| use super::implicit_clone::is_clone_like; |
| use super::unnecessary_iter_cloned::{self, is_into_iter}; |
| use clippy_config::msrvs::{self, Msrv}; |
| use clippy_utils::diagnostics::span_lint_and_sugg; |
| use clippy_utils::source::snippet_opt; |
| use clippy_utils::ty::{ |
| get_iterator_item_ty, implements_trait, is_copy, is_type_diagnostic_item, is_type_lang_item, peel_mid_ty_refs, |
| }; |
| use clippy_utils::visitors::find_all_ret_expressions; |
| use clippy_utils::{fn_def_id, get_parent_expr, is_diag_item_method, is_diag_trait_item, return_ty}; |
| use rustc_errors::Applicability; |
| use rustc_hir::def::{DefKind, Res}; |
| use rustc_hir::def_id::DefId; |
| use rustc_hir::{BorrowKind, Expr, ExprKind, ItemKind, LangItem, Node}; |
| use rustc_hir_typeck::{FnCtxt, Inherited}; |
| use rustc_infer::infer::TyCtxtInferExt; |
| use rustc_lint::LateContext; |
| use rustc_middle::mir::Mutability; |
| use rustc_middle::ty::adjustment::{Adjust, Adjustment, OverloadedDeref}; |
| use rustc_middle::ty::{ |
| self, ClauseKind, GenericArg, GenericArgKind, GenericArgsRef, ImplPolarity, ParamTy, ProjectionPredicate, |
| TraitPredicate, Ty, |
| }; |
| use rustc_span::{sym, Symbol}; |
| use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _; |
| use rustc_trait_selection::traits::{Obligation, ObligationCause}; |
| |
| use super::UNNECESSARY_TO_OWNED; |
| |
| pub fn check<'tcx>( |
| cx: &LateContext<'tcx>, |
| expr: &'tcx Expr<'tcx>, |
| method_name: Symbol, |
| receiver: &'tcx Expr<'_>, |
| args: &'tcx [Expr<'_>], |
| msrv: &Msrv, |
| ) { |
| if let Some(method_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id) |
| && args.is_empty() |
| { |
| if is_cloned_or_copied(cx, method_name, method_def_id) { |
| unnecessary_iter_cloned::check(cx, expr, method_name, receiver); |
| } else if is_to_owned_like(cx, expr, method_name, method_def_id) { |
| if check_split_call_arg(cx, expr, method_name, receiver) { |
| return; |
| } |
| // At this point, we know the call is of a `to_owned`-like function. The functions |
| // `check_addr_of_expr` and `check_call_arg` determine whether the call is unnecessary |
| // based on its context, that is, whether it is a referent in an `AddrOf` expression, an |
| // argument in a `into_iter` call, or an argument in the call of some other function. |
| if check_addr_of_expr(cx, expr, method_name, method_def_id, receiver) { |
| return; |
| } |
| if check_into_iter_call_arg(cx, expr, method_name, receiver, msrv) { |
| return; |
| } |
| check_other_call_arg(cx, expr, method_name, receiver); |
| } |
| } else { |
| check_borrow_predicate(cx, expr); |
| } |
| } |
| |
| /// Checks whether `expr` is a referent in an `AddrOf` expression and, if so, determines whether its |
| /// call of a `to_owned`-like function is unnecessary. |
| #[allow(clippy::too_many_lines)] |
| fn check_addr_of_expr( |
| cx: &LateContext<'_>, |
| expr: &Expr<'_>, |
| method_name: Symbol, |
| method_def_id: DefId, |
| receiver: &Expr<'_>, |
| ) -> bool { |
| if let Some(parent) = get_parent_expr(cx, expr) |
| && let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, _) = parent.kind |
| && let adjustments = cx.typeck_results().expr_adjustments(parent).iter().collect::<Vec<_>>() |
| && let |
| // For matching uses of `Cow::from` |
| [ |
| Adjustment { |
| kind: Adjust::Deref(None), |
| target: referent_ty, |
| }, |
| Adjustment { |
| kind: Adjust::Borrow(_), |
| target: target_ty, |
| }, |
| ] |
| // For matching uses of arrays |
| | [ |
| Adjustment { |
| kind: Adjust::Deref(None), |
| target: referent_ty, |
| }, |
| Adjustment { |
| kind: Adjust::Borrow(_), |
| .. |
| }, |
| Adjustment { |
| kind: Adjust::Pointer(_), |
| target: target_ty, |
| }, |
| ] |
| // For matching everything else |
| | [ |
| Adjustment { |
| kind: Adjust::Deref(None), |
| target: referent_ty, |
| }, |
| Adjustment { |
| kind: Adjust::Deref(Some(OverloadedDeref { .. })), |
| .. |
| }, |
| Adjustment { |
| kind: Adjust::Borrow(_), |
| target: target_ty, |
| }, |
| ] = adjustments[..] |
| && let receiver_ty = cx.typeck_results().expr_ty(receiver) |
| && let (target_ty, n_target_refs) = peel_mid_ty_refs(*target_ty) |
| && let (receiver_ty, n_receiver_refs) = peel_mid_ty_refs(receiver_ty) |
| // Only flag cases satisfying at least one of the following three conditions: |
| // * the referent and receiver types are distinct |
| // * the referent/receiver type is a copyable array |
| // * the method is `Cow::into_owned` |
| // This restriction is to ensure there is no overlap between `redundant_clone` and this |
| // lint. It also avoids the following false positive: |
| // https://github.com/rust-lang/rust-clippy/issues/8759 |
| // Arrays are a bit of a corner case. Non-copyable arrays are handled by |
| // `redundant_clone`, but copyable arrays are not. |
| && (*referent_ty != receiver_ty |
| || (matches!(referent_ty.kind(), ty::Array(..)) && is_copy(cx, *referent_ty)) |
| || is_cow_into_owned(cx, method_name, method_def_id)) |
| && let Some(receiver_snippet) = snippet_opt(cx, receiver.span) |
| { |
| if receiver_ty == target_ty && n_target_refs >= n_receiver_refs { |
| span_lint_and_sugg( |
| cx, |
| UNNECESSARY_TO_OWNED, |
| parent.span, |
| &format!("unnecessary use of `{method_name}`"), |
| "use", |
| format!( |
| "{:&>width$}{receiver_snippet}", |
| "", |
| width = n_target_refs - n_receiver_refs |
| ), |
| Applicability::MachineApplicable, |
| ); |
| return true; |
| } |
| if let Some(deref_trait_id) = cx.tcx.get_diagnostic_item(sym::Deref) |
| && implements_trait(cx, receiver_ty, deref_trait_id, &[]) |
| && cx.get_associated_type(receiver_ty, deref_trait_id, "Target") == Some(target_ty) |
| // Make sure that it's actually calling the right `.to_string()`, (#10033) |
| // *or* this is a `Cow::into_owned()` call (which would be the wrong into_owned receiver (str != Cow) |
| // but that's ok for Cow::into_owned specifically) |
| && (cx.typeck_results().expr_ty_adjusted(receiver).peel_refs() == target_ty |
| || is_cow_into_owned(cx, method_name, method_def_id)) |
| { |
| if n_receiver_refs > 0 { |
| span_lint_and_sugg( |
| cx, |
| UNNECESSARY_TO_OWNED, |
| parent.span, |
| &format!("unnecessary use of `{method_name}`"), |
| "use", |
| receiver_snippet, |
| Applicability::MachineApplicable, |
| ); |
| } else { |
| span_lint_and_sugg( |
| cx, |
| UNNECESSARY_TO_OWNED, |
| expr.span.with_lo(receiver.span.hi()), |
| &format!("unnecessary use of `{method_name}`"), |
| "remove this", |
| String::new(), |
| Applicability::MachineApplicable, |
| ); |
| } |
| return true; |
| } |
| if let Some(as_ref_trait_id) = cx.tcx.get_diagnostic_item(sym::AsRef) |
| && implements_trait(cx, receiver_ty, as_ref_trait_id, &[GenericArg::from(target_ty)]) |
| { |
| span_lint_and_sugg( |
| cx, |
| UNNECESSARY_TO_OWNED, |
| parent.span, |
| &format!("unnecessary use of `{method_name}`"), |
| "use", |
| format!("{receiver_snippet}.as_ref()"), |
| Applicability::MachineApplicable, |
| ); |
| return true; |
| } |
| } |
| false |
| } |
| |
| /// Checks whether `expr` is an argument in an `into_iter` call and, if so, determines whether its |
| /// call of a `to_owned`-like function is unnecessary. |
| fn check_into_iter_call_arg( |
| cx: &LateContext<'_>, |
| expr: &Expr<'_>, |
| method_name: Symbol, |
| receiver: &Expr<'_>, |
| msrv: &Msrv, |
| ) -> bool { |
| if let Some(parent) = get_parent_expr(cx, expr) |
| && let Some(callee_def_id) = fn_def_id(cx, parent) |
| && is_into_iter(cx, callee_def_id) |
| && let Some(iterator_trait_id) = cx.tcx.get_diagnostic_item(sym::Iterator) |
| && let parent_ty = cx.typeck_results().expr_ty(parent) |
| && implements_trait(cx, parent_ty, iterator_trait_id, &[]) |
| && let Some(item_ty) = get_iterator_item_ty(cx, parent_ty) |
| && let Some(receiver_snippet) = snippet_opt(cx, receiver.span) |
| { |
| if unnecessary_iter_cloned::check_for_loop_iter(cx, parent, method_name, receiver, true) { |
| return true; |
| } |
| let cloned_or_copied = if is_copy(cx, item_ty) && msrv.meets(msrvs::ITERATOR_COPIED) { |
| "copied" |
| } else { |
| "cloned" |
| }; |
| // The next suggestion may be incorrect because the removal of the `to_owned`-like |
| // function could cause the iterator to hold a reference to a resource that is used |
| // mutably. See https://github.com/rust-lang/rust-clippy/issues/8148. |
| span_lint_and_sugg( |
| cx, |
| UNNECESSARY_TO_OWNED, |
| parent.span, |
| &format!("unnecessary use of `{method_name}`"), |
| "use", |
| format!("{receiver_snippet}.iter().{cloned_or_copied}()"), |
| Applicability::MaybeIncorrect, |
| ); |
| return true; |
| } |
| false |
| } |
| |
| /// Checks whether `expr` is an argument in an `into_iter` call and, if so, determines whether its |
| /// call of a `to_owned`-like function is unnecessary. |
| fn check_split_call_arg(cx: &LateContext<'_>, expr: &Expr<'_>, method_name: Symbol, receiver: &Expr<'_>) -> bool { |
| if let Some(parent) = get_parent_expr(cx, expr) |
| && let Some((fn_name, argument_expr)) = get_fn_name_and_arg(cx, parent) |
| && fn_name.as_str() == "split" |
| && let Some(receiver_snippet) = snippet_opt(cx, receiver.span) |
| && let Some(arg_snippet) = snippet_opt(cx, argument_expr.span) |
| { |
| // We may end-up here because of an expression like `x.to_string().split(…)` where the type of `x` |
| // implements `AsRef<str>` but does not implement `Deref<Target = str>`. In this case, we have to |
| // add `.as_ref()` to the suggestion. |
| let as_ref = if is_type_lang_item(cx, cx.typeck_results().expr_ty(expr), LangItem::String) |
| && let Some(deref_trait_id) = cx.tcx.get_diagnostic_item(sym::Deref) |
| && cx.get_associated_type(cx.typeck_results().expr_ty(receiver), deref_trait_id, "Target") |
| != Some(cx.tcx.types.str_) |
| { |
| ".as_ref()" |
| } else { |
| "" |
| }; |
| |
| // The next suggestion may be incorrect because the removal of the `to_owned`-like |
| // function could cause the iterator to hold a reference to a resource that is used |
| // mutably. See https://github.com/rust-lang/rust-clippy/issues/8148. |
| span_lint_and_sugg( |
| cx, |
| UNNECESSARY_TO_OWNED, |
| parent.span, |
| &format!("unnecessary use of `{method_name}`"), |
| "use", |
| format!("{receiver_snippet}{as_ref}.split({arg_snippet})"), |
| Applicability::MaybeIncorrect, |
| ); |
| return true; |
| } |
| false |
| } |
| |
| fn get_fn_name_and_arg<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>) -> Option<(Symbol, Expr<'tcx>)> { |
| match &expr.kind { |
| ExprKind::MethodCall(path, _, [arg_expr], ..) => Some((path.ident.name, *arg_expr)), |
| ExprKind::Call( |
| Expr { |
| kind: ExprKind::Path(qpath), |
| hir_id: path_hir_id, |
| .. |
| }, |
| [arg_expr], |
| ) => { |
| // Only return Fn-like DefIds, not the DefIds of statics/consts/etc that contain or |
| // deref to fn pointers, dyn Fn, impl Fn - #8850 |
| if let Res::Def(DefKind::Fn | DefKind::Ctor(..) | DefKind::AssocFn, def_id) = |
| cx.typeck_results().qpath_res(qpath, *path_hir_id) |
| && let Some(fn_name) = cx.tcx.opt_item_name(def_id) |
| { |
| Some((fn_name, *arg_expr)) |
| } else { |
| None |
| } |
| }, |
| _ => None, |
| } |
| } |
| |
| /// Checks whether `expr` is an argument in a function call and, if so, determines whether its call |
| /// of a `to_owned`-like function is unnecessary. |
| fn check_other_call_arg<'tcx>( |
| cx: &LateContext<'tcx>, |
| expr: &'tcx Expr<'tcx>, |
| method_name: Symbol, |
| receiver: &'tcx Expr<'tcx>, |
| ) -> bool { |
| if let Some((maybe_call, maybe_arg)) = skip_addr_of_ancestors(cx, expr) |
| && let Some((callee_def_id, _, recv, call_args)) = get_callee_generic_args_and_args(cx, maybe_call) |
| && let fn_sig = cx.tcx.fn_sig(callee_def_id).instantiate_identity().skip_binder() |
| && let Some(i) = recv.into_iter().chain(call_args).position(|arg| arg.hir_id == maybe_arg.hir_id) |
| && let Some(input) = fn_sig.inputs().get(i) |
| && let (input, n_refs) = peel_mid_ty_refs(*input) |
| && let (trait_predicates, _) = get_input_traits_and_projections(cx, callee_def_id, input) |
| && let Some(sized_def_id) = cx.tcx.lang_items().sized_trait() |
| && let [trait_predicate] = trait_predicates |
| .iter() |
| .filter(|trait_predicate| trait_predicate.def_id() != sized_def_id) |
| .collect::<Vec<_>>()[..] |
| && let Some(deref_trait_id) = cx.tcx.get_diagnostic_item(sym::Deref) |
| && let Some(as_ref_trait_id) = cx.tcx.get_diagnostic_item(sym::AsRef) |
| && (trait_predicate.def_id() == deref_trait_id || trait_predicate.def_id() == as_ref_trait_id) |
| && let receiver_ty = cx.typeck_results().expr_ty(receiver) |
| // We can't add an `&` when the trait is `Deref` because `Target = &T` won't match |
| // `Target = T`. |
| && let Some((n_refs, receiver_ty)) = if n_refs > 0 || is_copy(cx, receiver_ty) { |
| Some((n_refs, receiver_ty)) |
| } else if trait_predicate.def_id() != deref_trait_id { |
| Some((1, Ty::new_ref(cx.tcx, |
| cx.tcx.lifetimes.re_erased, |
| ty::TypeAndMut { |
| ty: receiver_ty, |
| mutbl: Mutability::Not, |
| }, |
| ))) |
| } else { |
| None |
| } |
| && can_change_type(cx, maybe_arg, receiver_ty) |
| && let Some(receiver_snippet) = snippet_opt(cx, receiver.span) |
| { |
| span_lint_and_sugg( |
| cx, |
| UNNECESSARY_TO_OWNED, |
| maybe_arg.span, |
| &format!("unnecessary use of `{method_name}`"), |
| "use", |
| format!("{:&>n_refs$}{receiver_snippet}", ""), |
| Applicability::MachineApplicable, |
| ); |
| return true; |
| } |
| false |
| } |
| |
| /// Walks an expression's ancestors until it finds a non-`AddrOf` expression. Returns the first such |
| /// expression found (if any) along with the immediately prior expression. |
| fn skip_addr_of_ancestors<'tcx>( |
| cx: &LateContext<'tcx>, |
| mut expr: &'tcx Expr<'tcx>, |
| ) -> Option<(&'tcx Expr<'tcx>, &'tcx Expr<'tcx>)> { |
| while let Some(parent) = get_parent_expr(cx, expr) { |
| if let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, _) = parent.kind { |
| expr = parent; |
| } else { |
| return Some((parent, expr)); |
| } |
| } |
| None |
| } |
| |
| /// Checks whether an expression is a function or method call and, if so, returns its `DefId`, |
| /// `GenericArgs`, and arguments. |
| fn get_callee_generic_args_and_args<'tcx>( |
| cx: &LateContext<'tcx>, |
| expr: &'tcx Expr<'tcx>, |
| ) -> Option<( |
| DefId, |
| GenericArgsRef<'tcx>, |
| Option<&'tcx Expr<'tcx>>, |
| &'tcx [Expr<'tcx>], |
| )> { |
| if let ExprKind::Call(callee, args) = expr.kind |
| && let callee_ty = cx.typeck_results().expr_ty(callee) |
| && let ty::FnDef(callee_def_id, _) = callee_ty.kind() |
| { |
| let generic_args = cx.typeck_results().node_args(callee.hir_id); |
| return Some((*callee_def_id, generic_args, None, args)); |
| } |
| if let ExprKind::MethodCall(_, recv, args, _) = expr.kind |
| && let Some(method_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id) |
| { |
| let generic_args = cx.typeck_results().node_args(expr.hir_id); |
| return Some((method_def_id, generic_args, Some(recv), args)); |
| } |
| None |
| } |
| |
| /// Returns the `TraitPredicate`s and `ProjectionPredicate`s for a function's input type. |
| fn get_input_traits_and_projections<'tcx>( |
| cx: &LateContext<'tcx>, |
| callee_def_id: DefId, |
| input: Ty<'tcx>, |
| ) -> (Vec<TraitPredicate<'tcx>>, Vec<ProjectionPredicate<'tcx>>) { |
| let mut trait_predicates = Vec::new(); |
| let mut projection_predicates = Vec::new(); |
| for predicate in cx.tcx.param_env(callee_def_id).caller_bounds() { |
| match predicate.kind().skip_binder() { |
| ClauseKind::Trait(trait_predicate) => { |
| if trait_predicate.trait_ref.self_ty() == input { |
| trait_predicates.push(trait_predicate); |
| } |
| }, |
| ClauseKind::Projection(projection_predicate) => { |
| if projection_predicate.projection_ty.self_ty() == input { |
| projection_predicates.push(projection_predicate); |
| } |
| }, |
| _ => {}, |
| } |
| } |
| (trait_predicates, projection_predicates) |
| } |
| |
| #[expect(clippy::too_many_lines)] |
| fn can_change_type<'a>(cx: &LateContext<'a>, mut expr: &'a Expr<'a>, mut ty: Ty<'a>) -> bool { |
| for (_, node) in cx.tcx.hir().parent_iter(expr.hir_id) { |
| match node { |
| Node::Stmt(_) => return true, |
| Node::Block(..) => continue, |
| Node::Item(item) => { |
| if let ItemKind::Fn(_, _, body_id) = &item.kind |
| && let output_ty = return_ty(cx, item.owner_id) |
| && let inherited = Inherited::new(cx.tcx, item.owner_id.def_id) |
| && let fn_ctxt = FnCtxt::new(&inherited, cx.param_env, item.owner_id.def_id) |
| && fn_ctxt.can_coerce(ty, output_ty) |
| { |
| if has_lifetime(output_ty) && has_lifetime(ty) { |
| return false; |
| } |
| let body = cx.tcx.hir().body(*body_id); |
| let body_expr = &body.value; |
| let mut count = 0; |
| return find_all_ret_expressions(cx, body_expr, |_| { |
| count += 1; |
| count <= 1 |
| }); |
| } |
| }, |
| Node::Expr(parent_expr) => { |
| if let Some((callee_def_id, call_generic_args, recv, call_args)) = |
| get_callee_generic_args_and_args(cx, parent_expr) |
| { |
| let bound_fn_sig = cx.tcx.fn_sig(callee_def_id); |
| let fn_sig = bound_fn_sig.skip_binder(); |
| if let Some(arg_index) = recv |
| .into_iter() |
| .chain(call_args) |
| .position(|arg| arg.hir_id == expr.hir_id) |
| && let param_ty = fn_sig.input(arg_index).skip_binder() |
| && let ty::Param(ParamTy { index: param_index , ..}) = *param_ty.kind() |
| // https://github.com/rust-lang/rust-clippy/issues/9504 and https://github.com/rust-lang/rust-clippy/issues/10021 |
| && (param_index as usize) < call_generic_args.len() |
| { |
| if fn_sig |
| .skip_binder() |
| .inputs() |
| .iter() |
| .enumerate() |
| .filter(|(i, _)| *i != arg_index) |
| .any(|(_, ty)| ty.contains(param_ty)) |
| { |
| return false; |
| } |
| |
| let mut trait_predicates = |
| cx.tcx |
| .param_env(callee_def_id) |
| .caller_bounds() |
| .iter() |
| .filter(|predicate| { |
| if let ClauseKind::Trait(trait_predicate) = predicate.kind().skip_binder() |
| && trait_predicate.trait_ref.self_ty() == param_ty |
| { |
| true |
| } else { |
| false |
| } |
| }); |
| |
| let new_subst = cx |
| .tcx |
| .mk_args_from_iter(call_generic_args.iter().enumerate().map(|(i, t)| { |
| if i == param_index as usize { |
| GenericArg::from(ty) |
| } else { |
| t |
| } |
| })); |
| |
| if trait_predicates.any(|predicate| { |
| let predicate = bound_fn_sig.rebind(predicate).instantiate(cx.tcx, new_subst); |
| let obligation = Obligation::new(cx.tcx, ObligationCause::dummy(), cx.param_env, predicate); |
| !cx.tcx |
| .infer_ctxt() |
| .build() |
| .predicate_must_hold_modulo_regions(&obligation) |
| }) { |
| return false; |
| } |
| |
| let output_ty = cx.tcx.instantiate_bound_regions_with_erased(fn_sig.output()); |
| if output_ty.contains(param_ty) { |
| if let Ok(new_ty) = cx.tcx.try_instantiate_and_normalize_erasing_regions( |
| new_subst, |
| cx.param_env, |
| bound_fn_sig.rebind(output_ty), |
| ) { |
| expr = parent_expr; |
| ty = new_ty; |
| continue; |
| } |
| return false; |
| } |
| |
| return true; |
| } |
| } else if let ExprKind::Block(..) = parent_expr.kind { |
| continue; |
| } |
| return false; |
| }, |
| _ => return false, |
| } |
| } |
| |
| false |
| } |
| |
| fn has_lifetime(ty: Ty<'_>) -> bool { |
| ty.walk().any(|t| matches!(t.unpack(), GenericArgKind::Lifetime(_))) |
| } |
| |
| /// Returns true if the named method is `Iterator::cloned` or `Iterator::copied`. |
| fn is_cloned_or_copied(cx: &LateContext<'_>, method_name: Symbol, method_def_id: DefId) -> bool { |
| (method_name.as_str() == "cloned" || method_name.as_str() == "copied") |
| && is_diag_trait_item(cx, method_def_id, sym::Iterator) |
| } |
| |
| /// Returns true if the named method can be used to convert the receiver to its "owned" |
| /// representation. |
| fn is_to_owned_like<'a>(cx: &LateContext<'a>, call_expr: &Expr<'a>, method_name: Symbol, method_def_id: DefId) -> bool { |
| is_clone_like(cx, method_name.as_str(), method_def_id) |
| || is_cow_into_owned(cx, method_name, method_def_id) |
| || is_to_string_on_string_like(cx, call_expr, method_name, method_def_id) |
| } |
| |
| /// Returns true if the named method is `Cow::into_owned`. |
| fn is_cow_into_owned(cx: &LateContext<'_>, method_name: Symbol, method_def_id: DefId) -> bool { |
| method_name.as_str() == "into_owned" && is_diag_item_method(cx, method_def_id, sym::Cow) |
| } |
| |
| /// Returns true if the named method is `ToString::to_string` and it's called on a type that |
| /// is string-like i.e. implements `AsRef<str>` or `Deref<Target = str>`. |
| fn is_to_string_on_string_like<'a>( |
| cx: &LateContext<'_>, |
| call_expr: &'a Expr<'a>, |
| method_name: Symbol, |
| method_def_id: DefId, |
| ) -> bool { |
| if method_name != sym::to_string || !is_diag_trait_item(cx, method_def_id, sym::ToString) { |
| return false; |
| } |
| |
| if let Some(args) = cx.typeck_results().node_args_opt(call_expr.hir_id) |
| && let [generic_arg] = args.as_slice() |
| && let GenericArgKind::Type(ty) = generic_arg.unpack() |
| && let Some(deref_trait_id) = cx.tcx.get_diagnostic_item(sym::Deref) |
| && let Some(as_ref_trait_id) = cx.tcx.get_diagnostic_item(sym::AsRef) |
| && (cx.get_associated_type(ty, deref_trait_id, "Target") == Some(cx.tcx.types.str_) |
| || implements_trait(cx, ty, as_ref_trait_id, &[cx.tcx.types.str_.into()])) |
| { |
| true |
| } else { |
| false |
| } |
| } |
| |
| fn is_a_std_map_type(cx: &LateContext<'_>, ty: Ty<'_>) -> bool { |
| is_type_diagnostic_item(cx, ty, sym::HashSet) |
| || is_type_diagnostic_item(cx, ty, sym::HashMap) |
| || is_type_diagnostic_item(cx, ty, sym::BTreeMap) |
| || is_type_diagnostic_item(cx, ty, sym::BTreeSet) |
| } |
| |
| fn is_str_and_string(cx: &LateContext<'_>, arg_ty: Ty<'_>, original_arg_ty: Ty<'_>) -> bool { |
| original_arg_ty.is_str() && is_type_lang_item(cx, arg_ty, LangItem::String) |
| } |
| |
| fn is_slice_and_vec(cx: &LateContext<'_>, arg_ty: Ty<'_>, original_arg_ty: Ty<'_>) -> bool { |
| (original_arg_ty.is_slice() || original_arg_ty.is_array() || original_arg_ty.is_array_slice()) |
| && is_type_diagnostic_item(cx, arg_ty, sym::Vec) |
| } |
| |
| // This function will check the following: |
| // 1. The argument is a non-mutable reference. |
| // 2. It calls `to_owned()`, `to_string()` or `to_vec()`. |
| // 3. That the method is called on `String` or on `Vec` (only types supported for the moment). |
| fn check_if_applicable_to_argument<'tcx>(cx: &LateContext<'tcx>, arg: &Expr<'tcx>) { |
| if let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, expr) = arg.kind |
| && let ExprKind::MethodCall(method_path, caller, &[], _) = expr.kind |
| && let Some(method_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id) |
| && let method_name = method_path.ident.name.as_str() |
| && match method_name { |
| "to_owned" => cx.tcx.is_diagnostic_item(sym::to_owned_method, method_def_id), |
| "to_string" => cx.tcx.is_diagnostic_item(sym::to_string_method, method_def_id), |
| "to_vec" => cx |
| .tcx |
| .impl_of_method(method_def_id) |
| .filter(|&impl_did| cx.tcx.type_of(impl_did).instantiate_identity().is_slice()) |
| .is_some(), |
| _ => false, |
| } |
| && let original_arg_ty = cx.typeck_results().node_type(caller.hir_id).peel_refs() |
| && let arg_ty = cx.typeck_results().expr_ty(arg) |
| && let ty::Ref(_, arg_ty, Mutability::Not) = arg_ty.kind() |
| // FIXME: try to fix `can_change_type` to make it work in this case. |
| // && can_change_type(cx, caller, *arg_ty) |
| && let arg_ty = arg_ty.peel_refs() |
| // For now we limit this lint to `String` and `Vec`. |
| && (is_str_and_string(cx, arg_ty, original_arg_ty) || is_slice_and_vec(cx, arg_ty, original_arg_ty)) |
| && let Some(snippet) = snippet_opt(cx, caller.span) |
| { |
| span_lint_and_sugg( |
| cx, |
| UNNECESSARY_TO_OWNED, |
| arg.span, |
| &format!("unnecessary use of `{method_name}`"), |
| "replace it with", |
| if original_arg_ty.is_array() { |
| format!("{snippet}.as_slice()") |
| } else { |
| snippet |
| }, |
| Applicability::MaybeIncorrect, |
| ); |
| } |
| } |
| |
| // In std "map types", the getters all expect a `Borrow<Key>` generic argument. So in here, we |
| // check that: |
| // 1. This is a method with only one argument that doesn't come from a trait. |
| // 2. That it has `Borrow` in its generic predicates. |
| // 3. `Self` is a std "map type" (ie `HashSet`, `HashMap`, BTreeSet`, `BTreeMap`). |
| fn check_borrow_predicate<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>) { |
| if let ExprKind::MethodCall(_, caller, &[arg], _) = expr.kind |
| && let Some(method_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id) |
| && cx.tcx.trait_of_item(method_def_id).is_none() |
| && let Some(borrow_id) = cx.tcx.get_diagnostic_item(sym::Borrow) |
| && cx.tcx.predicates_of(method_def_id).predicates.iter().any(|(pred, _)| { |
| if let ClauseKind::Trait(trait_pred) = pred.kind().skip_binder() |
| && trait_pred.polarity == ImplPolarity::Positive |
| && trait_pred.trait_ref.def_id == borrow_id |
| { |
| true |
| } else { |
| false |
| } |
| }) |
| && let caller_ty = cx.typeck_results().expr_ty(caller) |
| // For now we limit it to "map types". |
| && is_a_std_map_type(cx, caller_ty) |
| { |
| check_if_applicable_to_argument(cx, &arg); |
| } |
| } |
