From 2955fbc7e1e49b96565505bf599e950b11d370ac Mon Sep 17 00:00:00 2001 From: Florian Diebold Date: Sat, 12 Oct 2019 17:39:20 +0200 Subject: Split up infer.rs further - coercion logic goes to `coerce.rs` - expression inference goes to `expr.rs` - pattern inference goes to `pat.rs` --- crates/ra_hir/src/ty/infer.rs | 1153 +--------------------------------- crates/ra_hir/src/ty/infer/coerce.rs | 336 ++++++++++ crates/ra_hir/src/ty/infer/expr.rs | 658 +++++++++++++++++++ crates/ra_hir/src/ty/infer/pat.rs | 180 ++++++ 4 files changed, 1192 insertions(+), 1135 deletions(-) create mode 100644 crates/ra_hir/src/ty/infer/coerce.rs create mode 100644 crates/ra_hir/src/ty/infer/expr.rs create mode 100644 crates/ra_hir/src/ty/infer/pat.rs (limited to 'crates/ra_hir/src') diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs index a69f04ff1..cb28fc6bc 100644 --- a/crates/ra_hir/src/ty/infer.rs +++ b/crates/ra_hir/src/ty/infer.rs @@ -14,7 +14,6 @@ //! the `ena` crate, which is extracted from rustc. use std::borrow::Cow; -use std::iter::{repeat, repeat_with}; use std::mem; use std::ops::Index; use std::sync::Arc; @@ -27,33 +26,39 @@ use ra_prof::profile; use test_utils::tested_by; use super::{ - autoderef, lower, method_resolution, op, primitive, + lower, primitive, traits::{Guidance, Obligation, ProjectionPredicate, Solution}, - ApplicationTy, CallableDef, InEnvironment, ProjectionTy, Substs, TraitEnvironment, TraitRef, - Ty, TypableDef, TypeCtor, TypeWalk, + ApplicationTy, InEnvironment, ProjectionTy, Substs, TraitEnvironment, TraitRef, Ty, TypableDef, + TypeCtor, TypeWalk, }; use crate::{ adt::VariantDef, code_model::TypeAlias, db::HirDatabase, diagnostics::DiagnosticSink, - expr::{ - self, Array, BinaryOp, BindingAnnotation, Body, Expr, ExprId, Literal, Pat, PatId, - RecordFieldPat, Statement, UnaryOp, - }, - generics::{GenericParams, HasGenericParams}, - lang_item::LangItemTarget, + expr::{BindingAnnotation, Body, ExprId, PatId}, name, - nameres::Namespace, - path::{known, GenericArg, GenericArgs}, + path::known, resolve::{Resolver, TypeNs}, ty::infer::diagnostics::InferenceDiagnostic, type_ref::{Mutability, TypeRef}, - Adt, AssocItem, ConstData, DefWithBody, FnData, Function, HasBody, Name, Path, StructField, + Adt, AssocItem, ConstData, DefWithBody, FnData, Function, HasBody, Path, StructField, }; +macro_rules! ty_app { + ($ctor:pat, $param:pat) => { + crate::ty::Ty::Apply(crate::ty::ApplicationTy { ctor: $ctor, parameters: $param }) + }; + ($ctor:pat) => { + ty_app!($ctor, _) + }; +} + mod unify; mod path; +mod expr; +mod pat; +mod coerce; /// The entry point of type inference. pub fn infer_query(db: &impl HirDatabase, def: DefWithBody) -> Arc { @@ -197,15 +202,6 @@ struct InferenceContext<'a, D: HirDatabase> { coerce_unsized_map: FxHashMap<(TypeCtor, TypeCtor), usize>, } -macro_rules! ty_app { - ($ctor:pat, $param:pat) => { - Ty::Apply(ApplicationTy { ctor: $ctor, parameters: $param }) - }; - ($ctor:pat) => { - ty_app!($ctor, _) - }; -} - impl<'a, D: HirDatabase> InferenceContext<'a, D> { fn new(db: &'a D, body: Arc, resolver: Resolver) -> Self { InferenceContext { @@ -221,45 +217,6 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> { } } - fn init_coerce_unsized_map( - db: &'a D, - resolver: &Resolver, - ) -> FxHashMap<(TypeCtor, TypeCtor), usize> { - let krate = resolver.krate().unwrap(); - let impls = match db.lang_item(krate, "coerce_unsized".into()) { - Some(LangItemTarget::Trait(trait_)) => db.impls_for_trait(krate, trait_), - _ => return FxHashMap::default(), - }; - - impls - .iter() - .filter_map(|impl_block| { - // `CoerseUnsized` has one generic parameter for the target type. - let trait_ref = impl_block.target_trait_ref(db)?; - let cur_from_ty = trait_ref.substs.0.get(0)?; - let cur_to_ty = trait_ref.substs.0.get(1)?; - - match (&cur_from_ty, cur_to_ty) { - (ty_app!(ctor1, st1), ty_app!(ctor2, st2)) => { - // FIXME: We return the first non-equal bound as the type parameter to coerce to unsized type. - // This works for smart-pointer-like coercion, which covers all impls from std. - st1.iter().zip(st2.iter()).enumerate().find_map(|(i, (ty1, ty2))| { - match (ty1, ty2) { - (Ty::Param { idx: p1, .. }, Ty::Param { idx: p2, .. }) - if p1 != p2 => - { - Some(((*ctor1, *ctor2), i)) - } - _ => None, - } - }) - } - _ => None, - } - }) - .collect() - } - fn resolve_all(mut self) -> InferenceResult { // FIXME resolve obligations as well (use Guidance if necessary) let mut result = mem::replace(&mut self.result, InferenceResult::default()); @@ -595,1080 +552,6 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> { } } - fn infer_tuple_struct_pat( - &mut self, - path: Option<&Path>, - subpats: &[PatId], - expected: &Ty, - default_bm: BindingMode, - ) -> Ty { - let (ty, def) = self.resolve_variant(path); - - self.unify(&ty, expected); - - let substs = ty.substs().unwrap_or_else(Substs::empty); - - for (i, &subpat) in subpats.iter().enumerate() { - let expected_ty = def - .and_then(|d| d.field(self.db, &Name::new_tuple_field(i))) - .map_or(Ty::Unknown, |field| field.ty(self.db)) - .subst(&substs); - let expected_ty = self.normalize_associated_types_in(expected_ty); - self.infer_pat(subpat, &expected_ty, default_bm); - } - - ty - } - - fn infer_record_pat( - &mut self, - path: Option<&Path>, - subpats: &[RecordFieldPat], - expected: &Ty, - default_bm: BindingMode, - id: PatId, - ) -> Ty { - let (ty, def) = self.resolve_variant(path); - if let Some(variant) = def { - self.write_variant_resolution(id.into(), variant); - } - - self.unify(&ty, expected); - - let substs = ty.substs().unwrap_or_else(Substs::empty); - - for subpat in subpats { - let matching_field = def.and_then(|it| it.field(self.db, &subpat.name)); - let expected_ty = - matching_field.map_or(Ty::Unknown, |field| field.ty(self.db)).subst(&substs); - let expected_ty = self.normalize_associated_types_in(expected_ty); - self.infer_pat(subpat.pat, &expected_ty, default_bm); - } - - ty - } - - fn infer_pat(&mut self, pat: PatId, mut expected: &Ty, mut default_bm: BindingMode) -> Ty { - let body = Arc::clone(&self.body); // avoid borrow checker problem - - let is_non_ref_pat = match &body[pat] { - Pat::Tuple(..) - | Pat::TupleStruct { .. } - | Pat::Record { .. } - | Pat::Range { .. } - | Pat::Slice { .. } => true, - // FIXME: Path/Lit might actually evaluate to ref, but inference is unimplemented. - Pat::Path(..) | Pat::Lit(..) => true, - Pat::Wild | Pat::Bind { .. } | Pat::Ref { .. } | Pat::Missing => false, - }; - if is_non_ref_pat { - while let Some((inner, mutability)) = expected.as_reference() { - expected = inner; - default_bm = match default_bm { - BindingMode::Move => BindingMode::Ref(mutability), - BindingMode::Ref(Mutability::Shared) => BindingMode::Ref(Mutability::Shared), - BindingMode::Ref(Mutability::Mut) => BindingMode::Ref(mutability), - } - } - } else if let Pat::Ref { .. } = &body[pat] { - tested_by!(match_ergonomics_ref); - // When you encounter a `&pat` pattern, reset to Move. - // This is so that `w` is by value: `let (_, &w) = &(1, &2);` - default_bm = BindingMode::Move; - } - - // Lose mutability. - let default_bm = default_bm; - let expected = expected; - - let ty = match &body[pat] { - Pat::Tuple(ref args) => { - let expectations = match expected.as_tuple() { - Some(parameters) => &*parameters.0, - _ => &[], - }; - let expectations_iter = expectations.iter().chain(repeat(&Ty::Unknown)); - - let inner_tys = args - .iter() - .zip(expectations_iter) - .map(|(&pat, ty)| self.infer_pat(pat, ty, default_bm)) - .collect(); - - Ty::apply(TypeCtor::Tuple { cardinality: args.len() as u16 }, Substs(inner_tys)) - } - Pat::Ref { pat, mutability } => { - let expectation = match expected.as_reference() { - Some((inner_ty, exp_mut)) => { - if *mutability != exp_mut { - // FIXME: emit type error? - } - inner_ty - } - _ => &Ty::Unknown, - }; - let subty = self.infer_pat(*pat, expectation, default_bm); - Ty::apply_one(TypeCtor::Ref(*mutability), subty) - } - Pat::TupleStruct { path: p, args: subpats } => { - self.infer_tuple_struct_pat(p.as_ref(), subpats, expected, default_bm) - } - Pat::Record { path: p, args: fields } => { - self.infer_record_pat(p.as_ref(), fields, expected, default_bm, pat) - } - Pat::Path(path) => { - // FIXME use correct resolver for the surrounding expression - let resolver = self.resolver.clone(); - self.infer_path(&resolver, &path, pat.into()).unwrap_or(Ty::Unknown) - } - Pat::Bind { mode, name: _, subpat } => { - let mode = if mode == &BindingAnnotation::Unannotated { - default_bm - } else { - BindingMode::convert(*mode) - }; - let inner_ty = if let Some(subpat) = subpat { - self.infer_pat(*subpat, expected, default_bm) - } else { - expected.clone() - }; - let inner_ty = self.insert_type_vars_shallow(inner_ty); - - let bound_ty = match mode { - BindingMode::Ref(mutability) => { - Ty::apply_one(TypeCtor::Ref(mutability), inner_ty.clone()) - } - BindingMode::Move => inner_ty.clone(), - }; - let bound_ty = self.resolve_ty_as_possible(&mut vec![], bound_ty); - self.write_pat_ty(pat, bound_ty); - return inner_ty; - } - _ => Ty::Unknown, - }; - // use a new type variable if we got Ty::Unknown here - let ty = self.insert_type_vars_shallow(ty); - self.unify(&ty, expected); - let ty = self.resolve_ty_as_possible(&mut vec![], ty); - self.write_pat_ty(pat, ty.clone()); - ty - } - - fn substs_for_method_call( - &mut self, - def_generics: Option>, - generic_args: Option<&GenericArgs>, - receiver_ty: &Ty, - ) -> Substs { - let (parent_param_count, param_count) = - def_generics.as_ref().map_or((0, 0), |g| (g.count_parent_params(), g.params.len())); - let mut substs = Vec::with_capacity(parent_param_count + param_count); - // Parent arguments are unknown, except for the receiver type - if let Some(parent_generics) = def_generics.and_then(|p| p.parent_params.clone()) { - for param in &parent_generics.params { - if param.name == name::SELF_TYPE { - substs.push(receiver_ty.clone()); - } else { - substs.push(Ty::Unknown); - } - } - } - // handle provided type arguments - if let Some(generic_args) = generic_args { - // if args are provided, it should be all of them, but we can't rely on that - for arg in generic_args.args.iter().take(param_count) { - match arg { - GenericArg::Type(type_ref) => { - let ty = self.make_ty(type_ref); - substs.push(ty); - } - } - } - }; - let supplied_params = substs.len(); - for _ in supplied_params..parent_param_count + param_count { - substs.push(Ty::Unknown); - } - assert_eq!(substs.len(), parent_param_count + param_count); - Substs(substs.into()) - } - - fn register_obligations_for_call(&mut self, callable_ty: &Ty) { - if let Ty::Apply(a_ty) = callable_ty { - if let TypeCtor::FnDef(def) = a_ty.ctor { - let generic_predicates = self.db.generic_predicates(def.into()); - for predicate in generic_predicates.iter() { - let predicate = predicate.clone().subst(&a_ty.parameters); - if let Some(obligation) = Obligation::from_predicate(predicate) { - self.obligations.push(obligation); - } - } - // add obligation for trait implementation, if this is a trait method - match def { - CallableDef::Function(f) => { - if let Some(trait_) = f.parent_trait(self.db) { - // construct a TraitDef - let substs = a_ty.parameters.prefix( - trait_.generic_params(self.db).count_params_including_parent(), - ); - self.obligations.push(Obligation::Trait(TraitRef { trait_, substs })); - } - } - CallableDef::Struct(_) | CallableDef::EnumVariant(_) => {} - } - } - } - } - - fn infer_method_call( - &mut self, - tgt_expr: ExprId, - receiver: ExprId, - args: &[ExprId], - method_name: &Name, - generic_args: Option<&GenericArgs>, - ) -> Ty { - let receiver_ty = self.infer_expr(receiver, &Expectation::none()); - let canonicalized_receiver = self.canonicalizer().canonicalize_ty(receiver_ty.clone()); - let resolved = method_resolution::lookup_method( - &canonicalized_receiver.value, - self.db, - method_name, - &self.resolver, - ); - let (derefed_receiver_ty, method_ty, def_generics) = match resolved { - Some((ty, func)) => { - let ty = canonicalized_receiver.decanonicalize_ty(ty); - self.write_method_resolution(tgt_expr, func); - ( - ty, - self.db.type_for_def(func.into(), Namespace::Values), - Some(func.generic_params(self.db)), - ) - } - None => (receiver_ty, Ty::Unknown, None), - }; - let substs = self.substs_for_method_call(def_generics, generic_args, &derefed_receiver_ty); - let method_ty = method_ty.apply_substs(substs); - let method_ty = self.insert_type_vars(method_ty); - self.register_obligations_for_call(&method_ty); - let (expected_receiver_ty, param_tys, ret_ty) = match method_ty.callable_sig(self.db) { - Some(sig) => { - if !sig.params().is_empty() { - (sig.params()[0].clone(), sig.params()[1..].to_vec(), sig.ret().clone()) - } else { - (Ty::Unknown, Vec::new(), sig.ret().clone()) - } - } - None => (Ty::Unknown, Vec::new(), Ty::Unknown), - }; - // Apply autoref so the below unification works correctly - // FIXME: return correct autorefs from lookup_method - let actual_receiver_ty = match expected_receiver_ty.as_reference() { - Some((_, mutability)) => Ty::apply_one(TypeCtor::Ref(mutability), derefed_receiver_ty), - _ => derefed_receiver_ty, - }; - self.unify(&expected_receiver_ty, &actual_receiver_ty); - - self.check_call_arguments(args, ¶m_tys); - let ret_ty = self.normalize_associated_types_in(ret_ty); - ret_ty - } - - /// Infer type of expression with possibly implicit coerce to the expected type. - /// Return the type after possible coercion. - fn infer_expr_coerce(&mut self, expr: ExprId, expected: &Expectation) -> Ty { - let ty = self.infer_expr_inner(expr, &expected); - let ty = if !self.coerce(&ty, &expected.ty) { - self.result - .type_mismatches - .insert(expr, TypeMismatch { expected: expected.ty.clone(), actual: ty.clone() }); - // Return actual type when type mismatch. - // This is needed for diagnostic when return type mismatch. - ty - } else if expected.ty == Ty::Unknown { - ty - } else { - expected.ty.clone() - }; - - self.resolve_ty_as_possible(&mut vec![], ty) - } - - /// Merge two types from different branches, with possible implicit coerce. - /// - /// Note that it is only possible that one type are coerced to another. - /// Coercing both types to another least upper bound type is not possible in rustc, - /// which will simply result in "incompatible types" error. - fn coerce_merge_branch<'t>(&mut self, ty1: &Ty, ty2: &Ty) -> Ty { - if self.coerce(ty1, ty2) { - ty2.clone() - } else if self.coerce(ty2, ty1) { - ty1.clone() - } else { - tested_by!(coerce_merge_fail_fallback); - // For incompatible types, we use the latter one as result - // to be better recovery for `if` without `else`. - ty2.clone() - } - } - - /// Unify two types, but may coerce the first one to the second one - /// using "implicit coercion rules" if needed. - /// - /// See: https://doc.rust-lang.org/nomicon/coercions.html - fn coerce(&mut self, from_ty: &Ty, to_ty: &Ty) -> bool { - let from_ty = self.resolve_ty_shallow(from_ty).into_owned(); - let to_ty = self.resolve_ty_shallow(to_ty); - self.coerce_inner(from_ty, &to_ty) - } - - fn coerce_inner(&mut self, mut from_ty: Ty, to_ty: &Ty) -> bool { - match (&from_ty, to_ty) { - // Never type will make type variable to fallback to Never Type instead of Unknown. - (ty_app!(TypeCtor::Never), Ty::Infer(InferTy::TypeVar(tv))) => { - let var = self.new_maybe_never_type_var(); - self.var_unification_table.union_value(*tv, TypeVarValue::Known(var)); - return true; - } - (ty_app!(TypeCtor::Never), _) => return true, - - // Trivial cases, this should go after `never` check to - // avoid infer result type to be never - _ => { - if self.unify_inner_trivial(&from_ty, &to_ty) { - return true; - } - } - } - - // Pointer weakening and function to pointer - match (&mut from_ty, to_ty) { - // `*mut T`, `&mut T, `&T`` -> `*const T` - // `&mut T` -> `&T` - // `&mut T` -> `*mut T` - (ty_app!(c1@TypeCtor::RawPtr(_)), ty_app!(c2@TypeCtor::RawPtr(Mutability::Shared))) - | (ty_app!(c1@TypeCtor::Ref(_)), ty_app!(c2@TypeCtor::RawPtr(Mutability::Shared))) - | (ty_app!(c1@TypeCtor::Ref(_)), ty_app!(c2@TypeCtor::Ref(Mutability::Shared))) - | (ty_app!(c1@TypeCtor::Ref(Mutability::Mut)), ty_app!(c2@TypeCtor::RawPtr(_))) => { - *c1 = *c2; - } - - // Illegal mutablity conversion - ( - ty_app!(TypeCtor::RawPtr(Mutability::Shared)), - ty_app!(TypeCtor::RawPtr(Mutability::Mut)), - ) - | ( - ty_app!(TypeCtor::Ref(Mutability::Shared)), - ty_app!(TypeCtor::Ref(Mutability::Mut)), - ) => return false, - - // `{function_type}` -> `fn()` - (ty_app!(TypeCtor::FnDef(_)), ty_app!(TypeCtor::FnPtr { .. })) => { - match from_ty.callable_sig(self.db) { - None => return false, - Some(sig) => { - let num_args = sig.params_and_return.len() as u16 - 1; - from_ty = - Ty::apply(TypeCtor::FnPtr { num_args }, Substs(sig.params_and_return)); - } - } - } - - _ => {} - } - - if let Some(ret) = self.try_coerce_unsized(&from_ty, &to_ty) { - return ret; - } - - // Auto Deref if cannot coerce - match (&from_ty, to_ty) { - // FIXME: DerefMut - (ty_app!(TypeCtor::Ref(_), st1), ty_app!(TypeCtor::Ref(_), st2)) => { - self.unify_autoderef_behind_ref(&st1[0], &st2[0]) - } - - // Otherwise, normal unify - _ => self.unify(&from_ty, to_ty), - } - } - - /// Coerce a type using `from_ty: CoerceUnsized` - /// - /// See: https://doc.rust-lang.org/nightly/std/marker/trait.CoerceUnsized.html - fn try_coerce_unsized(&mut self, from_ty: &Ty, to_ty: &Ty) -> Option { - let (ctor1, st1, ctor2, st2) = match (from_ty, to_ty) { - (ty_app!(ctor1, st1), ty_app!(ctor2, st2)) => (ctor1, st1, ctor2, st2), - _ => return None, - }; - - let coerce_generic_index = *self.coerce_unsized_map.get(&(*ctor1, *ctor2))?; - - // Check `Unsize` first - match self.check_unsize_and_coerce( - st1.0.get(coerce_generic_index)?, - st2.0.get(coerce_generic_index)?, - 0, - ) { - Some(true) => {} - ret => return ret, - } - - let ret = st1 - .iter() - .zip(st2.iter()) - .enumerate() - .filter(|&(idx, _)| idx != coerce_generic_index) - .all(|(_, (ty1, ty2))| self.unify(ty1, ty2)); - - Some(ret) - } - - /// Check if `from_ty: Unsize`, and coerce to `to_ty` if it holds. - /// - /// It should not be directly called. It is only used by `try_coerce_unsized`. - /// - /// See: https://doc.rust-lang.org/nightly/std/marker/trait.Unsize.html - fn check_unsize_and_coerce(&mut self, from_ty: &Ty, to_ty: &Ty, depth: usize) -> Option { - if depth > 1000 { - panic!("Infinite recursion in coercion"); - } - - match (&from_ty, &to_ty) { - // `[T; N]` -> `[T]` - (ty_app!(TypeCtor::Array, st1), ty_app!(TypeCtor::Slice, st2)) => { - Some(self.unify(&st1[0], &st2[0])) - } - - // `T` -> `dyn Trait` when `T: Trait` - (_, Ty::Dyn(_)) => { - // FIXME: Check predicates - Some(true) - } - - // `(..., T)` -> `(..., U)` when `T: Unsize` - ( - ty_app!(TypeCtor::Tuple { cardinality: len1 }, st1), - ty_app!(TypeCtor::Tuple { cardinality: len2 }, st2), - ) => { - if len1 != len2 || *len1 == 0 { - return None; - } - - match self.check_unsize_and_coerce( - st1.last().unwrap(), - st2.last().unwrap(), - depth + 1, - ) { - Some(true) => {} - ret => return ret, - } - - let ret = st1[..st1.len() - 1] - .iter() - .zip(&st2[..st2.len() - 1]) - .all(|(ty1, ty2)| self.unify(ty1, ty2)); - - Some(ret) - } - - // Foo<..., T, ...> is Unsize> if: - // - T: Unsize - // - Foo is a struct - // - Only the last field of Foo has a type involving T - // - T is not part of the type of any other fields - // - Bar: Unsize>, if the last field of Foo has type Bar - ( - ty_app!(TypeCtor::Adt(Adt::Struct(struct1)), st1), - ty_app!(TypeCtor::Adt(Adt::Struct(struct2)), st2), - ) if struct1 == struct2 => { - let fields = struct1.fields(self.db); - let (last_field, prev_fields) = fields.split_last()?; - - // Get the generic parameter involved in the last field. - let unsize_generic_index = { - let mut index = None; - let mut multiple_param = false; - last_field.ty(self.db).walk(&mut |ty| match ty { - &Ty::Param { idx, .. } => { - if index.is_none() { - index = Some(idx); - } else if Some(idx) != index { - multiple_param = true; - } - } - _ => {} - }); - - if multiple_param { - return None; - } - index? - }; - - // Check other fields do not involve it. - let mut multiple_used = false; - prev_fields.iter().for_each(|field| { - field.ty(self.db).walk(&mut |ty| match ty { - &Ty::Param { idx, .. } if idx == unsize_generic_index => { - multiple_used = true - } - _ => {} - }) - }); - if multiple_used { - return None; - } - - let unsize_generic_index = unsize_generic_index as usize; - - // Check `Unsize` first - match self.check_unsize_and_coerce( - st1.get(unsize_generic_index)?, - st2.get(unsize_generic_index)?, - depth + 1, - ) { - Some(true) => {} - ret => return ret, - } - - // Then unify other parameters - let ret = st1 - .iter() - .zip(st2.iter()) - .enumerate() - .filter(|&(idx, _)| idx != unsize_generic_index) - .all(|(_, (ty1, ty2))| self.unify(ty1, ty2)); - - Some(ret) - } - - _ => None, - } - } - - /// Unify `from_ty` to `to_ty` with optional auto Deref - /// - /// Note that the parameters are already stripped the outer reference. - fn unify_autoderef_behind_ref(&mut self, from_ty: &Ty, to_ty: &Ty) -> bool { - let canonicalized = self.canonicalizer().canonicalize_ty(from_ty.clone()); - let to_ty = self.resolve_ty_shallow(&to_ty); - // FIXME: Auto DerefMut - for derefed_ty in - autoderef::autoderef(self.db, &self.resolver.clone(), canonicalized.value.clone()) - { - let derefed_ty = canonicalized.decanonicalize_ty(derefed_ty.value); - match (&*self.resolve_ty_shallow(&derefed_ty), &*to_ty) { - // Stop when constructor matches. - (ty_app!(from_ctor, st1), ty_app!(to_ctor, st2)) if from_ctor == to_ctor => { - // It will not recurse to `coerce`. - return self.unify_substs(st1, st2, 0); - } - _ => {} - } - } - - false - } - - fn infer_expr(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty { - let ty = self.infer_expr_inner(tgt_expr, expected); - let could_unify = self.unify(&ty, &expected.ty); - if !could_unify { - self.result.type_mismatches.insert( - tgt_expr, - TypeMismatch { expected: expected.ty.clone(), actual: ty.clone() }, - ); - } - let ty = self.resolve_ty_as_possible(&mut vec![], ty); - ty - } - - fn infer_expr_inner(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty { - let body = Arc::clone(&self.body); // avoid borrow checker problem - let ty = match &body[tgt_expr] { - Expr::Missing => Ty::Unknown, - Expr::If { condition, then_branch, else_branch } => { - // if let is desugared to match, so this is always simple if - self.infer_expr(*condition, &Expectation::has_type(Ty::simple(TypeCtor::Bool))); - - let then_ty = self.infer_expr_inner(*then_branch, &expected); - let else_ty = match else_branch { - Some(else_branch) => self.infer_expr_inner(*else_branch, &expected), - None => Ty::unit(), - }; - - self.coerce_merge_branch(&then_ty, &else_ty) - } - Expr::Block { statements, tail } => self.infer_block(statements, *tail, expected), - Expr::TryBlock { body } => { - let _inner = self.infer_expr(*body, expected); - // FIXME should be std::result::Result<{inner}, _> - Ty::Unknown - } - Expr::Loop { body } => { - self.infer_expr(*body, &Expectation::has_type(Ty::unit())); - // FIXME handle break with value - Ty::simple(TypeCtor::Never) - } - Expr::While { condition, body } => { - // while let is desugared to a match loop, so this is always simple while - self.infer_expr(*condition, &Expectation::has_type(Ty::simple(TypeCtor::Bool))); - self.infer_expr(*body, &Expectation::has_type(Ty::unit())); - Ty::unit() - } - Expr::For { iterable, body, pat } => { - let iterable_ty = self.infer_expr(*iterable, &Expectation::none()); - - let pat_ty = match self.resolve_into_iter_item() { - Some(into_iter_item_alias) => { - let pat_ty = self.new_type_var(); - let projection = ProjectionPredicate { - ty: pat_ty.clone(), - projection_ty: ProjectionTy { - associated_ty: into_iter_item_alias, - parameters: Substs::single(iterable_ty), - }, - }; - self.obligations.push(Obligation::Projection(projection)); - self.resolve_ty_as_possible(&mut vec![], pat_ty) - } - None => Ty::Unknown, - }; - - self.infer_pat(*pat, &pat_ty, BindingMode::default()); - self.infer_expr(*body, &Expectation::has_type(Ty::unit())); - Ty::unit() - } - Expr::Lambda { body, args, arg_types } => { - assert_eq!(args.len(), arg_types.len()); - - let mut sig_tys = Vec::new(); - - for (arg_pat, arg_type) in args.iter().zip(arg_types.iter()) { - let expected = if let Some(type_ref) = arg_type { - self.make_ty(type_ref) - } else { - Ty::Unknown - }; - let arg_ty = self.infer_pat(*arg_pat, &expected, BindingMode::default()); - sig_tys.push(arg_ty); - } - - // add return type - let ret_ty = self.new_type_var(); - sig_tys.push(ret_ty.clone()); - let sig_ty = Ty::apply( - TypeCtor::FnPtr { num_args: sig_tys.len() as u16 - 1 }, - Substs(sig_tys.into()), - ); - let closure_ty = Ty::apply_one( - TypeCtor::Closure { def: self.body.owner(), expr: tgt_expr }, - sig_ty, - ); - - // Eagerly try to relate the closure type with the expected - // type, otherwise we often won't have enough information to - // infer the body. - self.coerce(&closure_ty, &expected.ty); - - self.infer_expr(*body, &Expectation::has_type(ret_ty)); - closure_ty - } - Expr::Call { callee, args } => { - let callee_ty = self.infer_expr(*callee, &Expectation::none()); - let (param_tys, ret_ty) = match callee_ty.callable_sig(self.db) { - Some(sig) => (sig.params().to_vec(), sig.ret().clone()), - None => { - // Not callable - // FIXME: report an error - (Vec::new(), Ty::Unknown) - } - }; - self.register_obligations_for_call(&callee_ty); - self.check_call_arguments(args, ¶m_tys); - let ret_ty = self.normalize_associated_types_in(ret_ty); - ret_ty - } - Expr::MethodCall { receiver, args, method_name, generic_args } => self - .infer_method_call(tgt_expr, *receiver, &args, &method_name, generic_args.as_ref()), - Expr::Match { expr, arms } => { - let input_ty = self.infer_expr(*expr, &Expectation::none()); - - let mut result_ty = self.new_maybe_never_type_var(); - - for arm in arms { - for &pat in &arm.pats { - let _pat_ty = self.infer_pat(pat, &input_ty, BindingMode::default()); - } - if let Some(guard_expr) = arm.guard { - self.infer_expr( - guard_expr, - &Expectation::has_type(Ty::simple(TypeCtor::Bool)), - ); - } - - let arm_ty = self.infer_expr_inner(arm.expr, &expected); - result_ty = self.coerce_merge_branch(&result_ty, &arm_ty); - } - - result_ty - } - Expr::Path(p) => { - // FIXME this could be more efficient... - let resolver = expr::resolver_for_expr(self.body.clone(), self.db, tgt_expr); - self.infer_path(&resolver, p, tgt_expr.into()).unwrap_or(Ty::Unknown) - } - Expr::Continue => Ty::simple(TypeCtor::Never), - Expr::Break { expr } => { - if let Some(expr) = expr { - // FIXME handle break with value - self.infer_expr(*expr, &Expectation::none()); - } - Ty::simple(TypeCtor::Never) - } - Expr::Return { expr } => { - if let Some(expr) = expr { - self.infer_expr(*expr, &Expectation::has_type(self.return_ty.clone())); - } - Ty::simple(TypeCtor::Never) - } - Expr::RecordLit { path, fields, spread } => { - let (ty, def_id) = self.resolve_variant(path.as_ref()); - if let Some(variant) = def_id { - self.write_variant_resolution(tgt_expr.into(), variant); - } - - self.unify(&ty, &expected.ty); - - let substs = ty.substs().unwrap_or_else(Substs::empty); - for (field_idx, field) in fields.iter().enumerate() { - let field_ty = def_id - .and_then(|it| match it.field(self.db, &field.name) { - Some(field) => Some(field), - None => { - self.push_diagnostic(InferenceDiagnostic::NoSuchField { - expr: tgt_expr, - field: field_idx, - }); - None - } - }) - .map_or(Ty::Unknown, |field| field.ty(self.db)) - .subst(&substs); - self.infer_expr_coerce(field.expr, &Expectation::has_type(field_ty)); - } - if let Some(expr) = spread { - self.infer_expr(*expr, &Expectation::has_type(ty.clone())); - } - ty - } - Expr::Field { expr, name } => { - let receiver_ty = self.infer_expr(*expr, &Expectation::none()); - let canonicalized = self.canonicalizer().canonicalize_ty(receiver_ty); - let ty = autoderef::autoderef( - self.db, - &self.resolver.clone(), - canonicalized.value.clone(), - ) - .find_map(|derefed_ty| match canonicalized.decanonicalize_ty(derefed_ty.value) { - Ty::Apply(a_ty) => match a_ty.ctor { - TypeCtor::Tuple { .. } => name - .as_tuple_index() - .and_then(|idx| a_ty.parameters.0.get(idx).cloned()), - TypeCtor::Adt(Adt::Struct(s)) => s.field(self.db, name).map(|field| { - self.write_field_resolution(tgt_expr, field); - field.ty(self.db).subst(&a_ty.parameters) - }), - _ => None, - }, - _ => None, - }) - .unwrap_or(Ty::Unknown); - let ty = self.insert_type_vars(ty); - self.normalize_associated_types_in(ty) - } - Expr::Await { expr } => { - let inner_ty = self.infer_expr(*expr, &Expectation::none()); - let ty = match self.resolve_future_future_output() { - Some(future_future_output_alias) => { - let ty = self.new_type_var(); - let projection = ProjectionPredicate { - ty: ty.clone(), - projection_ty: ProjectionTy { - associated_ty: future_future_output_alias, - parameters: Substs::single(inner_ty), - }, - }; - self.obligations.push(Obligation::Projection(projection)); - self.resolve_ty_as_possible(&mut vec![], ty) - } - None => Ty::Unknown, - }; - ty - } - Expr::Try { expr } => { - let inner_ty = self.infer_expr(*expr, &Expectation::none()); - let ty = match self.resolve_ops_try_ok() { - Some(ops_try_ok_alias) => { - let ty = self.new_type_var(); - let projection = ProjectionPredicate { - ty: ty.clone(), - projection_ty: ProjectionTy { - associated_ty: ops_try_ok_alias, - parameters: Substs::single(inner_ty), - }, - }; - self.obligations.push(Obligation::Projection(projection)); - self.resolve_ty_as_possible(&mut vec![], ty) - } - None => Ty::Unknown, - }; - ty - } - Expr::Cast { expr, type_ref } => { - let _inner_ty = self.infer_expr(*expr, &Expectation::none()); - let cast_ty = self.make_ty(type_ref); - // FIXME check the cast... - cast_ty - } - Expr::Ref { expr, mutability } => { - let expectation = - if let Some((exp_inner, exp_mutability)) = &expected.ty.as_reference() { - if *exp_mutability == Mutability::Mut && *mutability == Mutability::Shared { - // FIXME: throw type error - expected mut reference but found shared ref, - // which cannot be coerced - } - Expectation::has_type(Ty::clone(exp_inner)) - } else { - Expectation::none() - }; - // FIXME reference coercions etc. - let inner_ty = self.infer_expr(*expr, &expectation); - Ty::apply_one(TypeCtor::Ref(*mutability), inner_ty) - } - Expr::Box { expr } => { - let inner_ty = self.infer_expr(*expr, &Expectation::none()); - if let Some(box_) = self.resolve_boxed_box() { - Ty::apply_one(TypeCtor::Adt(box_), inner_ty) - } else { - Ty::Unknown - } - } - Expr::UnaryOp { expr, op } => { - let inner_ty = self.infer_expr(*expr, &Expectation::none()); - match op { - UnaryOp::Deref => { - let canonicalized = self.canonicalizer().canonicalize_ty(inner_ty); - if let Some(derefed_ty) = - autoderef::deref(self.db, &self.resolver, &canonicalized.value) - { - canonicalized.decanonicalize_ty(derefed_ty.value) - } else { - Ty::Unknown - } - } - UnaryOp::Neg => { - match &inner_ty { - Ty::Apply(a_ty) => match a_ty.ctor { - TypeCtor::Int(primitive::UncertainIntTy::Unknown) - | TypeCtor::Int(primitive::UncertainIntTy::Known( - primitive::IntTy { - signedness: primitive::Signedness::Signed, - .. - }, - )) - | TypeCtor::Float(..) => inner_ty, - _ => Ty::Unknown, - }, - Ty::Infer(InferTy::IntVar(..)) | Ty::Infer(InferTy::FloatVar(..)) => { - inner_ty - } - // FIXME: resolve ops::Neg trait - _ => Ty::Unknown, - } - } - UnaryOp::Not => { - match &inner_ty { - Ty::Apply(a_ty) => match a_ty.ctor { - TypeCtor::Bool | TypeCtor::Int(_) => inner_ty, - _ => Ty::Unknown, - }, - Ty::Infer(InferTy::IntVar(..)) => inner_ty, - // FIXME: resolve ops::Not trait for inner_ty - _ => Ty::Unknown, - } - } - } - } - Expr::BinaryOp { lhs, rhs, op } => match op { - Some(op) => { - let lhs_expectation = match op { - BinaryOp::LogicOp(..) => Expectation::has_type(Ty::simple(TypeCtor::Bool)), - _ => Expectation::none(), - }; - let lhs_ty = self.infer_expr(*lhs, &lhs_expectation); - // FIXME: find implementation of trait corresponding to operation - // symbol and resolve associated `Output` type - let rhs_expectation = op::binary_op_rhs_expectation(*op, lhs_ty); - let rhs_ty = self.infer_expr(*rhs, &Expectation::has_type(rhs_expectation)); - - // FIXME: similar as above, return ty is often associated trait type - op::binary_op_return_ty(*op, rhs_ty) - } - _ => Ty::Unknown, - }, - Expr::Index { base, index } => { - let _base_ty = self.infer_expr(*base, &Expectation::none()); - let _index_ty = self.infer_expr(*index, &Expectation::none()); - // FIXME: use `std::ops::Index::Output` to figure out the real return type - Ty::Unknown - } - Expr::Tuple { exprs } => { - let mut tys = match &expected.ty { - ty_app!(TypeCtor::Tuple { .. }, st) => st - .iter() - .cloned() - .chain(repeat_with(|| self.new_type_var())) - .take(exprs.len()) - .collect::>(), - _ => (0..exprs.len()).map(|_| self.new_type_var()).collect(), - }; - - for (expr, ty) in exprs.iter().zip(tys.iter_mut()) { - self.infer_expr_coerce(*expr, &Expectation::has_type(ty.clone())); - } - - Ty::apply(TypeCtor::Tuple { cardinality: tys.len() as u16 }, Substs(tys.into())) - } - Expr::Array(array) => { - let elem_ty = match &expected.ty { - ty_app!(TypeCtor::Array, st) | ty_app!(TypeCtor::Slice, st) => { - st.as_single().clone() - } - _ => self.new_type_var(), - }; - - match array { - Array::ElementList(items) => { - for expr in items.iter() { - self.infer_expr_coerce(*expr, &Expectation::has_type(elem_ty.clone())); - } - } - Array::Repeat { initializer, repeat } => { - self.infer_expr_coerce( - *initializer, - &Expectation::has_type(elem_ty.clone()), - ); - self.infer_expr( - *repeat, - &Expectation::has_type(Ty::simple(TypeCtor::Int( - primitive::UncertainIntTy::Known(primitive::IntTy::usize()), - ))), - ); - } - } - - Ty::apply_one(TypeCtor::Array, elem_ty) - } - Expr::Literal(lit) => match lit { - Literal::Bool(..) => Ty::simple(TypeCtor::Bool), - Literal::String(..) => { - Ty::apply_one(TypeCtor::Ref(Mutability::Shared), Ty::simple(TypeCtor::Str)) - } - Literal::ByteString(..) => { - let byte_type = Ty::simple(TypeCtor::Int(primitive::UncertainIntTy::Known( - primitive::IntTy::u8(), - ))); - let slice_type = Ty::apply_one(TypeCtor::Slice, byte_type); - Ty::apply_one(TypeCtor::Ref(Mutability::Shared), slice_type) - } - Literal::Char(..) => Ty::simple(TypeCtor::Char), - Literal::Int(_v, ty) => Ty::simple(TypeCtor::Int(*ty)), - Literal::Float(_v, ty) => Ty::simple(TypeCtor::Float(*ty)), - }, - }; - // use a new type variable if we got Ty::Unknown here - let ty = self.insert_type_vars_shallow(ty); - let ty = self.resolve_ty_as_possible(&mut vec![], ty); - self.write_expr_ty(tgt_expr, ty.clone()); - ty - } - - fn infer_block( - &mut self, - statements: &[Statement], - tail: Option, - expected: &Expectation, - ) -> Ty { - let mut diverges = false; - for stmt in statements { - match stmt { - Statement::Let { pat, type_ref, initializer } => { - let decl_ty = - type_ref.as_ref().map(|tr| self.make_ty(tr)).unwrap_or(Ty::Unknown); - - // Always use the declared type when specified - let mut ty = decl_ty.clone(); - - if let Some(expr) = initializer { - let actual_ty = - self.infer_expr_coerce(*expr, &Expectation::has_type(decl_ty.clone())); - if decl_ty == Ty::Unknown { - ty = actual_ty; - } - } - - let ty = self.resolve_ty_as_possible(&mut vec![], ty); - self.infer_pat(*pat, &ty, BindingMode::default()); - } - Statement::Expr(expr) => { - if let ty_app!(TypeCtor::Never) = self.infer_expr(*expr, &Expectation::none()) { - diverges = true; - } - } - } - } - - let ty = if let Some(expr) = tail { - self.infer_expr_coerce(expr, expected) - } else { - self.coerce(&Ty::unit(), &expected.ty); - Ty::unit() - }; - if diverges { - Ty::simple(TypeCtor::Never) - } else { - ty - } - } - - fn check_call_arguments(&mut self, args: &[ExprId], param_tys: &[Ty]) { - // Quoting https://github.com/rust-lang/rust/blob/6ef275e6c3cb1384ec78128eceeb4963ff788dca/src/librustc_typeck/check/mod.rs#L3325 -- - // We do this in a pretty awful way: first we type-check any arguments - // that are not closures, then we type-check the closures. This is so - // that we have more information about the types of arguments when we - // type-check the functions. This isn't really the right way to do this. - for &check_closures in &[false, true] { - let param_iter = param_tys.iter().cloned().chain(repeat(Ty::Unknown)); - for (&arg, param_ty) in args.iter().zip(param_iter) { - let is_closure = match &self.body[arg] { - Expr::Lambda { .. } => true, - _ => false, - }; - - if is_closure != check_closures { - continue; - } - - let param_ty = self.normalize_associated_types_in(param_ty); - self.infer_expr_coerce(arg, &Expectation::has_type(param_ty.clone())); - } - } - } - fn collect_const(&mut self, data: &ConstData) { self.return_ty = self.make_ty(data.type_ref()); } diff --git a/crates/ra_hir/src/ty/infer/coerce.rs b/crates/ra_hir/src/ty/infer/coerce.rs new file mode 100644 index 000000000..0429a9866 --- /dev/null +++ b/crates/ra_hir/src/ty/infer/coerce.rs @@ -0,0 +1,336 @@ +//! Coercion logic. Coercions are certain type conversions that can implicitly +//! happen in certain places, e.g. weakening `&mut` to `&` or deref coercions +//! like going from `&Vec` to `&[T]`. +//! +//! See: https://doc.rust-lang.org/nomicon/coercions.html + +use rustc_hash::FxHashMap; + +use test_utils::tested_by; + +use super::{InferTy, InferenceContext, TypeVarValue}; +use crate::{ + db::HirDatabase, + lang_item::LangItemTarget, + resolve::Resolver, + ty::{autoderef, Substs, Ty, TypeCtor, TypeWalk}, + type_ref::Mutability, + Adt, +}; + +impl<'a, D: HirDatabase> InferenceContext<'a, D> { + /// Unify two types, but may coerce the first one to the second one + /// using "implicit coercion rules" if needed. + pub(super) fn coerce(&mut self, from_ty: &Ty, to_ty: &Ty) -> bool { + let from_ty = self.resolve_ty_shallow(from_ty).into_owned(); + let to_ty = self.resolve_ty_shallow(to_ty); + self.coerce_inner(from_ty, &to_ty) + } + + /// Merge two types from different branches, with possible implicit coerce. + /// + /// Note that it is only possible that one type are coerced to another. + /// Coercing both types to another least upper bound type is not possible in rustc, + /// which will simply result in "incompatible types" error. + pub(super) fn coerce_merge_branch<'t>(&mut self, ty1: &Ty, ty2: &Ty) -> Ty { + if self.coerce(ty1, ty2) { + ty2.clone() + } else if self.coerce(ty2, ty1) { + ty1.clone() + } else { + tested_by!(coerce_merge_fail_fallback); + // For incompatible types, we use the latter one as result + // to be better recovery for `if` without `else`. + ty2.clone() + } + } + + pub(super) fn init_coerce_unsized_map( + db: &'a D, + resolver: &Resolver, + ) -> FxHashMap<(TypeCtor, TypeCtor), usize> { + let krate = resolver.krate().unwrap(); + let impls = match db.lang_item(krate, "coerce_unsized".into()) { + Some(LangItemTarget::Trait(trait_)) => db.impls_for_trait(krate, trait_), + _ => return FxHashMap::default(), + }; + + impls + .iter() + .filter_map(|impl_block| { + // `CoerseUnsized` has one generic parameter for the target type. + let trait_ref = impl_block.target_trait_ref(db)?; + let cur_from_ty = trait_ref.substs.0.get(0)?; + let cur_to_ty = trait_ref.substs.0.get(1)?; + + match (&cur_from_ty, cur_to_ty) { + (ty_app!(ctor1, st1), ty_app!(ctor2, st2)) => { + // FIXME: We return the first non-equal bound as the type parameter to coerce to unsized type. + // This works for smart-pointer-like coercion, which covers all impls from std. + st1.iter().zip(st2.iter()).enumerate().find_map(|(i, (ty1, ty2))| { + match (ty1, ty2) { + (Ty::Param { idx: p1, .. }, Ty::Param { idx: p2, .. }) + if p1 != p2 => + { + Some(((*ctor1, *ctor2), i)) + } + _ => None, + } + }) + } + _ => None, + } + }) + .collect() + } + + fn coerce_inner(&mut self, mut from_ty: Ty, to_ty: &Ty) -> bool { + match (&from_ty, to_ty) { + // Never type will make type variable to fallback to Never Type instead of Unknown. + (ty_app!(TypeCtor::Never), Ty::Infer(InferTy::TypeVar(tv))) => { + let var = self.new_maybe_never_type_var(); + self.var_unification_table.union_value(*tv, TypeVarValue::Known(var)); + return true; + } + (ty_app!(TypeCtor::Never), _) => return true, + + // Trivial cases, this should go after `never` check to + // avoid infer result type to be never + _ => { + if self.unify_inner_trivial(&from_ty, &to_ty) { + return true; + } + } + } + + // Pointer weakening and function to pointer + match (&mut from_ty, to_ty) { + // `*mut T`, `&mut T, `&T`` -> `*const T` + // `&mut T` -> `&T` + // `&mut T` -> `*mut T` + (ty_app!(c1@TypeCtor::RawPtr(_)), ty_app!(c2@TypeCtor::RawPtr(Mutability::Shared))) + | (ty_app!(c1@TypeCtor::Ref(_)), ty_app!(c2@TypeCtor::RawPtr(Mutability::Shared))) + | (ty_app!(c1@TypeCtor::Ref(_)), ty_app!(c2@TypeCtor::Ref(Mutability::Shared))) + | (ty_app!(c1@TypeCtor::Ref(Mutability::Mut)), ty_app!(c2@TypeCtor::RawPtr(_))) => { + *c1 = *c2; + } + + // Illegal mutablity conversion + ( + ty_app!(TypeCtor::RawPtr(Mutability::Shared)), + ty_app!(TypeCtor::RawPtr(Mutability::Mut)), + ) + | ( + ty_app!(TypeCtor::Ref(Mutability::Shared)), + ty_app!(TypeCtor::Ref(Mutability::Mut)), + ) => return false, + + // `{function_type}` -> `fn()` + (ty_app!(TypeCtor::FnDef(_)), ty_app!(TypeCtor::FnPtr { .. })) => { + match from_ty.callable_sig(self.db) { + None => return false, + Some(sig) => { + let num_args = sig.params_and_return.len() as u16 - 1; + from_ty = + Ty::apply(TypeCtor::FnPtr { num_args }, Substs(sig.params_and_return)); + } + } + } + + _ => {} + } + + if let Some(ret) = self.try_coerce_unsized(&from_ty, &to_ty) { + return ret; + } + + // Auto Deref if cannot coerce + match (&from_ty, to_ty) { + // FIXME: DerefMut + (ty_app!(TypeCtor::Ref(_), st1), ty_app!(TypeCtor::Ref(_), st2)) => { + self.unify_autoderef_behind_ref(&st1[0], &st2[0]) + } + + // Otherwise, normal unify + _ => self.unify(&from_ty, to_ty), + } + } + + /// Coerce a type using `from_ty: CoerceUnsized` + /// + /// See: https://doc.rust-lang.org/nightly/std/marker/trait.CoerceUnsized.html + fn try_coerce_unsized(&mut self, from_ty: &Ty, to_ty: &Ty) -> Option { + let (ctor1, st1, ctor2, st2) = match (from_ty, to_ty) { + (ty_app!(ctor1, st1), ty_app!(ctor2, st2)) => (ctor1, st1, ctor2, st2), + _ => return None, + }; + + let coerce_generic_index = *self.coerce_unsized_map.get(&(*ctor1, *ctor2))?; + + // Check `Unsize` first + match self.check_unsize_and_coerce( + st1.0.get(coerce_generic_index)?, + st2.0.get(coerce_generic_index)?, + 0, + ) { + Some(true) => {} + ret => return ret, + } + + let ret = st1 + .iter() + .zip(st2.iter()) + .enumerate() + .filter(|&(idx, _)| idx != coerce_generic_index) + .all(|(_, (ty1, ty2))| self.unify(ty1, ty2)); + + Some(ret) + } + + /// Check if `from_ty: Unsize`, and coerce to `to_ty` if it holds. + /// + /// It should not be directly called. It is only used by `try_coerce_unsized`. + /// + /// See: https://doc.rust-lang.org/nightly/std/marker/trait.Unsize.html + fn check_unsize_and_coerce(&mut self, from_ty: &Ty, to_ty: &Ty, depth: usize) -> Option { + if depth > 1000 { + panic!("Infinite recursion in coercion"); + } + + match (&from_ty, &to_ty) { + // `[T; N]` -> `[T]` + (ty_app!(TypeCtor::Array, st1), ty_app!(TypeCtor::Slice, st2)) => { + Some(self.unify(&st1[0], &st2[0])) + } + + // `T` -> `dyn Trait` when `T: Trait` + (_, Ty::Dyn(_)) => { + // FIXME: Check predicates + Some(true) + } + + // `(..., T)` -> `(..., U)` when `T: Unsize` + ( + ty_app!(TypeCtor::Tuple { cardinality: len1 }, st1), + ty_app!(TypeCtor::Tuple { cardinality: len2 }, st2), + ) => { + if len1 != len2 || *len1 == 0 { + return None; + } + + match self.check_unsize_and_coerce( + st1.last().unwrap(), + st2.last().unwrap(), + depth + 1, + ) { + Some(true) => {} + ret => return ret, + } + + let ret = st1[..st1.len() - 1] + .iter() + .zip(&st2[..st2.len() - 1]) + .all(|(ty1, ty2)| self.unify(ty1, ty2)); + + Some(ret) + } + + // Foo<..., T, ...> is Unsize> if: + // - T: Unsize + // - Foo is a struct + // - Only the last field of Foo has a type involving T + // - T is not part of the type of any other fields + // - Bar: Unsize>, if the last field of Foo has type Bar + ( + ty_app!(TypeCtor::Adt(Adt::Struct(struct1)), st1), + ty_app!(TypeCtor::Adt(Adt::Struct(struct2)), st2), + ) if struct1 == struct2 => { + let fields = struct1.fields(self.db); + let (last_field, prev_fields) = fields.split_last()?; + + // Get the generic parameter involved in the last field. + let unsize_generic_index = { + let mut index = None; + let mut multiple_param = false; + last_field.ty(self.db).walk(&mut |ty| match ty { + &Ty::Param { idx, .. } => { + if index.is_none() { + index = Some(idx); + } else if Some(idx) != index { + multiple_param = true; + } + } + _ => {} + }); + + if multiple_param { + return None; + } + index? + }; + + // Check other fields do not involve it. + let mut multiple_used = false; + prev_fields.iter().for_each(|field| { + field.ty(self.db).walk(&mut |ty| match ty { + &Ty::Param { idx, .. } if idx == unsize_generic_index => { + multiple_used = true + } + _ => {} + }) + }); + if multiple_used { + return None; + } + + let unsize_generic_index = unsize_generic_index as usize; + + // Check `Unsize` first + match self.check_unsize_and_coerce( + st1.get(unsize_generic_index)?, + st2.get(unsize_generic_index)?, + depth + 1, + ) { + Some(true) => {} + ret => return ret, + } + + // Then unify other parameters + let ret = st1 + .iter() + .zip(st2.iter()) + .enumerate() + .filter(|&(idx, _)| idx != unsize_generic_index) + .all(|(_, (ty1, ty2))| self.unify(ty1, ty2)); + + Some(ret) + } + + _ => None, + } + } + + /// Unify `from_ty` to `to_ty` with optional auto Deref + /// + /// Note that the parameters are already stripped the outer reference. + fn unify_autoderef_behind_ref(&mut self, from_ty: &Ty, to_ty: &Ty) -> bool { + let canonicalized = self.canonicalizer().canonicalize_ty(from_ty.clone()); + let to_ty = self.resolve_ty_shallow(&to_ty); + // FIXME: Auto DerefMut + for derefed_ty in + autoderef::autoderef(self.db, &self.resolver.clone(), canonicalized.value.clone()) + { + let derefed_ty = canonicalized.decanonicalize_ty(derefed_ty.value); + match (&*self.resolve_ty_shallow(&derefed_ty), &*to_ty) { + // Stop when constructor matches. + (ty_app!(from_ctor, st1), ty_app!(to_ctor, st2)) if from_ctor == to_ctor => { + // It will not recurse to `coerce`. + return self.unify_substs(st1, st2, 0); + } + _ => {} + } + } + + false + } +} diff --git a/crates/ra_hir/src/ty/infer/expr.rs b/crates/ra_hir/src/ty/infer/expr.rs new file mode 100644 index 000000000..f8807c742 --- /dev/null +++ b/crates/ra_hir/src/ty/infer/expr.rs @@ -0,0 +1,658 @@ +//! Type inference for expressions. + +use std::iter::{repeat, repeat_with}; +use std::sync::Arc; + +use super::{BindingMode, Expectation, InferenceContext, InferenceDiagnostic, TypeMismatch}; +use crate::{ + db::HirDatabase, + expr::{self, Array, BinaryOp, Expr, ExprId, Literal, Statement, UnaryOp}, + generics::{GenericParams, HasGenericParams}, + name, + nameres::Namespace, + path::{GenericArg, GenericArgs}, + ty::{ + autoderef, method_resolution, op, primitive, CallableDef, InferTy, Mutability, Obligation, + ProjectionPredicate, ProjectionTy, Substs, TraitRef, Ty, TypeCtor, TypeWalk, + }, + Adt, Name, +}; + +impl<'a, D: HirDatabase> InferenceContext<'a, D> { + pub(super) fn infer_expr(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty { + let ty = self.infer_expr_inner(tgt_expr, expected); + let could_unify = self.unify(&ty, &expected.ty); + if !could_unify { + self.result.type_mismatches.insert( + tgt_expr, + TypeMismatch { expected: expected.ty.clone(), actual: ty.clone() }, + ); + } + let ty = self.resolve_ty_as_possible(&mut vec![], ty); + ty + } + + /// Infer type of expression with possibly implicit coerce to the expected type. + /// Return the type after possible coercion. + fn infer_expr_coerce(&mut self, expr: ExprId, expected: &Expectation) -> Ty { + let ty = self.infer_expr_inner(expr, &expected); + let ty = if !self.coerce(&ty, &expected.ty) { + self.result + .type_mismatches + .insert(expr, TypeMismatch { expected: expected.ty.clone(), actual: ty.clone() }); + // Return actual type when type mismatch. + // This is needed for diagnostic when return type mismatch. + ty + } else if expected.ty == Ty::Unknown { + ty + } else { + expected.ty.clone() + }; + + self.resolve_ty_as_possible(&mut vec![], ty) + } + + fn infer_expr_inner(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty { + let body = Arc::clone(&self.body); // avoid borrow checker problem + let ty = match &body[tgt_expr] { + Expr::Missing => Ty::Unknown, + Expr::If { condition, then_branch, else_branch } => { + // if let is desugared to match, so this is always simple if + self.infer_expr(*condition, &Expectation::has_type(Ty::simple(TypeCtor::Bool))); + + let then_ty = self.infer_expr_inner(*then_branch, &expected); + let else_ty = match else_branch { + Some(else_branch) => self.infer_expr_inner(*else_branch, &expected), + None => Ty::unit(), + }; + + self.coerce_merge_branch(&then_ty, &else_ty) + } + Expr::Block { statements, tail } => self.infer_block(statements, *tail, expected), + Expr::TryBlock { body } => { + let _inner = self.infer_expr(*body, expected); + // FIXME should be std::result::Result<{inner}, _> + Ty::Unknown + } + Expr::Loop { body } => { + self.infer_expr(*body, &Expectation::has_type(Ty::unit())); + // FIXME handle break with value + Ty::simple(TypeCtor::Never) + } + Expr::While { condition, body } => { + // while let is desugared to a match loop, so this is always simple while + self.infer_expr(*condition, &Expectation::has_type(Ty::simple(TypeCtor::Bool))); + self.infer_expr(*body, &Expectation::has_type(Ty::unit())); + Ty::unit() + } + Expr::For { iterable, body, pat } => { + let iterable_ty = self.infer_expr(*iterable, &Expectation::none()); + + let pat_ty = match self.resolve_into_iter_item() { + Some(into_iter_item_alias) => { + let pat_ty = self.new_type_var(); + let projection = ProjectionPredicate { + ty: pat_ty.clone(), + projection_ty: ProjectionTy { + associated_ty: into_iter_item_alias, + parameters: Substs::single(iterable_ty), + }, + }; + self.obligations.push(Obligation::Projection(projection)); + self.resolve_ty_as_possible(&mut vec![], pat_ty) + } + None => Ty::Unknown, + }; + + self.infer_pat(*pat, &pat_ty, BindingMode::default()); + self.infer_expr(*body, &Expectation::has_type(Ty::unit())); + Ty::unit() + } + Expr::Lambda { body, args, arg_types } => { + assert_eq!(args.len(), arg_types.len()); + + let mut sig_tys = Vec::new(); + + for (arg_pat, arg_type) in args.iter().zip(arg_types.iter()) { + let expected = if let Some(type_ref) = arg_type { + self.make_ty(type_ref) + } else { + Ty::Unknown + }; + let arg_ty = self.infer_pat(*arg_pat, &expected, BindingMode::default()); + sig_tys.push(arg_ty); + } + + // add return type + let ret_ty = self.new_type_var(); + sig_tys.push(ret_ty.clone()); + let sig_ty = Ty::apply( + TypeCtor::FnPtr { num_args: sig_tys.len() as u16 - 1 }, + Substs(sig_tys.into()), + ); + let closure_ty = Ty::apply_one( + TypeCtor::Closure { def: self.body.owner(), expr: tgt_expr }, + sig_ty, + ); + + // Eagerly try to relate the closure type with the expected + // type, otherwise we often won't have enough information to + // infer the body. + self.coerce(&closure_ty, &expected.ty); + + self.infer_expr(*body, &Expectation::has_type(ret_ty)); + closure_ty + } + Expr::Call { callee, args } => { + let callee_ty = self.infer_expr(*callee, &Expectation::none()); + let (param_tys, ret_ty) = match callee_ty.callable_sig(self.db) { + Some(sig) => (sig.params().to_vec(), sig.ret().clone()), + None => { + // Not callable + // FIXME: report an error + (Vec::new(), Ty::Unknown) + } + }; + self.register_obligations_for_call(&callee_ty); + self.check_call_arguments(args, ¶m_tys); + let ret_ty = self.normalize_associated_types_in(ret_ty); + ret_ty + } + Expr::MethodCall { receiver, args, method_name, generic_args } => self + .infer_method_call(tgt_expr, *receiver, &args, &method_name, generic_args.as_ref()), + Expr::Match { expr, arms } => { + let input_ty = self.infer_expr(*expr, &Expectation::none()); + + let mut result_ty = self.new_maybe_never_type_var(); + + for arm in arms { + for &pat in &arm.pats { + let _pat_ty = self.infer_pat(pat, &input_ty, BindingMode::default()); + } + if let Some(guard_expr) = arm.guard { + self.infer_expr( + guard_expr, + &Expectation::has_type(Ty::simple(TypeCtor::Bool)), + ); + } + + let arm_ty = self.infer_expr_inner(arm.expr, &expected); + result_ty = self.coerce_merge_branch(&result_ty, &arm_ty); + } + + result_ty + } + Expr::Path(p) => { + // FIXME this could be more efficient... + let resolver = expr::resolver_for_expr(self.body.clone(), self.db, tgt_expr); + self.infer_path(&resolver, p, tgt_expr.into()).unwrap_or(Ty::Unknown) + } + Expr::Continue => Ty::simple(TypeCtor::Never), + Expr::Break { expr } => { + if let Some(expr) = expr { + // FIXME handle break with value + self.infer_expr(*expr, &Expectation::none()); + } + Ty::simple(TypeCtor::Never) + } + Expr::Return { expr } => { + if let Some(expr) = expr { + self.infer_expr(*expr, &Expectation::has_type(self.return_ty.clone())); + } + Ty::simple(TypeCtor::Never) + } + Expr::RecordLit { path, fields, spread } => { + let (ty, def_id) = self.resolve_variant(path.as_ref()); + if let Some(variant) = def_id { + self.write_variant_resolution(tgt_expr.into(), variant); + } + + self.unify(&ty, &expected.ty); + + let substs = ty.substs().unwrap_or_else(Substs::empty); + for (field_idx, field) in fields.iter().enumerate() { + let field_ty = def_id + .and_then(|it| match it.field(self.db, &field.name) { + Some(field) => Some(field), + None => { + self.push_diagnostic(InferenceDiagnostic::NoSuchField { + expr: tgt_expr, + field: field_idx, + }); + None + } + }) + .map_or(Ty::Unknown, |field| field.ty(self.db)) + .subst(&substs); + self.infer_expr_coerce(field.expr, &Expectation::has_type(field_ty)); + } + if let Some(expr) = spread { + self.infer_expr(*expr, &Expectation::has_type(ty.clone())); + } + ty + } + Expr::Field { expr, name } => { + let receiver_ty = self.infer_expr(*expr, &Expectation::none()); + let canonicalized = self.canonicalizer().canonicalize_ty(receiver_ty); + let ty = autoderef::autoderef( + self.db, + &self.resolver.clone(), + canonicalized.value.clone(), + ) + .find_map(|derefed_ty| match canonicalized.decanonicalize_ty(derefed_ty.value) { + Ty::Apply(a_ty) => match a_ty.ctor { + TypeCtor::Tuple { .. } => name + .as_tuple_index() + .and_then(|idx| a_ty.parameters.0.get(idx).cloned()), + TypeCtor::Adt(Adt::Struct(s)) => s.field(self.db, name).map(|field| { + self.write_field_resolution(tgt_expr, field); + field.ty(self.db).subst(&a_ty.parameters) + }), + _ => None, + }, + _ => None, + }) + .unwrap_or(Ty::Unknown); + let ty = self.insert_type_vars(ty); + self.normalize_associated_types_in(ty) + } + Expr::Await { expr } => { + let inner_ty = self.infer_expr(*expr, &Expectation::none()); + let ty = match self.resolve_future_future_output() { + Some(future_future_output_alias) => { + let ty = self.new_type_var(); + let projection = ProjectionPredicate { + ty: ty.clone(), + projection_ty: ProjectionTy { + associated_ty: future_future_output_alias, + parameters: Substs::single(inner_ty), + }, + }; + self.obligations.push(Obligation::Projection(projection)); + self.resolve_ty_as_possible(&mut vec![], ty) + } + None => Ty::Unknown, + }; + ty + } + Expr::Try { expr } => { + let inner_ty = self.infer_expr(*expr, &Expectation::none()); + let ty = match self.resolve_ops_try_ok() { + Some(ops_try_ok_alias) => { + let ty = self.new_type_var(); + let projection = ProjectionPredicate { + ty: ty.clone(), + projection_ty: ProjectionTy { + associated_ty: ops_try_ok_alias, + parameters: Substs::single(inner_ty), + }, + }; + self.obligations.push(Obligation::Projection(projection)); + self.resolve_ty_as_possible(&mut vec![], ty) + } + None => Ty::Unknown, + }; + ty + } + Expr::Cast { expr, type_ref } => { + let _inner_ty = self.infer_expr(*expr, &Expectation::none()); + let cast_ty = self.make_ty(type_ref); + // FIXME check the cast... + cast_ty + } + Expr::Ref { expr, mutability } => { + let expectation = + if let Some((exp_inner, exp_mutability)) = &expected.ty.as_reference() { + if *exp_mutability == Mutability::Mut && *mutability == Mutability::Shared { + // FIXME: throw type error - expected mut reference but found shared ref, + // which cannot be coerced + } + Expectation::has_type(Ty::clone(exp_inner)) + } else { + Expectation::none() + }; + // FIXME reference coercions etc. + let inner_ty = self.infer_expr(*expr, &expectation); + Ty::apply_one(TypeCtor::Ref(*mutability), inner_ty) + } + Expr::Box { expr } => { + let inner_ty = self.infer_expr(*expr, &Expectation::none()); + if let Some(box_) = self.resolve_boxed_box() { + Ty::apply_one(TypeCtor::Adt(box_), inner_ty) + } else { + Ty::Unknown + } + } + Expr::UnaryOp { expr, op } => { + let inner_ty = self.infer_expr(*expr, &Expectation::none()); + match op { + UnaryOp::Deref => { + let canonicalized = self.canonicalizer().canonicalize_ty(inner_ty); + if let Some(derefed_ty) = + autoderef::deref(self.db, &self.resolver, &canonicalized.value) + { + canonicalized.decanonicalize_ty(derefed_ty.value) + } else { + Ty::Unknown + } + } + UnaryOp::Neg => { + match &inner_ty { + Ty::Apply(a_ty) => match a_ty.ctor { + TypeCtor::Int(primitive::UncertainIntTy::Unknown) + | TypeCtor::Int(primitive::UncertainIntTy::Known( + primitive::IntTy { + signedness: primitive::Signedness::Signed, + .. + }, + )) + | TypeCtor::Float(..) => inner_ty, + _ => Ty::Unknown, + }, + Ty::Infer(InferTy::IntVar(..)) | Ty::Infer(InferTy::FloatVar(..)) => { + inner_ty + } + // FIXME: resolve ops::Neg trait + _ => Ty::Unknown, + } + } + UnaryOp::Not => { + match &inner_ty { + Ty::Apply(a_ty) => match a_ty.ctor { + TypeCtor::Bool | TypeCtor::Int(_) => inner_ty, + _ => Ty::Unknown, + }, + Ty::Infer(InferTy::IntVar(..)) => inner_ty, + // FIXME: resolve ops::Not trait for inner_ty + _ => Ty::Unknown, + } + } + } + } + Expr::BinaryOp { lhs, rhs, op } => match op { + Some(op) => { + let lhs_expectation = match op { + BinaryOp::LogicOp(..) => Expectation::has_type(Ty::simple(TypeCtor::Bool)), + _ => Expectation::none(), + }; + let lhs_ty = self.infer_expr(*lhs, &lhs_expectation); + // FIXME: find implementation of trait corresponding to operation + // symbol and resolve associated `Output` type + let rhs_expectation = op::binary_op_rhs_expectation(*op, lhs_ty); + let rhs_ty = self.infer_expr(*rhs, &Expectation::has_type(rhs_expectation)); + + // FIXME: similar as above, return ty is often associated trait type + op::binary_op_return_ty(*op, rhs_ty) + } + _ => Ty::Unknown, + }, + Expr::Index { base, index } => { + let _base_ty = self.infer_expr(*base, &Expectation::none()); + let _index_ty = self.infer_expr(*index, &Expectation::none()); + // FIXME: use `std::ops::Index::Output` to figure out the real return type + Ty::Unknown + } + Expr::Tuple { exprs } => { + let mut tys = match &expected.ty { + ty_app!(TypeCtor::Tuple { .. }, st) => st + .iter() + .cloned() + .chain(repeat_with(|| self.new_type_var())) + .take(exprs.len()) + .collect::>(), + _ => (0..exprs.len()).map(|_| self.new_type_var()).collect(), + }; + + for (expr, ty) in exprs.iter().zip(tys.iter_mut()) { + self.infer_expr_coerce(*expr, &Expectation::has_type(ty.clone())); + } + + Ty::apply(TypeCtor::Tuple { cardinality: tys.len() as u16 }, Substs(tys.into())) + } + Expr::Array(array) => { + let elem_ty = match &expected.ty { + ty_app!(TypeCtor::Array, st) | ty_app!(TypeCtor::Slice, st) => { + st.as_single().clone() + } + _ => self.new_type_var(), + }; + + match array { + Array::ElementList(items) => { + for expr in items.iter() { + self.infer_expr_coerce(*expr, &Expectation::has_type(elem_ty.clone())); + } + } + Array::Repeat { initializer, repeat } => { + self.infer_expr_coerce( + *initializer, + &Expectation::has_type(elem_ty.clone()), + ); + self.infer_expr( + *repeat, + &Expectation::has_type(Ty::simple(TypeCtor::Int( + primitive::UncertainIntTy::Known(primitive::IntTy::usize()), + ))), + ); + } + } + + Ty::apply_one(TypeCtor::Array, elem_ty) + } + Expr::Literal(lit) => match lit { + Literal::Bool(..) => Ty::simple(TypeCtor::Bool), + Literal::String(..) => { + Ty::apply_one(TypeCtor::Ref(Mutability::Shared), Ty::simple(TypeCtor::Str)) + } + Literal::ByteString(..) => { + let byte_type = Ty::simple(TypeCtor::Int(primitive::UncertainIntTy::Known( + primitive::IntTy::u8(), + ))); + let slice_type = Ty::apply_one(TypeCtor::Slice, byte_type); + Ty::apply_one(TypeCtor::Ref(Mutability::Shared), slice_type) + } + Literal::Char(..) => Ty::simple(TypeCtor::Char), + Literal::Int(_v, ty) => Ty::simple(TypeCtor::Int(*ty)), + Literal::Float(_v, ty) => Ty::simple(TypeCtor::Float(*ty)), + }, + }; + // use a new type variable if we got Ty::Unknown here + let ty = self.insert_type_vars_shallow(ty); + let ty = self.resolve_ty_as_possible(&mut vec![], ty); + self.write_expr_ty(tgt_expr, ty.clone()); + ty + } + + fn infer_block( + &mut self, + statements: &[Statement], + tail: Option, + expected: &Expectation, + ) -> Ty { + let mut diverges = false; + for stmt in statements { + match stmt { + Statement::Let { pat, type_ref, initializer } => { + let decl_ty = + type_ref.as_ref().map(|tr| self.make_ty(tr)).unwrap_or(Ty::Unknown); + + // Always use the declared type when specified + let mut ty = decl_ty.clone(); + + if let Some(expr) = initializer { + let actual_ty = + self.infer_expr_coerce(*expr, &Expectation::has_type(decl_ty.clone())); + if decl_ty == Ty::Unknown { + ty = actual_ty; + } + } + + let ty = self.resolve_ty_as_possible(&mut vec![], ty); + self.infer_pat(*pat, &ty, BindingMode::default()); + } + Statement::Expr(expr) => { + if let ty_app!(TypeCtor::Never) = self.infer_expr(*expr, &Expectation::none()) { + diverges = true; + } + } + } + } + + let ty = if let Some(expr) = tail { + self.infer_expr_coerce(expr, expected) + } else { + self.coerce(&Ty::unit(), &expected.ty); + Ty::unit() + }; + if diverges { + Ty::simple(TypeCtor::Never) + } else { + ty + } + } + + fn infer_method_call( + &mut self, + tgt_expr: ExprId, + receiver: ExprId, + args: &[ExprId], + method_name: &Name, + generic_args: Option<&GenericArgs>, + ) -> Ty { + let receiver_ty = self.infer_expr(receiver, &Expectation::none()); + let canonicalized_receiver = self.canonicalizer().canonicalize_ty(receiver_ty.clone()); + let resolved = method_resolution::lookup_method( + &canonicalized_receiver.value, + self.db, + method_name, + &self.resolver, + ); + let (derefed_receiver_ty, method_ty, def_generics) = match resolved { + Some((ty, func)) => { + let ty = canonicalized_receiver.decanonicalize_ty(ty); + self.write_method_resolution(tgt_expr, func); + ( + ty, + self.db.type_for_def(func.into(), Namespace::Values), + Some(func.generic_params(self.db)), + ) + } + None => (receiver_ty, Ty::Unknown, None), + }; + let substs = self.substs_for_method_call(def_generics, generic_args, &derefed_receiver_ty); + let method_ty = method_ty.apply_substs(substs); + let method_ty = self.insert_type_vars(method_ty); + self.register_obligations_for_call(&method_ty); + let (expected_receiver_ty, param_tys, ret_ty) = match method_ty.callable_sig(self.db) { + Some(sig) => { + if !sig.params().is_empty() { + (sig.params()[0].clone(), sig.params()[1..].to_vec(), sig.ret().clone()) + } else { + (Ty::Unknown, Vec::new(), sig.ret().clone()) + } + } + None => (Ty::Unknown, Vec::new(), Ty::Unknown), + }; + // Apply autoref so the below unification works correctly + // FIXME: return correct autorefs from lookup_method + let actual_receiver_ty = match expected_receiver_ty.as_reference() { + Some((_, mutability)) => Ty::apply_one(TypeCtor::Ref(mutability), derefed_receiver_ty), + _ => derefed_receiver_ty, + }; + self.unify(&expected_receiver_ty, &actual_receiver_ty); + + self.check_call_arguments(args, ¶m_tys); + let ret_ty = self.normalize_associated_types_in(ret_ty); + ret_ty + } + + fn check_call_arguments(&mut self, args: &[ExprId], param_tys: &[Ty]) { + // Quoting https://github.com/rust-lang/rust/blob/6ef275e6c3cb1384ec78128eceeb4963ff788dca/src/librustc_typeck/check/mod.rs#L3325 -- + // We do this in a pretty awful way: first we type-check any arguments + // that are not closures, then we type-check the closures. This is so + // that we have more information about the types of arguments when we + // type-check the functions. This isn't really the right way to do this. + for &check_closures in &[false, true] { + let param_iter = param_tys.iter().cloned().chain(repeat(Ty::Unknown)); + for (&arg, param_ty) in args.iter().zip(param_iter) { + let is_closure = match &self.body[arg] { + Expr::Lambda { .. } => true, + _ => false, + }; + + if is_closure != check_closures { + continue; + } + + let param_ty = self.normalize_associated_types_in(param_ty); + self.infer_expr_coerce(arg, &Expectation::has_type(param_ty.clone())); + } + } + } + + fn substs_for_method_call( + &mut self, + def_generics: Option>, + generic_args: Option<&GenericArgs>, + receiver_ty: &Ty, + ) -> Substs { + let (parent_param_count, param_count) = + def_generics.as_ref().map_or((0, 0), |g| (g.count_parent_params(), g.params.len())); + let mut substs = Vec::with_capacity(parent_param_count + param_count); + // Parent arguments are unknown, except for the receiver type + if let Some(parent_generics) = def_generics.and_then(|p| p.parent_params.clone()) { + for param in &parent_generics.params { + if param.name == name::SELF_TYPE { + substs.push(receiver_ty.clone()); + } else { + substs.push(Ty::Unknown); + } + } + } + // handle provided type arguments + if let Some(generic_args) = generic_args { + // if args are provided, it should be all of them, but we can't rely on that + for arg in generic_args.args.iter().take(param_count) { + match arg { + GenericArg::Type(type_ref) => { + let ty = self.make_ty(type_ref); + substs.push(ty); + } + } + } + }; + let supplied_params = substs.len(); + for _ in supplied_params..parent_param_count + param_count { + substs.push(Ty::Unknown); + } + assert_eq!(substs.len(), parent_param_count + param_count); + Substs(substs.into()) + } + + fn register_obligations_for_call(&mut self, callable_ty: &Ty) { + if let Ty::Apply(a_ty) = callable_ty { + if let TypeCtor::FnDef(def) = a_ty.ctor { + let generic_predicates = self.db.generic_predicates(def.into()); + for predicate in generic_predicates.iter() { + let predicate = predicate.clone().subst(&a_ty.parameters); + if let Some(obligation) = Obligation::from_predicate(predicate) { + self.obligations.push(obligation); + } + } + // add obligation for trait implementation, if this is a trait method + match def { + CallableDef::Function(f) => { + if let Some(trait_) = f.parent_trait(self.db) { + // construct a TraitDef + let substs = a_ty.parameters.prefix( + trait_.generic_params(self.db).count_params_including_parent(), + ); + self.obligations.push(Obligation::Trait(TraitRef { trait_, substs })); + } + } + CallableDef::Struct(_) | CallableDef::EnumVariant(_) => {} + } + } + } + } +} diff --git a/crates/ra_hir/src/ty/infer/pat.rs b/crates/ra_hir/src/ty/infer/pat.rs new file mode 100644 index 000000000..c125ddfbc --- /dev/null +++ b/crates/ra_hir/src/ty/infer/pat.rs @@ -0,0 +1,180 @@ +//! Type inference for patterns. + +use std::iter::repeat; +use std::sync::Arc; + +use test_utils::tested_by; + +use super::{BindingMode, InferenceContext}; +use crate::{ + db::HirDatabase, + expr::{BindingAnnotation, Pat, PatId, RecordFieldPat}, + ty::{Mutability, Substs, Ty, TypeCtor, TypeWalk}, + Name, Path, +}; + +impl<'a, D: HirDatabase> InferenceContext<'a, D> { + fn infer_tuple_struct_pat( + &mut self, + path: Option<&Path>, + subpats: &[PatId], + expected: &Ty, + default_bm: BindingMode, + ) -> Ty { + let (ty, def) = self.resolve_variant(path); + + self.unify(&ty, expected); + + let substs = ty.substs().unwrap_or_else(Substs::empty); + + for (i, &subpat) in subpats.iter().enumerate() { + let expected_ty = def + .and_then(|d| d.field(self.db, &Name::new_tuple_field(i))) + .map_or(Ty::Unknown, |field| field.ty(self.db)) + .subst(&substs); + let expected_ty = self.normalize_associated_types_in(expected_ty); + self.infer_pat(subpat, &expected_ty, default_bm); + } + + ty + } + + fn infer_record_pat( + &mut self, + path: Option<&Path>, + subpats: &[RecordFieldPat], + expected: &Ty, + default_bm: BindingMode, + id: PatId, + ) -> Ty { + let (ty, def) = self.resolve_variant(path); + if let Some(variant) = def { + self.write_variant_resolution(id.into(), variant); + } + + self.unify(&ty, expected); + + let substs = ty.substs().unwrap_or_else(Substs::empty); + + for subpat in subpats { + let matching_field = def.and_then(|it| it.field(self.db, &subpat.name)); + let expected_ty = + matching_field.map_or(Ty::Unknown, |field| field.ty(self.db)).subst(&substs); + let expected_ty = self.normalize_associated_types_in(expected_ty); + self.infer_pat(subpat.pat, &expected_ty, default_bm); + } + + ty + } + + pub(super) fn infer_pat( + &mut self, + pat: PatId, + mut expected: &Ty, + mut default_bm: BindingMode, + ) -> Ty { + let body = Arc::clone(&self.body); // avoid borrow checker problem + + let is_non_ref_pat = match &body[pat] { + Pat::Tuple(..) + | Pat::TupleStruct { .. } + | Pat::Record { .. } + | Pat::Range { .. } + | Pat::Slice { .. } => true, + // FIXME: Path/Lit might actually evaluate to ref, but inference is unimplemented. + Pat::Path(..) | Pat::Lit(..) => true, + Pat::Wild | Pat::Bind { .. } | Pat::Ref { .. } | Pat::Missing => false, + }; + if is_non_ref_pat { + while let Some((inner, mutability)) = expected.as_reference() { + expected = inner; + default_bm = match default_bm { + BindingMode::Move => BindingMode::Ref(mutability), + BindingMode::Ref(Mutability::Shared) => BindingMode::Ref(Mutability::Shared), + BindingMode::Ref(Mutability::Mut) => BindingMode::Ref(mutability), + } + } + } else if let Pat::Ref { .. } = &body[pat] { + tested_by!(match_ergonomics_ref); + // When you encounter a `&pat` pattern, reset to Move. + // This is so that `w` is by value: `let (_, &w) = &(1, &2);` + default_bm = BindingMode::Move; + } + + // Lose mutability. + let default_bm = default_bm; + let expected = expected; + + let ty = match &body[pat] { + Pat::Tuple(ref args) => { + let expectations = match expected.as_tuple() { + Some(parameters) => &*parameters.0, + _ => &[], + }; + let expectations_iter = expectations.iter().chain(repeat(&Ty::Unknown)); + + let inner_tys = args + .iter() + .zip(expectations_iter) + .map(|(&pat, ty)| self.infer_pat(pat, ty, default_bm)) + .collect(); + + Ty::apply(TypeCtor::Tuple { cardinality: args.len() as u16 }, Substs(inner_tys)) + } + Pat::Ref { pat, mutability } => { + let expectation = match expected.as_reference() { + Some((inner_ty, exp_mut)) => { + if *mutability != exp_mut { + // FIXME: emit type error? + } + inner_ty + } + _ => &Ty::Unknown, + }; + let subty = self.infer_pat(*pat, expectation, default_bm); + Ty::apply_one(TypeCtor::Ref(*mutability), subty) + } + Pat::TupleStruct { path: p, args: subpats } => { + self.infer_tuple_struct_pat(p.as_ref(), subpats, expected, default_bm) + } + Pat::Record { path: p, args: fields } => { + self.infer_record_pat(p.as_ref(), fields, expected, default_bm, pat) + } + Pat::Path(path) => { + // FIXME use correct resolver for the surrounding expression + let resolver = self.resolver.clone(); + self.infer_path(&resolver, &path, pat.into()).unwrap_or(Ty::Unknown) + } + Pat::Bind { mode, name: _, subpat } => { + let mode = if mode == &BindingAnnotation::Unannotated { + default_bm + } else { + BindingMode::convert(*mode) + }; + let inner_ty = if let Some(subpat) = subpat { + self.infer_pat(*subpat, expected, default_bm) + } else { + expected.clone() + }; + let inner_ty = self.insert_type_vars_shallow(inner_ty); + + let bound_ty = match mode { + BindingMode::Ref(mutability) => { + Ty::apply_one(TypeCtor::Ref(mutability), inner_ty.clone()) + } + BindingMode::Move => inner_ty.clone(), + }; + let bound_ty = self.resolve_ty_as_possible(&mut vec![], bound_ty); + self.write_pat_ty(pat, bound_ty); + return inner_ty; + } + _ => Ty::Unknown, + }; + // use a new type variable if we got Ty::Unknown here + let ty = self.insert_type_vars_shallow(ty); + self.unify(&ty, expected); + let ty = self.resolve_ty_as_possible(&mut vec![], ty); + self.write_pat_ty(pat, ty.clone()); + ty + } +} -- cgit v1.2.3