize, chalk_ir::UintTy::Usize) + | (ty::UintTy::U8, chalk_ir::UintTy::U8) + | (ty::UintTy::U16, chalk_ir::UintTy::U16) + | (ty::UintTy::U32, chalk_ir::UintTy::U32) + | (ty::UintTy::U64, chalk_ir::UintTy::U64) + | (ty::UintTy::U128, chalk_ir::UintTy::U128) + ), + (ty::Float(ty1), Scalar(Float(ty2))) => matches!( + (ty1, ty2), + (ty::FloatTy::F32, chalk_ir::FloatTy::F32) + | (ty::FloatTy::F64, chalk_ir::FloatTy::F64) + ), + (&ty::Tuple(substs), Tuple(len, _)) => substs.len() == *len, + (&ty::Array(..), Array(..)) => true, + (&ty::Slice(..), Slice(..)) => true, + (&ty::RawPtr(type_and_mut), Raw(mutability, _)) => { + match (type_and_mut.mutbl, mutability) { + (ast::Mutability::Mut, chalk_ir::Mutability::Mut) => true, + (ast::Mutability::Mut, chalk_ir::Mutability::Not) => false, + (ast::Mutability::Not, chalk_ir::Mutability::Mut) => false, + (ast::Mutability::Not, chalk_ir::Mutability::Not) => true, + } + } + (&ty::Ref(.., mutability1), Ref(mutability2, ..)) => { + match (mutability1, mutability2) { + (ast::Mutability::Mut, chalk_ir::Mutability::Mut) => true, + (ast::Mutability::Mut, chalk_ir::Mutability::Not) => false, + (ast::Mutability::Not, chalk_ir::Mutability::Mut) => false, + (ast::Mutability::Not, chalk_ir::Mutability::Not) => true, + } + } + (&ty::Opaque(def_id, ..), OpaqueType(opaque_ty_id, ..)) => def_id == opaque_ty_id.0, + (&ty::FnDef(def_id, ..), FnDef(fn_def_id, ..)) => def_id == fn_def_id.0, + (&ty::Str, Str) => true, + (&ty::Never, Never) => true, + (&ty::Closure(def_id, ..), Closure(closure_id, _)) => def_id == closure_id.0, + (&ty::Foreign(def_id), Foreign(foreign_def_id)) => def_id == foreign_def_id.0, + (&ty::Error(..), Error) => false, + _ => false, + }; + if provides { + return true; + } + } + false + } + + fn associated_ty_value( + &self, + associated_ty_id: chalk_solve::rust_ir::AssociatedTyValueId<RustInterner<'tcx>>, + ) -> Arc<chalk_solve::rust_ir::AssociatedTyValue<RustInterner<'tcx>>> { + let def_id = associated_ty_id.0; + let assoc_item = self.interner.tcx.associated_item(def_id); + let impl_id = assoc_item.container_id(self.interner.tcx); + match assoc_item.kind { + AssocKind::Type => {} + _ => unimplemented!("Not possible??"), + } + + let trait_item_id = assoc_item.trait_item_def_id.expect("assoc_ty with no trait version"); + let bound_vars = bound_vars_for_item(self.interner.tcx, def_id); + let binders = binders_for(self.interner, bound_vars); + let ty = self + .interner + .tcx + .bound_type_of(def_id) + .subst(self.interner.tcx, bound_vars) + .lower_into(self.interner); + + Arc::new(chalk_solve::rust_ir::AssociatedTyValue { + impl_id: chalk_ir::ImplId(impl_id), + associated_ty_id: chalk_ir::AssocTypeId(trait_item_id), + value: chalk_ir::Binders::new( + binders, + chalk_solve::rust_ir::AssociatedTyValueBound { ty }, + ), + }) + } + + fn custom_clauses(&self) -> Vec<chalk_ir::ProgramClause<RustInterner<'tcx>>> { + vec![] + } + + fn local_impls_to_coherence_check( + &self, + _trait_id: chalk_ir::TraitId<RustInterner<'tcx>>, + ) -> Vec<chalk_ir::ImplId<RustInterner<'tcx>>> { + unimplemented!() + } + + fn opaque_ty_data( + &self, + opaque_ty_id: chalk_ir::OpaqueTyId<RustInterner<'tcx>>, + ) -> Arc<chalk_solve::rust_ir::OpaqueTyDatum<RustInterner<'tcx>>> { + let bound_vars = ty::fold::shift_vars( + self.interner.tcx, + bound_vars_for_item(self.interner.tcx, opaque_ty_id.0), + 1, + ); + let where_clauses = self.where_clauses_for(opaque_ty_id.0, bound_vars); + + let identity_substs = InternalSubsts::identity_for_item(self.interner.tcx, opaque_ty_id.0); + + let explicit_item_bounds = self.interner.tcx.bound_explicit_item_bounds(opaque_ty_id.0); + let bounds = + explicit_item_bounds + .0 + .iter() + .map(|(bound, _)| { + explicit_item_bounds.rebind(*bound).subst(self.interner.tcx, &bound_vars) + }) + .map(|bound| { + bound.fold_with(&mut ReplaceOpaqueTyFolder { + tcx: self.interner.tcx, + opaque_ty_id, + identity_substs, + binder_index: ty::INNERMOST, + }) + }) + .filter_map(|bound| { + LowerInto::< + Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>> + >::lower_into(bound, self.interner) + }) + .collect(); + + // Binder for the bound variable representing the concrete impl Trait type. + let existential_binder = chalk_ir::VariableKinds::from1( + self.interner, + chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General), + ); + + let value = chalk_solve::rust_ir::OpaqueTyDatumBound { + bounds: chalk_ir::Binders::new(existential_binder.clone(), bounds), + where_clauses: chalk_ir::Binders::new(existential_binder, where_clauses), + }; + + let binders = binders_for(self.interner, bound_vars); + Arc::new(chalk_solve::rust_ir::OpaqueTyDatum { + opaque_ty_id, + bound: chalk_ir::Binders::new(binders, value), + }) + } + + fn program_clauses_for_env( + &self, + environment: &chalk_ir::Environment<RustInterner<'tcx>>, + ) -> chalk_ir::ProgramClauses<RustInterner<'tcx>> { + chalk_solve::program_clauses_for_env(self, environment) + } + + fn well_known_trait_id( + &self, + well_known_trait: chalk_solve::rust_ir::WellKnownTrait, + ) -> Option<chalk_ir::TraitId<RustInterner<'tcx>>> { + use chalk_solve::rust_ir::WellKnownTrait::*; + let lang_items = self.interner.tcx.lang_items(); + let def_id = match well_known_trait { + Sized => lang_items.sized_trait(), + Copy => lang_items.copy_trait(), + Clone => lang_items.clone_trait(), + Drop => lang_items.drop_trait(), + Fn => lang_items.fn_trait(), + FnMut => lang_items.fn_mut_trait(), + FnOnce => lang_items.fn_once_trait(), + Generator => lang_items.gen_trait(), + Unsize => lang_items.unsize_trait(), + Unpin => lang_items.unpin_trait(), + CoerceUnsized => lang_items.coerce_unsized_trait(), + DiscriminantKind => lang_items.discriminant_kind_trait(), + DispatchFromDyn => lang_items.dispatch_from_dyn_trait(), + }; + def_id.map(chalk_ir::TraitId) + } + + fn is_object_safe(&self, trait_id: chalk_ir::TraitId<RustInterner<'tcx>>) -> bool { + self.interner.tcx.is_object_safe(trait_id.0) + } + + fn hidden_opaque_type( + &self, + _id: chalk_ir::OpaqueTyId<RustInterner<'tcx>>, + ) -> chalk_ir::Ty<RustInterner<'tcx>> { + // FIXME(chalk): actually get hidden ty + self.interner + .tcx + .mk_ty(ty::Tuple(self.interner.tcx.intern_type_list(&[]))) + .lower_into(self.interner) + } + + fn closure_kind( + &self, + _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>, + substs: &chalk_ir::Substitution<RustInterner<'tcx>>, + ) -> chalk_solve::rust_ir::ClosureKind { + let kind = &substs.as_slice(self.interner)[substs.len(self.interner) - 3]; + match kind.assert_ty_ref(self.interner).kind(self.interner) { + chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Int(int_ty)) => match int_ty { + chalk_ir::IntTy::I8 => chalk_solve::rust_ir::ClosureKind::Fn, + chalk_ir::IntTy::I16 => chalk_solve::rust_ir::ClosureKind::FnMut, + chalk_ir::IntTy::I32 => chalk_solve::rust_ir::ClosureKind::FnOnce, + _ => bug!("bad closure kind"), + }, + _ => bug!("bad closure kind"), + } + } + + fn closure_inputs_and_output( + &self, + _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>, + substs: &chalk_ir::Substitution<RustInterner<'tcx>>, + ) -> chalk_ir::Binders<chalk_solve::rust_ir::FnDefInputsAndOutputDatum<RustInterner<'tcx>>> + { + let sig = &substs.as_slice(self.interner)[substs.len(self.interner) - 2]; + match sig.assert_ty_ref(self.interner).kind(self.interner) { + chalk_ir::TyKind::Function(f) => { + let substitution = f.substitution.0.as_slice(self.interner); + let return_type = substitution.last().unwrap().assert_ty_ref(self.interner).clone(); + // Closure arguments are tupled + let argument_tuple = substitution[0].assert_ty_ref(self.interner); + let argument_types = match argument_tuple.kind(self.interner) { + chalk_ir::TyKind::Tuple(_len, substitution) => substitution + .iter(self.interner) + .map(|arg| arg.assert_ty_ref(self.interner)) + .cloned() + .collect(), + _ => bug!("Expecting closure FnSig args to be tupled."), + }; + + chalk_ir::Binders::new( + chalk_ir::VariableKinds::from_iter( + self.interner, + (0..f.num_binders).map(|_| chalk_ir::VariableKind::Lifetime), + ), + chalk_solve::rust_ir::FnDefInputsAndOutputDatum { argument_types, return_type }, + ) + } + _ => panic!("Invalid sig."), + } + } + + fn closure_upvars( + &self, + _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>, + substs: &chalk_ir::Substitution<RustInterner<'tcx>>, + ) -> chalk_ir::Binders<chalk_ir::Ty<RustInterner<'tcx>>> { + let inputs_and_output = self.closure_inputs_and_output(_closure_id, substs); + let tuple = substs.as_slice(self.interner).last().unwrap().assert_ty_ref(self.interner); + inputs_and_output.map_ref(|_| tuple.clone()) + } + + fn closure_fn_substitution( + &self, + _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>, + substs: &chalk_ir::Substitution<RustInterner<'tcx>>, + ) -> chalk_ir::Substitution<RustInterner<'tcx>> { + let substitution = &substs.as_slice(self.interner)[0..substs.len(self.interner) - 3]; + chalk_ir::Substitution::from_iter(self.interner, substitution) + } + + fn generator_datum( + &self, + _generator_id: chalk_ir::GeneratorId<RustInterner<'tcx>>, + ) -> Arc<chalk_solve::rust_ir::GeneratorDatum<RustInterner<'tcx>>> { + unimplemented!() + } + + fn generator_witness_datum( + &self, + _generator_id: chalk_ir::GeneratorId<RustInterner<'tcx>>, + ) -> Arc<chalk_solve::rust_ir::GeneratorWitnessDatum<RustInterner<'tcx>>> { + unimplemented!() + } + + fn unification_database(&self) -> &dyn chalk_ir::UnificationDatabase<RustInterner<'tcx>> { + self + } + + fn discriminant_type( + &self, + _: chalk_ir::Ty<RustInterner<'tcx>>, + ) -> chalk_ir::Ty<RustInterner<'tcx>> { + unimplemented!() + } +} + +impl<'tcx> chalk_ir::UnificationDatabase<RustInterner<'tcx>> for RustIrDatabase<'tcx> { + fn fn_def_variance( + &self, + def_id: chalk_ir::FnDefId<RustInterner<'tcx>>, + ) -> chalk_ir::Variances<RustInterner<'tcx>> { + let variances = self.interner.tcx.variances_of(def_id.0); + chalk_ir::Variances::from_iter( + self.interner, + variances.iter().map(|v| v.lower_into(self.interner)), + ) + } + + fn adt_variance( + &self, + adt_id: chalk_ir::AdtId<RustInterner<'tcx>>, + ) -> chalk_ir::Variances<RustInterner<'tcx>> { + let variances = self.interner.tcx.variances_of(adt_id.0.did()); + chalk_ir::Variances::from_iter( + self.interner, + variances.iter().map(|v| v.lower_into(self.interner)), + ) + } +} + +/// Creates an `InternalSubsts` that maps each generic parameter to a higher-ranked +/// var bound at index `0`. For types, we use a `BoundVar` index equal to +/// the type parameter index. For regions, we use the `BoundRegionKind::BrNamed` +/// variant (which has a `DefId`). +fn bound_vars_for_item<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> SubstsRef<'tcx> { + InternalSubsts::for_item(tcx, def_id, |param, substs| match param.kind { + ty::GenericParamDefKind::Type { .. } => tcx + .mk_ty(ty::Bound( + ty::INNERMOST, + ty::BoundTy { + var: ty::BoundVar::from(param.index), + kind: ty::BoundTyKind::Param(param.name), + }, + )) + .into(), + + ty::GenericParamDefKind::Lifetime => { + let br = ty::BoundRegion { + var: ty::BoundVar::from_usize(substs.len()), + kind: ty::BrAnon(substs.len() as u32), + }; + tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br)).into() + } + + ty::GenericParamDefKind::Const { .. } => tcx + .mk_const(ty::ConstS { + kind: ty::ConstKind::Bound(ty::INNERMOST, ty::BoundVar::from(param.index)), + ty: tcx.type_of(param.def_id), + }) + .into(), + }) +} + +fn binders_for<'tcx>( + interner: RustInterner<'tcx>, + bound_vars: SubstsRef<'tcx>, +) -> chalk_ir::VariableKinds<RustInterner<'tcx>> { + chalk_ir::VariableKinds::from_iter( + interner, + bound_vars.iter().map(|arg| match arg.unpack() { + ty::subst::GenericArgKind::Lifetime(_re) => chalk_ir::VariableKind::Lifetime, + ty::subst::GenericArgKind::Type(_ty) => { + chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General) + } + ty::subst::GenericArgKind::Const(c) => { + chalk_ir::VariableKind::Const(c.ty().lower_into(interner)) + } + }), + ) +} + +struct ReplaceOpaqueTyFolder<'tcx> { + tcx: TyCtxt<'tcx>, + opaque_ty_id: chalk_ir::OpaqueTyId<RustInterner<'tcx>>, + identity_substs: SubstsRef<'tcx>, + binder_index: ty::DebruijnIndex, +} + +impl<'tcx> ty::TypeFolder<'tcx> for ReplaceOpaqueTyFolder<'tcx> { + fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { + self.tcx + } + + fn fold_binder<T: TypeFoldable<'tcx>>( + &mut self, + t: ty::Binder<'tcx, T>, + ) -> ty::Binder<'tcx, T> { + self.binder_index.shift_in(1); + let t = t.super_fold_with(self); + self.binder_index.shift_out(1); + t + } + + fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> { + if let ty::Opaque(def_id, substs) = *ty.kind() { + if def_id == self.opaque_ty_id.0 && substs == self.identity_substs { + return self.tcx.mk_ty(ty::Bound( + self.binder_index, + ty::BoundTy::from(ty::BoundVar::from_u32(0)), + )); + } + } + ty + } +} diff --git a/compiler/rustc_traits/src/chalk/lowering.rs b/compiler/rustc_traits/src/chalk/lowering.rs new file mode 100644 index 000000000..c7c604e14 --- /dev/null +++ b/compiler/rustc_traits/src/chalk/lowering.rs @@ -0,0 +1,1172 @@ +//! Contains the logic to lower rustc types into Chalk types +//! +//! In many cases there is a 1:1 relationship between a rustc type and a Chalk type. +//! For example, a `SubstsRef` maps almost directly to a `Substitution`. In some +//! other cases, such as `Param`s, there is no Chalk type, so we have to handle +//! accordingly. +//! +//! ## `Ty` lowering +//! Much of the `Ty` lowering is 1:1 with Chalk. (Or will be eventually). A +//! helpful table for what types lower to what can be found in the +//! [Chalk book](https://rust-lang.github.io/chalk/book/types/rust_types.html). +//! The most notable difference lies with `Param`s. To convert from rustc to +//! Chalk, we eagerly and deeply convert `Param`s to placeholders (in goals) or +//! bound variables (for clause generation through functions in `db`). +//! +//! ## `Region` lowering +//! Regions are handled in rustc and Chalk is quite differently. In rustc, there +//! is a difference between "early bound" and "late bound" regions, where only +//! the late bound regions have a `DebruijnIndex`. Moreover, in Chalk all +//! regions (Lifetimes) have an associated index. In rustc, only `BrAnon`s have +//! an index, whereas `BrNamed` don't. In order to lower regions to Chalk, we +//! convert all regions into `BrAnon` late-bound regions. +//! +//! ## `Const` lowering +//! Chalk doesn't handle consts currently, so consts are currently lowered to +//! an empty tuple. +//! +//! ## Bound variable collection +//! Another difference between rustc and Chalk lies in the handling of binders. +//! Chalk requires that we store the bound parameter kinds, whereas rustc does +//! not. To lower anything wrapped in a `Binder`, we first deeply find any bound +//! variables from the current `Binder`. + +use rustc_ast::ast; +use rustc_middle::traits::{ChalkEnvironmentAndGoal, ChalkRustInterner as RustInterner}; +use rustc_middle::ty::subst::{GenericArg, GenericArgKind, SubstsRef}; +use rustc_middle::ty::{ + self, Binder, Region, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable, + TypeSuperVisitable, TypeVisitable, TypeVisitor, +}; +use rustc_span::def_id::DefId; + +use chalk_ir::{FnSig, ForeignDefId}; +use rustc_hir::Unsafety; +use std::collections::btree_map::{BTreeMap, Entry}; +use std::ops::ControlFlow; + +/// Essentially an `Into` with a `&RustInterner` parameter +pub(crate) trait LowerInto<'tcx, T> { + /// Lower a rustc construct (e.g., `ty::TraitPredicate`) to a chalk type, consuming `self`. + fn lower_into(self, interner: RustInterner<'tcx>) -> T; +} + +impl<'tcx> LowerInto<'tcx, chalk_ir::Substitution<RustInterner<'tcx>>> for SubstsRef<'tcx> { + fn lower_into( + self, + interner: RustInterner<'tcx>, + ) -> chalk_ir::Substitution<RustInterner<'tcx>> { + chalk_ir::Substitution::from_iter(interner, self.iter().map(|s| s.lower_into(interner))) + } +} + +impl<'tcx> LowerInto<'tcx, SubstsRef<'tcx>> for &chalk_ir::Substitution<RustInterner<'tcx>> { + fn lower_into(self, interner: RustInterner<'tcx>) -> SubstsRef<'tcx> { + interner.tcx.mk_substs(self.iter(interner).map(|subst| subst.lower_into(interner))) + } +} + +impl<'tcx> LowerInto<'tcx, chalk_ir::AliasTy<RustInterner<'tcx>>> for ty::ProjectionTy<'tcx> { + fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::AliasTy<RustInterner<'tcx>> { + chalk_ir::AliasTy::Projection(chalk_ir::ProjectionTy { + associated_ty_id: chalk_ir::AssocTypeId(self.item_def_id), + substitution: self.substs.lower_into(interner), + }) + } +} + +impl<'tcx> LowerInto<'tcx, chalk_ir::InEnvironment<chalk_ir::Goal<RustInterner<'tcx>>>> + for ChalkEnvironmentAndGoal<'tcx> +{ + fn lower_into( + self, + interner: RustInterner<'tcx>, + ) -> chalk_ir::InEnvironment<chalk_ir::Goal<RustInterner<'tcx>>> { + let clauses = self.environment.into_iter().map(|predicate| { + let (predicate, binders, _named_regions) = + collect_bound_vars(interner, interner.tcx, predicate.kind()); + let consequence = match predicate { + ty::PredicateKind::TypeWellFormedFromEnv(ty) => { + chalk_ir::DomainGoal::FromEnv(chalk_ir::FromEnv::Ty(ty.lower_into(interner))) + } + ty::PredicateKind::Trait(predicate) => chalk_ir::DomainGoal::FromEnv( + chalk_ir::FromEnv::Trait(predicate.trait_ref.lower_into(interner)), + ), + ty::PredicateKind::RegionOutlives(predicate) => chalk_ir::DomainGoal::Holds( + chalk_ir::WhereClause::LifetimeOutlives(chalk_ir::LifetimeOutlives { + a: predicate.0.lower_into(interner), + b: predicate.1.lower_into(interner), + }), + ), + ty::PredicateKind::TypeOutlives(predicate) => chalk_ir::DomainGoal::Holds( + chalk_ir::WhereClause::TypeOutlives(chalk_ir::TypeOutlives { + ty: predicate.0.lower_into(interner), + lifetime: predicate.1.lower_into(interner), + }), + ), + ty::PredicateKind::Projection(predicate) => chalk_ir::DomainGoal::Holds( + chalk_ir::WhereClause::AliasEq(predicate.lower_into(interner)), + ), + ty::PredicateKind::WellFormed(arg) => match arg.unpack() { + ty::GenericArgKind::Type(ty) => chalk_ir::DomainGoal::WellFormed( + chalk_ir::WellFormed::Ty(ty.lower_into(interner)), + ), + // FIXME(chalk): we need to change `WellFormed` in Chalk to take a `GenericArg` + _ => chalk_ir::DomainGoal::WellFormed(chalk_ir::WellFormed::Ty( + interner.tcx.types.unit.lower_into(interner), + )), + }, + ty::PredicateKind::ObjectSafe(..) + | ty::PredicateKind::ClosureKind(..) + | ty::PredicateKind::Subtype(..) + | ty::PredicateKind::Coerce(..) + | ty::PredicateKind::ConstEvaluatable(..) + | ty::PredicateKind::ConstEquate(..) => bug!("unexpected predicate {}", predicate), + }; + let value = chalk_ir::ProgramClauseImplication { + consequence, + conditions: chalk_ir::Goals::empty(interner), + priority: chalk_ir::ClausePriority::High, + constraints: chalk_ir::Constraints::empty(interner), + }; + chalk_ir::ProgramClauseData(chalk_ir::Binders::new(binders, value)).intern(interner) + }); + + let goal: chalk_ir::GoalData<RustInterner<'tcx>> = self.goal.lower_into(interner); + chalk_ir::InEnvironment { + environment: chalk_ir::Environment { + clauses: chalk_ir::ProgramClauses::from_iter(interner, clauses), + }, + goal: goal.intern(interner), + } + } +} + +impl<'tcx> LowerInto<'tcx, chalk_ir::GoalData<RustInterner<'tcx>>> for ty::Predicate<'tcx> { + fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::GoalData<RustInterner<'tcx>> { + let (predicate, binders, _named_regions) = + collect_bound_vars(interner, interner.tcx, self.kind()); + + let value = match predicate { + ty::PredicateKind::Trait(predicate) => { + chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds( + chalk_ir::WhereClause::Implemented(predicate.trait_ref.lower_into(interner)), + )) + } + ty::PredicateKind::RegionOutlives(predicate) => { + chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds( + chalk_ir::WhereClause::LifetimeOutlives(chalk_ir::LifetimeOutlives { + a: predicate.0.lower_into(interner), + b: predicate.1.lower_into(interner), + }), + )) + } + ty::PredicateKind::TypeOutlives(predicate) => { + chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds( + chalk_ir::WhereClause::TypeOutlives(chalk_ir::TypeOutlives { + ty: predicate.0.lower_into(interner), + lifetime: predicate.1.lower_into(interner), + }), + )) + } + ty::PredicateKind::Projection(predicate) => { + chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds( + chalk_ir::WhereClause::AliasEq(predicate.lower_into(interner)), + )) + } + ty::PredicateKind::WellFormed(arg) => match arg.unpack() { + GenericArgKind::Type(ty) => match ty.kind() { + // FIXME(chalk): In Chalk, a placeholder is WellFormed if it + // `FromEnv`. However, when we "lower" Params, we don't update + // the environment. + ty::Placeholder(..) => { + chalk_ir::GoalData::All(chalk_ir::Goals::empty(interner)) + } + + _ => chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::WellFormed( + chalk_ir::WellFormed::Ty(ty.lower_into(interner)), + )), + }, + // FIXME(chalk): handle well formed consts + GenericArgKind::Const(..) => { + chalk_ir::GoalData::All(chalk_ir::Goals::empty(interner)) + } + GenericArgKind::Lifetime(lt) => bug!("unexpect well formed predicate: {:?}", lt), + }, + + ty::PredicateKind::ObjectSafe(t) => chalk_ir::GoalData::DomainGoal( + chalk_ir::DomainGoal::ObjectSafe(chalk_ir::TraitId(t)), + ), + + ty::PredicateKind::Subtype(ty::SubtypePredicate { a, b, a_is_expected: _ }) => { + chalk_ir::GoalData::SubtypeGoal(chalk_ir::SubtypeGoal { + a: a.lower_into(interner), + b: b.lower_into(interner), + }) + } + + // FIXME(chalk): other predicates + // + // We can defer this, but ultimately we'll want to express + // some of these in terms of chalk operations. + ty::PredicateKind::ClosureKind(..) + | ty::PredicateKind::Coerce(..) + | ty::PredicateKind::ConstEvaluatable(..) + | ty::PredicateKind::ConstEquate(..) => { + chalk_ir::GoalData::All(chalk_ir::Goals::empty(interner)) + } + ty::PredicateKind::TypeWellFormedFromEnv(ty) => chalk_ir::GoalData::DomainGoal( + chalk_ir::DomainGoal::FromEnv(chalk_ir::FromEnv::Ty(ty.lower_into(interner))), + ), + }; + + chalk_ir::GoalData::Quantified( + chalk_ir::QuantifierKind::ForAll, + chalk_ir::Binders::new(binders, value.intern(interner)), + ) + } +} + +impl<'tcx> LowerInto<'tcx, chalk_ir::TraitRef<RustInterner<'tcx>>> + for rustc_middle::ty::TraitRef<'tcx> +{ + fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::TraitRef<RustInterner<'tcx>> { + chalk_ir::TraitRef { + trait_id: chalk_ir::TraitId(self.def_id), + substitution: self.substs.lower_into(interner), + } + } +} + +impl<'tcx> LowerInto<'tcx, chalk_ir::AliasEq<RustInterner<'tcx>>> + for rustc_middle::ty::ProjectionPredicate<'tcx> +{ + fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::AliasEq<RustInterner<'tcx>> { + // FIXME(associated_const_equality): teach chalk about terms for alias eq. + chalk_ir::AliasEq { + ty: self.term.ty().unwrap().lower_into(interner), + alias: self.projection_ty.lower_into(interner), + } + } +} + +/* +// FIXME(...): Where do I add this to Chalk? I can't find it in the rustc repo anywhere. +impl<'tcx> LowerInto<'tcx, chalk_ir::Term<RustInterner<'tcx>>> for rustc_middle::ty::Term<'tcx> { + fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::Term<RustInterner<'tcx>> { + match self { + ty::Term::Ty(ty) => ty.lower_into(interner).into(), + ty::Term::Const(c) => c.lower_into(interner).into(), + } + } +} +*/ + +impl<'tcx> LowerInto<'tcx, chalk_ir::Ty<RustInterner<'tcx>>> for Ty<'tcx> { + fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::Ty<RustInterner<'tcx>> { + let int = |i| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Int(i)); + let uint = |i| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Uint(i)); + let float = |f| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Float(f)); + + match *self.kind() { + ty::Bool => chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Bool), + ty::Char => chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Char), + ty::Int(ty) => match ty { + ty::IntTy::Isize => int(chalk_ir::IntTy::Isize), + ty::IntTy::I8 => int(chalk_ir::IntTy::I8), + ty::IntTy::I16 => int(chalk_ir::IntTy::I16), + ty::IntTy::I32 => int(chalk_ir::IntTy::I32), + ty::IntTy::I64 => int(chalk_ir::IntTy::I64), + ty::IntTy::I128 => int(chalk_ir::IntTy::I128), + }, + ty::Uint(ty) => match ty { + ty::UintTy::Usize => uint(chalk_ir::UintTy::Usize), + ty::UintTy::U8 => uint(chalk_ir::UintTy::U8), + ty::UintTy::U16 => uint(chalk_ir::UintTy::U16), + ty::UintTy::U32 => uint(chalk_ir::UintTy::U32), + ty::UintTy::U64 => uint(chalk_ir::UintTy::U64), + ty::UintTy::U128 => uint(chalk_ir::UintTy::U128), + }, + ty::Float(ty) => match ty { + ty::FloatTy::F32 => float(chalk_ir::FloatTy::F32), + ty::FloatTy::F64 => float(chalk_ir::FloatTy::F64), + }, + ty::Adt(def, substs) => { + chalk_ir::TyKind::Adt(chalk_ir::AdtId(def), substs.lower_into(interner)) + } + ty::Foreign(def_id) => chalk_ir::TyKind::Foreign(ForeignDefId(def_id)), + ty::Str => chalk_ir::TyKind::Str, + ty::Array(ty, len) => { + chalk_ir::TyKind::Array(ty.lower_into(interner), len.lower_into(interner)) + } + ty::Slice(ty) => chalk_ir::TyKind::Slice(ty.lower_into(interner)), + + ty::RawPtr(ptr) => { + chalk_ir::TyKind::Raw(ptr.mutbl.lower_into(interner), ptr.ty.lower_into(interner)) + } + ty::Ref(region, ty, mutability) => chalk_ir::TyKind::Ref( + mutability.lower_into(interner), + region.lower_into(interner), + ty.lower_into(interner), + ), + ty::FnDef(def_id, substs) => { + chalk_ir::TyKind::FnDef(chalk_ir::FnDefId(def_id), substs.lower_into(interner)) + } + ty::FnPtr(sig) => { + let (inputs_and_outputs, binders, _named_regions) = + collect_bound_vars(interner, interner.tcx, sig.inputs_and_output()); + chalk_ir::TyKind::Function(chalk_ir::FnPointer { + num_binders: binders.len(interner), + sig: sig.lower_into(interner), + substitution: chalk_ir::FnSubst(chalk_ir::Substitution::from_iter( + interner, + inputs_and_outputs.iter().map(|ty| { + chalk_ir::GenericArgData::Ty(ty.lower_into(interner)).intern(interner) + }), + )), + }) + } + ty::Dynamic(predicates, region) => chalk_ir::TyKind::Dyn(chalk_ir::DynTy { + bounds: predicates.lower_into(interner), + lifetime: region.lower_into(interner), + }), + ty::Closure(def_id, substs) => { + chalk_ir::TyKind::Closure(chalk_ir::ClosureId(def_id), substs.lower_into(interner)) + } + ty::Generator(def_id, substs, _) => chalk_ir::TyKind::Generator( + chalk_ir::GeneratorId(def_id), + substs.lower_into(interner), + ), + ty::GeneratorWitness(_) => unimplemented!(), + ty::Never => chalk_ir::TyKind::Never, + ty::Tuple(types) => { + chalk_ir::TyKind::Tuple(types.len(), types.as_substs().lower_into(interner)) + } + ty::Projection(proj) => chalk_ir::TyKind::Alias(proj.lower_into(interner)), + ty::Opaque(def_id, substs) => { + chalk_ir::TyKind::Alias(chalk_ir::AliasTy::Opaque(chalk_ir::OpaqueTy { + opaque_ty_id: chalk_ir::OpaqueTyId(def_id), + substitution: substs.lower_into(interner), + })) + } + // This should have been done eagerly prior to this, and all Params + // should have been substituted to placeholders + ty::Param(_) => panic!("Lowering Param when not expected."), + ty::Bound(db, bound) => chalk_ir::TyKind::BoundVar(chalk_ir::BoundVar::new( + chalk_ir::DebruijnIndex::new(db.as_u32()), + bound.var.index(), + )), + ty::Placeholder(_placeholder) => { + chalk_ir::TyKind::Placeholder(chalk_ir::PlaceholderIndex { + ui: chalk_ir::UniverseIndex { counter: _placeholder.universe.as_usize() }, + idx: _placeholder.name.as_usize(), + }) + } + ty::Infer(_infer) => unimplemented!(), + ty::Error(_) => chalk_ir::TyKind::Error, + } + .intern(interner) + } +} + +impl<'tcx> LowerInto<'tcx, Ty<'tcx>> for &chalk_ir::Ty<RustInterner<'tcx>> { + fn lower_into(self, interner: RustInterner<'tcx>) -> Ty<'tcx> { + use chalk_ir::TyKind; + + let kind = match self.kind(interner) { + TyKind::Adt(struct_id, substitution) => { + ty::Adt(struct_id.0, substitution.lower_into(interner)) + } + TyKind::Scalar(scalar) => match scalar { + chalk_ir::Scalar::Bool => ty::Bool, + chalk_ir::Scalar::Char => ty::Char, + chalk_ir::Scalar::Int(int_ty) => match int_ty { + chalk_ir::IntTy::Isize => ty::Int(ty::IntTy::Isize), + chalk_ir::IntTy::I8 => ty::Int(ty::IntTy::I8), + chalk_ir::IntTy::I16 => ty::Int(ty::IntTy::I16), + chalk_ir::IntTy::I32 => ty::Int(ty::IntTy::I32), + chalk_ir::IntTy::I64 => ty::Int(ty::IntTy::I64), + chalk_ir::IntTy::I128 => ty::Int(ty::IntTy::I128), + }, + chalk_ir::Scalar::Uint(int_ty) => match int_ty { + chalk_ir::UintTy::Usize => ty::Uint(ty::UintTy::Usize), + chalk_ir::UintTy::U8 => ty::Uint(ty::UintTy::U8), + chalk_ir::UintTy::U16 => ty::Uint(ty::UintTy::U16), + chalk_ir::UintTy::U32 => ty::Uint(ty::UintTy::U32), + chalk_ir::UintTy::U64 => ty::Uint(ty::UintTy::U64), + chalk_ir::UintTy::U128 => ty::Uint(ty::UintTy::U128), + }, + chalk_ir::Scalar::Float(float_ty) => match float_ty { + chalk_ir::FloatTy::F32 => ty::Float(ty::FloatTy::F32), + chalk_ir::FloatTy::F64 => ty::Float(ty::FloatTy::F64), + }, + }, + TyKind::Array(ty, c) => { + let ty = ty.lower_into(interner); + let c = c.lower_into(interner); + ty::Array(ty, c) + } + TyKind::FnDef(id, substitution) => ty::FnDef(id.0, substitution.lower_into(interner)), + TyKind::Closure(closure, substitution) => { + ty::Closure(closure.0, substitution.lower_into(interner)) + } + TyKind::Generator(..) => unimplemented!(), + TyKind::GeneratorWitness(..) => unimplemented!(), + TyKind::Never => ty::Never, + TyKind::Tuple(_len, substitution) => { + ty::Tuple(substitution.lower_into(interner).try_as_type_list().unwrap()) + } + TyKind::Slice(ty) => ty::Slice(ty.lower_into(interner)), + TyKind::Raw(mutbl, ty) => ty::RawPtr(ty::TypeAndMut { + ty: ty.lower_into(interner), + mutbl: mutbl.lower_into(interner), + }), + TyKind::Ref(mutbl, lifetime, ty) => ty::Ref( + lifetime.lower_into(interner), + ty.lower_into(interner), + mutbl.lower_into(interner), + ), + TyKind::Str => ty::Str, + TyKind::OpaqueType(opaque_ty, substitution) => { + ty::Opaque(opaque_ty.0, substitution.lower_into(interner)) + } + TyKind::AssociatedType(assoc_ty, substitution) => ty::Projection(ty::ProjectionTy { + substs: substitution.lower_into(interner), + item_def_id: assoc_ty.0, + }), + TyKind::Foreign(def_id) => ty::Foreign(def_id.0), + TyKind::Error => return interner.tcx.ty_error(), + TyKind::Placeholder(placeholder) => ty::Placeholder(ty::Placeholder { + universe: ty::UniverseIndex::from_usize(placeholder.ui.counter), + name: ty::BoundVar::from_usize(placeholder.idx), + }), + TyKind::Alias(alias_ty) => match alias_ty { + chalk_ir::AliasTy::Projection(projection) => ty::Projection(ty::ProjectionTy { + item_def_id: projection.associated_ty_id.0, + substs: projection.substitution.lower_into(interner), + }), + chalk_ir::AliasTy::Opaque(opaque) => { + ty::Opaque(opaque.opaque_ty_id.0, opaque.substitution.lower_into(interner)) + } + }, + TyKind::Function(_quantified_ty) => unimplemented!(), + TyKind::BoundVar(_bound) => ty::Bound( + ty::DebruijnIndex::from_usize(_bound.debruijn.depth() as usize), + ty::BoundTy { + var: ty::BoundVar::from_usize(_bound.index), + kind: ty::BoundTyKind::Anon, + }, + ), + TyKind::InferenceVar(_, _) => unimplemented!(), + TyKind::Dyn(_) => unimplemented!(), + }; + interner.tcx.mk_ty(kind) + } +} + +impl<'tcx> LowerInto<'tcx, chalk_ir::Lifetime<RustInterner<'tcx>>> for Region<'tcx> { + fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::Lifetime<RustInterner<'tcx>> { + match *self { + ty::ReEarlyBound(_) => { + panic!("Should have already been substituted."); + } + ty::ReLateBound(db, br) => chalk_ir::LifetimeData::BoundVar(chalk_ir::BoundVar::new( + chalk_ir::DebruijnIndex::new(db.as_u32()), + br.var.as_usize(), + )) + .intern(interner), + ty::ReFree(_) => unimplemented!(), + ty::ReStatic => chalk_ir::LifetimeData::Static.intern(interner), + ty::ReVar(_) => unimplemented!(), + ty::RePlaceholder(placeholder_region) => { + chalk_ir::LifetimeData::Placeholder(chalk_ir::PlaceholderIndex { + ui: chalk_ir::UniverseIndex { counter: placeholder_region.universe.index() }, + idx: 0, + }) + .intern(interner) + } + ty::ReEmpty(ui) => { + chalk_ir::LifetimeData::Empty(chalk_ir::UniverseIndex { counter: ui.index() }) + .intern(interner) + } + ty::ReErased => chalk_ir::LifetimeData::Erased.intern(interner), + } + } +} + +impl<'tcx> LowerInto<'tcx, Region<'tcx>> for &chalk_ir::Lifetime<RustInterner<'tcx>> { + fn lower_into(self, interner: RustInterner<'tcx>) -> Region<'tcx> { + let kind = match self.data(interner) { + chalk_ir::LifetimeData::BoundVar(var) => ty::ReLateBound( + ty::DebruijnIndex::from_u32(var.debruijn.depth()), + ty::BoundRegion { + var: ty::BoundVar::from_usize(var.index), + kind: ty::BrAnon(var.index as u32), + }, + ), + chalk_ir::LifetimeData::InferenceVar(_var) => unimplemented!(), + chalk_ir::LifetimeData::Placeholder(p) => ty::RePlaceholder(ty::Placeholder { + universe: ty::UniverseIndex::from_usize(p.ui.counter), + name: ty::BoundRegionKind::BrAnon(p.idx as u32), + }), + chalk_ir::LifetimeData::Static => return interner.tcx.lifetimes.re_static, + chalk_ir::LifetimeData::Empty(ui) => { + ty::ReEmpty(ty::UniverseIndex::from_usize(ui.counter)) + } + chalk_ir::LifetimeData::Erased => return interner.tcx.lifetimes.re_erased, + chalk_ir::LifetimeData::Phantom(void, _) => match *void {}, + }; + interner.tcx.mk_region(kind) + } +} + +impl<'tcx> LowerInto<'tcx, chalk_ir::Const<RustInterner<'tcx>>> for ty::Const<'tcx> { + fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::Const<RustInterner<'tcx>> { + let ty = self.ty().lower_into(interner); + let value = match self.kind() { + ty::ConstKind::Value(val) => { + chalk_ir::ConstValue::Concrete(chalk_ir::ConcreteConst { interned: val }) + } + ty::ConstKind::Bound(db, bound) => chalk_ir::ConstValue::BoundVar( + chalk_ir::BoundVar::new(chalk_ir::DebruijnIndex::new(db.as_u32()), bound.index()), + ), + _ => unimplemented!("Const not implemented. {:?}", self), + }; + chalk_ir::ConstData { ty, value }.intern(interner) + } +} + +impl<'tcx> LowerInto<'tcx, ty::Const<'tcx>> for &chalk_ir::Const<RustInterner<'tcx>> { + fn lower_into(self, interner: RustInterner<'tcx>) -> ty::Const<'tcx> { + let data = self.data(interner); + let ty = data.ty.lower_into(interner); + let kind = match data.value { + chalk_ir::ConstValue::BoundVar(var) => ty::ConstKind::Bound( + ty::DebruijnIndex::from_u32(var.debruijn.depth()), + ty::BoundVar::from_u32(var.index as u32), + ), + chalk_ir::ConstValue::InferenceVar(_var) => unimplemented!(), + chalk_ir::ConstValue::Placeholder(_p) => unimplemented!(), + chalk_ir::ConstValue::Concrete(c) => ty::ConstKind::Value(c.interned), + }; + interner.tcx.mk_const(ty::ConstS { ty, kind }) + } +} + +impl<'tcx> LowerInto<'tcx, chalk_ir::GenericArg<RustInterner<'tcx>>> for GenericArg<'tcx> { + fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::GenericArg<RustInterner<'tcx>> { + match self.unpack() { + ty::subst::GenericArgKind::Type(ty) => { + chalk_ir::GenericArgData::Ty(ty.lower_into(interner)) + } + ty::subst::GenericArgKind::Lifetime(lifetime) => { + chalk_ir::GenericArgData::Lifetime(lifetime.lower_into(interner)) + } + ty::subst::GenericArgKind::Const(c) => { + chalk_ir::GenericArgData::Const(c.lower_into(interner)) + } + } + .intern(interner) + } +} + +impl<'tcx> LowerInto<'tcx, ty::subst::GenericArg<'tcx>> + for &chalk_ir::GenericArg<RustInterner<'tcx>> +{ + fn lower_into(self, interner: RustInterner<'tcx>) -> ty::subst::GenericArg<'tcx> { + match self.data(interner) { + chalk_ir::GenericArgData::Ty(ty) => { + let t: Ty<'tcx> = ty.lower_into(interner); + t.into() + } + chalk_ir::GenericArgData::Lifetime(lifetime) => { + let r: Region<'tcx> = lifetime.lower_into(interner); + r.into() + } + chalk_ir::GenericArgData::Const(c) => { + let c: ty::Const<'tcx> = c.lower_into(interner); + c.into() + } + } + } +} + +// We lower into an Option here since there are some predicates which Chalk +// doesn't have a representation for yet (as a `WhereClause`), but are so common +// that we just are accepting the unsoundness for now. The `Option` will +// eventually be removed. +impl<'tcx> LowerInto<'tcx, Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>> + for ty::Predicate<'tcx> +{ + fn lower_into( + self, + interner: RustInterner<'tcx>, + ) -> Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>> { + let (predicate, binders, _named_regions) = + collect_bound_vars(interner, interner.tcx, self.kind()); + let value = match predicate { + ty::PredicateKind::Trait(predicate) => { + Some(chalk_ir::WhereClause::Implemented(predicate.trait_ref.lower_into(interner))) + } + ty::PredicateKind::RegionOutlives(predicate) => { + Some(chalk_ir::WhereClause::LifetimeOutlives(chalk_ir::LifetimeOutlives { + a: predicate.0.lower_into(interner), + b: predicate.1.lower_into(interner), + })) + } + ty::PredicateKind::TypeOutlives(predicate) => { + Some(chalk_ir::WhereClause::TypeOutlives(chalk_ir::TypeOutlives { + ty: predicate.0.lower_into(interner), + lifetime: predicate.1.lower_into(interner), + })) + } + ty::PredicateKind::Projection(predicate) => { + Some(chalk_ir::WhereClause::AliasEq(predicate.lower_into(interner))) + } + ty::PredicateKind::WellFormed(_ty) => None, + + ty::PredicateKind::ObjectSafe(..) + | ty::PredicateKind::ClosureKind(..) + | ty::PredicateKind::Subtype(..) + | ty::PredicateKind::Coerce(..) + | ty::PredicateKind::ConstEvaluatable(..) + | ty::PredicateKind::ConstEquate(..) + | ty::PredicateKind::TypeWellFormedFromEnv(..) => { + bug!("unexpected predicate {}", &self) + } + }; + value.map(|value| chalk_ir::Binders::new(binders, value)) + } +} + +impl<'tcx> LowerInto<'tcx, chalk_ir::Binders<chalk_ir::QuantifiedWhereClauses<RustInterner<'tcx>>>> + for &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>> +{ + fn lower_into( + self, + interner: RustInterner<'tcx>, + ) -> chalk_ir::Binders<chalk_ir::QuantifiedWhereClauses<RustInterner<'tcx>>> { + // `Self` has one binder: + // Binder<&'tcx ty::List<ty::ExistentialPredicate<'tcx>>> + // The return type has two: + // Binders<&[Binders<WhereClause<I>>]> + // This means that any variables that are escaping `self` need to be + // shifted in by one so that they are still escaping. + let predicates = ty::fold::shift_vars(interner.tcx, self, 1); + + let self_ty = interner.tcx.mk_ty(ty::Bound( + // This is going to be wrapped in a binder + ty::DebruijnIndex::from_usize(1), + ty::BoundTy { var: ty::BoundVar::from_usize(0), kind: ty::BoundTyKind::Anon }, + )); + let where_clauses = predicates.into_iter().map(|predicate| { + let (predicate, binders, _named_regions) = + collect_bound_vars(interner, interner.tcx, predicate); + match predicate { + ty::ExistentialPredicate::Trait(ty::ExistentialTraitRef { def_id, substs }) => { + chalk_ir::Binders::new( + binders.clone(), + chalk_ir::WhereClause::Implemented(chalk_ir::TraitRef { + trait_id: chalk_ir::TraitId(def_id), + substitution: interner + .tcx + .mk_substs_trait(self_ty, substs) + .lower_into(interner), + }), + ) + } + ty::ExistentialPredicate::Projection(predicate) => chalk_ir::Binders::new( + binders.clone(), + chalk_ir::WhereClause::AliasEq(chalk_ir::AliasEq { + alias: chalk_ir::AliasTy::Projection(chalk_ir::ProjectionTy { + associated_ty_id: chalk_ir::AssocTypeId(predicate.item_def_id), + substitution: interner + .tcx + .mk_substs_trait(self_ty, predicate.substs) + .lower_into(interner), + }), + // FIXME(associated_const_equality): teach chalk about terms for alias eq. + ty: predicate.term.ty().unwrap().lower_into(interner), + }), + ), + ty::ExistentialPredicate::AutoTrait(def_id) => chalk_ir::Binders::new( + binders.clone(), + chalk_ir::WhereClause::Implemented(chalk_ir::TraitRef { + trait_id: chalk_ir::TraitId(def_id), + substitution: interner + .tcx + .mk_substs_trait(self_ty, &[]) + .lower_into(interner), + }), + ), + } + }); + + // Binder for the bound variable representing the concrete underlying type. + let existential_binder = chalk_ir::VariableKinds::from1( + interner, + chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General), + ); + let value = chalk_ir::QuantifiedWhereClauses::from_iter(interner, where_clauses); + chalk_ir::Binders::new(existential_binder, value) + } +} + +impl<'tcx> LowerInto<'tcx, chalk_ir::FnSig<RustInterner<'tcx>>> + for ty::Binder<'tcx, ty::FnSig<'tcx>> +{ + fn lower_into(self, _interner: RustInterner<'_>) -> FnSig<RustInterner<'tcx>> { + chalk_ir::FnSig { + abi: self.abi(), + safety: match self.unsafety() { + Unsafety::Normal => chalk_ir::Safety::Safe, + Unsafety::Unsafe => chalk_ir::Safety::Unsafe, + }, + variadic: self.c_variadic(), + } + } +} + +// We lower into an Option here since there are some predicates which Chalk +// doesn't have a representation for yet (as an `InlineBound`). The `Option` will +// eventually be removed. +impl<'tcx> LowerInto<'tcx, Option<chalk_solve::rust_ir::QuantifiedInlineBound<RustInterner<'tcx>>>> + for ty::Predicate<'tcx> +{ + fn lower_into( + self, + interner: RustInterner<'tcx>, + ) -> Option<chalk_solve::rust_ir::QuantifiedInlineBound<RustInterner<'tcx>>> { + let (predicate, binders, _named_regions) = + collect_bound_vars(interner, interner.tcx, self.kind()); + match predicate { + ty::PredicateKind::Trait(predicate) => Some(chalk_ir::Binders::new( + binders, + chalk_solve::rust_ir::InlineBound::TraitBound( + predicate.trait_ref.lower_into(interner), + ), + )), + ty::PredicateKind::Projection(predicate) => Some(chalk_ir::Binders::new( + binders, + chalk_solve::rust_ir::InlineBound::AliasEqBound(predicate.lower_into(interner)), + )), + ty::PredicateKind::TypeOutlives(_predicate) => None, + ty::PredicateKind::WellFormed(_ty) => None, + + ty::PredicateKind::RegionOutlives(..) + | ty::PredicateKind::ObjectSafe(..) + | ty::PredicateKind::ClosureKind(..) + | ty::PredicateKind::Subtype(..) + | ty::PredicateKind::Coerce(..) + | ty::PredicateKind::ConstEvaluatable(..) + | ty::PredicateKind::ConstEquate(..) + | ty::PredicateKind::TypeWellFormedFromEnv(..) => { + bug!("unexpected predicate {}", &self) + } + } + } +} + +impl<'tcx> LowerInto<'tcx, chalk_solve::rust_ir::TraitBound<RustInterner<'tcx>>> + for ty::TraitRef<'tcx> +{ + fn lower_into( + self, + interner: RustInterner<'tcx>, + ) -> chalk_solve::rust_ir::TraitBound<RustInterner<'tcx>> { + chalk_solve::rust_ir::TraitBound { + trait_id: chalk_ir::TraitId(self.def_id), + args_no_self: self.substs[1..].iter().map(|arg| arg.lower_into(interner)).collect(), + } + } +} + +impl<'tcx> LowerInto<'tcx, chalk_ir::Mutability> for ast::Mutability { + fn lower_into(self, _interner: RustInterner<'tcx>) -> chalk_ir::Mutability { + match self { + rustc_ast::Mutability::Mut => chalk_ir::Mutability::Mut, + rustc_ast::Mutability::Not => chalk_ir::Mutability::Not, + } + } +} + +impl<'tcx> LowerInto<'tcx, ast::Mutability> for chalk_ir::Mutability { + fn lower_into(self, _interner: RustInterner<'tcx>) -> ast::Mutability { + match self { + chalk_ir::Mutability::Mut => ast::Mutability::Mut, + chalk_ir::Mutability::Not => ast::Mutability::Not, + } + } +} + +impl<'tcx> LowerInto<'tcx, chalk_solve::rust_ir::Polarity> for ty::ImplPolarity { + fn lower_into(self, _interner: RustInterner<'tcx>) -> chalk_solve::rust_ir::Polarity { + match self { + ty::ImplPolarity::Positive => chalk_solve::rust_ir::Polarity::Positive, + ty::ImplPolarity::Negative => chalk_solve::rust_ir::Polarity::Negative, + // FIXME(chalk) reservation impls + ty::ImplPolarity::Reservation => chalk_solve::rust_ir::Polarity::Negative, + } + } +} +impl<'tcx> LowerInto<'tcx, chalk_ir::Variance> for ty::Variance { + fn lower_into(self, _interner: RustInterner<'tcx>) -> chalk_ir::Variance { + match self { + ty::Variance::Covariant => chalk_ir::Variance::Covariant, + ty::Variance::Invariant => chalk_ir::Variance::Invariant, + ty::Variance::Contravariant => chalk_ir::Variance::Contravariant, + ty::Variance::Bivariant => unimplemented!(), + } + } +} + +impl<'tcx> LowerInto<'tcx, chalk_solve::rust_ir::AliasEqBound<RustInterner<'tcx>>> + for ty::ProjectionPredicate<'tcx> +{ + fn lower_into( + self, + interner: RustInterner<'tcx>, + ) -> chalk_solve::rust_ir::AliasEqBound<RustInterner<'tcx>> { + let (trait_ref, own_substs) = self.projection_ty.trait_ref_and_own_substs(interner.tcx); + chalk_solve::rust_ir::AliasEqBound { + trait_bound: trait_ref.lower_into(interner), + associated_ty_id: chalk_ir::AssocTypeId(self.projection_ty.item_def_id), + parameters: own_substs.iter().map(|arg| arg.lower_into(interner)).collect(), + value: self.term.ty().unwrap().lower_into(interner), + } + } +} + +/// To collect bound vars, we have to do two passes. In the first pass, we +/// collect all `BoundRegionKind`s and `ty::Bound`s. In the second pass, we then +/// replace `BrNamed` into `BrAnon`. The two separate passes are important, +/// since we can only replace `BrNamed` with `BrAnon`s with indices *after* all +/// "real" `BrAnon`s. +/// +/// It's important to note that because of prior substitution, we may have +/// late-bound regions, even outside of fn contexts, since this is the best way +/// to prep types for chalk lowering. +pub(crate) fn collect_bound_vars<'tcx, T: TypeFoldable<'tcx>>( + interner: RustInterner<'tcx>, + tcx: TyCtxt<'tcx>, + ty: Binder<'tcx, T>, +) -> (T, chalk_ir::VariableKinds<RustInterner<'tcx>>, BTreeMap<DefId, u32>) { + let mut bound_vars_collector = BoundVarsCollector::new(); + ty.as_ref().skip_binder().visit_with(&mut bound_vars_collector); + let mut parameters = bound_vars_collector.parameters; + let named_parameters: BTreeMap<DefId, u32> = bound_vars_collector + .named_parameters + .into_iter() + .enumerate() + .map(|(i, def_id)| (def_id, (i + parameters.len()) as u32)) + .collect(); + + let mut bound_var_substitutor = NamedBoundVarSubstitutor::new(tcx, &named_parameters); + let new_ty = ty.skip_binder().fold_with(&mut bound_var_substitutor); + + for var in named_parameters.values() { + parameters.insert(*var, chalk_ir::VariableKind::Lifetime); + } + + (0..parameters.len()).for_each(|i| { + parameters + .get(&(i as u32)) + .or_else(|| bug!("Skipped bound var index: parameters={:?}", parameters)); + }); + + let binders = + chalk_ir::VariableKinds::from_iter(interner, parameters.into_iter().map(|(_, v)| v)); + + (new_ty, binders, named_parameters) +} + +pub(crate) struct BoundVarsCollector<'tcx> { + binder_index: ty::DebruijnIndex, + pub(crate) parameters: BTreeMap<u32, chalk_ir::VariableKind<RustInterner<'tcx>>>, + pub(crate) named_parameters: Vec<DefId>, +} + +impl<'tcx> BoundVarsCollector<'tcx> { + pub(crate) fn new() -> Self { + BoundVarsCollector { + binder_index: ty::INNERMOST, + parameters: BTreeMap::new(), + named_parameters: vec![], + } + } +} + +impl<'tcx> TypeVisitor<'tcx> for BoundVarsCollector<'tcx> { + fn visit_binder<T: TypeVisitable<'tcx>>( + &mut self, + t: &Binder<'tcx, T>, + ) -> ControlFlow<Self::BreakTy> { + self.binder_index.shift_in(1); + let result = t.super_visit_with(self); + self.binder_index.shift_out(1); + result + } + + fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> { + match *t.kind() { + ty::Bound(debruijn, bound_ty) if debruijn == self.binder_index => { + match self.parameters.entry(bound_ty.var.as_u32()) { + Entry::Vacant(entry) => { + entry.insert(chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General)); + } + Entry::Occupied(entry) => match entry.get() { + chalk_ir::VariableKind::Ty(_) => {} + _ => panic!(), + }, + } + } + + _ => (), + }; + + t.super_visit_with(self) + } + + fn visit_region(&mut self, r: Region<'tcx>) -> ControlFlow<Self::BreakTy> { + match *r { + ty::ReLateBound(index, br) if index == self.binder_index => match br.kind { + ty::BoundRegionKind::BrNamed(def_id, _name) => { + if !self.named_parameters.iter().any(|d| *d == def_id) { + self.named_parameters.push(def_id); + } + } + + ty::BoundRegionKind::BrAnon(var) => match self.parameters.entry(var) { + Entry::Vacant(entry) => { + entry.insert(chalk_ir::VariableKind::Lifetime); + } + Entry::Occupied(entry) => match entry.get() { + chalk_ir::VariableKind::Lifetime => {} + _ => panic!(), + }, + }, + + ty::BoundRegionKind::BrEnv => unimplemented!(), + }, + + ty::ReEarlyBound(_re) => { + // FIXME(chalk): jackh726 - I think we should always have already + // substituted away `ReEarlyBound`s for `ReLateBound`s, but need to confirm. + unimplemented!(); + } + + _ => (), + }; + + r.super_visit_with(self) + } +} + +/// This is used to replace `BoundRegionKind::BrNamed` with `BoundRegionKind::BrAnon`. +/// Note: we assume that we will always have room for more bound vars. (i.e. we +/// won't ever hit the `u32` limit in `BrAnon`s). +struct NamedBoundVarSubstitutor<'a, 'tcx> { + tcx: TyCtxt<'tcx>, + binder_index: ty::DebruijnIndex, + named_parameters: &'a BTreeMap<DefId, u32>, +} + +impl<'a, 'tcx> NamedBoundVarSubstitutor<'a, 'tcx> { + fn new(tcx: TyCtxt<'tcx>, named_parameters: &'a BTreeMap<DefId, u32>) -> Self { + NamedBoundVarSubstitutor { tcx, binder_index: ty::INNERMOST, named_parameters } + } +} + +impl<'a, 'tcx> TypeFolder<'tcx> for NamedBoundVarSubstitutor<'a, 'tcx> { + fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { + self.tcx + } + + fn fold_binder<T: TypeFoldable<'tcx>>(&mut self, t: Binder<'tcx, T>) -> Binder<'tcx, T> { + self.binder_index.shift_in(1); + let result = t.super_fold_with(self); + self.binder_index.shift_out(1); + result + } + + fn fold_region(&mut self, r: Region<'tcx>) -> Region<'tcx> { + match *r { + ty::ReLateBound(index, br) if index == self.binder_index => match br.kind { + ty::BrNamed(def_id, _name) => match self.named_parameters.get(&def_id) { + Some(idx) => { + let new_br = ty::BoundRegion { var: br.var, kind: ty::BrAnon(*idx) }; + return self.tcx.mk_region(ty::ReLateBound(index, new_br)); + } + None => panic!("Missing `BrNamed`."), + }, + ty::BrEnv => unimplemented!(), + ty::BrAnon(_) => {} + }, + _ => (), + }; + + r.super_fold_with(self) + } +} + +/// Used to substitute `Param`s with placeholders. We do this since Chalk +/// have a notion of `Param`s. +pub(crate) struct ParamsSubstitutor<'tcx> { + tcx: TyCtxt<'tcx>, + binder_index: ty::DebruijnIndex, + list: Vec<rustc_middle::ty::ParamTy>, + next_ty_placeholder: usize, + pub(crate) params: rustc_data_structures::fx::FxHashMap<usize, rustc_middle::ty::ParamTy>, + pub(crate) named_regions: BTreeMap<DefId, u32>, +} + +impl<'tcx> ParamsSubstitutor<'tcx> { + pub(crate) fn new(tcx: TyCtxt<'tcx>, next_ty_placeholder: usize) -> Self { + ParamsSubstitutor { + tcx, + binder_index: ty::INNERMOST, + list: vec![], + next_ty_placeholder, + params: rustc_data_structures::fx::FxHashMap::default(), + named_regions: BTreeMap::default(), + } + } +} + +impl<'tcx> TypeFolder<'tcx> for ParamsSubstitutor<'tcx> { + fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { + self.tcx + } + + fn fold_binder<T: TypeFoldable<'tcx>>(&mut self, t: Binder<'tcx, T>) -> Binder<'tcx, T> { + self.binder_index.shift_in(1); + let result = t.super_fold_with(self); + self.binder_index.shift_out(1); + result + } + + fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { + match *t.kind() { + ty::Param(param) => match self.list.iter().position(|r| r == ¶m) { + Some(idx) => self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType { + universe: ty::UniverseIndex::from_usize(0), + name: ty::BoundVar::from_usize(idx), + })), + None => { + self.list.push(param); + let idx = self.list.len() - 1 + self.next_ty_placeholder; + self.params.insert(idx, param); + self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType { + universe: ty::UniverseIndex::from_usize(0), + name: ty::BoundVar::from_usize(idx), + })) + } + }, + _ => t.super_fold_with(self), + } + } + + fn fold_region(&mut self, r: Region<'tcx>) -> Region<'tcx> { + match *r { + // FIXME(chalk) - jackh726 - this currently isn't hit in any tests, + // since canonicalization will already change these to canonical + // variables (ty::ReLateBound). + ty::ReEarlyBound(_re) => match self.named_regions.get(&_re.def_id) { + Some(idx) => { + let br = ty::BoundRegion { + var: ty::BoundVar::from_u32(*idx), + kind: ty::BrAnon(*idx), + }; + self.tcx.mk_region(ty::ReLateBound(self.binder_index, br)) + } + None => { + let idx = self.named_regions.len() as u32; + let br = + ty::BoundRegion { var: ty::BoundVar::from_u32(idx), kind: ty::BrAnon(idx) }; + self.named_regions.insert(_re.def_id, idx); + self.tcx.mk_region(ty::ReLateBound(self.binder_index, br)) + } + }, + + _ => r.super_fold_with(self), + } + } +} + +pub(crate) struct ReverseParamsSubstitutor<'tcx> { + tcx: TyCtxt<'tcx>, + params: rustc_data_structures::fx::FxHashMap<usize, rustc_middle::ty::ParamTy>, +} + +impl<'tcx> ReverseParamsSubstitutor<'tcx> { + pub(crate) fn new( + tcx: TyCtxt<'tcx>, + params: rustc_data_structures::fx::FxHashMap<usize, rustc_middle::ty::ParamTy>, + ) -> Self { + Self { tcx, params } + } +} + +impl<'tcx> TypeFolder<'tcx> for ReverseParamsSubstitutor<'tcx> { + fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { + self.tcx + } + + fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { + match *t.kind() { + ty::Placeholder(ty::PlaceholderType { universe: ty::UniverseIndex::ROOT, name }) => { + match self.params.get(&name.as_usize()) { + Some(param) => self.tcx.mk_ty(ty::Param(*param)), + None => t, + } + } + + _ => t.super_fold_with(self), + } + } +} + +/// Used to collect `Placeholder`s. +pub(crate) struct PlaceholdersCollector { + universe_index: ty::UniverseIndex, + pub(crate) next_ty_placeholder: usize, + pub(crate) next_anon_region_placeholder: u32, +} + +impl PlaceholdersCollector { + pub(crate) fn new() -> Self { + PlaceholdersCollector { + universe_index: ty::UniverseIndex::ROOT, + next_ty_placeholder: 0, + next_anon_region_placeholder: 0, + } + } +} + +impl<'tcx> TypeVisitor<'tcx> for PlaceholdersCollector { + fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> { + match t.kind() { + ty::Placeholder(p) if p.universe == self.universe_index => { + self.next_ty_placeholder = self.next_ty_placeholder.max(p.name.as_usize() + 1); + } + + _ => (), + }; + + t.super_visit_with(self) + } + + fn visit_region(&mut self, r: Region<'tcx>) -> ControlFlow<Self::BreakTy> { + match *r { + ty::RePlaceholder(p) if p.universe == self.universe_index => { + if let ty::BoundRegionKind::BrAnon(anon) = p.name { + self.next_anon_region_placeholder = self.next_anon_region_placeholder.max(anon); + } + } + + _ => (), + }; + + r.super_visit_with(self) + } +} diff --git a/compiler/rustc_traits/src/chalk/mod.rs b/compiler/rustc_traits/src/chalk/mod.rs new file mode 100644 index 000000000..f76386fa7 --- /dev/null +++ b/compiler/rustc_traits/src/chalk/mod.rs @@ -0,0 +1,176 @@ +//! Calls `chalk-solve` to solve a `ty::Predicate` +//! +//! In order to call `chalk-solve`, this file must convert a `CanonicalChalkEnvironmentAndGoal` into +//! a Chalk uncanonical goal. It then calls Chalk, and converts the answer back into rustc solution. + +pub(crate) mod db; +pub(crate) mod lowering; + +use rustc_data_structures::fx::FxHashMap; + +use rustc_index::vec::IndexVec; + +use rustc_middle::infer::canonical::{CanonicalTyVarKind, CanonicalVarKind}; +use rustc_middle::traits::ChalkRustInterner; +use rustc_middle::ty::query::Providers; +use rustc_middle::ty::subst::GenericArg; +use rustc_middle::ty::{self, BoundVar, ParamTy, TyCtxt, TypeFoldable, TypeVisitable}; + +use rustc_infer::infer::canonical::{ + Canonical, CanonicalVarValues, Certainty, QueryRegionConstraints, QueryResponse, +}; +use rustc_infer::traits::{self, CanonicalChalkEnvironmentAndGoal}; + +use crate::chalk::db::RustIrDatabase as ChalkRustIrDatabase; +use crate::chalk::lowering::LowerInto; +use crate::chalk::lowering::{ParamsSubstitutor, PlaceholdersCollector, ReverseParamsSubstitutor}; + +use chalk_solve::Solution; + +pub(crate) fn provide(p: &mut Providers) { + *p = Providers { evaluate_goal, ..*p }; +} + +pub(crate) fn evaluate_goal<'tcx>( + tcx: TyCtxt<'tcx>, + obligation: CanonicalChalkEnvironmentAndGoal<'tcx>, +) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, ()>>, traits::query::NoSolution> { + let interner = ChalkRustInterner { tcx }; + + // Chalk doesn't have a notion of `Params`, so instead we use placeholders. + let mut placeholders_collector = PlaceholdersCollector::new(); + obligation.visit_with(&mut placeholders_collector); + + let mut params_substitutor = + ParamsSubstitutor::new(tcx, placeholders_collector.next_ty_placeholder); + let obligation = obligation.fold_with(&mut params_substitutor); + let params: FxHashMap<usize, ParamTy> = params_substitutor.params; + + let max_universe = obligation.max_universe.index(); + + let lowered_goal: chalk_ir::UCanonical< + chalk_ir::InEnvironment<chalk_ir::Goal<ChalkRustInterner<'tcx>>>, + > = chalk_ir::UCanonical { + canonical: chalk_ir::Canonical { + binders: chalk_ir::CanonicalVarKinds::from_iter( + interner, + obligation.variables.iter().map(|v| match v.kind { + CanonicalVarKind::PlaceholderTy(_ty) => unimplemented!(), + CanonicalVarKind::PlaceholderRegion(_ui) => unimplemented!(), + CanonicalVarKind::Ty(ty) => match ty { + CanonicalTyVarKind::General(ui) => chalk_ir::WithKind::new( + chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General), + chalk_ir::UniverseIndex { counter: ui.index() }, + ), + CanonicalTyVarKind::Int => chalk_ir::WithKind::new( + chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::Integer), + chalk_ir::UniverseIndex::root(), + ), + CanonicalTyVarKind::Float => chalk_ir::WithKind::new( + chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::Float), + chalk_ir::UniverseIndex::root(), + ), + }, + CanonicalVarKind::Region(ui) => chalk_ir::WithKind::new( + chalk_ir::VariableKind::Lifetime, + chalk_ir::UniverseIndex { counter: ui.index() }, + ), + CanonicalVarKind::Const(_ui, _ty) => unimplemented!(), + CanonicalVarKind::PlaceholderConst(_pc, _ty) => unimplemented!(), + }), + ), + value: obligation.value.lower_into(interner), + }, + universes: max_universe + 1, + }; + + use chalk_solve::Solver; + let mut solver = chalk_engine::solve::SLGSolver::new(32, None); + let db = ChalkRustIrDatabase { interner }; + debug!(?lowered_goal); + let solution = solver.solve(&db, &lowered_goal); + debug!(?obligation, ?solution, "evaluate goal"); + + // Ideally, the code to convert *back* to rustc types would live close to + // the code to convert *from* rustc types. Right now though, we don't + // really need this and so it's really minimal. + // Right now, we also treat a `Unique` solution the same as + // `Ambig(Definite)`. This really isn't right. + let make_solution = |subst: chalk_ir::Substitution<_>, + binders: chalk_ir::CanonicalVarKinds<_>| { + use rustc_middle::infer::canonical::CanonicalVarInfo; + + let mut var_values: IndexVec<BoundVar, GenericArg<'tcx>> = IndexVec::new(); + let mut reverse_param_substitutor = ReverseParamsSubstitutor::new(tcx, params); + subst.as_slice(interner).iter().for_each(|p| { + var_values.push(p.lower_into(interner).fold_with(&mut reverse_param_substitutor)); + }); + let variables: Vec<_> = binders + .iter(interner) + .map(|var| { + let kind = match var.kind { + chalk_ir::VariableKind::Ty(ty_kind) => CanonicalVarKind::Ty(match ty_kind { + chalk_ir::TyVariableKind::General => CanonicalTyVarKind::General( + ty::UniverseIndex::from_usize(var.skip_kind().counter), + ), + chalk_ir::TyVariableKind::Integer => CanonicalTyVarKind::Int, + chalk_ir::TyVariableKind::Float => CanonicalTyVarKind::Float, + }), + chalk_ir::VariableKind::Lifetime => CanonicalVarKind::Region( + ty::UniverseIndex::from_usize(var.skip_kind().counter), + ), + // FIXME(compiler-errors): We don't currently have a way of turning + // a Chalk ty back into a rustc ty, right? + chalk_ir::VariableKind::Const(_) => todo!(), + }; + CanonicalVarInfo { kind } + }) + .collect(); + let max_universe = binders.iter(interner).map(|v| v.skip_kind().counter).max().unwrap_or(0); + let sol = Canonical { + max_universe: ty::UniverseIndex::from_usize(max_universe), + variables: tcx.intern_canonical_var_infos(&variables), + value: QueryResponse { + var_values: CanonicalVarValues { var_values }, + region_constraints: QueryRegionConstraints::default(), + certainty: Certainty::Proven, + opaque_types: vec![], + value: (), + }, + }; + tcx.arena.alloc(sol) + }; + solution + .map(|s| match s { + Solution::Unique(subst) => { + // FIXME(chalk): handle constraints + make_solution(subst.value.subst, subst.binders) + } + Solution::Ambig(guidance) => { + match guidance { + chalk_solve::Guidance::Definite(subst) => { + make_solution(subst.value, subst.binders) + } + chalk_solve::Guidance::Suggested(_) => unimplemented!(), + chalk_solve::Guidance::Unknown => { + // chalk_fulfill doesn't use the var_values here, so + // let's just ignore that + let sol = Canonical { + max_universe: ty::UniverseIndex::from_usize(0), + variables: obligation.variables, + value: QueryResponse { + var_values: CanonicalVarValues { var_values: IndexVec::new() } + .make_identity(tcx), + region_constraints: QueryRegionConstraints::default(), + certainty: Certainty::Ambiguous, + opaque_types: vec![], + value: (), + }, + }; + &*tcx.arena.alloc(sol) + } + } + } + }) + .ok_or(traits::query::NoSolution) +} diff --git a/compiler/rustc_traits/src/dropck_outlives.rs b/compiler/rustc_traits/src/dropck_outlives.rs new file mode 100644 index 000000000..a20de08b4 --- /dev/null +++ b/compiler/rustc_traits/src/dropck_outlives.rs @@ -0,0 +1,348 @@ +use rustc_data_structures::fx::FxHashSet; +use rustc_hir::def_id::DefId; +use rustc_infer::infer::canonical::{Canonical, QueryResponse}; +use rustc_infer::infer::TyCtxtInferExt; +use rustc_infer::traits::TraitEngineExt as _; +use rustc_middle::ty::query::Providers; +use rustc_middle::ty::subst::{InternalSubsts, Subst}; +use rustc_middle::ty::{self, EarlyBinder, ParamEnvAnd, Ty, TyCtxt}; +use rustc_span::source_map::{Span, DUMMY_SP}; +use rustc_trait_selection::traits::query::dropck_outlives::trivial_dropck_outlives; +use rustc_trait_selection::traits::query::dropck_outlives::{ + DropckConstraint, DropckOutlivesResult, +}; +use rustc_trait_selection::traits::query::normalize::AtExt; +use rustc_trait_selection::traits::query::{CanonicalTyGoal, NoSolution}; +use rustc_trait_selection::traits::{ + Normalized, ObligationCause, TraitEngine, TraitEngineExt as _, +}; + +pub(crate) fn provide(p: &mut Providers) { + *p = Providers { dropck_outlives, adt_dtorck_constraint, ..*p }; +} + +fn dropck_outlives<'tcx>( + tcx: TyCtxt<'tcx>, + canonical_goal: CanonicalTyGoal<'tcx>, +) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, DropckOutlivesResult<'tcx>>>, NoSolution> { + debug!("dropck_outlives(goal={:#?})", canonical_goal); + + tcx.infer_ctxt().enter_with_canonical( + DUMMY_SP, + &canonical_goal, + |ref infcx, goal, canonical_inference_vars| { + let tcx = infcx.tcx; + let ParamEnvAnd { param_env, value: for_ty } = goal; + + let mut result = DropckOutlivesResult { kinds: vec![], overflows: vec![] }; + + // A stack of types left to process. Each round, we pop + // something from the stack and invoke + // `dtorck_constraint_for_ty`. This may produce new types that + // have to be pushed on the stack. This continues until we have explored + // all the reachable types from the type `for_ty`. + // + // Example: Imagine that we have the following code: + // + // ```rust + // struct A { + // value: B, + // children: Vec<A>, + // } + // + // struct B { + // value: u32 + // } + // + // fn f() { + // let a: A = ...; + // .. + // } // here, `a` is dropped + // ``` + // + // at the point where `a` is dropped, we need to figure out + // which types inside of `a` contain region data that may be + // accessed by any destructors in `a`. We begin by pushing `A` + // onto the stack, as that is the type of `a`. We will then + // invoke `dtorck_constraint_for_ty` which will expand `A` + // into the types of its fields `(B, Vec<A>)`. These will get + // pushed onto the stack. Eventually, expanding `Vec<A>` will + // lead to us trying to push `A` a second time -- to prevent + // infinite recursion, we notice that `A` was already pushed + // once and stop. + let mut ty_stack = vec![(for_ty, 0)]; + + // Set used to detect infinite recursion. + let mut ty_set = FxHashSet::default(); + + let mut fulfill_cx = <dyn TraitEngine<'_>>::new(infcx.tcx); + + let cause = ObligationCause::dummy(); + let mut constraints = DropckConstraint::empty(); + while let Some((ty, depth)) = ty_stack.pop() { + debug!( + "{} kinds, {} overflows, {} ty_stack", + result.kinds.len(), + result.overflows.len(), + ty_stack.len() + ); + dtorck_constraint_for_ty(tcx, DUMMY_SP, for_ty, depth, ty, &mut constraints)?; + + // "outlives" represent types/regions that may be touched + // by a destructor. + result.kinds.append(&mut constraints.outlives); + result.overflows.append(&mut constraints.overflows); + + // If we have even one overflow, we should stop trying to evaluate further -- + // chances are, the subsequent overflows for this evaluation won't provide useful + // information and will just decrease the speed at which we can emit these errors + // (since we'll be printing for just that much longer for the often enormous types + // that result here). + if !result.overflows.is_empty() { + break; + } + + // dtorck types are "types that will get dropped but which + // do not themselves define a destructor", more or less. We have + // to push them onto the stack to be expanded. + for ty in constraints.dtorck_types.drain(..) { + match infcx.at(&cause, param_env).normalize(ty) { + Ok(Normalized { value: ty, obligations }) => { + fulfill_cx.register_predicate_obligations(infcx, obligations); + + debug!("dropck_outlives: ty from dtorck_types = {:?}", ty); + + match ty.kind() { + // All parameters live for the duration of the + // function. + ty::Param(..) => {} + + // A projection that we couldn't resolve - it + // might have a destructor. + ty::Projection(..) | ty::Opaque(..) => { + result.kinds.push(ty.into()); + } + + _ => { + if ty_set.insert(ty) { + ty_stack.push((ty, depth + 1)); + } + } + } + } + + // We don't actually expect to fail to normalize. + // That implies a WF error somewhere else. + Err(NoSolution) => { + return Err(NoSolution); + } + } + } + } + + debug!("dropck_outlives: result = {:#?}", result); + + infcx.make_canonicalized_query_response( + canonical_inference_vars, + result, + &mut *fulfill_cx, + ) + }, + ) +} + +/// Returns a set of constraints that needs to be satisfied in +/// order for `ty` to be valid for destruction. +fn dtorck_constraint_for_ty<'tcx>( + tcx: TyCtxt<'tcx>, + span: Span, + for_ty: Ty<'tcx>, + depth: usize, + ty: Ty<'tcx>, + constraints: &mut DropckConstraint<'tcx>, +) -> Result<(), NoSolution> { + debug!("dtorck_constraint_for_ty({:?}, {:?}, {:?}, {:?})", span, for_ty, depth, ty); + + if !tcx.recursion_limit().value_within_limit(depth) { + constraints.overflows.push(ty); + return Ok(()); + } + + if trivial_dropck_outlives(tcx, ty) { + return Ok(()); + } + + match ty.kind() { + ty::Bool + | ty::Char + | ty::Int(_) + | ty::Uint(_) + | ty::Float(_) + | ty::Str + | ty::Never + | ty::Foreign(..) + | ty::RawPtr(..) + | ty::Ref(..) + | ty::FnDef(..) + | ty::FnPtr(_) + | ty::GeneratorWitness(..) => { + // these types never have a destructor + } + + ty::Array(ety, _) | ty::Slice(ety) => { + // single-element containers, behave like their element + rustc_data_structures::stack::ensure_sufficient_stack(|| { + dtorck_constraint_for_ty(tcx, span, for_ty, depth + 1, *ety, constraints) + })?; + } + + ty::Tuple(tys) => rustc_data_structures::stack::ensure_sufficient_stack(|| { + for ty in tys.iter() { + dtorck_constraint_for_ty(tcx, span, for_ty, depth + 1, ty, constraints)?; + } + Ok::<_, NoSolution>(()) + })?, + + ty::Closure(_, substs) => { + if !substs.as_closure().is_valid() { + // By the time this code runs, all type variables ought to + // be fully resolved. + + tcx.sess.delay_span_bug( + span, + &format!("upvar_tys for closure not found. Expected capture information for closure {}", ty,), + ); + return Err(NoSolution); + } + + rustc_data_structures::stack::ensure_sufficient_stack(|| { + for ty in substs.as_closure().upvar_tys() { + dtorck_constraint_for_ty(tcx, span, for_ty, depth + 1, ty, constraints)?; + } + Ok::<_, NoSolution>(()) + })? + } + + ty::Generator(_, substs, _movability) => { + // rust-lang/rust#49918: types can be constructed, stored + // in the interior, and sit idle when generator yields + // (and is subsequently dropped). + // + // It would be nice to descend into interior of a + // generator to determine what effects dropping it might + // have (by looking at any drop effects associated with + // its interior). + // + // However, the interior's representation uses things like + // GeneratorWitness that explicitly assume they are not + // traversed in such a manner. So instead, we will + // simplify things for now by treating all generators as + // if they were like trait objects, where its upvars must + // all be alive for the generator's (potential) + // destructor. + // + // In particular, skipping over `_interior` is safe + // because any side-effects from dropping `_interior` can + // only take place through references with lifetimes + // derived from lifetimes attached to the upvars and resume + // argument, and we *do* incorporate those here. + + if !substs.as_generator().is_valid() { + // By the time this code runs, all type variables ought to + // be fully resolved. + tcx.sess.delay_span_bug( + span, + &format!("upvar_tys for generator not found. Expected capture information for generator {}", ty,), + ); + return Err(NoSolution); + } + + constraints.outlives.extend( + substs + .as_generator() + .upvar_tys() + .map(|t| -> ty::subst::GenericArg<'tcx> { t.into() }), + ); + constraints.outlives.push(substs.as_generator().resume_ty().into()); + } + + ty::Adt(def, substs) => { + let DropckConstraint { dtorck_types, outlives, overflows } = + tcx.at(span).adt_dtorck_constraint(def.did())?; + // FIXME: we can try to recursively `dtorck_constraint_on_ty` + // there, but that needs some way to handle cycles. + constraints + .dtorck_types + .extend(dtorck_types.iter().map(|t| EarlyBinder(*t).subst(tcx, substs))); + constraints + .outlives + .extend(outlives.iter().map(|t| EarlyBinder(*t).subst(tcx, substs))); + constraints + .overflows + .extend(overflows.iter().map(|t| EarlyBinder(*t).subst(tcx, substs))); + } + + // Objects must be alive in order for their destructor + // to be called. + ty::Dynamic(..) => { + constraints.outlives.push(ty.into()); + } + + // Types that can't be resolved. Pass them forward. + ty::Projection(..) | ty::Opaque(..) | ty::Param(..) => { + constraints.dtorck_types.push(ty); + } + + ty::Placeholder(..) | ty::Bound(..) | ty::Infer(..) | ty::Error(_) => { + // By the time this code runs, all type variables ought to + // be fully resolved. + return Err(NoSolution); + } + } + + Ok(()) +} + +/// Calculates the dtorck constraint for a type. +pub(crate) fn adt_dtorck_constraint( + tcx: TyCtxt<'_>, + def_id: DefId, +) -> Result<&DropckConstraint<'_>, NoSolution> { + let def = tcx.adt_def(def_id); + let span = tcx.def_span(def_id); + debug!("dtorck_constraint: {:?}", def); + + if def.is_phantom_data() { + // The first generic parameter here is guaranteed to be a type because it's + // `PhantomData`. + let substs = InternalSubsts::identity_for_item(tcx, def_id); + assert_eq!(substs.len(), 1); + let result = DropckConstraint { + outlives: vec![], + dtorck_types: vec![substs.type_at(0)], + overflows: vec![], + }; + debug!("dtorck_constraint: {:?} => {:?}", def, result); + return Ok(tcx.arena.alloc(result)); + } + + let mut result = DropckConstraint::empty(); + for field in def.all_fields() { + let fty = tcx.type_of(field.did); + dtorck_constraint_for_ty(tcx, span, fty, 0, fty, &mut result)?; + } + result.outlives.extend(tcx.destructor_constraints(def)); + dedup_dtorck_constraint(&mut result); + + debug!("dtorck_constraint: {:?} => {:?}", def, result); + + Ok(tcx.arena.alloc(result)) +} + +fn dedup_dtorck_constraint(c: &mut DropckConstraint<'_>) { + let mut outlives = FxHashSet::default(); + let mut dtorck_types = FxHashSet::default(); + + c.outlives.retain(|&val| outlives.replace(val).is_none()); + c.dtorck_types.retain(|&val| dtorck_types.replace(val).is_none()); +} diff --git a/compiler/rustc_traits/src/evaluate_obligation.rs b/compiler/rustc_traits/src/evaluate_obligation.rs new file mode 100644 index 000000000..49c9ba459 --- /dev/null +++ b/compiler/rustc_traits/src/evaluate_obligation.rs @@ -0,0 +1,34 @@ +use rustc_infer::infer::{DefiningAnchor, TyCtxtInferExt}; +use rustc_middle::ty::query::Providers; +use rustc_middle::ty::{ParamEnvAnd, TyCtxt}; +use rustc_span::source_map::DUMMY_SP; +use rustc_trait_selection::traits::query::CanonicalPredicateGoal; +use rustc_trait_selection::traits::{ + EvaluationResult, Obligation, ObligationCause, OverflowError, SelectionContext, TraitQueryMode, +}; + +pub(crate) fn provide(p: &mut Providers) { + *p = Providers { evaluate_obligation, ..*p }; +} + +fn evaluate_obligation<'tcx>( + tcx: TyCtxt<'tcx>, + canonical_goal: CanonicalPredicateGoal<'tcx>, +) -> Result<EvaluationResult, OverflowError> { + debug!("evaluate_obligation(canonical_goal={:#?})", canonical_goal); + // HACK This bubble is required for this tests to pass: + // impl-trait/issue99642.rs + tcx.infer_ctxt().with_opaque_type_inference(DefiningAnchor::Bubble).enter_with_canonical( + DUMMY_SP, + &canonical_goal, + |ref infcx, goal, _canonical_inference_vars| { + debug!("evaluate_obligation: goal={:#?}", goal); + let ParamEnvAnd { param_env, value: predicate } = goal; + + let mut selcx = SelectionContext::with_query_mode(&infcx, TraitQueryMode::Canonical); + let obligation = Obligation::new(ObligationCause::dummy(), param_env, predicate); + + selcx.evaluate_root_obligation(&obligation) + }, + ) +} diff --git a/compiler/rustc_traits/src/implied_outlives_bounds.rs b/compiler/rustc_traits/src/implied_outlives_bounds.rs new file mode 100644 index 000000000..e3e78f70b --- /dev/null +++ b/compiler/rustc_traits/src/implied_outlives_bounds.rs @@ -0,0 +1,172 @@ +//! Provider for the `implied_outlives_bounds` query. +//! Do not call this query directory. See +//! [`rustc_trait_selection::traits::query::type_op::implied_outlives_bounds`]. + +use rustc_hir as hir; +use rustc_infer::infer::canonical::{self, Canonical}; +use rustc_infer::infer::outlives::components::{push_outlives_components, Component}; +use rustc_infer::infer::{InferCtxt, TyCtxtInferExt}; +use rustc_infer::traits::query::OutlivesBound; +use rustc_infer::traits::TraitEngineExt as _; +use rustc_middle::ty::query::Providers; +use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitable}; +use rustc_span::source_map::DUMMY_SP; +use rustc_trait_selection::infer::InferCtxtBuilderExt; +use rustc_trait_selection::traits::query::{CanonicalTyGoal, Fallible, NoSolution}; +use rustc_trait_selection::traits::wf; +use rustc_trait_selection::traits::{TraitEngine, TraitEngineExt}; +use smallvec::{smallvec, SmallVec}; + +pub(crate) fn provide(p: &mut Providers) { + *p = Providers { implied_outlives_bounds, ..*p }; +} + +fn implied_outlives_bounds<'tcx>( + tcx: TyCtxt<'tcx>, + goal: CanonicalTyGoal<'tcx>, +) -> Result< + &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, Vec<OutlivesBound<'tcx>>>>, + NoSolution, +> { + tcx.infer_ctxt().enter_canonical_trait_query(&goal, |infcx, _fulfill_cx, key| { + let (param_env, ty) = key.into_parts(); + compute_implied_outlives_bounds(&infcx, param_env, ty) + }) +} + +fn compute_implied_outlives_bounds<'tcx>( + infcx: &InferCtxt<'_, 'tcx>, + param_env: ty::ParamEnv<'tcx>, + ty: Ty<'tcx>, +) -> Fallible<Vec<OutlivesBound<'tcx>>> { + let tcx = infcx.tcx; + + // Sometimes when we ask what it takes for T: WF, we get back that + // U: WF is required; in that case, we push U onto this stack and + // process it next. Because the resulting predicates aren't always + // guaranteed to be a subset of the original type, so we need to store the + // WF args we've computed in a set. + let mut checked_wf_args = rustc_data_structures::fx::FxHashSet::default(); + let mut wf_args = vec![ty.into()]; + + let mut implied_bounds = vec![]; + + let mut fulfill_cx = <dyn TraitEngine<'tcx>>::new(tcx); + + while let Some(arg) = wf_args.pop() { + if !checked_wf_args.insert(arg) { + continue; + } + + // Compute the obligations for `arg` to be well-formed. If `arg` is + // an unresolved inference variable, just substituted an empty set + // -- because the return type here is going to be things we *add* + // to the environment, it's always ok for this set to be smaller + // than the ultimate set. (Note: normally there won't be + // unresolved inference variables here anyway, but there might be + // during typeck under some circumstances.) + let obligations = wf::obligations(infcx, param_env, hir::CRATE_HIR_ID, 0, arg, DUMMY_SP) + .unwrap_or_default(); + + // N.B., all of these predicates *ought* to be easily proven + // true. In fact, their correctness is (mostly) implied by + // other parts of the program. However, in #42552, we had + // an annoying scenario where: + // + // - Some `T::Foo` gets normalized, resulting in a + // variable `_1` and a `T: Trait<Foo=_1>` constraint + // (not sure why it couldn't immediately get + // solved). This result of `_1` got cached. + // - These obligations were dropped on the floor here, + // rather than being registered. + // - Then later we would get a request to normalize + // `T::Foo` which would result in `_1` being used from + // the cache, but hence without the `T: Trait<Foo=_1>` + // constraint. As a result, `_1` never gets resolved, + // and we get an ICE (in dropck). + // + // Therefore, we register any predicates involving + // inference variables. We restrict ourselves to those + // involving inference variables both for efficiency and + // to avoids duplicate errors that otherwise show up. + fulfill_cx.register_predicate_obligations( + infcx, + obligations.iter().filter(|o| o.predicate.has_infer_types_or_consts()).cloned(), + ); + + // From the full set of obligations, just filter down to the + // region relationships. + implied_bounds.extend(obligations.into_iter().flat_map(|obligation| { + assert!(!obligation.has_escaping_bound_vars()); + match obligation.predicate.kind().no_bound_vars() { + None => vec![], + Some(pred) => match pred { + ty::PredicateKind::Trait(..) + | ty::PredicateKind::Subtype(..) + | ty::PredicateKind::Coerce(..) + | ty::PredicateKind::Projection(..) + | ty::PredicateKind::ClosureKind(..) + | ty::PredicateKind::ObjectSafe(..) + | ty::PredicateKind::ConstEvaluatable(..) + | ty::PredicateKind::ConstEquate(..) + | ty::PredicateKind::TypeWellFormedFromEnv(..) => vec![], + ty::PredicateKind::WellFormed(arg) => { + wf_args.push(arg); + vec![] + } + + ty::PredicateKind::RegionOutlives(ty::OutlivesPredicate(r_a, r_b)) => { + vec![OutlivesBound::RegionSubRegion(r_b, r_a)] + } + + ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(ty_a, r_b)) => { + let ty_a = infcx.resolve_vars_if_possible(ty_a); + let mut components = smallvec![]; + push_outlives_components(tcx, ty_a, &mut components); + implied_bounds_from_components(r_b, components) + } + }, + } + })); + } + + // Ensure that those obligations that we had to solve + // get solved *here*. + match fulfill_cx.select_all_or_error(infcx).as_slice() { + [] => Ok(implied_bounds), + _ => Err(NoSolution), + } +} + +/// When we have an implied bound that `T: 'a`, we can further break +/// this down to determine what relationships would have to hold for +/// `T: 'a` to hold. We get to assume that the caller has validated +/// those relationships. +fn implied_bounds_from_components<'tcx>( + sub_region: ty::Region<'tcx>, + sup_components: SmallVec<[Component<'tcx>; 4]>, +) -> Vec<OutlivesBound<'tcx>> { + sup_components + .into_iter() + .filter_map(|component| { + match component { + Component::Region(r) => Some(OutlivesBound::RegionSubRegion(sub_region, r)), + Component::Param(p) => Some(OutlivesBound::RegionSubParam(sub_region, p)), + Component::Projection(p) => Some(OutlivesBound::RegionSubProjection(sub_region, p)), + Component::EscapingProjection(_) => + // If the projection has escaping regions, don't + // try to infer any implied bounds even for its + // free components. This is conservative, because + // the caller will still have to prove that those + // free components outlive `sub_region`. But the + // idea is that the WAY that the caller proves + // that may change in the future and we want to + // give ourselves room to get smarter here. + { + None + } + Component::UnresolvedInferenceVariable(..) => None, + } + }) + .collect() +} diff --git a/compiler/rustc_traits/src/lib.rs b/compiler/rustc_traits/src/lib.rs new file mode 100644 index 000000000..2bea164c0 --- /dev/null +++ b/compiler/rustc_traits/src/lib.rs @@ -0,0 +1,32 @@ +//! New recursive solver modeled on Chalk's recursive solver. Most of +//! the guts are broken up into modules; see the comments in those modules. + +#![feature(let_else)] +#![recursion_limit = "256"] + +#[macro_use] +extern crate tracing; +#[macro_use] +extern crate rustc_middle; + +mod chalk; +mod dropck_outlives; +mod evaluate_obligation; +mod implied_outlives_bounds; +mod normalize_erasing_regions; +mod normalize_projection_ty; +mod type_op; + +pub use type_op::{type_op_ascribe_user_type_with_span, type_op_prove_predicate_with_cause}; + +use rustc_middle::ty::query::Providers; + +pub fn provide(p: &mut Providers) { + dropck_outlives::provide(p); + evaluate_obligation::provide(p); + implied_outlives_bounds::provide(p); + chalk::provide(p); + normalize_projection_ty::provide(p); + normalize_erasing_regions::provide(p); + type_op::provide(p); +} diff --git a/compiler/rustc_traits/src/normalize_erasing_regions.rs b/compiler/rustc_traits/src/normalize_erasing_regions.rs new file mode 100644 index 000000000..5d394ed22 --- /dev/null +++ b/compiler/rustc_traits/src/normalize_erasing_regions.rs @@ -0,0 +1,73 @@ +use rustc_infer::infer::TyCtxtInferExt; +use rustc_middle::traits::query::NoSolution; +use rustc_middle::ty::query::Providers; +use rustc_middle::ty::{self, ParamEnvAnd, TyCtxt, TypeFoldable}; +use rustc_trait_selection::traits::query::normalize::AtExt; +use rustc_trait_selection::traits::{Normalized, ObligationCause}; +use std::sync::atomic::Ordering; + +pub(crate) fn provide(p: &mut Providers) { + *p = Providers { + try_normalize_generic_arg_after_erasing_regions: |tcx, goal| { + debug!("try_normalize_generic_arg_after_erasing_regions(goal={:#?}", goal); + + tcx.sess + .perf_stats + .normalize_generic_arg_after_erasing_regions + .fetch_add(1, Ordering::Relaxed); + + try_normalize_after_erasing_regions(tcx, goal) + }, + try_normalize_mir_const_after_erasing_regions: |tcx, goal| { + try_normalize_after_erasing_regions(tcx, goal) + }, + ..*p + }; +} + +fn try_normalize_after_erasing_regions<'tcx, T: TypeFoldable<'tcx> + PartialEq + Copy>( + tcx: TyCtxt<'tcx>, + goal: ParamEnvAnd<'tcx, T>, +) -> Result<T, NoSolution> { + let ParamEnvAnd { param_env, value } = goal; + tcx.infer_ctxt().enter(|infcx| { + let cause = ObligationCause::dummy(); + match infcx.at(&cause, param_env).normalize(value) { + Ok(Normalized { value: normalized_value, obligations: normalized_obligations }) => { + // We don't care about the `obligations`; they are + // always only region relations, and we are about to + // erase those anyway: + debug_assert_eq!( + normalized_obligations.iter().find(|p| not_outlives_predicate(p.predicate)), + None, + ); + + let resolved_value = infcx.resolve_vars_if_possible(normalized_value); + // It's unclear when `resolve_vars` would have an effect in a + // fresh `InferCtxt`. If this assert does trigger, it will give + // us a test case. + debug_assert_eq!(normalized_value, resolved_value); + let erased = infcx.tcx.erase_regions(resolved_value); + debug_assert!(!erased.needs_infer(), "{:?}", erased); + Ok(erased) + } + Err(NoSolution) => Err(NoSolution), + } + }) +} + +fn not_outlives_predicate<'tcx>(p: ty::Predicate<'tcx>) -> bool { + match p.kind().skip_binder() { + ty::PredicateKind::RegionOutlives(..) | ty::PredicateKind::TypeOutlives(..) => false, + ty::PredicateKind::Trait(..) + | ty::PredicateKind::Projection(..) + | ty::PredicateKind::WellFormed(..) + | ty::PredicateKind::ObjectSafe(..) + | ty::PredicateKind::ClosureKind(..) + | ty::PredicateKind::Subtype(..) + | ty::PredicateKind::Coerce(..) + | ty::PredicateKind::ConstEvaluatable(..) + | ty::PredicateKind::ConstEquate(..) + | ty::PredicateKind::TypeWellFormedFromEnv(..) => true, + } +} diff --git a/compiler/rustc_traits/src/normalize_projection_ty.rs b/compiler/rustc_traits/src/normalize_projection_ty.rs new file mode 100644 index 000000000..98bb42c9a --- /dev/null +++ b/compiler/rustc_traits/src/normalize_projection_ty.rs @@ -0,0 +1,45 @@ +use rustc_infer::infer::canonical::{Canonical, QueryResponse}; +use rustc_infer::infer::TyCtxtInferExt; +use rustc_infer::traits::TraitEngineExt as _; +use rustc_middle::ty::query::Providers; +use rustc_middle::ty::{ParamEnvAnd, TyCtxt}; +use rustc_trait_selection::infer::InferCtxtBuilderExt; +use rustc_trait_selection::traits::query::{ + normalize::NormalizationResult, CanonicalProjectionGoal, NoSolution, +}; +use rustc_trait_selection::traits::{self, ObligationCause, SelectionContext}; +use std::sync::atomic::Ordering; + +pub(crate) fn provide(p: &mut Providers) { + *p = Providers { normalize_projection_ty, ..*p }; +} + +fn normalize_projection_ty<'tcx>( + tcx: TyCtxt<'tcx>, + goal: CanonicalProjectionGoal<'tcx>, +) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, NormalizationResult<'tcx>>>, NoSolution> { + debug!("normalize_provider(goal={:#?})", goal); + + tcx.sess.perf_stats.normalize_projection_ty.fetch_add(1, Ordering::Relaxed); + tcx.infer_ctxt().enter_canonical_trait_query( + &goal, + |infcx, fulfill_cx, ParamEnvAnd { param_env, value: goal }| { + let selcx = &mut SelectionContext::new(infcx); + let cause = ObligationCause::dummy(); + let mut obligations = vec![]; + let answer = traits::normalize_projection_type( + selcx, + param_env, + goal, + cause, + 0, + &mut obligations, + ); + fulfill_cx.register_predicate_obligations(infcx, obligations); + // FIXME(associated_const_equality): All users of normalize_projection_ty expected + // a type, but there is the possibility it could've been a const now. Maybe change + // it to a Term later? + Ok(NormalizationResult { normalized_ty: answer.ty().unwrap() }) + }, + ) +} diff --git a/compiler/rustc_traits/src/type_op.rs b/compiler/rustc_traits/src/type_op.rs new file mode 100644 index 000000000..d895b647d --- /dev/null +++ b/compiler/rustc_traits/src/type_op.rs @@ -0,0 +1,283 @@ +use rustc_hir as hir; +use rustc_hir::def_id::DefId; +use rustc_infer::infer::at::ToTrace; +use rustc_infer::infer::canonical::{Canonical, QueryResponse}; +use rustc_infer::infer::{DefiningAnchor, InferCtxt, TyCtxtInferExt}; +use rustc_infer::traits::TraitEngineExt as _; +use rustc_middle::ty::query::Providers; +use rustc_middle::ty::subst::{GenericArg, Subst, UserSelfTy, UserSubsts}; +use rustc_middle::ty::{ + self, EarlyBinder, FnSig, Lift, PolyFnSig, Ty, TyCtxt, TypeFoldable, Variance, +}; +use rustc_middle::ty::{ParamEnv, ParamEnvAnd, Predicate, ToPredicate}; +use rustc_span::{Span, DUMMY_SP}; +use rustc_trait_selection::infer::InferCtxtBuilderExt; +use rustc_trait_selection::infer::InferCtxtExt; +use rustc_trait_selection::traits::query::normalize::AtExt; +use rustc_trait_selection::traits::query::type_op::ascribe_user_type::AscribeUserType; +use rustc_trait_selection::traits::query::type_op::eq::Eq; +use rustc_trait_selection::traits::query::type_op::normalize::Normalize; +use rustc_trait_selection::traits::query::type_op::prove_predicate::ProvePredicate; +use rustc_trait_selection::traits::query::type_op::subtype::Subtype; +use rustc_trait_selection::traits::query::{Fallible, NoSolution}; +use rustc_trait_selection::traits::{Normalized, Obligation, ObligationCause, TraitEngine}; +use std::fmt; + +pub(crate) fn provide(p: &mut Providers) { + *p = Providers { + type_op_ascribe_user_type, + type_op_eq, + type_op_prove_predicate, + type_op_subtype, + type_op_normalize_ty, + type_op_normalize_predicate, + type_op_normalize_fn_sig, + type_op_normalize_poly_fn_sig, + ..*p + }; +} + +fn type_op_ascribe_user_type<'tcx>( + tcx: TyCtxt<'tcx>, + canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, AscribeUserType<'tcx>>>, +) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, ()>>, NoSolution> { + tcx.infer_ctxt().enter_canonical_trait_query(&canonicalized, |infcx, fulfill_cx, key| { + type_op_ascribe_user_type_with_span(infcx, fulfill_cx, key, None) + }) +} + +/// The core of the `type_op_ascribe_user_type` query: for diagnostics purposes in NLL HRTB errors, +/// this query can be re-run to better track the span of the obligation cause, and improve the error +/// message. Do not call directly unless you're in that very specific context. +pub fn type_op_ascribe_user_type_with_span<'a, 'tcx: 'a>( + infcx: &'a InferCtxt<'a, 'tcx>, + fulfill_cx: &'a mut dyn TraitEngine<'tcx>, + key: ParamEnvAnd<'tcx, AscribeUserType<'tcx>>, + span: Option<Span>, +) -> Result<(), NoSolution> { + let (param_env, AscribeUserType { mir_ty, def_id, user_substs }) = key.into_parts(); + debug!( + "type_op_ascribe_user_type: mir_ty={:?} def_id={:?} user_substs={:?}", + mir_ty, def_id, user_substs + ); + + let mut cx = AscribeUserTypeCx { infcx, param_env, fulfill_cx }; + cx.relate_mir_and_user_ty(mir_ty, def_id, user_substs, span)?; + Ok(()) +} + +struct AscribeUserTypeCx<'me, 'tcx> { + infcx: &'me InferCtxt<'me, 'tcx>, + param_env: ParamEnv<'tcx>, + fulfill_cx: &'me mut dyn TraitEngine<'tcx>, +} + +impl<'me, 'tcx> AscribeUserTypeCx<'me, 'tcx> { + fn normalize<T>(&mut self, value: T) -> T + where + T: TypeFoldable<'tcx>, + { + self.infcx + .partially_normalize_associated_types_in( + ObligationCause::misc(DUMMY_SP, hir::CRATE_HIR_ID), + self.param_env, + value, + ) + .into_value_registering_obligations(self.infcx, self.fulfill_cx) + } + + fn relate<T>(&mut self, a: T, variance: Variance, b: T) -> Result<(), NoSolution> + where + T: ToTrace<'tcx>, + { + self.infcx + .at(&ObligationCause::dummy(), self.param_env) + .relate(a, variance, b)? + .into_value_registering_obligations(self.infcx, self.fulfill_cx); + Ok(()) + } + + fn prove_predicate(&mut self, predicate: Predicate<'tcx>, span: Option<Span>) { + let cause = if let Some(span) = span { + ObligationCause::dummy_with_span(span) + } else { + ObligationCause::dummy() + }; + self.fulfill_cx.register_predicate_obligation( + self.infcx, + Obligation::new(cause, self.param_env, predicate), + ); + } + + fn tcx(&self) -> TyCtxt<'tcx> { + self.infcx.tcx + } + + fn subst<T>(&self, value: T, substs: &[GenericArg<'tcx>]) -> T + where + T: TypeFoldable<'tcx>, + { + EarlyBinder(value).subst(self.tcx(), substs) + } + + fn relate_mir_and_user_ty( + &mut self, + mir_ty: Ty<'tcx>, + def_id: DefId, + user_substs: UserSubsts<'tcx>, + span: Option<Span>, + ) -> Result<(), NoSolution> { + let UserSubsts { user_self_ty, substs } = user_substs; + let tcx = self.tcx(); + + let ty = tcx.type_of(def_id); + let ty = self.subst(ty, substs); + debug!("relate_type_and_user_type: ty of def-id is {:?}", ty); + let ty = self.normalize(ty); + + self.relate(mir_ty, Variance::Invariant, ty)?; + + // Prove the predicates coming along with `def_id`. + // + // Also, normalize the `instantiated_predicates` + // because otherwise we wind up with duplicate "type + // outlives" error messages. + let instantiated_predicates = + self.tcx().predicates_of(def_id).instantiate(self.tcx(), substs); + debug!(?instantiated_predicates.predicates); + for instantiated_predicate in instantiated_predicates.predicates { + let instantiated_predicate = self.normalize(instantiated_predicate); + self.prove_predicate(instantiated_predicate, span); + } + + if let Some(UserSelfTy { impl_def_id, self_ty }) = user_self_ty { + let impl_self_ty = self.tcx().type_of(impl_def_id); + let impl_self_ty = self.subst(impl_self_ty, &substs); + let impl_self_ty = self.normalize(impl_self_ty); + + self.relate(self_ty, Variance::Invariant, impl_self_ty)?; + + self.prove_predicate( + ty::Binder::dummy(ty::PredicateKind::WellFormed(impl_self_ty.into())) + .to_predicate(self.tcx()), + span, + ); + } + + // In addition to proving the predicates, we have to + // prove that `ty` is well-formed -- this is because + // the WF of `ty` is predicated on the substs being + // well-formed, and we haven't proven *that*. We don't + // want to prove the WF of types from `substs` directly because they + // haven't been normalized. + // + // FIXME(nmatsakis): Well, perhaps we should normalize + // them? This would only be relevant if some input + // type were ill-formed but did not appear in `ty`, + // which...could happen with normalization... + self.prove_predicate( + ty::Binder::dummy(ty::PredicateKind::WellFormed(ty.into())).to_predicate(self.tcx()), + span, + ); + Ok(()) + } +} + +fn type_op_eq<'tcx>( + tcx: TyCtxt<'tcx>, + canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, Eq<'tcx>>>, +) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, ()>>, NoSolution> { + tcx.infer_ctxt().enter_canonical_trait_query(&canonicalized, |infcx, fulfill_cx, key| { + let (param_env, Eq { a, b }) = key.into_parts(); + infcx + .at(&ObligationCause::dummy(), param_env) + .eq(a, b)? + .into_value_registering_obligations(infcx, fulfill_cx); + Ok(()) + }) +} + +fn type_op_normalize<'tcx, T>( + infcx: &InferCtxt<'_, 'tcx>, + fulfill_cx: &mut dyn TraitEngine<'tcx>, + key: ParamEnvAnd<'tcx, Normalize<T>>, +) -> Fallible<T> +where + T: fmt::Debug + TypeFoldable<'tcx> + Lift<'tcx>, +{ + let (param_env, Normalize { value }) = key.into_parts(); + let Normalized { value, obligations } = + infcx.at(&ObligationCause::dummy(), param_env).normalize(value)?; + fulfill_cx.register_predicate_obligations(infcx, obligations); + Ok(value) +} + +fn type_op_normalize_ty<'tcx>( + tcx: TyCtxt<'tcx>, + canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, Normalize<Ty<'tcx>>>>, +) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>, NoSolution> { + tcx.infer_ctxt().enter_canonical_trait_query(&canonicalized, type_op_normalize) +} + +fn type_op_normalize_predicate<'tcx>( + tcx: TyCtxt<'tcx>, + canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, Normalize<Predicate<'tcx>>>>, +) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, Predicate<'tcx>>>, NoSolution> { + tcx.infer_ctxt().enter_canonical_trait_query(&canonicalized, type_op_normalize) +} + +fn type_op_normalize_fn_sig<'tcx>( + tcx: TyCtxt<'tcx>, + canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, Normalize<FnSig<'tcx>>>>, +) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, FnSig<'tcx>>>, NoSolution> { + tcx.infer_ctxt().enter_canonical_trait_query(&canonicalized, type_op_normalize) +} + +fn type_op_normalize_poly_fn_sig<'tcx>( + tcx: TyCtxt<'tcx>, + canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, Normalize<PolyFnSig<'tcx>>>>, +) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, PolyFnSig<'tcx>>>, NoSolution> { + tcx.infer_ctxt().enter_canonical_trait_query(&canonicalized, type_op_normalize) +} + +fn type_op_subtype<'tcx>( + tcx: TyCtxt<'tcx>, + canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, Subtype<'tcx>>>, +) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, ()>>, NoSolution> { + tcx.infer_ctxt().enter_canonical_trait_query(&canonicalized, |infcx, fulfill_cx, key| { + let (param_env, Subtype { sub, sup }) = key.into_parts(); + infcx + .at(&ObligationCause::dummy(), param_env) + .sup(sup, sub)? + .into_value_registering_obligations(infcx, fulfill_cx); + Ok(()) + }) +} + +fn type_op_prove_predicate<'tcx>( + tcx: TyCtxt<'tcx>, + canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, ProvePredicate<'tcx>>>, +) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, ()>>, NoSolution> { + // HACK This bubble is required for this test to pass: + // impl-trait/issue-99642.rs + tcx.infer_ctxt().with_opaque_type_inference(DefiningAnchor::Bubble).enter_canonical_trait_query( + &canonicalized, + |infcx, fulfill_cx, key| { + type_op_prove_predicate_with_cause(infcx, fulfill_cx, key, ObligationCause::dummy()); + Ok(()) + }, + ) +} + +/// The core of the `type_op_prove_predicate` query: for diagnostics purposes in NLL HRTB errors, +/// this query can be re-run to better track the span of the obligation cause, and improve the error +/// message. Do not call directly unless you're in that very specific context. +pub fn type_op_prove_predicate_with_cause<'a, 'tcx: 'a>( + infcx: &'a InferCtxt<'a, 'tcx>, + fulfill_cx: &'a mut dyn TraitEngine<'tcx>, + key: ParamEnvAnd<'tcx, ProvePredicate<'tcx>>, + cause: ObligationCause<'tcx>, +) { + let (param_env, ProvePredicate { predicate }) = key.into_parts(); + fulfill_cx.register_predicate_obligation(infcx, Obligation::new(cause, param_env, predicate)); +} |