Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/hir-ty/src/infer/closure.rs')
| -rw-r--r-- | crates/hir-ty/src/infer/closure.rs | 722 |
1 files changed, 718 insertions, 4 deletions
diff --git a/crates/hir-ty/src/infer/closure.rs b/crates/hir-ty/src/infer/closure.rs index a6449d019f..28cb301f3e 100644 --- a/crates/hir-ty/src/infer/closure.rs +++ b/crates/hir-ty/src/infer/closure.rs @@ -1,12 +1,29 @@ //! Inference of closure parameter types based on the closure's expected type. -use chalk_ir::{cast::Cast, AliasEq, AliasTy, FnSubst, WhereClause}; -use hir_def::{expr::ExprId, HasModule}; +use std::{cmp, collections::HashMap, convert::Infallible, mem}; + +use chalk_ir::{cast::Cast, AliasEq, AliasTy, FnSubst, Mutability, TyKind, WhereClause}; +use hir_def::{ + hir::{ + Array, BinaryOp, BindingAnnotation, BindingId, CaptureBy, Expr, ExprId, Pat, PatId, + Statement, UnaryOp, + }, + lang_item::LangItem, + resolver::{resolver_for_expr, ResolveValueResult, ValueNs}, + FieldId, HasModule, VariantId, +}; +use hir_expand::name; +use rustc_hash::FxHashMap; use smallvec::SmallVec; +use stdx::never; use crate::{ - to_chalk_trait_id, utils, ChalkTraitId, DynTy, FnPointer, FnSig, Interner, Substitution, Ty, - TyExt, TyKind, + mir::{BorrowKind, ProjectionElem}, + static_lifetime, to_chalk_trait_id, + traits::FnTrait, + utils::{self, pattern_matching_dereference_count}, + Adjust, Adjustment, Canonical, CanonicalVarKinds, ChalkTraitId, ClosureId, DynTy, FnPointer, + FnSig, InEnvironment, Interner, Substitution, Ty, TyBuilder, TyExt, }; use super::{Expectation, InferenceContext}; @@ -86,3 +103,700 @@ impl InferenceContext<'_> { None } } + +// The below functions handle capture and closure kind (Fn, FnMut, ..) + +#[derive(Debug, Clone, PartialEq, Eq, Hash)] +pub(crate) struct HirPlace { + pub(crate) local: BindingId, + pub(crate) projections: Vec<ProjectionElem<Infallible, Ty>>, +} +impl HirPlace { + fn ty(&self, ctx: &mut InferenceContext<'_>) -> Ty { + let mut ty = ctx.table.resolve_completely(ctx.result[self.local].clone()); + for p in &self.projections { + ty = p.projected_ty(ty, ctx.db, |_, _| { + unreachable!("Closure field only happens in MIR"); + }); + } + ty.clone() + } +} + +#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)] +pub(crate) enum CaptureKind { + ByRef(BorrowKind), + ByValue, +} + +#[derive(Debug, Clone, PartialEq, Eq)] +pub(crate) struct CapturedItem { + pub(crate) place: HirPlace, + pub(crate) kind: CaptureKind, + pub(crate) ty: Ty, +} + +#[derive(Debug, Clone, PartialEq, Eq)] +pub(crate) struct CapturedItemWithoutTy { + pub(crate) place: HirPlace, + pub(crate) kind: CaptureKind, +} + +impl CapturedItemWithoutTy { + fn with_ty(self, ctx: &mut InferenceContext<'_>) -> CapturedItem { + let ty = self.place.ty(ctx).clone(); + let ty = match &self.kind { + CaptureKind::ByValue => ty, + CaptureKind::ByRef(bk) => { + let m = match bk { + BorrowKind::Mut { .. } => Mutability::Mut, + _ => Mutability::Not, + }; + TyKind::Ref(m, static_lifetime(), ty).intern(Interner) + } + }; + CapturedItem { place: self.place, kind: self.kind, ty } + } +} + +impl InferenceContext<'_> { + fn place_of_expr(&mut self, tgt_expr: ExprId) -> Option<HirPlace> { + let r = self.place_of_expr_without_adjust(tgt_expr)?; + let default = vec![]; + let adjustments = self.result.expr_adjustments.get(&tgt_expr).unwrap_or(&default); + apply_adjusts_to_place(r, adjustments) + } + + fn place_of_expr_without_adjust(&mut self, tgt_expr: ExprId) -> Option<HirPlace> { + match &self.body[tgt_expr] { + Expr::Path(p) => { + let resolver = resolver_for_expr(self.db.upcast(), self.owner, tgt_expr); + if let Some(r) = resolver.resolve_path_in_value_ns(self.db.upcast(), p) { + if let ResolveValueResult::ValueNs(v) = r { + if let ValueNs::LocalBinding(b) = v { + return Some(HirPlace { local: b, projections: vec![] }); + } + } + } + } + Expr::Field { expr, name } => { + let mut place = self.place_of_expr(*expr)?; + if let TyKind::Tuple(..) = self.expr_ty(*expr).kind(Interner) { + let index = name.as_tuple_index()?; + place.projections.push(ProjectionElem::TupleOrClosureField(index)) + } else { + let field = self.result.field_resolution(tgt_expr)?; + place.projections.push(ProjectionElem::Field(field)); + } + return Some(place); + } + _ => (), + } + None + } + + fn push_capture(&mut self, capture: CapturedItemWithoutTy) { + self.current_captures.push(capture); + } + + fn ref_expr(&mut self, expr: ExprId) { + if let Some(place) = self.place_of_expr(expr) { + self.add_capture(place, CaptureKind::ByRef(BorrowKind::Shared)); + } + self.walk_expr(expr); + } + + fn add_capture(&mut self, place: HirPlace, kind: CaptureKind) { + if self.is_upvar(&place) { + self.push_capture(CapturedItemWithoutTy { place, kind }); + } + } + + fn mutate_expr(&mut self, expr: ExprId) { + if let Some(place) = self.place_of_expr(expr) { + self.add_capture( + place, + CaptureKind::ByRef(BorrowKind::Mut { allow_two_phase_borrow: false }), + ); + } + self.walk_expr(expr); + } + + fn consume_expr(&mut self, expr: ExprId) { + if let Some(place) = self.place_of_expr(expr) { + self.consume_place(place); + } + self.walk_expr(expr); + } + + fn consume_place(&mut self, place: HirPlace) { + if self.is_upvar(&place) { + let ty = place.ty(self).clone(); + let kind = if self.is_ty_copy(ty) { + CaptureKind::ByRef(BorrowKind::Shared) + } else { + CaptureKind::ByValue + }; + self.push_capture(CapturedItemWithoutTy { place, kind }); + } + } + + fn walk_expr_with_adjust(&mut self, tgt_expr: ExprId, adjustment: &[Adjustment]) { + if let Some((last, rest)) = adjustment.split_last() { + match last.kind { + Adjust::NeverToAny | Adjust::Deref(None) | Adjust::Pointer(_) => { + self.walk_expr_with_adjust(tgt_expr, rest) + } + Adjust::Deref(Some(m)) => match m.0 { + Some(m) => { + self.ref_capture_with_adjusts(m, tgt_expr, rest); + } + None => unreachable!(), + }, + Adjust::Borrow(b) => { + self.ref_capture_with_adjusts(b.mutability(), tgt_expr, rest); + } + } + } else { + self.walk_expr_without_adjust(tgt_expr); + } + } + + fn ref_capture_with_adjusts(&mut self, m: Mutability, tgt_expr: ExprId, rest: &[Adjustment]) { + let capture_kind = match m { + Mutability::Mut => { + CaptureKind::ByRef(BorrowKind::Mut { allow_two_phase_borrow: false }) + } + Mutability::Not => CaptureKind::ByRef(BorrowKind::Shared), + }; + if let Some(place) = self.place_of_expr_without_adjust(tgt_expr) { + if let Some(place) = apply_adjusts_to_place(place, rest) { + if self.is_upvar(&place) { + self.push_capture(CapturedItemWithoutTy { place, kind: capture_kind }); + } + } + } + self.walk_expr_with_adjust(tgt_expr, rest); + } + + fn walk_expr(&mut self, tgt_expr: ExprId) { + if let Some(x) = self.result.expr_adjustments.get_mut(&tgt_expr) { + // FIXME: this take is completely unneeded, and just is here to make borrow checker + // happy. Remove it if you can. + let x_taken = mem::take(x); + self.walk_expr_with_adjust(tgt_expr, &x_taken); + *self.result.expr_adjustments.get_mut(&tgt_expr).unwrap() = x_taken; + } else { + self.walk_expr_without_adjust(tgt_expr); + } + } + + fn walk_expr_without_adjust(&mut self, tgt_expr: ExprId) { + match &self.body[tgt_expr] { + Expr::If { condition, then_branch, else_branch } => { + self.consume_expr(*condition); + self.consume_expr(*then_branch); + if let &Some(expr) = else_branch { + self.consume_expr(expr); + } + } + Expr::Async { statements, tail, .. } + | Expr::Const { statements, tail, .. } + | Expr::Unsafe { statements, tail, .. } + | Expr::Block { statements, tail, .. } => { + for s in statements.iter() { + match s { + Statement::Let { pat, type_ref: _, initializer, else_branch } => { + if let Some(else_branch) = else_branch { + self.consume_expr(*else_branch); + if let Some(initializer) = initializer { + self.consume_expr(*initializer); + } + return; + } + if let Some(initializer) = initializer { + self.walk_expr(*initializer); + if let Some(place) = self.place_of_expr(*initializer) { + let ty = self.expr_ty(*initializer); + self.consume_with_pat( + place, + ty, + BindingAnnotation::Unannotated, + *pat, + ); + } + } + } + Statement::Expr { expr, has_semi: _ } => { + self.consume_expr(*expr); + } + } + } + if let Some(tail) = tail { + self.consume_expr(*tail); + } + } + Expr::While { condition, body, label: _ } + | Expr::For { iterable: condition, pat: _, body, label: _ } => { + self.consume_expr(*condition); + self.consume_expr(*body); + } + Expr::Call { callee, args, is_assignee_expr: _ } => { + self.consume_expr(*callee); + self.consume_exprs(args.iter().copied()); + } + Expr::MethodCall { receiver, args, .. } => { + self.consume_expr(*receiver); + self.consume_exprs(args.iter().copied()); + } + Expr::Match { expr, arms } => { + self.consume_expr(*expr); + for arm in arms.iter() { + self.consume_expr(arm.expr); + } + } + Expr::Break { expr, label: _ } + | Expr::Return { expr } + | Expr::Yield { expr } + | Expr::Yeet { expr } => { + if let &Some(expr) = expr { + self.consume_expr(expr); + } + } + Expr::RecordLit { fields, spread, .. } => { + if let &Some(expr) = spread { + self.consume_expr(expr); + } + self.consume_exprs(fields.iter().map(|x| x.expr)); + } + Expr::Field { expr, name: _ } => self.select_from_expr(*expr), + Expr::UnaryOp { expr, op: UnaryOp::Deref } => { + if let Some((f, _)) = self.result.method_resolution(tgt_expr) { + let mutability = 'b: { + if let Some(deref_trait) = + self.resolve_lang_item(LangItem::DerefMut).and_then(|x| x.as_trait()) + { + if let Some(deref_fn) = + self.db.trait_data(deref_trait).method_by_name(&name![deref_mut]) + { + break 'b deref_fn == f; + } + } + false + }; + if mutability { + self.mutate_expr(*expr); + } else { + self.ref_expr(*expr); + } + } else { + self.select_from_expr(*expr); + } + } + Expr::UnaryOp { expr, op: _ } + | Expr::Array(Array::Repeat { initializer: expr, repeat: _ }) + | Expr::Await { expr } + | Expr::Loop { body: expr, label: _ } + | Expr::Let { pat: _, expr } + | Expr::Box { expr } + | Expr::Cast { expr, type_ref: _ } => { + self.consume_expr(*expr); + } + Expr::Ref { expr, rawness: _, mutability } => match mutability { + hir_def::type_ref::Mutability::Shared => self.ref_expr(*expr), + hir_def::type_ref::Mutability::Mut => self.mutate_expr(*expr), + }, + Expr::BinaryOp { lhs, rhs, op } => { + let Some(op) = op else { + return; + }; + if matches!(op, BinaryOp::Assignment { .. }) { + self.mutate_expr(*lhs); + self.consume_expr(*rhs); + return; + } + self.consume_expr(*lhs); + self.consume_expr(*rhs); + } + Expr::Range { lhs, rhs, range_type: _ } => { + if let &Some(expr) = lhs { + self.consume_expr(expr); + } + if let &Some(expr) = rhs { + self.consume_expr(expr); + } + } + Expr::Index { base, index } => { + self.select_from_expr(*base); + self.consume_expr(*index); + } + Expr::Closure { .. } => { + let ty = self.expr_ty(tgt_expr); + let TyKind::Closure(id, _) = ty.kind(Interner) else { + never!("closure type is always closure"); + return; + }; + let (captures, _) = + self.result.closure_info.get(id).expect( + "We sort closures, so we should always have data for inner closures", + ); + let mut cc = mem::take(&mut self.current_captures); + cc.extend( + captures + .iter() + .filter(|x| self.is_upvar(&x.place)) + .map(|x| CapturedItemWithoutTy { place: x.place.clone(), kind: x.kind }), + ); + self.current_captures = cc; + } + Expr::Array(Array::ElementList { elements: exprs, is_assignee_expr: _ }) + | Expr::Tuple { exprs, is_assignee_expr: _ } => { + self.consume_exprs(exprs.iter().copied()) + } + Expr::Missing + | Expr::Continue { .. } + | Expr::Path(_) + | Expr::Literal(_) + | Expr::Underscore => (), + } + } + + fn expr_ty(&mut self, expr: ExprId) -> Ty { + self.result[expr].clone() + } + + fn is_upvar(&self, place: &HirPlace) -> bool { + let b = &self.body[place.local]; + if let Some(c) = self.current_closure { + let (_, root) = self.db.lookup_intern_closure(c.into()); + return b.is_upvar(root); + } + false + } + + fn is_ty_copy(&self, ty: Ty) -> bool { + if let TyKind::Closure(id, _) = ty.kind(Interner) { + // FIXME: We handle closure as a special case, since chalk consider every closure as copy. We + // should probably let chalk know which closures are copy, but I don't know how doing it + // without creating query cycles. + return self.result.closure_info.get(id).map(|x| x.1 == FnTrait::Fn).unwrap_or(true); + } + let crate_id = self.owner.module(self.db.upcast()).krate(); + let Some(copy_trait) = self.db.lang_item(crate_id, LangItem::Copy).and_then(|x| x.as_trait()) else { + return false; + }; + let trait_ref = TyBuilder::trait_ref(self.db, copy_trait).push(ty).build(); + let env = self.db.trait_environment_for_body(self.owner); + let goal = Canonical { + value: InEnvironment::new(&env.env, trait_ref.cast(Interner)), + binders: CanonicalVarKinds::empty(Interner), + }; + self.db.trait_solve(crate_id, None, goal).is_some() + } + + fn select_from_expr(&mut self, expr: ExprId) { + self.walk_expr(expr); + } + + fn adjust_for_move_closure(&mut self) { + for capture in &mut self.current_captures { + if let Some(first_deref) = + capture.place.projections.iter().position(|proj| *proj == ProjectionElem::Deref) + { + capture.place.projections.truncate(first_deref); + } + capture.kind = CaptureKind::ByValue; + } + } + + fn minimize_captures(&mut self) { + self.current_captures.sort_by_key(|x| x.place.projections.len()); + let mut hash_map = HashMap::<HirPlace, usize>::new(); + let result = mem::take(&mut self.current_captures); + for item in result { + let mut lookup_place = HirPlace { local: item.place.local, projections: vec![] }; + let mut it = item.place.projections.iter(); + let prev_index = loop { + if let Some(k) = hash_map.get(&lookup_place) { + break Some(*k); + } + match it.next() { + Some(x) => lookup_place.projections.push(x.clone()), + None => break None, + } + }; + match prev_index { + Some(p) => { + self.current_captures[p].kind = + cmp::max(item.kind, self.current_captures[p].kind); + } + None => { + hash_map.insert(item.place.clone(), self.current_captures.len()); + self.current_captures.push(item); + } + } + } + } + + fn consume_with_pat( + &mut self, + mut place: HirPlace, + mut ty: Ty, + mut bm: BindingAnnotation, + pat: PatId, + ) { + match &self.body[pat] { + Pat::Missing | Pat::Wild => (), + Pat::Tuple { args, ellipsis } => { + pattern_matching_dereference(&mut ty, &mut bm, &mut place); + let (al, ar) = args.split_at(ellipsis.unwrap_or(args.len())); + let subst = match ty.kind(Interner) { + TyKind::Tuple(_, s) => s, + _ => return, + }; + let fields = subst.iter(Interner).map(|x| x.assert_ty_ref(Interner)).enumerate(); + let it = al.iter().zip(fields.clone()).chain(ar.iter().rev().zip(fields.rev())); + for (arg, (i, ty)) in it { + let mut p = place.clone(); + p.projections.push(ProjectionElem::TupleOrClosureField(i)); + self.consume_with_pat(p, ty.clone(), bm, *arg); + } + } + Pat::Or(pats) => { + for pat in pats.iter() { + self.consume_with_pat(place.clone(), ty.clone(), bm, *pat); + } + } + Pat::Record { args, .. } => { + pattern_matching_dereference(&mut ty, &mut bm, &mut place); + let subst = match ty.kind(Interner) { + TyKind::Adt(_, s) => s, + _ => return, + }; + let Some(variant) = self.result.variant_resolution_for_pat(pat) else { + return; + }; + match variant { + VariantId::EnumVariantId(_) | VariantId::UnionId(_) => { + self.consume_place(place) + } + VariantId::StructId(s) => { + let vd = &*self.db.struct_data(s).variant_data; + let field_types = self.db.field_types(variant); + for field_pat in args.iter() { + let arg = field_pat.pat; + let Some(local_id) = vd.field(&field_pat.name) else { + continue; + }; + let mut p = place.clone(); + p.projections.push(ProjectionElem::Field(FieldId { + parent: variant.into(), + local_id, + })); + self.consume_with_pat( + p, + field_types[local_id].clone().substitute(Interner, subst), + bm, + arg, + ); + } + } + } + } + Pat::Range { .. } + | Pat::Slice { .. } + | Pat::ConstBlock(_) + | Pat::Path(_) + | Pat::Lit(_) => self.consume_place(place), + Pat::Bind { id, subpat: _ } => { + let mode = self.body.bindings[*id].mode; + if matches!(mode, BindingAnnotation::Ref | BindingAnnotation::RefMut) { + bm = mode; + } + let capture_kind = match bm { + BindingAnnotation::Unannotated | BindingAnnotation::Mutable => { + self.consume_place(place); + return; + } + BindingAnnotation::Ref => BorrowKind::Shared, + BindingAnnotation::RefMut => BorrowKind::Mut { allow_two_phase_borrow: false }, + }; + self.add_capture(place, CaptureKind::ByRef(capture_kind)); + } + Pat::TupleStruct { path: _, args, ellipsis } => { + pattern_matching_dereference(&mut ty, &mut bm, &mut place); + let subst = match ty.kind(Interner) { + TyKind::Adt(_, s) => s, + _ => return, + }; + let Some(variant) = self.result.variant_resolution_for_pat(pat) else { + return; + }; + match variant { + VariantId::EnumVariantId(_) | VariantId::UnionId(_) => { + self.consume_place(place) + } + VariantId::StructId(s) => { + let vd = &*self.db.struct_data(s).variant_data; + let (al, ar) = args.split_at(ellipsis.unwrap_or(args.len())); + let fields = vd.fields().iter(); + let it = + al.iter().zip(fields.clone()).chain(ar.iter().rev().zip(fields.rev())); + let field_types = self.db.field_types(variant); + for (arg, (i, _)) in it { + let mut p = place.clone(); + p.projections.push(ProjectionElem::Field(FieldId { + parent: variant.into(), + local_id: i, + })); + self.consume_with_pat( + p, + field_types[i].clone().substitute(Interner, subst), + bm, + *arg, + ); + } + } + } + } + Pat::Ref { pat, mutability: _ } => { + if let Some((inner, _, _)) = ty.as_reference() { + ty = inner.clone(); + place.projections.push(ProjectionElem::Deref); + self.consume_with_pat(place, ty, bm, *pat) + } + } + Pat::Box { .. } => (), // not supported + } + } + + fn consume_exprs(&mut self, exprs: impl Iterator<Item = ExprId>) { + for expr in exprs { + self.consume_expr(expr); + } + } + + fn closure_kind(&self) -> FnTrait { + let mut r = FnTrait::Fn; + for x in &self.current_captures { + r = cmp::min( + r, + match &x.kind { + CaptureKind::ByRef(BorrowKind::Unique | BorrowKind::Mut { .. }) => { + FnTrait::FnMut + } + CaptureKind::ByRef(BorrowKind::Shallow | BorrowKind::Shared) => FnTrait::Fn, + CaptureKind::ByValue => FnTrait::FnOnce, + }, + ) + } + r + } + + fn analyze_closure(&mut self, closure: ClosureId) -> FnTrait { + let (_, root) = self.db.lookup_intern_closure(closure.into()); + self.current_closure = Some(closure); + let Expr::Closure { body, capture_by, .. } = &self.body[root] else { + unreachable!("Closure expression id is always closure"); + }; + self.consume_expr(*body); + for item in &self.current_captures { + if matches!(item.kind, CaptureKind::ByRef(BorrowKind::Mut { .. })) { + // FIXME: remove the `mutated_bindings_in_closure` completely and add proper fake reads in + // MIR. I didn't do that due duplicate diagnostics. + self.result.mutated_bindings_in_closure.insert(item.place.local); + } + } + // closure_kind should be done before adjust_for_move_closure + let closure_kind = self.closure_kind(); + match capture_by { + CaptureBy::Value => self.adjust_for_move_closure(), + CaptureBy::Ref => (), + } + self.minimize_captures(); + let result = mem::take(&mut self.current_captures); + let captures = result.into_iter().map(|x| x.with_ty(self)).collect::<Vec<_>>(); + self.result.closure_info.insert(closure, (captures, closure_kind)); + closure_kind + } + + pub(crate) fn infer_closures(&mut self) { + let deferred_closures = self.sort_closures(); + for (closure, exprs) in deferred_closures.into_iter().rev() { + self.current_captures = vec![]; + let kind = self.analyze_closure(closure); + + for (derefed_callee, callee_ty, params, expr) in exprs { + if let &Expr::Call { callee, .. } = &self.body[expr] { + let mut adjustments = + self.result.expr_adjustments.remove(&callee).unwrap_or_default(); + self.write_fn_trait_method_resolution( + kind, + &derefed_callee, + &mut adjustments, + &callee_ty, + ¶ms, + expr, + ); + self.result.expr_adjustments.insert(callee, adjustments); + } + } + } + } + + /// We want to analyze some closures before others, to have a correct analysis: + /// * We should analyze nested closures before the parent, since the parent should capture some of + /// the things that its children captures. + /// * If a closure calls another closure, we need to analyze the callee, to find out how we should + /// capture it (e.g. by move for FnOnce) + /// + /// These dependencies are collected in the main inference. We do a topological sort in this function. It + /// will consume the `deferred_closures` field and return its content in a sorted vector. + fn sort_closures(&mut self) -> Vec<(ClosureId, Vec<(Ty, Ty, Vec<Ty>, ExprId)>)> { + let mut deferred_closures = mem::take(&mut self.deferred_closures); + let mut dependents_count: FxHashMap<ClosureId, usize> = + deferred_closures.keys().map(|x| (*x, 0)).collect(); + for (_, deps) in &self.closure_dependecies { + for dep in deps { + *dependents_count.entry(*dep).or_default() += 1; + } + } + let mut queue: Vec<_> = + deferred_closures.keys().copied().filter(|x| dependents_count[x] == 0).collect(); + let mut result = vec![]; + while let Some(x) = queue.pop() { + if let Some(d) = deferred_closures.remove(&x) { + result.push((x, d)); + } + for dep in self.closure_dependecies.get(&x).into_iter().flat_map(|x| x.iter()) { + let cnt = dependents_count.get_mut(dep).unwrap(); + *cnt -= 1; + if *cnt == 0 { + queue.push(*dep); + } + } + } + result + } +} + +fn apply_adjusts_to_place(mut r: HirPlace, adjustments: &[Adjustment]) -> Option<HirPlace> { + for adj in adjustments { + match &adj.kind { + Adjust::Deref(None) => { + r.projections.push(ProjectionElem::Deref); + } + _ => return None, + } + } + Some(r) +} + +fn pattern_matching_dereference( + cond_ty: &mut Ty, + binding_mode: &mut BindingAnnotation, + cond_place: &mut HirPlace, +) { + let cnt = pattern_matching_dereference_count(cond_ty, binding_mode); + cond_place.projections.extend((0..cnt).map(|_| ProjectionElem::Deref)); +} |