| //! Type inference for patterns. |
| |
| use std::iter::repeat; |
| use std::sync::Arc; |
| |
| use hir_def::{ |
| expr::{BindingAnnotation, Expr, Literal, Pat, PatId, RecordFieldPat}, |
| path::Path, |
| type_ref::Mutability, |
| FieldId, |
| }; |
| use hir_expand::name::Name; |
| use test_utils::mark; |
| |
| use super::{BindingMode, Expectation, InferenceContext}; |
| use crate::{utils::variant_data, Substs, Ty, TypeCtor}; |
| |
| impl<'a> InferenceContext<'a> { |
| fn infer_tuple_struct_pat( |
| &mut self, |
| path: Option<&Path>, |
| subpats: &[PatId], |
| expected: &Ty, |
| default_bm: BindingMode, |
| id: PatId, |
| ) -> Ty { |
| let (ty, def) = self.resolve_variant(path); |
| let var_data = def.map(|it| variant_data(self.db.upcast(), it)); |
| 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); |
| |
| let field_tys = def.map(|it| self.db.field_types(it)).unwrap_or_default(); |
| |
| for (i, &subpat) in subpats.iter().enumerate() { |
| let expected_ty = var_data |
| .as_ref() |
| .and_then(|d| d.field(&Name::new_tuple_field(i))) |
| .map_or(Ty::Unknown, |field| field_tys[field].clone().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); |
| let var_data = def.map(|it| variant_data(self.db.upcast(), it)); |
| 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); |
| |
| let field_tys = def.map(|it| self.db.field_types(it)).unwrap_or_default(); |
| for subpat in subpats { |
| let matching_field = var_data.as_ref().and_then(|it| it.field(&subpat.name)); |
| if let Some(local_id) = matching_field { |
| let field_def = FieldId { parent: def.unwrap(), local_id }; |
| self.result.record_field_pat_resolutions.insert(subpat.pat, field_def); |
| } |
| |
| let expected_ty = |
| matching_field.map_or(Ty::Unknown, |field| field_tys[field].clone().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 |
| |
| if is_non_ref_pat(&body, 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] { |
| mark::hit!(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::Or(ref pats) => { |
| if let Some((first_pat, rest)) = pats.split_first() { |
| let ty = self.infer_pat(*first_pat, expected, default_bm); |
| for pat in rest { |
| self.infer_pat(*pat, expected, default_bm); |
| } |
| ty |
| } else { |
| Ty::Unknown |
| } |
| } |
| 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) |
| } |
| Pat::Record { path: p, args: fields, ellipsis: _ } => { |
| 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(bound_ty); |
| self.write_pat_ty(pat, bound_ty); |
| return inner_ty; |
| } |
| Pat::Slice { prefix, slice, suffix } => { |
| let (container_ty, elem_ty) = match &expected { |
| ty_app!(TypeCtor::Array, st) => (TypeCtor::Array, st.as_single().clone()), |
| ty_app!(TypeCtor::Slice, st) => (TypeCtor::Slice, st.as_single().clone()), |
| _ => (TypeCtor::Slice, Ty::Unknown), |
| }; |
| |
| for pat_id in prefix.iter().chain(suffix) { |
| self.infer_pat(*pat_id, &elem_ty, default_bm); |
| } |
| |
| let pat_ty = Ty::apply_one(container_ty, elem_ty); |
| if let Some(slice_pat_id) = slice { |
| self.infer_pat(*slice_pat_id, &pat_ty, default_bm); |
| } |
| |
| pat_ty |
| } |
| Pat::Wild => expected.clone(), |
| Pat::Range { start, end } => { |
| let start_ty = self.infer_expr(*start, &Expectation::has_type(expected.clone())); |
| let end_ty = self.infer_expr(*end, &Expectation::has_type(start_ty)); |
| end_ty |
| } |
| Pat::Lit(expr) => self.infer_expr(*expr, &Expectation::has_type(expected.clone())), |
| Pat::Missing => Ty::Unknown, |
| }; |
| // use a new type variable if we got Ty::Unknown here |
| let ty = self.insert_type_vars_shallow(ty); |
| if !self.unify(&ty, expected) { |
| // FIXME record mismatch, we need to change the type of self.type_mismatches for that |
| } |
| let ty = self.resolve_ty_as_possible(ty); |
| self.write_pat_ty(pat, ty.clone()); |
| ty |
| } |
| } |
| |
| fn is_non_ref_pat(body: &hir_def::body::Body, pat: PatId) -> bool { |
| match &body[pat] { |
| Pat::Tuple { .. } |
| | Pat::TupleStruct { .. } |
| | Pat::Record { .. } |
| | Pat::Range { .. } |
| | Pat::Slice { .. } => true, |
| Pat::Or(pats) => pats.iter().all(|p| is_non_ref_pat(body, *p)), |
| // FIXME: Path/Lit might actually evaluate to ref, but inference is unimplemented. |
| Pat::Path(..) => true, |
| Pat::Lit(expr) => match body[*expr] { |
| Expr::Literal(Literal::String(..)) => false, |
| _ => true, |
| }, |
| Pat::Wild | Pat::Bind { .. } | Pat::Ref { .. } | Pat::Missing => false, |
| } |
| } |