//! Type inference for expressions. use std::{ iter::{repeat, repeat_with}, mem, }; use chalk_ir::{cast::Cast, fold::Shift, DebruijnIndex, Mutability, TyVariableKind}; use either::Either; use hir_def::{ generics::TypeOrConstParamData, hir::{ ArithOp, Array, BinaryOp, ClosureKind, Expr, ExprId, LabelId, Literal, Statement, UnaryOp, }, lang_item::{LangItem, LangItemTarget}, path::{GenericArg, GenericArgs}, BlockId, ConstParamId, FieldId, ItemContainerId, Lookup, TupleFieldId, TupleId, }; use hir_expand::name::{name, Name}; use stdx::always; use syntax::ast::RangeOp; use crate::{ autoderef::{builtin_deref, deref_by_trait, Autoderef}, consteval, infer::{ coerce::{CoerceMany, CoercionCause}, find_continuable, pat::contains_explicit_ref_binding, BreakableKind, }, lang_items::lang_items_for_bin_op, lower::{ const_or_path_to_chalk, generic_arg_to_chalk, lower_to_chalk_mutability, ParamLoweringMode, }, mapping::{from_chalk, ToChalk}, method_resolution::{self, VisibleFromModule}, primitive::{self, UintTy}, static_lifetime, to_chalk_trait_id, traits::FnTrait, utils::{generics, Generics}, Adjust, Adjustment, AdtId, AutoBorrow, Binders, CallableDefId, FnPointer, FnSig, FnSubst, Interner, Rawness, Scalar, Substitution, TraitEnvironment, TraitRef, Ty, TyBuilder, TyExt, TyKind, }; use super::{ cast::CastCheck, coerce::auto_deref_adjust_steps, find_breakable, BreakableContext, Diverges, Expectation, InferenceContext, InferenceDiagnostic, TypeMismatch, }; impl InferenceContext<'_> { pub(crate) fn infer_expr(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty { let ty = self.infer_expr_inner(tgt_expr, expected); if let Some(expected_ty) = expected.only_has_type(&mut self.table) { let could_unify = self.unify(&ty, &expected_ty); if !could_unify { self.result.type_mismatches.insert( tgt_expr.into(), TypeMismatch { expected: expected_ty, actual: ty.clone() }, ); } } ty } pub(crate) fn infer_expr_no_expect(&mut self, tgt_expr: ExprId) -> Ty { self.infer_expr_inner(tgt_expr, &Expectation::None) } /// Infer type of expression with possibly implicit coerce to the expected type. /// Return the type after possible coercion. pub(super) fn infer_expr_coerce(&mut self, expr: ExprId, expected: &Expectation) -> Ty { let ty = self.infer_expr_inner(expr, expected); if let Some(target) = expected.only_has_type(&mut self.table) { match self.coerce(Some(expr), &ty, &target) { Ok(res) => res, Err(_) => { self.result.type_mismatches.insert( expr.into(), TypeMismatch { expected: target.clone(), actual: ty.clone() }, ); target } } } else { ty } } fn infer_expr_coerce_never(&mut self, expr: ExprId, expected: &Expectation) -> Ty { let ty = self.infer_expr_inner(expr, expected); // While we don't allow *arbitrary* coercions here, we *do* allow // coercions from `!` to `expected`. if ty.is_never() { if let Some(adjustments) = self.result.expr_adjustments.get(&expr) { return if let [Adjustment { kind: Adjust::NeverToAny, target }] = &**adjustments { target.clone() } else { self.err_ty() }; } if let Some(target) = expected.only_has_type(&mut self.table) { self.coerce(Some(expr), &ty, &target) .expect("never-to-any coercion should always succeed") } else { ty } } else { if let Some(expected_ty) = expected.only_has_type(&mut self.table) { let could_unify = self.unify(&ty, &expected_ty); if !could_unify { self.result.type_mismatches.insert( expr.into(), TypeMismatch { expected: expected_ty, actual: ty.clone() }, ); } } ty } } fn infer_expr_inner(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty { self.db.unwind_if_cancelled(); let ty = match &self.body[tgt_expr] { Expr::Missing => self.err_ty(), &Expr::If { condition, then_branch, else_branch } => { let expected = &expected.adjust_for_branches(&mut self.table); self.infer_expr_coerce_never( condition, &Expectation::HasType(self.result.standard_types.bool_.clone()), ); let condition_diverges = mem::replace(&mut self.diverges, Diverges::Maybe); let then_ty = self.infer_expr_inner(then_branch, expected); let then_diverges = mem::replace(&mut self.diverges, Diverges::Maybe); let mut coerce = CoerceMany::new(expected.coercion_target_type(&mut self.table)); coerce.coerce(self, Some(then_branch), &then_ty, CoercionCause::Expr(then_branch)); match else_branch { Some(else_branch) => { let else_ty = self.infer_expr_inner(else_branch, expected); let else_diverges = mem::replace(&mut self.diverges, Diverges::Maybe); coerce.coerce( self, Some(else_branch), &else_ty, CoercionCause::Expr(else_branch), ); self.diverges = condition_diverges | then_diverges & else_diverges; } None => { coerce.coerce_forced_unit(self, CoercionCause::Expr(tgt_expr)); self.diverges = condition_diverges; } } coerce.complete(self) } &Expr::Let { pat, expr } => { let input_ty = self.infer_expr(expr, &Expectation::none()); self.infer_top_pat(pat, &input_ty); self.result.standard_types.bool_.clone() } Expr::Block { statements, tail, label, id } => { self.infer_block(tgt_expr, *id, statements, *tail, *label, expected) } Expr::Unsafe { id, statements, tail } => { self.infer_block(tgt_expr, *id, statements, *tail, None, expected) } Expr::Const(id) => { self.with_breakable_ctx(BreakableKind::Border, None, None, |this| { let loc = this.db.lookup_intern_anonymous_const(*id); this.infer_expr(loc.root, expected) }) .1 } Expr::Async { id, statements, tail } => { self.infer_async_block(tgt_expr, id, statements, tail) } &Expr::Loop { body, label } => { // FIXME: should be: // let ty = expected.coercion_target_type(&mut self.table); let ty = self.table.new_type_var(); let (breaks, ()) = self.with_breakable_ctx(BreakableKind::Loop, Some(ty), label, |this| { this.infer_expr(body, &Expectation::HasType(TyBuilder::unit())); }); match breaks { Some(breaks) => { self.diverges = Diverges::Maybe; breaks } None => self.result.standard_types.never.clone(), } } Expr::Closure { body, args, ret_type, arg_types, closure_kind, capture_by: _ } => { assert_eq!(args.len(), arg_types.len()); let mut sig_tys = Vec::with_capacity(arg_types.len() + 1); // collect explicitly written argument types for arg_type in arg_types.iter() { let arg_ty = match arg_type { Some(type_ref) => self.make_ty(type_ref), None => self.table.new_type_var(), }; sig_tys.push(arg_ty); } // add return type let ret_ty = match ret_type { Some(type_ref) => self.make_ty(type_ref), None => self.table.new_type_var(), }; if let ClosureKind::Async = closure_kind { sig_tys.push(self.lower_async_block_type_impl_trait(ret_ty.clone(), *body)); } else { sig_tys.push(ret_ty.clone()); } let sig_ty = TyKind::Function(FnPointer { num_binders: 0, sig: FnSig { abi: (), safety: chalk_ir::Safety::Safe, variadic: false }, substitution: FnSubst( Substitution::from_iter(Interner, sig_tys.iter().cloned()) .shifted_in(Interner), ), }) .intern(Interner); let (id, ty, resume_yield_tys) = match closure_kind { ClosureKind::Generator(_) => { // FIXME: report error when there are more than 1 parameter. let resume_ty = match sig_tys.first() { // When `sig_tys.len() == 1` the first type is the return type, not the // first parameter type. Some(ty) if sig_tys.len() > 1 => ty.clone(), _ => self.result.standard_types.unit.clone(), }; let yield_ty = self.table.new_type_var(); let subst = TyBuilder::subst_for_generator(self.db, self.owner) .push(resume_ty.clone()) .push(yield_ty.clone()) .push(ret_ty.clone()) .build(); let generator_id = self.db.intern_generator((self.owner, tgt_expr)).into(); let generator_ty = TyKind::Generator(generator_id, subst).intern(Interner); (None, generator_ty, Some((resume_ty, yield_ty))) } ClosureKind::Closure | ClosureKind::Async => { let closure_id = self.db.intern_closure((self.owner, tgt_expr)).into(); let closure_ty = TyKind::Closure( closure_id, TyBuilder::subst_for_closure(self.db, self.owner, sig_ty.clone()), ) .intern(Interner); self.deferred_closures.entry(closure_id).or_default(); if let Some(c) = self.current_closure { self.closure_dependencies.entry(c).or_default().push(closure_id); } (Some(closure_id), closure_ty, None) } }; // Eagerly try to relate the closure type with the expected // type, otherwise we often won't have enough information to // infer the body. self.deduce_closure_type_from_expectations(tgt_expr, &ty, &sig_ty, expected); // Now go through the argument patterns for (arg_pat, arg_ty) in args.iter().zip(&sig_tys) { self.infer_top_pat(*arg_pat, &arg_ty); } // FIXME: lift these out into a struct let prev_diverges = mem::replace(&mut self.diverges, Diverges::Maybe); let prev_closure = mem::replace(&mut self.current_closure, id); let prev_ret_ty = mem::replace(&mut self.return_ty, ret_ty.clone()); let prev_ret_coercion = mem::replace(&mut self.return_coercion, Some(CoerceMany::new(ret_ty))); let prev_resume_yield_tys = mem::replace(&mut self.resume_yield_tys, resume_yield_tys); self.with_breakable_ctx(BreakableKind::Border, None, None, |this| { this.infer_return(*body); }); self.diverges = prev_diverges; self.return_ty = prev_ret_ty; self.return_coercion = prev_ret_coercion; self.current_closure = prev_closure; self.resume_yield_tys = prev_resume_yield_tys; ty } Expr::Call { callee, args, .. } => { let callee_ty = self.infer_expr(*callee, &Expectation::none()); let mut derefs = Autoderef::new(&mut self.table, callee_ty.clone(), false); let (res, derefed_callee) = 'b: { // manual loop to be able to access `derefs.table` while let Some((callee_deref_ty, _)) = derefs.next() { let res = derefs.table.callable_sig(&callee_deref_ty, args.len()); if res.is_some() { break 'b (res, callee_deref_ty); } } (None, callee_ty.clone()) }; // if the function is unresolved, we use is_varargs=true to // suppress the arg count diagnostic here let is_varargs = derefed_callee.callable_sig(self.db).map_or(false, |sig| sig.is_varargs) || res.is_none(); let (param_tys, ret_ty) = match res { Some((func, params, ret_ty)) => { let mut adjustments = auto_deref_adjust_steps(&derefs); if let TyKind::Closure(c, _) = self.table.resolve_completely(callee_ty.clone()).kind(Interner) { if let Some(par) = self.current_closure { self.closure_dependencies.entry(par).or_default().push(*c); } self.deferred_closures.entry(*c).or_default().push(( derefed_callee.clone(), callee_ty.clone(), params.clone(), tgt_expr, )); } if let Some(fn_x) = func { self.write_fn_trait_method_resolution( fn_x, &derefed_callee, &mut adjustments, &callee_ty, ¶ms, tgt_expr, ); } self.write_expr_adj(*callee, adjustments); (params, ret_ty) } None => { self.result.diagnostics.push(InferenceDiagnostic::ExpectedFunction { call_expr: tgt_expr, found: callee_ty.clone(), }); (Vec::new(), self.err_ty()) } }; let indices_to_skip = self.check_legacy_const_generics(derefed_callee, args); self.register_obligations_for_call(&callee_ty); let expected_inputs = self.expected_inputs_for_expected_output( expected, ret_ty.clone(), param_tys.clone(), ); self.check_call_arguments( tgt_expr, args, &expected_inputs, ¶m_tys, &indices_to_skip, is_varargs, ); self.normalize_associated_types_in(ret_ty) } Expr::MethodCall { receiver, args, method_name, generic_args } => self .infer_method_call( tgt_expr, *receiver, args, method_name, generic_args.as_deref(), expected, ), Expr::Match { expr, arms } => { let input_ty = self.infer_expr(*expr, &Expectation::none()); if arms.is_empty() { self.diverges = Diverges::Always; self.result.standard_types.never.clone() } else { let matchee_diverges = mem::replace(&mut self.diverges, Diverges::Maybe); let mut all_arms_diverge = Diverges::Always; for arm in arms.iter() { let input_ty = self.resolve_ty_shallow(&input_ty); self.infer_top_pat(arm.pat, &input_ty); } let expected = expected.adjust_for_branches(&mut self.table); let result_ty = match &expected { // We don't coerce to `()` so that if the match expression is a // statement it's branches can have any consistent type. Expectation::HasType(ty) if *ty != self.result.standard_types.unit => { ty.clone() } _ => self.table.new_type_var(), }; let mut coerce = CoerceMany::new(result_ty); for arm in arms.iter() { if let Some(guard_expr) = arm.guard { self.diverges = Diverges::Maybe; self.infer_expr_coerce_never( guard_expr, &Expectation::HasType(self.result.standard_types.bool_.clone()), ); } self.diverges = Diverges::Maybe; let arm_ty = self.infer_expr_inner(arm.expr, &expected); all_arms_diverge &= self.diverges; coerce.coerce(self, Some(arm.expr), &arm_ty, CoercionCause::Expr(arm.expr)); } self.diverges = matchee_diverges | all_arms_diverge; coerce.complete(self) } } Expr::Path(p) => { let g = self.resolver.update_to_inner_scope(self.db.upcast(), self.owner, tgt_expr); let ty = self.infer_path(p, tgt_expr.into()).unwrap_or_else(|| self.err_ty()); self.resolver.reset_to_guard(g); ty } &Expr::Continue { label } => { if let None = find_continuable(&mut self.breakables, label) { self.push_diagnostic(InferenceDiagnostic::BreakOutsideOfLoop { expr: tgt_expr, is_break: false, bad_value_break: false, }); }; self.result.standard_types.never.clone() } &Expr::Break { expr, label } => { let val_ty = if let Some(expr) = expr { let opt_coerce_to = match find_breakable(&mut self.breakables, label) { Some(ctxt) => match &ctxt.coerce { Some(coerce) => coerce.expected_ty(), None => { self.push_diagnostic(InferenceDiagnostic::BreakOutsideOfLoop { expr: tgt_expr, is_break: true, bad_value_break: true, }); self.err_ty() } }, None => self.err_ty(), }; self.infer_expr_inner(expr, &Expectation::HasType(opt_coerce_to)) } else { TyBuilder::unit() }; match find_breakable(&mut self.breakables, label) { Some(ctxt) => match ctxt.coerce.take() { Some(mut coerce) => { let cause = match expr { Some(expr) => CoercionCause::Expr(expr), None => CoercionCause::Expr(tgt_expr), }; coerce.coerce(self, expr, &val_ty, cause); // Avoiding borrowck let ctxt = find_breakable(&mut self.breakables, label) .expect("breakable stack changed during coercion"); ctxt.may_break = true; ctxt.coerce = Some(coerce); } None => ctxt.may_break = true, }, None => { self.push_diagnostic(InferenceDiagnostic::BreakOutsideOfLoop { expr: tgt_expr, is_break: true, bad_value_break: false, }); } } self.result.standard_types.never.clone() } &Expr::Return { expr } => self.infer_expr_return(tgt_expr, expr), Expr::Yield { expr } => { if let Some((resume_ty, yield_ty)) = self.resume_yield_tys.clone() { if let Some(expr) = expr { self.infer_expr_coerce(*expr, &Expectation::has_type(yield_ty)); } else { let unit = self.result.standard_types.unit.clone(); let _ = self.coerce(Some(tgt_expr), &unit, &yield_ty); } resume_ty } else { // FIXME: report error (yield expr in non-generator) self.result.standard_types.unknown.clone() } } Expr::Yeet { expr } => { if let &Some(expr) = expr { self.infer_expr_no_expect(expr); } self.result.standard_types.never.clone() } Expr::RecordLit { path, fields, spread, .. } => { let (ty, def_id) = self.resolve_variant(path.as_deref(), false); if let Some(t) = expected.only_has_type(&mut self.table) { self.unify(&ty, &t); } let substs = ty .as_adt() .map(|(_, s)| s.clone()) .unwrap_or_else(|| Substitution::empty(Interner)); if let Some(variant) = def_id { self.write_variant_resolution(tgt_expr.into(), variant); } match def_id { _ if fields.is_empty() => {} Some(def) => { let field_types = self.db.field_types(def); let variant_data = def.variant_data(self.db.upcast()); let visibilities = self.db.field_visibilities(def); for field in fields.iter() { let field_def = { match variant_data.field(&field.name) { Some(local_id) => { if !visibilities[local_id].is_visible_from( self.db.upcast(), self.resolver.module(), ) { self.push_diagnostic( InferenceDiagnostic::NoSuchField { field: field.expr.into(), private: true, }, ); } Some(local_id) } None => { self.push_diagnostic(InferenceDiagnostic::NoSuchField { field: field.expr.into(), private: false, }); None } } }; let field_ty = field_def.map_or(self.err_ty(), |it| { field_types[it].clone().substitute(Interner, &substs) }); // Field type might have some unknown types // FIXME: we may want to emit a single type variable for all instance of type fields? let field_ty = self.insert_type_vars(field_ty); self.infer_expr_coerce(field.expr, &Expectation::has_type(field_ty)); } } None => { for field in fields.iter() { self.infer_expr_coerce(field.expr, &Expectation::None); } } } if let Some(expr) = spread { self.infer_expr(*expr, &Expectation::has_type(ty.clone())); } ty } Expr::Field { expr, name } => self.infer_field_access(tgt_expr, *expr, name, expected), Expr::Await { expr } => { let inner_ty = self.infer_expr_inner(*expr, &Expectation::none()); self.resolve_associated_type(inner_ty, self.resolve_future_future_output()) } Expr::Cast { expr, type_ref } => { let cast_ty = self.make_ty(type_ref); let expr_ty = self.infer_expr(*expr, &Expectation::Castable(cast_ty.clone())); self.deferred_cast_checks.push(CastCheck::new(expr_ty, cast_ty.clone())); cast_ty } Expr::Ref { expr, rawness, mutability } => { let mutability = lower_to_chalk_mutability(*mutability); let expectation = if let Some((exp_inner, exp_rawness, exp_mutability)) = expected .only_has_type(&mut self.table) .as_ref() .and_then(|t| t.as_reference_or_ptr()) { if exp_mutability == Mutability::Mut && mutability == Mutability::Not { // FIXME: record type error - expected mut reference but found shared ref, // which cannot be coerced } if exp_rawness == Rawness::Ref && *rawness == Rawness::RawPtr { // FIXME: record type error - expected reference but found ptr, // which cannot be coerced } Expectation::rvalue_hint(self, Ty::clone(exp_inner)) } else { Expectation::none() }; let inner_ty = self.infer_expr_inner(*expr, &expectation); match rawness { Rawness::RawPtr => TyKind::Raw(mutability, inner_ty), Rawness::Ref => TyKind::Ref(mutability, static_lifetime(), inner_ty), } .intern(Interner) } &Expr::Box { expr } => self.infer_expr_box(expr, expected), Expr::UnaryOp { expr, op } => { let inner_ty = self.infer_expr_inner(*expr, &Expectation::none()); let inner_ty = self.resolve_ty_shallow(&inner_ty); // FIXME: Note down method resolution her match op { UnaryOp::Deref => { if let Some(deref_trait) = self.resolve_lang_trait(LangItem::Deref) { if let Some(deref_fn) = self.db.trait_data(deref_trait).method_by_name(&name![deref]) { // FIXME: this is wrong in multiple ways, subst is empty, and we emit it even for builtin deref (note that // the mutability is not wrong, and will be fixed in `self.infer_mut`). self.write_method_resolution( tgt_expr, deref_fn, Substitution::empty(Interner), ); } } if let Some(derefed) = builtin_deref(&mut self.table, &inner_ty, true) { self.resolve_ty_shallow(derefed) } else { deref_by_trait(&mut self.table, inner_ty) .unwrap_or_else(|| self.err_ty()) } } UnaryOp::Neg => { match inner_ty.kind(Interner) { // Fast path for builtins TyKind::Scalar(Scalar::Int(_) | Scalar::Uint(_) | Scalar::Float(_)) | TyKind::InferenceVar( _, TyVariableKind::Integer | TyVariableKind::Float, ) => inner_ty, // Otherwise we resolve via the std::ops::Neg trait _ => self .resolve_associated_type(inner_ty, self.resolve_ops_neg_output()), } } UnaryOp::Not => { match inner_ty.kind(Interner) { // Fast path for builtins TyKind::Scalar(Scalar::Bool | Scalar::Int(_) | Scalar::Uint(_)) | TyKind::InferenceVar(_, TyVariableKind::Integer) => inner_ty, // Otherwise we resolve via the std::ops::Not trait _ => self .resolve_associated_type(inner_ty, self.resolve_ops_not_output()), } } } } Expr::BinaryOp { lhs, rhs, op } => match op { Some(BinaryOp::Assignment { op: None }) => { let lhs = *lhs; let is_ordinary = match &self.body[lhs] { Expr::Array(_) | Expr::RecordLit { .. } | Expr::Tuple { .. } | Expr::Underscore => false, Expr::Call { callee, .. } => !matches!(&self.body[*callee], Expr::Path(_)), _ => true, }; // In ordinary (non-destructuring) assignments, the type of // `lhs` must be inferred first so that the ADT fields // instantiations in RHS can be coerced to it. Note that this // cannot happen in destructuring assignments because of how // they are desugared. if is_ordinary { let lhs_ty = self.infer_expr(lhs, &Expectation::none()); self.infer_expr_coerce(*rhs, &Expectation::has_type(lhs_ty)); } else { let rhs_ty = self.infer_expr(*rhs, &Expectation::none()); self.infer_assignee_expr(lhs, &rhs_ty); } self.result.standard_types.unit.clone() } Some(BinaryOp::LogicOp(_)) => { let bool_ty = self.result.standard_types.bool_.clone(); self.infer_expr_coerce(*lhs, &Expectation::HasType(bool_ty.clone())); let lhs_diverges = self.diverges; self.infer_expr_coerce(*rhs, &Expectation::HasType(bool_ty.clone())); // Depending on the LHS' value, the RHS can never execute. self.diverges = lhs_diverges; bool_ty } Some(op) => self.infer_overloadable_binop(*lhs, *op, *rhs, tgt_expr), _ => self.err_ty(), }, Expr::Range { lhs, rhs, range_type } => { let lhs_ty = lhs.map(|e| self.infer_expr_inner(e, &Expectation::none())); let rhs_expect = lhs_ty .as_ref() .map_or_else(Expectation::none, |ty| Expectation::has_type(ty.clone())); let rhs_ty = rhs.map(|e| self.infer_expr(e, &rhs_expect)); match (range_type, lhs_ty, rhs_ty) { (RangeOp::Exclusive, None, None) => match self.resolve_range_full() { Some(adt) => TyBuilder::adt(self.db, adt).build(), None => self.err_ty(), }, (RangeOp::Exclusive, None, Some(ty)) => match self.resolve_range_to() { Some(adt) => TyBuilder::adt(self.db, adt).push(ty).build(), None => self.err_ty(), }, (RangeOp::Inclusive, None, Some(ty)) => { match self.resolve_range_to_inclusive() { Some(adt) => TyBuilder::adt(self.db, adt).push(ty).build(), None => self.err_ty(), } } (RangeOp::Exclusive, Some(_), Some(ty)) => match self.resolve_range() { Some(adt) => TyBuilder::adt(self.db, adt).push(ty).build(), None => self.err_ty(), }, (RangeOp::Inclusive, Some(_), Some(ty)) => { match self.resolve_range_inclusive() { Some(adt) => TyBuilder::adt(self.db, adt).push(ty).build(), None => self.err_ty(), } } (RangeOp::Exclusive, Some(ty), None) => match self.resolve_range_from() { Some(adt) => TyBuilder::adt(self.db, adt).push(ty).build(), None => self.err_ty(), }, (RangeOp::Inclusive, _, None) => self.err_ty(), } } Expr::Index { base, index, is_assignee_expr } => { let base_ty = self.infer_expr_inner(*base, &Expectation::none()); let index_ty = self.infer_expr(*index, &Expectation::none()); if let Some(index_trait) = self.resolve_lang_trait(LangItem::Index) { let canonicalized = self.canonicalize(base_ty.clone()); let receiver_adjustments = method_resolution::resolve_indexing_op( self.db, self.table.trait_env.clone(), canonicalized.value, index_trait, ); let (self_ty, mut adj) = receiver_adjustments .map_or((self.err_ty(), Vec::new()), |adj| { adj.apply(&mut self.table, base_ty) }); // mutability will be fixed up in `InferenceContext::infer_mut`; adj.push(Adjustment::borrow(Mutability::Not, self_ty.clone())); self.write_expr_adj(*base, adj); if let Some(func) = self.db.trait_data(index_trait).method_by_name(&name!(index)) { let substs = TyBuilder::subst_for_def(self.db, index_trait, None) .push(self_ty.clone()) .push(index_ty.clone()) .build(); self.write_method_resolution(tgt_expr, func, substs); } let assoc = self.resolve_ops_index_output(); let res = self.resolve_associated_type_with_params( self_ty.clone(), assoc, &[index_ty.clone().cast(Interner)], ); if *is_assignee_expr { if let Some(index_trait) = self.resolve_lang_trait(LangItem::IndexMut) { let trait_ref = TyBuilder::trait_ref(self.db, index_trait) .push(self_ty) .fill(|_| index_ty.clone().cast(Interner)) .build(); self.push_obligation(trait_ref.cast(Interner)); } } res } else { self.err_ty() } } Expr::Tuple { exprs, .. } => { let mut tys = match expected .only_has_type(&mut self.table) .as_ref() .map(|t| t.kind(Interner)) { Some(TyKind::Tuple(_, substs)) => substs .iter(Interner) .map(|a| a.assert_ty_ref(Interner).clone()) .chain(repeat_with(|| self.table.new_type_var())) .take(exprs.len()) .collect::>(), _ => (0..exprs.len()).map(|_| self.table.new_type_var()).collect(), }; for (expr, ty) in exprs.iter().zip(tys.iter_mut()) { self.infer_expr_coerce(*expr, &Expectation::has_type(ty.clone())); } TyKind::Tuple(tys.len(), Substitution::from_iter(Interner, tys)).intern(Interner) } Expr::Array(array) => self.infer_expr_array(array, expected), Expr::Literal(lit) => match lit { Literal::Bool(..) => self.result.standard_types.bool_.clone(), Literal::String(..) => { TyKind::Ref(Mutability::Not, static_lifetime(), TyKind::Str.intern(Interner)) .intern(Interner) } Literal::ByteString(bs) => { let byte_type = TyKind::Scalar(Scalar::Uint(UintTy::U8)).intern(Interner); let len = consteval::usize_const( self.db, Some(bs.len() as u128), self.resolver.krate(), ); let array_type = TyKind::Array(byte_type, len).intern(Interner); TyKind::Ref(Mutability::Not, static_lifetime(), array_type).intern(Interner) } Literal::CString(..) => TyKind::Ref( Mutability::Not, static_lifetime(), self.resolve_lang_item(LangItem::CStr) .and_then(LangItemTarget::as_struct) .map_or_else( || self.err_ty(), |strukt| { TyKind::Adt(AdtId(strukt.into()), Substitution::empty(Interner)) .intern(Interner) }, ), ) .intern(Interner), Literal::Char(..) => TyKind::Scalar(Scalar::Char).intern(Interner), Literal::Int(_v, ty) => match ty { Some(int_ty) => { TyKind::Scalar(Scalar::Int(primitive::int_ty_from_builtin(*int_ty))) .intern(Interner) } None => self.table.new_integer_var(), }, Literal::Uint(_v, ty) => match ty { Some(int_ty) => { TyKind::Scalar(Scalar::Uint(primitive::uint_ty_from_builtin(*int_ty))) .intern(Interner) } None => self.table.new_integer_var(), }, Literal::Float(_v, ty) => match ty { Some(float_ty) => { TyKind::Scalar(Scalar::Float(primitive::float_ty_from_builtin(*float_ty))) .intern(Interner) } None => self.table.new_float_var(), }, }, Expr::Underscore => { // Underscore expressions may only appear in assignee expressions, // which are handled by `infer_assignee_expr()`. // Any other underscore expression is an error, we render a specialized diagnostic // to let the user know what type is expected though. let expected = expected.to_option(&mut self.table).unwrap_or_else(|| self.err_ty()); self.push_diagnostic(InferenceDiagnostic::TypedHole { expr: tgt_expr, expected: expected.clone(), }); expected } Expr::OffsetOf(_) => TyKind::Scalar(Scalar::Uint(UintTy::Usize)).intern(Interner), Expr::InlineAsm(it) => { self.infer_expr_no_expect(it.e); self.result.standard_types.unit.clone() } }; // use a new type variable if we got unknown here let ty = self.insert_type_vars_shallow(ty); self.write_expr_ty(tgt_expr, ty.clone()); if self.resolve_ty_shallow(&ty).is_never() { // Any expression that produces a value of type `!` must have diverged self.diverges = Diverges::Always; } ty } fn infer_async_block( &mut self, tgt_expr: ExprId, id: &Option, statements: &[Statement], tail: &Option, ) -> Ty { let ret_ty = self.table.new_type_var(); let prev_diverges = mem::replace(&mut self.diverges, Diverges::Maybe); let prev_ret_ty = mem::replace(&mut self.return_ty, ret_ty.clone()); let prev_ret_coercion = mem::replace(&mut self.return_coercion, Some(CoerceMany::new(ret_ty.clone()))); let (_, inner_ty) = self.with_breakable_ctx(BreakableKind::Border, None, None, |this| { this.infer_block(tgt_expr, *id, statements, *tail, None, &Expectation::has_type(ret_ty)) }); self.diverges = prev_diverges; self.return_ty = prev_ret_ty; self.return_coercion = prev_ret_coercion; self.lower_async_block_type_impl_trait(inner_ty, tgt_expr) } pub(crate) fn lower_async_block_type_impl_trait( &mut self, inner_ty: Ty, tgt_expr: ExprId, ) -> Ty { // Use the first type parameter as the output type of future. // existential type AsyncBlockImplTrait: Future let impl_trait_id = crate::ImplTraitId::AsyncBlockTypeImplTrait(self.owner, tgt_expr); let opaque_ty_id = self.db.intern_impl_trait_id(impl_trait_id).into(); TyKind::OpaqueType(opaque_ty_id, Substitution::from1(Interner, inner_ty)).intern(Interner) } pub(crate) fn write_fn_trait_method_resolution( &mut self, fn_x: FnTrait, derefed_callee: &Ty, adjustments: &mut Vec, callee_ty: &Ty, params: &Vec, tgt_expr: ExprId, ) { match fn_x { FnTrait::FnOnce => (), FnTrait::FnMut => { if let TyKind::Ref(Mutability::Mut, _, inner) = derefed_callee.kind(Interner) { if adjustments .last() .map(|it| matches!(it.kind, Adjust::Borrow(_))) .unwrap_or(true) { // prefer reborrow to move adjustments .push(Adjustment { kind: Adjust::Deref(None), target: inner.clone() }); adjustments.push(Adjustment::borrow(Mutability::Mut, inner.clone())) } } else { adjustments.push(Adjustment::borrow(Mutability::Mut, derefed_callee.clone())); } } FnTrait::Fn => { if !matches!(derefed_callee.kind(Interner), TyKind::Ref(Mutability::Not, _, _)) { adjustments.push(Adjustment::borrow(Mutability::Not, derefed_callee.clone())); } } } let Some(trait_) = fn_x.get_id(self.db, self.table.trait_env.krate) else { return; }; let trait_data = self.db.trait_data(trait_); if let Some(func) = trait_data.method_by_name(&fn_x.method_name()) { let subst = TyBuilder::subst_for_def(self.db, trait_, None) .push(callee_ty.clone()) .push(TyBuilder::tuple_with(params.iter().cloned())) .build(); self.write_method_resolution(tgt_expr, func, subst); } } fn infer_expr_array( &mut self, array: &Array, expected: &Expectation, ) -> chalk_ir::Ty { let elem_ty = match expected.to_option(&mut self.table).as_ref().map(|t| t.kind(Interner)) { Some(TyKind::Array(st, _) | TyKind::Slice(st)) => st.clone(), _ => self.table.new_type_var(), }; let krate = self.resolver.krate(); let expected = Expectation::has_type(elem_ty.clone()); let (elem_ty, len) = match array { Array::ElementList { elements, .. } if elements.is_empty() => { (elem_ty, consteval::usize_const(self.db, Some(0), krate)) } Array::ElementList { elements, .. } => { let mut coerce = CoerceMany::new(elem_ty); for &expr in elements.iter() { let cur_elem_ty = self.infer_expr_inner(expr, &expected); coerce.coerce(self, Some(expr), &cur_elem_ty, CoercionCause::Expr(expr)); } ( coerce.complete(self), consteval::usize_const(self.db, Some(elements.len() as u128), krate), ) } &Array::Repeat { initializer, repeat } => { self.infer_expr_coerce(initializer, &Expectation::has_type(elem_ty.clone())); let usize = TyKind::Scalar(Scalar::Uint(UintTy::Usize)).intern(Interner); match self.body[repeat] { Expr::Underscore => { self.write_expr_ty(repeat, usize); } _ => _ = self.infer_expr(repeat, &Expectation::HasType(usize)), } ( elem_ty, if let Some(g_def) = self.owner.as_generic_def_id() { let generics = generics(self.db.upcast(), g_def); consteval::eval_to_const( repeat, ParamLoweringMode::Placeholder, self, || generics, DebruijnIndex::INNERMOST, ) } else { consteval::usize_const(self.db, None, krate) }, ) } }; // Try to evaluate unevaluated constant, and insert variable if is not possible. let len = self.table.insert_const_vars_shallow(len); TyKind::Array(elem_ty, len).intern(Interner) } pub(super) fn infer_return(&mut self, expr: ExprId) { let ret_ty = self .return_coercion .as_mut() .expect("infer_return called outside function body") .expected_ty(); let return_expr_ty = self.infer_expr_inner(expr, &Expectation::HasType(ret_ty)); let mut coerce_many = self.return_coercion.take().unwrap(); coerce_many.coerce(self, Some(expr), &return_expr_ty, CoercionCause::Expr(expr)); self.return_coercion = Some(coerce_many); } fn infer_expr_return(&mut self, ret: ExprId, expr: Option) -> Ty { match self.return_coercion { Some(_) => { if let Some(expr) = expr { self.infer_return(expr); } else { let mut coerce = self.return_coercion.take().unwrap(); coerce.coerce_forced_unit(self, CoercionCause::Expr(ret)); self.return_coercion = Some(coerce); } } None => { // FIXME: diagnose return outside of function if let Some(expr) = expr { self.infer_expr_no_expect(expr); } } } self.result.standard_types.never.clone() } fn infer_expr_box(&mut self, inner_expr: ExprId, expected: &Expectation) -> Ty { if let Some(box_id) = self.resolve_boxed_box() { let table = &mut self.table; let inner_exp = expected .to_option(table) .as_ref() .map(|e| e.as_adt()) .flatten() .filter(|(e_adt, _)| e_adt == &box_id) .map(|(_, subts)| { let g = subts.at(Interner, 0); Expectation::rvalue_hint(self, Ty::clone(g.assert_ty_ref(Interner))) }) .unwrap_or_else(Expectation::none); let inner_ty = self.infer_expr_inner(inner_expr, &inner_exp); TyBuilder::adt(self.db, box_id) .push(inner_ty) .fill_with_defaults(self.db, || self.table.new_type_var()) .build() } else { self.err_ty() } } pub(super) fn infer_assignee_expr(&mut self, lhs: ExprId, rhs_ty: &Ty) -> Ty { let is_rest_expr = |expr| { matches!( &self.body[expr], Expr::Range { lhs: None, rhs: None, range_type: RangeOp::Exclusive }, ) }; let rhs_ty = self.resolve_ty_shallow(rhs_ty); let ty = match &self.body[lhs] { Expr::Tuple { exprs, .. } => { // We don't consider multiple ellipses. This is analogous to // `hir_def::body::lower::ExprCollector::collect_tuple_pat()`. let ellipsis = exprs.iter().position(|e| is_rest_expr(*e)); let exprs: Vec<_> = exprs.iter().filter(|e| !is_rest_expr(**e)).copied().collect(); self.infer_tuple_pat_like(&rhs_ty, (), ellipsis, &exprs) } Expr::Call { callee, args, .. } => { // Tuple structs let path = match &self.body[*callee] { Expr::Path(path) => Some(path), _ => None, }; // We don't consider multiple ellipses. This is analogous to // `hir_def::body::lower::ExprCollector::collect_tuple_pat()`. let ellipsis = args.iter().position(|e| is_rest_expr(*e)); let args: Vec<_> = args.iter().filter(|e| !is_rest_expr(**e)).copied().collect(); self.infer_tuple_struct_pat_like(path, &rhs_ty, (), lhs, ellipsis, &args) } Expr::Array(Array::ElementList { elements, .. }) => { let elem_ty = match rhs_ty.kind(Interner) { TyKind::Array(st, _) => st.clone(), _ => self.err_ty(), }; // There's no need to handle `..` as it cannot be bound. let sub_exprs = elements.iter().filter(|e| !is_rest_expr(**e)); for e in sub_exprs { self.infer_assignee_expr(*e, &elem_ty); } match rhs_ty.kind(Interner) { TyKind::Array(_, _) => rhs_ty.clone(), // Even when `rhs_ty` is not an array type, this assignee // expression is inferred to be an array (of unknown element // type and length). This should not be just an error type, // because we are to compute the unifiability of this type and // `rhs_ty` in the end of this function to issue type mismatches. _ => TyKind::Array( self.err_ty(), crate::consteval::usize_const(self.db, None, self.resolver.krate()), ) .intern(Interner), } } Expr::RecordLit { path, fields, .. } => { let subs = fields.iter().map(|f| (f.name.clone(), f.expr)); self.infer_record_pat_like(path.as_deref(), &rhs_ty, (), lhs, subs) } Expr::Underscore => rhs_ty.clone(), _ => { // `lhs` is a place expression, a unit struct, or an enum variant. let lhs_ty = self.infer_expr_inner(lhs, &Expectation::none()); // This is the only branch where this function may coerce any type. // We are returning early to avoid the unifiability check below. let lhs_ty = self.insert_type_vars_shallow(lhs_ty); let ty = match self.coerce(None, &rhs_ty, &lhs_ty) { Ok(ty) => ty, Err(_) => { self.result.type_mismatches.insert( lhs.into(), TypeMismatch { expected: rhs_ty.clone(), actual: lhs_ty.clone() }, ); // `rhs_ty` is returned so no further type mismatches are // reported because of this mismatch. rhs_ty } }; self.write_expr_ty(lhs, ty.clone()); return ty; } }; let ty = self.insert_type_vars_shallow(ty); if !self.unify(&ty, &rhs_ty) { self.result .type_mismatches .insert(lhs.into(), TypeMismatch { expected: rhs_ty.clone(), actual: ty.clone() }); } self.write_expr_ty(lhs, ty.clone()); ty } fn infer_overloadable_binop( &mut self, lhs: ExprId, op: BinaryOp, rhs: ExprId, tgt_expr: ExprId, ) -> Ty { let lhs_expectation = Expectation::none(); let lhs_ty = self.infer_expr(lhs, &lhs_expectation); let rhs_ty = self.table.new_type_var(); let trait_func = lang_items_for_bin_op(op).and_then(|(name, lang_item)| { let trait_id = self.resolve_lang_item(lang_item)?.as_trait()?; let func = self.db.trait_data(trait_id).method_by_name(&name)?; Some((trait_id, func)) }); let (trait_, func) = match trait_func { Some(it) => it, None => { // HACK: `rhs_ty` is a general inference variable with no clue at all at this // point. Passing `lhs_ty` as both operands just to check if `lhs_ty` is a builtin // type applicable to `op`. let ret_ty = if self.is_builtin_binop(&lhs_ty, &lhs_ty, op) { // Assume both operands are builtin so we can continue inference. No guarantee // on the correctness, rustc would complain as necessary lang items don't seem // to exist anyway. self.enforce_builtin_binop_types(&lhs_ty, &rhs_ty, op) } else { self.err_ty() }; self.infer_expr_coerce(rhs, &Expectation::has_type(rhs_ty)); return ret_ty; } }; // HACK: We can use this substitution for the function because the function itself doesn't // have its own generic parameters. let subst = TyBuilder::subst_for_def(self.db, trait_, None) .push(lhs_ty.clone()) .push(rhs_ty.clone()) .build(); self.write_method_resolution(tgt_expr, func, subst.clone()); let method_ty = self.db.value_ty(func.into()).substitute(Interner, &subst); self.register_obligations_for_call(&method_ty); self.infer_expr_coerce(rhs, &Expectation::has_type(rhs_ty.clone())); let ret_ty = match method_ty.callable_sig(self.db) { Some(sig) => { let p_left = &sig.params()[0]; if matches!(op, BinaryOp::CmpOp(..) | BinaryOp::Assignment { .. }) { if let &TyKind::Ref(mtbl, _, _) = p_left.kind(Interner) { self.write_expr_adj( lhs, vec![Adjustment { kind: Adjust::Borrow(AutoBorrow::Ref(mtbl)), target: p_left.clone(), }], ); } } let p_right = &sig.params()[1]; if matches!(op, BinaryOp::CmpOp(..)) { if let &TyKind::Ref(mtbl, _, _) = p_right.kind(Interner) { self.write_expr_adj( rhs, vec![Adjustment { kind: Adjust::Borrow(AutoBorrow::Ref(mtbl)), target: p_right.clone(), }], ); } } sig.ret().clone() } None => self.err_ty(), }; let ret_ty = self.normalize_associated_types_in(ret_ty); if self.is_builtin_binop(&lhs_ty, &rhs_ty, op) { // use knowledge of built-in binary ops, which can sometimes help inference let builtin_ret = self.enforce_builtin_binop_types(&lhs_ty, &rhs_ty, op); self.unify(&builtin_ret, &ret_ty); } ret_ty } fn infer_block( &mut self, expr: ExprId, block_id: Option, statements: &[Statement], tail: Option, label: Option, expected: &Expectation, ) -> Ty { let coerce_ty = expected.coercion_target_type(&mut self.table); let g = self.resolver.update_to_inner_scope(self.db.upcast(), self.owner, expr); let prev_env = block_id.map(|block_id| { let prev_env = self.table.trait_env.clone(); TraitEnvironment::with_block(&mut self.table.trait_env, block_id); prev_env }); let (break_ty, ty) = self.with_breakable_ctx(BreakableKind::Block, Some(coerce_ty), label, |this| { for stmt in statements { match stmt { Statement::Let { pat, type_ref, initializer, else_branch } => { let decl_ty = type_ref .as_ref() .map(|tr| this.make_ty(tr)) .unwrap_or_else(|| this.table.new_type_var()); let ty = if let Some(expr) = initializer { let ty = if contains_explicit_ref_binding(&this.body, *pat) { this.infer_expr(*expr, &Expectation::has_type(decl_ty.clone())) } else { this.infer_expr_coerce( *expr, &Expectation::has_type(decl_ty.clone()), ) }; if type_ref.is_some() { decl_ty } else { ty } } else { decl_ty }; this.infer_top_pat(*pat, &ty); if let Some(expr) = else_branch { let previous_diverges = mem::replace(&mut this.diverges, Diverges::Maybe); this.infer_expr_coerce( *expr, &Expectation::HasType(this.result.standard_types.never.clone()), ); this.diverges = previous_diverges; } } &Statement::Expr { expr, has_semi } => { if has_semi { this.infer_expr(expr, &Expectation::none()); } else { this.infer_expr_coerce( expr, &Expectation::HasType(this.result.standard_types.unit.clone()), ); } } } } // FIXME: This should make use of the breakable CoerceMany if let Some(expr) = tail { this.infer_expr_coerce(expr, expected) } else { // Citing rustc: if there is no explicit tail expression, // that is typically equivalent to a tail expression // of `()` -- except if the block diverges. In that // case, there is no value supplied from the tail // expression (assuming there are no other breaks, // this implies that the type of the block will be // `!`). if this.diverges.is_always() { // we don't even make an attempt at coercion this.table.new_maybe_never_var() } else if let Some(t) = expected.only_has_type(&mut this.table) { if this .coerce(Some(expr), &this.result.standard_types.unit.clone(), &t) .is_err() { this.result.type_mismatches.insert( expr.into(), TypeMismatch { expected: t.clone(), actual: this.result.standard_types.unit.clone(), }, ); } t } else { this.result.standard_types.unit.clone() } } }); self.resolver.reset_to_guard(g); if let Some(prev_env) = prev_env { self.table.trait_env = prev_env; } break_ty.unwrap_or(ty) } fn lookup_field( &mut self, receiver_ty: &Ty, name: &Name, ) -> Option<(Ty, Either, Vec, bool)> { let mut autoderef = Autoderef::new(&mut self.table, receiver_ty.clone(), false); let mut private_field = None; let res = autoderef.by_ref().find_map(|(derefed_ty, _)| { let (field_id, parameters) = match derefed_ty.kind(Interner) { TyKind::Tuple(_, substs) => { return name.as_tuple_index().and_then(|idx| { substs .as_slice(Interner) .get(idx) .map(|a| a.assert_ty_ref(Interner)) .cloned() .map(|ty| { ( Either::Right(TupleFieldId { tuple: TupleId( self.tuple_field_accesses_rev .insert_full(substs.clone()) .0 as u32, ), index: idx as u32, }), ty, ) }) }); } TyKind::Adt(AdtId(hir_def::AdtId::StructId(s)), parameters) => { let local_id = self.db.struct_data(*s).variant_data.field(name)?; let field = FieldId { parent: (*s).into(), local_id }; (field, parameters.clone()) } TyKind::Adt(AdtId(hir_def::AdtId::UnionId(u)), parameters) => { let local_id = self.db.union_data(*u).variant_data.field(name)?; let field = FieldId { parent: (*u).into(), local_id }; (field, parameters.clone()) } _ => return None, }; let is_visible = self.db.field_visibilities(field_id.parent)[field_id.local_id] .is_visible_from(self.db.upcast(), self.resolver.module()); if !is_visible { if private_field.is_none() { private_field = Some((field_id, parameters)); } return None; } let ty = self.db.field_types(field_id.parent)[field_id.local_id] .clone() .substitute(Interner, ¶meters); Some((Either::Left(field_id), ty)) }); Some(match res { Some((field_id, ty)) => { let adjustments = auto_deref_adjust_steps(&autoderef); let ty = self.insert_type_vars(ty); let ty = self.normalize_associated_types_in(ty); (ty, field_id, adjustments, true) } None => { let (field_id, subst) = private_field?; let adjustments = auto_deref_adjust_steps(&autoderef); let ty = self.db.field_types(field_id.parent)[field_id.local_id] .clone() .substitute(Interner, &subst); let ty = self.insert_type_vars(ty); let ty = self.normalize_associated_types_in(ty); (ty, Either::Left(field_id), adjustments, false) } }) } fn infer_field_access( &mut self, tgt_expr: ExprId, receiver: ExprId, name: &Name, expected: &Expectation, ) -> Ty { let receiver_ty = self.infer_expr_inner(receiver, &Expectation::none()); if name.is_missing() { // Bail out early, don't even try to look up field. Also, we don't issue an unresolved // field diagnostic because this is a syntax error rather than a semantic error. return self.err_ty(); } match self.lookup_field(&receiver_ty, name) { Some((ty, field_id, adjustments, is_public)) => { self.write_expr_adj(receiver, adjustments); self.result.field_resolutions.insert(tgt_expr, field_id); if !is_public { if let Either::Left(field) = field_id { // FIXME: Merge this diagnostic into UnresolvedField? self.result .diagnostics .push(InferenceDiagnostic::PrivateField { expr: tgt_expr, field }); } } ty } None => { // no field found, lets attempt to resolve it like a function so that IDE things // work out while people are typing let canonicalized_receiver = self.canonicalize(receiver_ty.clone()); let resolved = method_resolution::lookup_method( self.db, &canonicalized_receiver.value, self.table.trait_env.clone(), self.get_traits_in_scope().as_ref().left_or_else(|&it| it), VisibleFromModule::Filter(self.resolver.module()), name, ); self.result.diagnostics.push(InferenceDiagnostic::UnresolvedField { expr: tgt_expr, receiver: receiver_ty.clone(), name: name.clone(), method_with_same_name_exists: resolved.is_some(), }); match resolved { Some((adjust, func, _)) => { let (ty, adjustments) = adjust.apply(&mut self.table, receiver_ty); let generics = generics(self.db.upcast(), func.into()); let substs = self.substs_for_method_call(generics, None); self.write_expr_adj(receiver, adjustments); self.write_method_resolution(tgt_expr, func, substs.clone()); self.check_method_call( tgt_expr, &[], self.db.value_ty(func.into()), substs, ty, expected, ) } None => self.err_ty(), } } } } fn infer_method_call( &mut self, tgt_expr: ExprId, receiver: ExprId, args: &[ExprId], method_name: &Name, generic_args: Option<&GenericArgs>, expected: &Expectation, ) -> Ty { let receiver_ty = self.infer_expr_inner(receiver, &Expectation::none()); let canonicalized_receiver = self.canonicalize(receiver_ty.clone()); let resolved = method_resolution::lookup_method( self.db, &canonicalized_receiver.value, self.table.trait_env.clone(), self.get_traits_in_scope().as_ref().left_or_else(|&it| it), VisibleFromModule::Filter(self.resolver.module()), method_name, ); let (receiver_ty, method_ty, substs) = match resolved { Some((adjust, func, visible)) => { let (ty, adjustments) = adjust.apply(&mut self.table, receiver_ty); let generics = generics(self.db.upcast(), func.into()); let substs = self.substs_for_method_call(generics, generic_args); self.write_expr_adj(receiver, adjustments); self.write_method_resolution(tgt_expr, func, substs.clone()); if !visible { self.push_diagnostic(InferenceDiagnostic::PrivateAssocItem { id: tgt_expr.into(), item: func.into(), }) } (ty, self.db.value_ty(func.into()), substs) } None => { let field_with_same_name_exists = match self.lookup_field(&receiver_ty, method_name) { Some((ty, field_id, adjustments, _public)) => { self.write_expr_adj(receiver, adjustments); self.result.field_resolutions.insert(tgt_expr, field_id); Some(ty) } None => None, }; let assoc_func_with_same_name = method_resolution::iterate_method_candidates( &canonicalized_receiver.value, self.db, self.table.trait_env.clone(), self.get_traits_in_scope().as_ref().left_or_else(|&it| it), VisibleFromModule::Filter(self.resolver.module()), Some(method_name), method_resolution::LookupMode::Path, |_ty, item, visible| { if visible { Some(item) } else { None } }, ); self.result.diagnostics.push(InferenceDiagnostic::UnresolvedMethodCall { expr: tgt_expr, receiver: receiver_ty.clone(), name: method_name.clone(), field_with_same_name: field_with_same_name_exists, assoc_func_with_same_name, }); ( receiver_ty, Binders::empty(Interner, self.err_ty()), Substitution::empty(Interner), ) } }; self.check_method_call(tgt_expr, args, method_ty, substs, receiver_ty, expected) } fn check_method_call( &mut self, tgt_expr: ExprId, args: &[ExprId], method_ty: Binders, substs: Substitution, receiver_ty: Ty, expected: &Expectation, ) -> Ty { let method_ty = method_ty.substitute(Interner, &substs); self.register_obligations_for_call(&method_ty); let ((formal_receiver_ty, param_tys), ret_ty, is_varargs) = match method_ty.callable_sig(self.db) { Some(sig) => ( if !sig.params().is_empty() { (sig.params()[0].clone(), sig.params()[1..].to_vec()) } else { (self.err_ty(), Vec::new()) }, sig.ret().clone(), sig.is_varargs, ), None => ((self.err_ty(), Vec::new()), self.err_ty(), true), }; self.unify(&formal_receiver_ty, &receiver_ty); let expected_inputs = self.expected_inputs_for_expected_output(expected, ret_ty.clone(), param_tys.clone()); self.check_call_arguments(tgt_expr, args, &expected_inputs, ¶m_tys, &[], is_varargs); self.normalize_associated_types_in(ret_ty) } fn expected_inputs_for_expected_output( &mut self, expected_output: &Expectation, output: Ty, inputs: Vec, ) -> Vec { if let Some(expected_ty) = expected_output.only_has_type(&mut self.table) { self.table.fudge_inference(|table| { if table.try_unify(&expected_ty, &output).is_ok() { table.resolve_with_fallback(inputs, &|var, kind, _, _| match kind { chalk_ir::VariableKind::Ty(tk) => var.to_ty(Interner, tk).cast(Interner), chalk_ir::VariableKind::Lifetime => { var.to_lifetime(Interner).cast(Interner) } chalk_ir::VariableKind::Const(ty) => { var.to_const(Interner, ty).cast(Interner) } }) } else { Vec::new() } }) } else { Vec::new() } } fn check_call_arguments( &mut self, expr: ExprId, args: &[ExprId], expected_inputs: &[Ty], param_tys: &[Ty], skip_indices: &[u32], is_varargs: bool, ) { if args.len() != param_tys.len() + skip_indices.len() && !is_varargs { self.push_diagnostic(InferenceDiagnostic::MismatchedArgCount { call_expr: expr, expected: param_tys.len() + skip_indices.len(), found: args.len(), }); } // 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 mut skip_indices = skip_indices.into_iter().copied().fuse().peekable(); let param_iter = param_tys.iter().cloned().chain(repeat(self.err_ty())); let expected_iter = expected_inputs .iter() .cloned() .chain(param_iter.clone().skip(expected_inputs.len())); for (idx, ((&arg, param_ty), expected_ty)) in args.iter().zip(param_iter).zip(expected_iter).enumerate() { let is_closure = matches!(&self.body[arg], Expr::Closure { .. }); if is_closure != check_closures { continue; } while skip_indices.peek().map_or(false, |i| *i < idx as u32) { skip_indices.next(); } if skip_indices.peek().copied() == Some(idx as u32) { continue; } // the difference between param_ty and expected here is that // expected is the parameter when the expected *return* type is // taken into account. So in `let _: &[i32] = identity(&[1, 2])` // the expected type is already `&[i32]`, whereas param_ty is // still an unbound type variable. We don't always want to force // the parameter to coerce to the expected type (for example in // `coerce_unsize_expected_type_4`). let param_ty = self.normalize_associated_types_in(param_ty); let expected_ty = self.normalize_associated_types_in(expected_ty); let expected = Expectation::rvalue_hint(self, expected_ty); // infer with the expected type we have... let ty = self.infer_expr_inner(arg, &expected); // then coerce to either the expected type or just the formal parameter type let coercion_target = if let Some(ty) = expected.only_has_type(&mut self.table) { // if we are coercing to the expectation, unify with the // formal parameter type to connect everything self.unify(&ty, ¶m_ty); ty } else { param_ty }; // The function signature may contain some unknown types, so we need to insert // type vars here to avoid type mismatch false positive. let coercion_target = self.insert_type_vars(coercion_target); if self.coerce(Some(arg), &ty, &coercion_target).is_err() { self.result.type_mismatches.insert( arg.into(), TypeMismatch { expected: coercion_target, actual: ty.clone() }, ); } } } } fn substs_for_method_call( &mut self, def_generics: Generics, generic_args: Option<&GenericArgs>, ) -> Substitution { let (parent_params, self_params, type_params, const_params, impl_trait_params) = def_generics.provenance_split(); assert_eq!(self_params, 0); // method shouldn't have another Self param let total_len = parent_params + type_params + const_params + impl_trait_params; let mut substs = Vec::with_capacity(total_len); // handle provided 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, kind_id) in generic_args .args .iter() .filter(|arg| !matches!(arg, GenericArg::Lifetime(_))) .take(type_params + const_params) .zip(def_generics.iter_id()) { if let Some(g) = generic_arg_to_chalk( self.db, kind_id, arg, self, |this, type_ref| this.make_ty(type_ref), |this, c, ty| { const_or_path_to_chalk( this.db, &this.resolver, this.owner.into(), ty, c, ParamLoweringMode::Placeholder, || generics(this.db.upcast(), this.resolver.generic_def().unwrap()), DebruijnIndex::INNERMOST, ) }, ) { substs.push(g); } } }; // Handle everything else as unknown. This also handles generic arguments for the method's // parent (impl or trait), which should come after those for the method. for (id, data) in def_generics.iter().skip(substs.len()) { match data { TypeOrConstParamData::TypeParamData(_) => { substs.push(self.table.new_type_var().cast(Interner)) } TypeOrConstParamData::ConstParamData(_) => substs.push( self.table .new_const_var(self.db.const_param_ty(ConstParamId::from_unchecked(id))) .cast(Interner), ), } } assert_eq!(substs.len(), total_len); Substitution::from_iter(Interner, substs) } fn register_obligations_for_call(&mut self, callable_ty: &Ty) { let callable_ty = self.resolve_ty_shallow(callable_ty); if let TyKind::FnDef(fn_def, parameters) = callable_ty.kind(Interner) { let def: CallableDefId = from_chalk(self.db, *fn_def); let generic_predicates = self.db.generic_predicates(def.into()); for predicate in generic_predicates.iter() { let (predicate, binders) = predicate .clone() .substitute(Interner, parameters) .into_value_and_skipped_binders(); always!(binders.len(Interner) == 0); // quantified where clauses not yet handled self.push_obligation(predicate.cast(Interner)); } // add obligation for trait implementation, if this is a trait method match def { CallableDefId::FunctionId(f) => { if let ItemContainerId::TraitId(trait_) = f.lookup(self.db.upcast()).container { // construct a TraitRef let params_len = parameters.len(Interner); let trait_params_len = generics(self.db.upcast(), trait_.into()).len(); let substs = Substitution::from_iter( Interner, // The generic parameters for the trait come after those for the // function. ¶meters.as_slice(Interner)[params_len - trait_params_len..], ); self.push_obligation( TraitRef { trait_id: to_chalk_trait_id(trait_), substitution: substs } .cast(Interner), ); } } CallableDefId::StructId(_) | CallableDefId::EnumVariantId(_) => {} } } } /// Returns the argument indices to skip. fn check_legacy_const_generics(&mut self, callee: Ty, args: &[ExprId]) -> Box<[u32]> { let (func, subst) = match callee.kind(Interner) { TyKind::FnDef(fn_id, subst) => { let callable = CallableDefId::from_chalk(self.db, *fn_id); let func = match callable { CallableDefId::FunctionId(f) => f, _ => return Default::default(), }; (func, subst) } _ => return Default::default(), }; let data = self.db.function_data(func); if data.legacy_const_generics_indices.is_empty() { return Default::default(); } // only use legacy const generics if the param count matches with them if data.params.len() + data.legacy_const_generics_indices.len() != args.len() { if args.len() <= data.params.len() { return Default::default(); } else { // there are more parameters than there should be without legacy // const params; use them let mut indices = data.legacy_const_generics_indices.clone(); indices.sort(); return indices; } } // check legacy const parameters for (subst_idx, arg_idx) in data.legacy_const_generics_indices.iter().copied().enumerate() { let arg = match subst.at(Interner, subst_idx).constant(Interner) { Some(c) => c, None => continue, // not a const parameter? }; if arg_idx >= args.len() as u32 { continue; } let _ty = arg.data(Interner).ty.clone(); let expected = Expectation::none(); // FIXME use actual const ty, when that is lowered correctly self.infer_expr(args[arg_idx as usize], &expected); // FIXME: evaluate and unify with the const } let mut indices = data.legacy_const_generics_indices.clone(); indices.sort(); indices } /// Dereferences a single level of immutable referencing. fn deref_ty_if_possible(&mut self, ty: &Ty) -> Ty { let ty = self.resolve_ty_shallow(ty); match ty.kind(Interner) { TyKind::Ref(Mutability::Not, _, inner) => self.resolve_ty_shallow(inner), _ => ty, } } /// Enforces expectations on lhs type and rhs type depending on the operator and returns the /// output type of the binary op. fn enforce_builtin_binop_types(&mut self, lhs: &Ty, rhs: &Ty, op: BinaryOp) -> Ty { // Special-case a single layer of referencing, so that things like `5.0 + &6.0f32` work (See rust-lang/rust#57447). let lhs = self.deref_ty_if_possible(lhs); let rhs = self.deref_ty_if_possible(rhs); let (op, is_assign) = match op { BinaryOp::Assignment { op: Some(inner) } => (BinaryOp::ArithOp(inner), true), _ => (op, false), }; let output_ty = match op { BinaryOp::LogicOp(_) => { let bool_ = self.result.standard_types.bool_.clone(); self.unify(&lhs, &bool_); self.unify(&rhs, &bool_); bool_ } BinaryOp::ArithOp(ArithOp::Shl | ArithOp::Shr) => { // result type is same as LHS always lhs } BinaryOp::ArithOp(_) => { // LHS, RHS, and result will have the same type self.unify(&lhs, &rhs); lhs } BinaryOp::CmpOp(_) => { // LHS and RHS will have the same type self.unify(&lhs, &rhs); self.result.standard_types.bool_.clone() } BinaryOp::Assignment { op: None } => { stdx::never!("Simple assignment operator is not binary op."); lhs } BinaryOp::Assignment { .. } => unreachable!("handled above"), }; if is_assign { self.result.standard_types.unit.clone() } else { output_ty } } fn is_builtin_binop(&mut self, lhs: &Ty, rhs: &Ty, op: BinaryOp) -> bool { // Special-case a single layer of referencing, so that things like `5.0 + &6.0f32` work (See rust-lang/rust#57447). let lhs = self.deref_ty_if_possible(lhs); let rhs = self.deref_ty_if_possible(rhs); let op = match op { BinaryOp::Assignment { op: Some(inner) } => BinaryOp::ArithOp(inner), _ => op, }; match op { BinaryOp::LogicOp(_) => true, BinaryOp::ArithOp(ArithOp::Shl | ArithOp::Shr) => { lhs.is_integral() && rhs.is_integral() } BinaryOp::ArithOp( ArithOp::Add | ArithOp::Sub | ArithOp::Mul | ArithOp::Div | ArithOp::Rem, ) => { lhs.is_integral() && rhs.is_integral() || lhs.is_floating_point() && rhs.is_floating_point() } BinaryOp::ArithOp(ArithOp::BitAnd | ArithOp::BitOr | ArithOp::BitXor) => { lhs.is_integral() && rhs.is_integral() || lhs.is_floating_point() && rhs.is_floating_point() || matches!( (lhs.kind(Interner), rhs.kind(Interner)), (TyKind::Scalar(Scalar::Bool), TyKind::Scalar(Scalar::Bool)) ) } BinaryOp::CmpOp(_) => { let is_scalar = |kind| { matches!( kind, &TyKind::Scalar(_) | TyKind::FnDef(..) | TyKind::Function(_) | TyKind::Raw(..) | TyKind::InferenceVar( _, TyVariableKind::Integer | TyVariableKind::Float ) ) }; is_scalar(lhs.kind(Interner)) && is_scalar(rhs.kind(Interner)) } BinaryOp::Assignment { op: None } => { stdx::never!("Simple assignment operator is not binary op."); false } BinaryOp::Assignment { .. } => unreachable!("handled above"), } } fn with_breakable_ctx( &mut self, kind: BreakableKind, ty: Option, label: Option, cb: impl FnOnce(&mut Self) -> T, ) -> (Option, T) { self.breakables.push({ BreakableContext { kind, may_break: false, coerce: ty.map(CoerceMany::new), label } }); let res = cb(self); let ctx = self.breakables.pop().expect("breakable stack broken"); (if ctx.may_break { ctx.coerce.map(|ctx| ctx.complete(self)) } else { None }, res) } }