diff options
| -rw-r--r-- | clippy_lints/src/dereference.rs | 307 | ||||
| -rw-r--r-- | clippy_lints/src/lib.rs | 2 | ||||
| -rw-r--r-- | clippy_lints/src/methods/unnecessary_to_owned.rs | 19 | ||||
| -rw-r--r-- | clippy_utils/src/msrvs.rs | 2 | ||||
| -rw-r--r-- | tests/ui/needless_borrow.fixed | 117 | ||||
| -rw-r--r-- | tests/ui/needless_borrow.rs | 117 | ||||
| -rw-r--r-- | tests/ui/needless_borrow.stderr | 48 |
7 files changed, 559 insertions, 53 deletions
diff --git a/clippy_lints/src/dereference.rs b/clippy_lints/src/dereference.rs index e0b94f7190a..e38704701ea 100644 --- a/clippy_lints/src/dereference.rs +++ b/clippy_lints/src/dereference.rs @@ -1,24 +1,31 @@ use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_hir_and_then}; use clippy_utils::source::{snippet_with_applicability, snippet_with_context}; use clippy_utils::sugg::has_enclosing_paren; -use clippy_utils::ty::{expr_sig, peel_mid_ty_refs, ty_sig, variant_of_res}; -use clippy_utils::{get_parent_expr, is_lint_allowed, path_to_local, walk_to_expr_usage}; +use clippy_utils::ty::{contains_ty, expr_sig, is_copy, peel_mid_ty_refs, ty_sig, variant_of_res}; +use clippy_utils::{fn_def_id, get_parent_expr, is_lint_allowed, meets_msrv, msrvs, path_to_local, walk_to_expr_usage}; use rustc_ast::util::parser::{PREC_POSTFIX, PREC_PREFIX}; use rustc_data_structures::fx::FxIndexMap; use rustc_errors::Applicability; use rustc_hir::intravisit::{walk_ty, Visitor}; use rustc_hir::{ - self as hir, BindingAnnotation, Body, BodyId, BorrowKind, Closure, Expr, ExprKind, FnRetTy, GenericArg, HirId, - ImplItem, ImplItemKind, Item, ItemKind, Local, MatchSource, Mutability, Node, Pat, PatKind, Path, QPath, TraitItem, - TraitItemKind, TyKind, UnOp, + self as hir, def_id::DefId, BindingAnnotation, Body, BodyId, BorrowKind, Closure, Expr, ExprKind, FnRetTy, + GenericArg, HirId, ImplItem, ImplItemKind, Item, ItemKind, Local, MatchSource, Mutability, Node, Pat, PatKind, + Path, QPath, TraitItem, TraitItemKind, TyKind, UnOp, }; +use rustc_index::bit_set::BitSet; use rustc_infer::infer::TyCtxtInferExt; use rustc_lint::{LateContext, LateLintPass}; use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow, AutoBorrowMutability}; -use rustc_middle::ty::{self, Binder, BoundVariableKind, List, Ty, TyCtxt, TypeVisitable, TypeckResults}; +use rustc_middle::ty::{ + self, subst::Subst, Binder, BoundVariableKind, EarlyBinder, FnSig, GenericArgKind, List, ParamTy, PredicateKind, + ProjectionPredicate, Ty, TyCtxt, TypeVisitable, TypeckResults, +}; +use rustc_semver::RustcVersion; use rustc_session::{declare_tool_lint, impl_lint_pass}; use rustc_span::{symbol::sym, Span, Symbol, DUMMY_SP}; -use rustc_trait_selection::infer::InferCtxtExt; +use rustc_trait_selection::infer::InferCtxtExt as _; +use rustc_trait_selection::traits::{query::evaluate_obligation::InferCtxtExt as _, Obligation, ObligationCause}; +use std::collections::VecDeque; declare_clippy_lint! { /// ### What it does @@ -151,6 +158,7 @@ pub struct Dereferencing { /// been finished. Note we can't lint at the end of every body as they can be nested within each /// other. current_body: Option<BodyId>, + /// The list of locals currently being checked by the lint. /// If the value is `None`, then the binding has been seen as a ref pattern, but is not linted. /// This is needed for or patterns where one of the branches can be linted, but another can not @@ -158,6 +166,19 @@ pub struct Dereferencing { /// /// e.g. `m!(x) | Foo::Bar(ref x)` ref_locals: FxIndexMap<HirId, Option<RefPat>>, + + // `IntoIterator` for arrays requires Rust 1.53. + msrv: Option<RustcVersion>, +} + +impl Dereferencing { + #[must_use] + pub fn new(msrv: Option<RustcVersion>) -> Self { + Self { + msrv, + ..Dereferencing::default() + } + } } struct StateData { @@ -170,6 +191,7 @@ struct StateData { struct DerefedBorrow { count: usize, msg: &'static str, + snip_expr: Option<HirId>, } enum State { @@ -250,7 +272,7 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing { match (self.state.take(), kind) { (None, kind) => { let expr_ty = typeck.expr_ty(expr); - let (position, adjustments) = walk_parents(cx, expr); + let (position, adjustments) = walk_parents(cx, expr, self.msrv); match kind { RefOp::Deref => { @@ -331,20 +353,23 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing { let deref_msg = "this expression creates a reference which is immediately dereferenced by the compiler"; let borrow_msg = "this expression borrows a value the compiler would automatically borrow"; + let impl_msg = "the borrowed expression implements the required traits"; - let (required_refs, msg) = if position.can_auto_borrow() { - (1, if deref_count == 1 { borrow_msg } else { deref_msg }) + let (required_refs, msg, snip_expr) = if position.can_auto_borrow() { + (1, if deref_count == 1 { borrow_msg } else { deref_msg }, None) + } else if let Position::ImplArg(hir_id) = position { + (0, impl_msg, Some(hir_id)) } else if let Some(&Adjust::Borrow(AutoBorrow::Ref(_, mutability))) = next_adjust.map(|a| &a.kind) { if matches!(mutability, AutoBorrowMutability::Mut { .. }) && !position.is_reborrow_stable() { - (3, deref_msg) + (3, deref_msg, None) } else { - (2, deref_msg) + (2, deref_msg, None) } } else { - (2, deref_msg) + (2, deref_msg, None) }; if deref_count >= required_refs { @@ -354,6 +379,7 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing { // can't be removed without breaking the code. See earlier comment. count: deref_count - required_refs, msg, + snip_expr, }), StateData { span: expr.span, hir_id: expr.hir_id, position }, )); @@ -510,7 +536,7 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing { spans: vec![pat.span], app, replacements: vec![(pat.span, snip.into())], - hir_id: pat.hir_id + hir_id: pat.hir_id, }), ); } @@ -542,6 +568,8 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing { self.current_body = None; } } + + extract_msrv_attr!(LateContext); } fn try_parse_ref_op<'tcx>( @@ -594,6 +622,7 @@ enum Position { /// The method is defined on a reference type. e.g. `impl Foo for &T` MethodReceiverRefImpl, Callee, + ImplArg(HirId), FieldAccess(Symbol), Postfix, Deref, @@ -630,7 +659,7 @@ impl Position { | Self::Callee | Self::FieldAccess(_) | Self::Postfix => PREC_POSTFIX, - Self::Deref => PREC_PREFIX, + Self::ImplArg(_) | Self::Deref => PREC_PREFIX, Self::DerefStable(p, _) | Self::ReborrowStable(p) | Self::Other(p) => p, } } @@ -639,8 +668,12 @@ impl Position { /// Walks up the parent expressions attempting to determine both how stable the auto-deref result /// is, and which adjustments will be applied to it. Note this will not consider auto-borrow /// locations as those follow different rules. -#[allow(clippy::too_many_lines)] -fn walk_parents<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> (Position, &'tcx [Adjustment<'tcx>]) { +#[expect(clippy::too_many_lines)] +fn walk_parents<'tcx>( + cx: &LateContext<'tcx>, + e: &'tcx Expr<'_>, + msrv: Option<RustcVersion>, +) -> (Position, &'tcx [Adjustment<'tcx>]) { let mut adjustments = [].as_slice(); let mut precedence = 0i8; let ctxt = e.span.ctxt(); @@ -732,13 +765,20 @@ fn walk_parents<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> (Position, & .iter() .position(|arg| arg.hir_id == child_id) .zip(expr_sig(cx, func)) - .and_then(|(i, sig)| sig.input_with_hir(i)) - .map(|(hir_ty, ty)| match hir_ty { - // Type inference for closures can depend on how they're called. Only go by the explicit - // types here. - Some(hir_ty) => binding_ty_auto_deref_stability(cx, hir_ty, precedence, ty.bound_vars()), - None => ty_auto_deref_stability(cx, cx.tcx.erase_late_bound_regions(ty), precedence) - .position_for_arg(), + .and_then(|(i, sig)| { + sig.input_with_hir(i).map(|(hir_ty, ty)| match hir_ty { + // Type inference for closures can depend on how they're called. Only go by the explicit + // types here. + Some(hir_ty) => binding_ty_auto_deref_stability(cx, hir_ty, precedence, ty.bound_vars()), + None => { + if let ty::Param(param_ty) = ty.skip_binder().kind() { + needless_borrow_impl_arg_position(cx, parent, i, *param_ty, e, precedence, msrv) + } else { + ty_auto_deref_stability(cx, cx.tcx.erase_late_bound_regions(ty), precedence) + .position_for_arg() + } + }, + }) }), ExprKind::MethodCall(_, args, _) => { let id = cx.typeck_results().type_dependent_def_id(parent.hir_id).unwrap(); @@ -779,12 +819,17 @@ fn walk_parents<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> (Position, & Position::MethodReceiver } } else { - ty_auto_deref_stability( - cx, - cx.tcx.erase_late_bound_regions(cx.tcx.fn_sig(id).input(i)), - precedence, - ) - .position_for_arg() + let ty = cx.tcx.fn_sig(id).skip_binder().inputs()[i]; + if let ty::Param(param_ty) = ty.kind() { + needless_borrow_impl_arg_position(cx, parent, i, *param_ty, e, precedence, msrv) + } else { + ty_auto_deref_stability( + cx, + cx.tcx.erase_late_bound_regions(cx.tcx.fn_sig(id).input(i)), + precedence, + ) + .position_for_arg() + } } }) }, @@ -946,6 +991,205 @@ fn ty_contains_infer(ty: &hir::Ty<'_>) -> bool { v.0 } +// Checks whether: +// * child is an expression of the form `&e` in an argument position requiring an `impl Trait` +// * `e`'s type implements `Trait` and is copyable +// If the conditions are met, returns `Some(Position::ImplArg(..))`; otherwise, returns `None`. +// The "is copyable" condition is to avoid the case where removing the `&` means `e` would have to +// be moved, but it cannot be. +fn needless_borrow_impl_arg_position<'tcx>( + cx: &LateContext<'tcx>, + parent: &Expr<'tcx>, + arg_index: usize, + param_ty: ParamTy, + mut expr: &Expr<'tcx>, + precedence: i8, + msrv: Option<RustcVersion>, +) -> Position { + let destruct_trait_def_id = cx.tcx.lang_items().destruct_trait(); + let sized_trait_def_id = cx.tcx.lang_items().sized_trait(); + + let Some(callee_def_id) = fn_def_id(cx, parent) else { return Position::Other(precedence) }; + let fn_sig = cx.tcx.fn_sig(callee_def_id).skip_binder(); + let substs_with_expr_ty = cx + .typeck_results() + .node_substs(if let ExprKind::Call(callee, _) = parent.kind { + callee.hir_id + } else { + parent.hir_id + }); + + let predicates = cx.tcx.param_env(callee_def_id).caller_bounds(); + let projection_predicates = predicates + .iter() + .filter_map(|predicate| { + if let PredicateKind::Projection(projection_predicate) = predicate.kind().skip_binder() { + Some(projection_predicate) + } else { + None + } + }) + .collect::<Vec<_>>(); + + let mut trait_with_ref_mut_self_method = false; + + // If no traits were found, or only the `Destruct`, `Sized`, or `Any` traits were found, return. + if predicates + .iter() + .filter_map(|predicate| { + if let PredicateKind::Trait(trait_predicate) = predicate.kind().skip_binder() + && trait_predicate.trait_ref.self_ty() == param_ty.to_ty(cx.tcx) + { + Some(trait_predicate.trait_ref.def_id) + } else { + None + } + }) + .inspect(|trait_def_id| { + trait_with_ref_mut_self_method |= has_ref_mut_self_method(cx, *trait_def_id); + }) + .all(|trait_def_id| { + Some(trait_def_id) == destruct_trait_def_id + || Some(trait_def_id) == sized_trait_def_id + || cx.tcx.is_diagnostic_item(sym::Any, trait_def_id) + }) + { + return Position::Other(precedence); + } + + // `substs_with_referent_ty` can be constructed outside of `check_referent` because the same + // elements are modified each time `check_referent` is called. + let mut substs_with_referent_ty = substs_with_expr_ty.to_vec(); + + let mut check_referent = |referent| { + let referent_ty = cx.typeck_results().expr_ty(referent); + + if !is_copy(cx, referent_ty) { + return false; + } + + // https://github.com/rust-lang/rust-clippy/pull/9136#pullrequestreview-1037379321 + if trait_with_ref_mut_self_method && !matches!(referent_ty.kind(), ty::Ref(_, _, Mutability::Mut)) { + return false; + } + + if !replace_types( + cx, + param_ty, + referent_ty, + fn_sig, + arg_index, + &projection_predicates, + &mut substs_with_referent_ty, + ) { + return false; + } + + predicates.iter().all(|predicate| { + if let PredicateKind::Trait(trait_predicate) = predicate.kind().skip_binder() + && cx.tcx.is_diagnostic_item(sym::IntoIterator, trait_predicate.trait_ref.def_id) + && let ty::Param(param_ty) = trait_predicate.self_ty().kind() + && let GenericArgKind::Type(ty) = substs_with_referent_ty[param_ty.index as usize].unpack() + && ty.is_array() + && !meets_msrv(msrv, msrvs::ARRAY_INTO_ITERATOR) + { + return false; + } + + let predicate = EarlyBinder(predicate).subst(cx.tcx, &substs_with_referent_ty); + let obligation = Obligation::new(ObligationCause::dummy(), cx.param_env, predicate); + cx.tcx + .infer_ctxt() + .enter(|infcx| infcx.predicate_must_hold_modulo_regions(&obligation)) + }) + }; + + let mut needless_borrow = false; + while let ExprKind::AddrOf(_, _, referent) = expr.kind { + if !check_referent(referent) { + break; + } + expr = referent; + needless_borrow = true; + } + + if needless_borrow { + Position::ImplArg(expr.hir_id) + } else { + Position::Other(precedence) + } +} + +fn has_ref_mut_self_method(cx: &LateContext<'_>, trait_def_id: DefId) -> bool { + cx.tcx + .associated_items(trait_def_id) + .in_definition_order() + .any(|assoc_item| { + if assoc_item.fn_has_self_parameter { + let self_ty = cx.tcx.fn_sig(assoc_item.def_id).skip_binder().inputs()[0]; + matches!(self_ty.kind(), ty::Ref(_, _, Mutability::Mut)) + } else { + false + } + }) +} + +// Iteratively replaces `param_ty` with `new_ty` in `substs`, and similarly for each resulting +// projected type that is a type parameter. Returns `false` if replacing the types would have an +// effect on the function signature beyond substituting `new_ty` for `param_ty`. +// See: https://github.com/rust-lang/rust-clippy/pull/9136#discussion_r927212757 +fn replace_types<'tcx>( + cx: &LateContext<'tcx>, + param_ty: ParamTy, + new_ty: Ty<'tcx>, + fn_sig: FnSig<'tcx>, + arg_index: usize, + projection_predicates: &[ProjectionPredicate<'tcx>], + substs: &mut [ty::GenericArg<'tcx>], +) -> bool { + let mut replaced = BitSet::new_empty(substs.len()); + + let mut deque = VecDeque::with_capacity(substs.len()); + deque.push_back((param_ty, new_ty)); + + while let Some((param_ty, new_ty)) = deque.pop_front() { + // If `replaced.is_empty()`, then `param_ty` and `new_ty` are those initially passed in. + if !fn_sig + .inputs_and_output + .iter() + .enumerate() + .all(|(i, ty)| (replaced.is_empty() && i == arg_index) || !contains_ty(ty, param_ty.to_ty(cx.tcx))) + { + return false; + } + + substs[param_ty.index as usize] = ty::GenericArg::from(new_ty); + + // The `replaced.insert(...)` check provides some protection against infinite loops. + if replaced.insert(param_ty.index) { + for projection_predicate in projection_predicates { + if projection_predicate.projection_ty.self_ty() == param_ty.to_ty(cx.tcx) + && let ty::Term::Ty(term_ty) = projection_predicate.term + && let ty::Param(term_param_ty) = term_ty.kind() + { + let item_def_id = projection_predicate.projection_ty.item_def_id; + let assoc_item = cx.tcx.associated_item(item_def_id); + let projection = cx.tcx + .mk_projection(assoc_item.def_id, cx.tcx.mk_substs_trait(new_ty, &[])); + + if let Ok(projected_ty) = cx.tcx.try_normalize_erasing_regions(cx.param_env, projection) + && substs[term_param_ty.index as usize] != ty::GenericArg::from(projected_ty) + { + deque.push_back((*term_param_ty, projected_ty)); + } + } + } + } + } + + true +} + struct TyPosition<'tcx> { position: Position, ty: Option<Ty<'tcx>>, @@ -1084,7 +1328,8 @@ fn report<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, state: State, data }, State::DerefedBorrow(state) => { let mut app = Applicability::MachineApplicable; - let (snip, snip_is_macro) = snippet_with_context(cx, expr.span, data.span.ctxt(), "..", &mut app); + let snip_expr = state.snip_expr.map_or(expr, |hir_id| cx.tcx.hir().expect_expr(hir_id)); + let (snip, snip_is_macro) = snippet_with_context(cx, snip_expr.span, data.span.ctxt(), "..", &mut app); span_lint_hir_and_then(cx, NEEDLESS_BORROW, data.hir_id, data.span, state.msg, |diag| { let calls_field = matches!(expr.kind, ExprKind::Field(..)) && matches!(data.position, Position::Callee); let sugg = if !snip_is_macro diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs index e6a405f8170..521739c28ff 100644 --- a/clippy_lints/src/lib.rs +++ b/clippy_lints/src/lib.rs @@ -821,7 +821,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: store.register_late_pass(|| Box::new(verbose_file_reads::VerboseFileReads)); store.register_late_pass(|| Box::new(redundant_pub_crate::RedundantPubCrate::default())); store.register_late_pass(|| Box::new(unnamed_address::UnnamedAddress)); - store.register_late_pass(|| Box::new(dereference::Dereferencing::default())); + store.register_late_pass(move || Box::new(dereference::Dereferencing::new(msrv))); store.register_late_pass(|| Box::new(option_if_let_else::OptionIfLetElse)); store.register_late_pass(|| Box::new(future_not_send::FutureNotSend)); store.register_late_pass(|| Box::new(if_let_mutex::IfLetMutex)); diff --git a/clippy_lints/src/methods/unnecessary_to_owned.rs b/clippy_lints/src/methods/unnecessary_to_owned.rs index 99b56da7a50..e4624167ad0 100644 --- a/clippy_lints/src/methods/unnecessary_to_owned.rs +++ b/clippy_lints/src/methods/unnecessary_to_owned.rs @@ -6,9 +6,8 @@ use clippy_utils::ty::{ contains_ty, get_associated_type, get_iterator_item_ty, implements_trait, is_copy, is_type_diagnostic_item, peel_mid_ty_refs, }; -use clippy_utils::{meets_msrv, msrvs}; - use clippy_utils::{fn_def_id, get_parent_expr, is_diag_item_method, is_diag_trait_item}; +use clippy_utils::{meets_msrv, msrvs}; use rustc_errors::Applicability; use rustc_hir::{def_id::DefId, BorrowKind, Expr, ExprKind}; use rustc_lint::LateContext; @@ -373,25 +372,15 @@ fn get_input_traits_and_projections<'tcx>( ) -> (Vec<TraitPredicate<'tcx>>, Vec<ProjectionPredicate<'tcx>>) { let mut trait_predicates = Vec::new(); let mut projection_predicates = Vec::new(); - for (predicate, _) in cx.tcx.predicates_of(callee_def_id).predicates.iter() { - // `substs` should have 1 + n elements. The first is the type on the left hand side of an - // `as`. The remaining n are trait parameters. - let is_input_substs = |substs: SubstsRef<'tcx>| { - if_chain! { - if let Some(arg) = substs.iter().next(); - if let GenericArgKind::Type(arg_ty) = arg.unpack(); - if arg_ty == input; - then { true } else { false } - } - }; + for predicate in cx.tcx.param_env(callee_def_id).caller_bounds() { match predicate.kind().skip_binder() { PredicateKind::Trait(trait_predicate) => { - if is_input_substs(trait_predicate.trait_ref.substs) { + if trait_predicate.trait_ref.self_ty() == input { trait_predicates.push(trait_predicate); } }, PredicateKind::Projection(projection_predicate) => { - if is_input_substs(projection_predicate.projection_ty.substs) { + if projection_predicate.projection_ty.self_ty() == input { projection_predicates.push(projection_predicate); } }, diff --git a/clippy_utils/src/msrvs.rs b/clippy_utils/src/msrvs.rs index 9e238c6f1ac..7fa0046a267 100644 --- a/clippy_utils/src/msrvs.rs +++ b/clippy_utils/src/msrvs.rs @@ -13,7 +13,7 @@ macro_rules! msrv_aliases { // names may refer to stabilized feature flags or library items msrv_aliases! { 1,62,0 { BOOL_THEN_SOME } - 1,53,0 { OR_PATTERNS, MANUAL_BITS, BTREE_MAP_RETAIN, BTREE_SET_RETAIN } + 1,53,0 { OR_PATTERNS, MANUAL_BITS, BTREE_MAP_RETAIN, BTREE_SET_RETAIN, ARRAY_INTO_ITERATOR } 1,52,0 { STR_SPLIT_ONCE, REM_EUCLID_CONST } 1,51,0 { BORROW_AS_PTR, UNSIGNED_ABS } 1,50,0 { BOOL_THEN } diff --git a/tests/ui/needless_borrow.fixed b/tests/ui/needless_borrow.fixed index bfd2725ecaa..8cf93bd2481 100644 --- a/tests/ui/needless_borrow.fixed +++ b/tests/ui/needless_borrow.fixed @@ -1,6 +1,6 @@ // run-rustfix -#![feature(lint_reasons)] +#![feature(custom_inner_attributes, lint_reasons)] #[warn(clippy::all, clippy::needless_borrow)] #[allow(unused_variables, clippy::unnecessary_mut_passed)] @@ -127,6 +127,20 @@ fn main() { 0 } } + + let _ = std::process::Command::new("ls").args(["-a", "-l"]).status().unwrap(); + let _ = std::path::Path::new(".").join("."); + deref_target_is_x(X); + multiple_constraints([[""]]); + multiple_constraints_normalizes_to_same(X, X); + let _ = Some("").unwrap_or(""); + + only_sized(&""); // Don't lint. `Sized` is only bound + let _ = std::any::Any::type_id(&""); // Don't lint. `Any` is only bound + let _ = Box::new(&""); // Don't lint. Type parameter appears in return type + ref_as_ref_path(&""); // Don't lint. Argument type is not a type parameter + refs_only(&()); // Don't lint. `&T` implements trait, but `T` doesn't + multiple_constraints_normalizes_to_different(&[[""]], &[""]); // Don't lint. Projected type appears in arguments } #[allow(clippy::needless_borrowed_reference)] @@ -183,3 +197,104 @@ mod issue9160 { } } } + +#[derive(Clone, Copy)] +struct X; + +impl std::ops::Deref for X { + type Target = X; + fn deref(&self) -> &Self::Target { + self + } +} + +fn deref_target_is_x<T>(_: T) +where + T: std::ops::Deref<Target = X>, +{ +} + +fn multiple_constraints<T, U, V, X, Y>(_: T) +where + T: IntoIterator<Item = U> + IntoIterator<Item = X>, + U: IntoIterator<Item = V>, + V: AsRef<str>, + X: IntoIterator<Item = Y>, + Y: AsRef<std::ffi::OsStr>, +{ +} + +fn multiple_constraints_normalizes_to_same<T, U, V>(_: T, _: V) +where + T: std::ops::Deref<Target = U>, + U: std::ops::Deref<Target = V>, +{ +} + +fn only_sized<T>(_: T) {} + +fn ref_as_ref_path<T: 'static>(_: &'static T) +where + &'static T: AsRef<std::path::Path>, +{ +} + +trait RefsOnly { + type Referent; +} + +impl<T> RefsOnly for &T { + type Referent = T; +} + +fn refs_only<T, U>(_: T) +where + T: RefsOnly<Referent = U>, +{ +} + +fn multiple_constraints_normalizes_to_different<T, U, V>(_: T, _: U) +where + T: IntoIterator<Item = U>, + U: IntoIterator<Item = V>, + V: AsRef<str>, +{ +} + +// https://github.com/rust-lang/rust-clippy/pull/9136#pullrequestreview-1037379321 +#[allow(dead_code)] +mod copyable_iterator { + #[derive(Clone, Copy)] + struct Iter; + impl Iterator for Iter { + type Item = (); + fn next(&mut self) -> Option<Self::Item> { + None + } + } + fn takes_iter(_: impl Iterator) {} + fn dont_warn(mut x: Iter) { + takes_iter(&mut x); + } + fn warn(mut x: &mut Iter) { + takes_iter(&mut x) + } +} + +mod under_msrv { + #![allow(dead_code)] + #![clippy::msrv = "1.52.0"] + + fn foo() { + let _ = std::process::Command::new("ls").args(&["-a", "-l"]).status().unwrap(); + } +} + +mod meets_msrv { + #![allow(dead_code)] + #![clippy::msrv = "1.53.0"] + + fn foo() { + let _ = std::process::Command::new("ls").args(["-a", "-l"]).status().unwrap(); + } +} diff --git a/tests/ui/needless_borrow.rs b/tests/ui/needless_borrow.rs index c457d8c5471..fd9b2a11df9 100644 --- a/tests/ui/needless_borrow.rs +++ b/tests/ui/needless_borrow.rs @@ -1,6 +1,6 @@ // run-rustfix -#![feature(lint_reasons)] +#![feature(custom_inner_attributes, lint_reasons)] #[warn(clippy::all, clippy::needless_borrow)] #[allow(unused_variables, clippy::unnecessary_mut_passed)] @@ -127,6 +127,20 @@ fn main() { 0 } } + + let _ = std::process::Command::new("ls").args(&["-a", "-l"]).status().unwrap(); + let _ = std::path::Path::new(".").join(&&"."); + deref_target_is_x(&X); + multiple_constraints(&[[""]]); + multiple_constraints_normalizes_to_same(&X, X); + let _ = Some("").unwrap_or(&""); + + only_sized(&""); // Don't lint. `Sized` is only bound + let _ = std::any::Any::type_id(&""); // Don't lint. `Any` is only bound + let _ = Box::new(&""); // Don't lint. Type parameter appears in return type + ref_as_ref_path(&""); // Don't lint. Argument type is not a type parameter + refs_only(&()); // Don't lint. `&T` implements trait, but `T` doesn't + multiple_constraints_normalizes_to_different(&[[""]], &[""]); // Don't lint. Projected type appears in arguments } #[allow(clippy::needless_borrowed_reference)] @@ -183,3 +197,104 @@ mod issue9160 { } } } + +#[derive(Clone, Copy)] +struct X; + +impl std::ops::Deref for X { + type Target = X; + fn deref(&self) -> &Self::Target { + self + } +} + +fn deref_target_is_x<T>(_: T) +where + T: std::ops::Deref<Target = X>, +{ +} + +fn multiple_constraints<T, U, V, X, Y>(_: T) +where + T: IntoIterator<Item = U> + IntoIterator<Item = X>, + U: IntoIterator<Item = V>, + V: AsRef<str>, + X: IntoIterator<Item = Y>, + Y: AsRef<std::ffi::OsStr>, +{ +} + +fn multiple_constraints_normalizes_to_same<T, U, V>(_: T, _: V) +where + T: std::ops::Deref<Target = U>, + U: std::ops::Deref<Target = V>, +{ +} + +fn only_sized<T>(_: T) {} + +fn ref_as_ref_path<T: 'static>(_: &'static T) +where + &'static T: AsRef<std::path::Path>, +{ +} + +trait RefsOnly { + type Referent; +} + +impl<T> RefsOnly for &T { + type Referent = T; +} + +fn refs_only<T, U>(_: T) +where + T: RefsOnly<Referent = U>, +{ +} + +fn multiple_constraints_normalizes_to_different<T, U, V>(_: T, _: U) +where + T: IntoIterator<Item = U>, + U: IntoIterator<Item = V>, + V: AsRef<str>, +{ +} + +// https://github.com/rust-lang/rust-clippy/pull/9136#pullrequestreview-1037379321 +#[allow(dead_code)] +mod copyable_iterator { + #[derive(Clone, Copy)] + struct Iter; + impl Iterator for Iter { + type Item = (); + fn next(&mut self) -> Option<Self::Item> { + None + } + } + fn takes_iter(_: impl Iterator) {} + fn dont_warn(mut x: Iter) { + takes_iter(&mut x); + } + fn warn(mut x: &mut Iter) { + takes_iter(&mut x) + } +} + +mod under_msrv { + #![allow(dead_code)] + #![clippy::msrv = "1.52.0"] + + fn foo() { + let _ = std::process::Command::new("ls").args(&["-a", "-l"]).status().unwrap(); + } +} + +mod meets_msrv { + #![allow(dead_code)] + #![clippy::msrv = "1.53.0"] + + fn foo() { + let _ = std::process::Command::new("ls").args(&["-a", "-l"]).status().unwrap(); + } +} diff --git a/tests/ui/needless_borrow.stderr b/tests/ui/needless_borrow.stderr index 66588689d81..5af68706d4b 100644 --- a/tests/ui/needless_borrow.stderr +++ b/tests/ui/needless_borrow.stderr @@ -120,17 +120,59 @@ error: this expression creates a reference which is immediately dereferenced by LL | (&&5).foo(); | ^^^^^ help: change this to: `(&5)` +error: the borrowed expression implements the required traits + --> $DIR/needless_borrow.rs:131:51 + | +LL | let _ = std::process::Command::new("ls").args(&["-a", "-l"]).status().unwrap(); + | ^^^^^^^^^^^^^ help: change this to: `["-a", "-l"]` + +error: the borrowed expression implements the required traits + --> $DIR/needless_borrow.rs:132:44 + | +LL | let _ = std::path::Path::new(".").join(&&"."); + | ^^^^^ help: change this to: `"."` + +error: the borrowed expression implements the required traits + --> $DIR/needless_borrow.rs:133:23 + | +LL | deref_target_is_x(&X); + | ^^ help: change this to: `X` + +error: the borrowed expression implements the required traits + --> $DIR/needless_borrow.rs:134:26 + | +LL | multiple_constraints(&[[""]]); + | ^^^^^^^ help: change this to: `[[""]]` + +error: the borrowed expression implements the required traits + --> $DIR/needless_borrow.rs:135:45 + | +LL | multiple_constraints_normalizes_to_same(&X, X); + | ^^ help: change this to: `X` + +error: this expression creates a reference which is immediately dereferenced by the compiler + --> $DIR/needless_borrow.rs:136:32 + | +LL | let _ = Some("").unwrap_or(&""); + | ^^^ help: change this to: `""` + error: this expression borrows a value the compiler would automatically borrow - --> $DIR/needless_borrow.rs:173:13 + --> $DIR/needless_borrow.rs:187:13 | LL | (&self.f)() | ^^^^^^^^^ help: change this to: `(self.f)` error: this expression borrows a value the compiler would automatically borrow - --> $DIR/needless_borrow.rs:182:13 + --> $DIR/needless_borrow.rs:196:13 | LL | (&mut self.f)() | ^^^^^^^^^^^^^ help: change this to: `(self.f)` -error: aborting due to 22 previous errors +error: the borrowed expression implements the required traits + --> $DIR/needless_borrow.rs:298:55 + | +LL | let _ = std::process::Command::new("ls").args(&["-a", "-l"]).status().unwrap(); + | ^^^^^^^^^^^^^ help: change this to: `["-a", "-l"]` + +error: aborting due to 29 previous errors |