diff --git a/CHANGELOG.md b/CHANGELOG.md index bc50ff3a44a..9bc93c1cb42 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -3400,6 +3400,7 @@ Released 2018-09-13 [`expect_fun_call`]: https://rust-lang.github.io/rust-clippy/master/index.html#expect_fun_call [`expect_used`]: https://rust-lang.github.io/rust-clippy/master/index.html#expect_used [`expl_impl_clone_on_copy`]: https://rust-lang.github.io/rust-clippy/master/index.html#expl_impl_clone_on_copy +[`explicit_auto_deref`]: https://rust-lang.github.io/rust-clippy/master/index.html#explicit_auto_deref [`explicit_counter_loop`]: https://rust-lang.github.io/rust-clippy/master/index.html#explicit_counter_loop [`explicit_deref_methods`]: https://rust-lang.github.io/rust-clippy/master/index.html#explicit_deref_methods [`explicit_into_iter_loop`]: https://rust-lang.github.io/rust-clippy/master/index.html#explicit_into_iter_loop diff --git a/clippy_lints/src/dereference.rs b/clippy_lints/src/dereference.rs index b47441eff37..77518933a23 100644 --- a/clippy_lints/src/dereference.rs +++ b/clippy_lints/src/dereference.rs @@ -1,18 +1,21 @@ 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::peel_mid_ty_refs; -use clippy_utils::{get_parent_expr, get_parent_node, is_lint_allowed, path_to_local}; +use clippy_utils::ty::{expr_sig, peel_mid_ty_refs, variant_of_res}; +use clippy_utils::{ + get_parent_expr, get_parent_node, is_lint_allowed, path_to_local, peel_hir_ty_refs, 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::{ - BindingAnnotation, Body, BodyId, BorrowKind, Destination, Expr, ExprKind, HirId, MatchSource, Mutability, Node, - Pat, PatKind, UnOp, + self as hir, BindingAnnotation, Body, BodyId, BorrowKind, Destination, Expr, ExprKind, FnRetTy, GenericArg, HirId, + ImplItem, ImplItemKind, Item, ItemKind, Local, MatchSource, Mutability, Node, Pat, PatKind, Path, QPath, TraitItem, + TraitItemKind, TyKind, UnOp, }; use rustc_lint::{LateContext, LateLintPass}; use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow, AutoBorrowMutability}; -use rustc_middle::ty::{self, Ty, TyCtxt, TypeckResults}; +use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeckResults}; use rustc_session::{declare_tool_lint, impl_lint_pass}; use rustc_span::{symbol::sym, Span}; @@ -104,10 +107,34 @@ declare_clippy_lint! { "`ref` binding to a reference" } +declare_clippy_lint! { + /// ### What it does + /// Checks for dereferencing expressions which would be covered by auto-deref. + /// + /// ### Why is this bad? + /// This unnecessarily complicates the code. + /// + /// ### Example + /// ```rust + /// let x = String::new(); + /// let y: &str = &*x; + /// ``` + /// Use instead: + /// ```rust + /// let x = String::new(); + /// let y: &str = &x; + /// ``` + #[clippy::version = "1.60.0"] + pub EXPLICIT_AUTO_DEREF, + complexity, + "dereferencing when the compiler would automatically dereference" +} + impl_lint_pass!(Dereferencing => [ EXPLICIT_DEREF_METHODS, NEEDLESS_BORROW, REF_BINDING_TO_REFERENCE, + EXPLICIT_AUTO_DEREF, ]); #[derive(Default)] @@ -152,6 +179,11 @@ enum State { required_precedence: i8, msg: &'static str, }, + ExplicitDeref { + deref_span: Span, + deref_hir_id: HirId, + }, + Borrow, } // A reference operation considered by this lint pass @@ -305,6 +337,14 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing { hir_id: expr.hir_id, }, )); + } else if is_stable_auto_deref_position(cx, expr) { + self.state = Some(( + State::Borrow, + StateData { + span: expr.span, + hir_id: expr.hir_id, + }, + )); } }, _ => (), @@ -354,6 +394,18 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing { data, )); }, + (Some((State::Borrow, data)), RefOp::Deref) => { + self.state = Some(( + State::ExplicitDeref { + deref_span: expr.span, + deref_hir_id: expr.hir_id, + }, + data, + )); + }, + (state @ Some((State::ExplicitDeref { .. }, _)), RefOp::Deref) => { + self.state = state; + }, (Some((state, data)), _) => report(cx, expr, state, data), } @@ -596,8 +648,230 @@ fn find_adjustments<'tcx>( } } +// Checks if the expression for the given id occurs in a position which auto dereferencing applies. +// Note that the target type must not be inferred in a way that may cause auto-deref to select a +// different type, nor may the position be the result of a macro expansion. +// +// e.g. the following should not linted +// macro_rules! foo { ($e:expr) => { let x: &str = $e; }} +// foo!(&*String::new()); +// fn foo(_: &T) {} +// foo(&*String::new()) +fn is_stable_auto_deref_position<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> bool { + walk_to_expr_usage(cx, e, |node, child_id| match node { + Node::Local(&Local { ty: Some(ty), .. }) => Some(is_binding_ty_auto_deref_stable(ty)), + Node::Item(&Item { + kind: ItemKind::Static(..) | ItemKind::Const(..), + .. + }) + | Node::TraitItem(&TraitItem { + kind: TraitItemKind::Const(..), + .. + }) + | Node::ImplItem(&ImplItem { + kind: ImplItemKind::Const(..), + .. + }) => Some(true), + + Node::Item(&Item { + kind: ItemKind::Fn(..), + def_id, + .. + }) + | Node::TraitItem(&TraitItem { + kind: TraitItemKind::Fn(..), + def_id, + .. + }) + | Node::ImplItem(&ImplItem { + kind: ImplItemKind::Fn(..), + def_id, + .. + }) => { + let output = cx.tcx.fn_sig(def_id.to_def_id()).skip_binder().output(); + Some(!(output.has_placeholders() || output.has_opaque_types())) + }, + + Node::Expr(e) => match e.kind { + ExprKind::Ret(_) => { + let output = cx + .tcx + .fn_sig(cx.tcx.hir().body_owner_def_id(cx.enclosing_body.unwrap())) + .skip_binder() + .output(); + Some(!(output.has_placeholders() || output.has_opaque_types())) + }, + ExprKind::Call(func, args) => Some( + args.iter() + .position(|arg| arg.hir_id == child_id) + .zip(expr_sig(cx, func)) + .and_then(|(i, sig)| sig.input_with_hir(i)) + .map_or(false, |(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(ty) => is_binding_ty_auto_deref_stable(ty), + None => is_param_auto_deref_stable(ty.skip_binder()), + }), + ), + ExprKind::MethodCall(_, [_, args @ ..], _) => { + let id = cx.typeck_results().type_dependent_def_id(e.hir_id).unwrap(); + Some(args.iter().position(|arg| arg.hir_id == child_id).map_or(false, |i| { + let arg = cx.tcx.fn_sig(id).skip_binder().inputs()[i + 1]; + is_param_auto_deref_stable(arg) + })) + }, + ExprKind::Struct(path, fields, _) => { + let variant = variant_of_res(cx, cx.qpath_res(path, e.hir_id)); + Some( + fields + .iter() + .find(|f| f.expr.hir_id == child_id) + .zip(variant) + .and_then(|(field, variant)| variant.fields.iter().find(|f| f.name == field.ident.name)) + .map_or(false, |field| is_param_auto_deref_stable(cx.tcx.type_of(field.did))), + ) + }, + _ => None, + }, + _ => None, + }) + .unwrap_or(false) +} + +// Checks whether auto-dereferencing any type into a binding of the given type will definitely +// produce the same result. +// +// e.g. +// let x = Box::new(Box::new(0u32)); +// let y1: &Box<_> = x.deref(); +// let y2: &Box<_> = &x; +// +// Here `y1` and `y2` would resolve to different types, so the type `&Box<_>` is not stable when +// switching to auto-dereferencing. +fn is_binding_ty_auto_deref_stable(ty: &hir::Ty<'_>) -> bool { + let (ty, count) = peel_hir_ty_refs(ty); + if count != 1 { + return false; + } + + match &ty.kind { + TyKind::Rptr(_, ty) => is_binding_ty_auto_deref_stable(ty.ty), + &TyKind::Path( + QPath::TypeRelative(_, path) + | QPath::Resolved( + _, + Path { + segments: [.., path], .. + }, + ), + ) => { + if let Some(args) = path.args { + args.args.iter().all(|arg| { + if let GenericArg::Type(ty) = arg { + !ty_contains_infer(ty) + } else { + true + } + }) + } else { + true + } + }, + TyKind::Slice(_) + | TyKind::Array(..) + | TyKind::BareFn(_) + | TyKind::Never + | TyKind::Tup(_) + | TyKind::Ptr(_) + | TyKind::TraitObject(..) + | TyKind::Path(_) => true, + TyKind::OpaqueDef(..) | TyKind::Infer | TyKind::Typeof(..) | TyKind::Err => false, + } +} + +// Checks whether a type is inferred at some point. +// e.g. `_`, `Box<_>`, `[_]` +fn ty_contains_infer(ty: &hir::Ty<'_>) -> bool { + match &ty.kind { + TyKind::Slice(ty) | TyKind::Array(ty, _) => ty_contains_infer(ty), + TyKind::Ptr(ty) | TyKind::Rptr(_, ty) => ty_contains_infer(ty.ty), + TyKind::Tup(tys) => tys.iter().any(ty_contains_infer), + TyKind::BareFn(ty) => { + if ty.decl.inputs.iter().any(ty_contains_infer) { + return true; + } + if let FnRetTy::Return(ty) = &ty.decl.output { + ty_contains_infer(ty) + } else { + false + } + }, + &TyKind::Path( + QPath::TypeRelative(_, path) + | QPath::Resolved( + _, + Path { + segments: [.., path], .. + }, + ), + ) => { + if let Some(args) = path.args { + args.args.iter().any(|arg| { + if let GenericArg::Type(ty) = arg { + ty_contains_infer(ty) + } else { + false + } + }) + } else { + false + } + }, + TyKind::Path(_) | TyKind::OpaqueDef(..) | TyKind::Infer | TyKind::Typeof(_) | TyKind::Err => true, + TyKind::Never | TyKind::TraitObject(..) => false, + } +} + +// Checks whether a type is stable when switching to auto dereferencing, +fn is_param_auto_deref_stable(ty: Ty<'_>) -> bool { + let (ty, count) = peel_mid_ty_refs(ty); + if count != 1 { + return false; + } + + match ty.kind() { + ty::Bool + | ty::Char + | ty::Int(_) + | ty::Uint(_) + | ty::Float(_) + | ty::Foreign(_) + | ty::Str + | ty::Array(..) + | ty::Slice(..) + | ty::RawPtr(..) + | ty::FnDef(..) + | ty::FnPtr(_) + | ty::Closure(..) + | ty::Generator(..) + | ty::GeneratorWitness(..) + | ty::Never + | ty::Tuple(_) + | ty::Ref(..) + | ty::Projection(_) => true, + ty::Infer(_) + | ty::Error(_) + | ty::Param(_) + | ty::Bound(..) + | ty::Opaque(..) + | ty::Placeholder(_) + | ty::Dynamic(..) => false, + ty::Adt(..) => !(ty.has_placeholders() || ty.has_param_types_or_consts()), + } +} + #[expect(clippy::needless_pass_by_value)] -fn report<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>, state: State, data: StateData) { +fn report<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, state: State, data: StateData) { match state { State::DerefMethod { ty_changed_count, @@ -663,6 +937,29 @@ fn report<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'tcx>, state: State, data: S diag.span_suggestion(data.span, "change this to", sugg, app); }); }, + State::ExplicitDeref { + deref_span, + deref_hir_id, + } => { + let (span, hir_id) = if cx.typeck_results().expr_ty(expr).is_ref() { + (data.span, data.hir_id) + } else { + (deref_span, deref_hir_id) + }; + span_lint_hir_and_then( + cx, + EXPLICIT_AUTO_DEREF, + hir_id, + span, + "deref which would be done by auto-deref", + |diag| { + let mut app = Applicability::MachineApplicable; + let snip = snippet_with_context(cx, expr.span, span.ctxt(), "..", &mut app).0; + diag.span_suggestion(span, "try this", snip.into_owned(), app); + }, + ); + }, + State::Borrow => (), } } diff --git a/clippy_lints/src/lib.register_all.rs b/clippy_lints/src/lib.register_all.rs index b4edb8ea90e..56262c8f96e 100644 --- a/clippy_lints/src/lib.register_all.rs +++ b/clippy_lints/src/lib.register_all.rs @@ -44,6 +44,7 @@ store.register_group(true, "clippy::all", Some("clippy_all"), vec![ LintId::of(crate_in_macro_def::CRATE_IN_MACRO_DEF), LintId::of(default::FIELD_REASSIGN_WITH_DEFAULT), LintId::of(default_instead_of_iter_empty::DEFAULT_INSTEAD_OF_ITER_EMPTY), + LintId::of(dereference::EXPLICIT_AUTO_DEREF), LintId::of(dereference::NEEDLESS_BORROW), LintId::of(derivable_impls::DERIVABLE_IMPLS), LintId::of(derive::DERIVE_HASH_XOR_EQ), diff --git a/clippy_lints/src/lib.register_complexity.rs b/clippy_lints/src/lib.register_complexity.rs index 27de11bf1ae..d7f6140ca4b 100644 --- a/clippy_lints/src/lib.register_complexity.rs +++ b/clippy_lints/src/lib.register_complexity.rs @@ -9,6 +9,7 @@ store.register_group(true, "clippy::complexity", Some("clippy_complexity"), vec! LintId::of(bytes_count_to_len::BYTES_COUNT_TO_LEN), LintId::of(casts::CHAR_LIT_AS_U8), LintId::of(casts::UNNECESSARY_CAST), + LintId::of(dereference::EXPLICIT_AUTO_DEREF), LintId::of(derivable_impls::DERIVABLE_IMPLS), LintId::of(double_comparison::DOUBLE_COMPARISONS), LintId::of(double_parens::DOUBLE_PARENS), diff --git a/clippy_lints/src/lib.register_lints.rs b/clippy_lints/src/lib.register_lints.rs index 29a5f368f23..75993fa168f 100644 --- a/clippy_lints/src/lib.register_lints.rs +++ b/clippy_lints/src/lib.register_lints.rs @@ -110,6 +110,7 @@ store.register_lints(&[ default_instead_of_iter_empty::DEFAULT_INSTEAD_OF_ITER_EMPTY, default_numeric_fallback::DEFAULT_NUMERIC_FALLBACK, default_union_representation::DEFAULT_UNION_REPRESENTATION, + dereference::EXPLICIT_AUTO_DEREF, dereference::EXPLICIT_DEREF_METHODS, dereference::NEEDLESS_BORROW, dereference::REF_BINDING_TO_REFERENCE, diff --git a/clippy_lints/src/matches/match_str_case_mismatch.rs b/clippy_lints/src/matches/match_str_case_mismatch.rs index 8302ce426e5..fa3b8d1fcea 100644 --- a/clippy_lints/src/matches/match_str_case_mismatch.rs +++ b/clippy_lints/src/matches/match_str_case_mismatch.rs @@ -118,7 +118,7 @@ fn lint(cx: &LateContext<'_>, case_method: &CaseMethod, bad_case_span: Span, bad MATCH_STR_CASE_MISMATCH, bad_case_span, "this `match` arm has a differing case than its expression", - &*format!("consider changing the case of this arm to respect `{}`", method_str), + &format!("consider changing the case of this arm to respect `{}`", method_str), format!("\"{}\"", suggestion), Applicability::MachineApplicable, ); diff --git a/clippy_lints/src/non_expressive_names.rs b/clippy_lints/src/non_expressive_names.rs index c93b4b2f205..b96af06b8d7 100644 --- a/clippy_lints/src/non_expressive_names.rs +++ b/clippy_lints/src/non_expressive_names.rs @@ -326,7 +326,7 @@ impl<'a, 'tcx> Visitor<'tcx> for SimilarNamesLocalVisitor<'a, 'tcx> { // add the pattern after the expression because the bindings aren't available // yet in the init // expression - SimilarNamesNameVisitor(self).visit_pat(&*local.pat); + SimilarNamesNameVisitor(self).visit_pat(&local.pat); } fn visit_block(&mut self, blk: &'tcx Block) { self.single_char_names.push(vec![]); diff --git a/clippy_lints/src/ptr.rs b/clippy_lints/src/ptr.rs index b06eba13d2f..5678b8f6ca6 100644 --- a/clippy_lints/src/ptr.rs +++ b/clippy_lints/src/ptr.rs @@ -574,14 +574,13 @@ fn check_ptr_arg_usage<'tcx>(cx: &LateContext<'tcx>, body: &'tcx Body<'_>, args: Some((Node::Expr(e), child_id)) => match e.kind { ExprKind::Call(f, expr_args) => { let i = expr_args.iter().position(|arg| arg.hir_id == child_id).unwrap_or(0); - if expr_sig(self.cx, f) - .map(|sig| sig.input(i).skip_binder().peel_refs()) - .map_or(true, |ty| match *ty.kind() { + if expr_sig(self.cx, f).and_then(|sig| sig.input(i)).map_or(true, |ty| { + match *ty.skip_binder().peel_refs().kind() { ty::Param(_) => true, ty::Adt(def, _) => def.did() == args.ty_did, _ => false, - }) - { + } + }) { // Passed to a function taking the non-dereferenced type. set_skip_flag(); } diff --git a/clippy_lints/src/redundant_static_lifetimes.rs b/clippy_lints/src/redundant_static_lifetimes.rs index 0825f00f421..f8801f769e8 100644 --- a/clippy_lints/src/redundant_static_lifetimes.rs +++ b/clippy_lints/src/redundant_static_lifetimes.rs @@ -87,7 +87,7 @@ impl RedundantStaticLifetimes { _ => {}, } } - self.visit_type(&*borrow_type.ty, cx, reason); + self.visit_type(&borrow_type.ty, cx, reason); }, _ => {}, } diff --git a/clippy_utils/src/lib.rs b/clippy_utils/src/lib.rs index 73c1bdd0e3f..ca056e7c1a0 100644 --- a/clippy_utils/src/lib.rs +++ b/clippy_utils/src/lib.rs @@ -2058,6 +2058,21 @@ pub fn peel_hir_expr_refs<'a>(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) { (e, count) } +/// Peels off all references on the type. Returns the underlying type and the number of references +/// removed. +pub fn peel_hir_ty_refs<'a>(mut ty: &'a hir::Ty<'a>) -> (&'a hir::Ty<'a>, usize) { + let mut count = 0; + loop { + match &ty.kind { + TyKind::Rptr(_, ref_ty) => { + ty = ref_ty.ty; + count += 1; + }, + _ => break (ty, count), + } + } +} + /// Removes `AddrOf` operators (`&`) or deref operators (`*`), but only if a reference type is /// dereferenced. An overloaded deref such as `Vec` to slice would not be removed. pub fn peel_ref_operators<'hir>(cx: &LateContext<'_>, mut expr: &'hir Expr<'hir>) -> &'hir Expr<'hir> { @@ -2110,7 +2125,7 @@ fn with_test_item_names<'tcx>(tcx: TyCtxt<'tcx>, module: LocalDefId, f: impl Fn( } } names.sort_unstable(); - f(&*entry.insert(names)) + f(entry.insert(names)) }, } } @@ -2168,6 +2183,57 @@ pub fn is_test_module_or_function(tcx: TyCtxt<'_>, item: &Item<'_>) -> bool { && item.ident.name.as_str().split('_').any(|a| a == "test" || a == "tests") } +/// Walks the HIR tree from the given expression, up to the node where the value produced by the +/// expression is consumed. Calls the function for every node encountered this way until it returns +/// `Some`. +/// +/// This allows walking through `if`, `match`, `break`, block expressions to find where the value +/// produced by the expression is consumed. +pub fn walk_to_expr_usage<'tcx, T>( + cx: &LateContext<'tcx>, + e: &Expr<'tcx>, + mut f: impl FnMut(Node<'tcx>, HirId) -> Option, +) -> Option { + let map = cx.tcx.hir(); + let mut iter = map.parent_iter(e.hir_id); + let mut child_id = e.hir_id; + + while let Some((parent_id, parent)) = iter.next() { + if let Some(x) = f(parent, child_id) { + return Some(x); + } + let parent = match parent { + Node::Expr(e) => e, + Node::Block(Block { expr: Some(body), .. }) | Node::Arm(Arm { body, .. }) if body.hir_id == child_id => { + child_id = parent_id; + continue; + }, + Node::Arm(a) if a.body.hir_id == child_id => { + child_id = parent_id; + continue; + }, + _ => return None, + }; + match parent.kind { + ExprKind::If(child, ..) | ExprKind::Match(child, ..) if child.hir_id != child_id => { + child_id = parent_id; + continue; + }, + ExprKind::Break(Destination { target_id: Ok(id), .. }, _) => { + child_id = id; + iter = map.parent_iter(id); + continue; + }, + ExprKind::Block(..) => { + child_id = parent_id; + continue; + }, + _ => return None, + } + } + None +} + macro_rules! op_utils { ($($name:ident $assign:ident)*) => { /// Binary operation traits like `LangItem::Add` diff --git a/clippy_utils/src/ty.rs b/clippy_utils/src/ty.rs index 12831ea4355..2c19e8a7adb 100644 --- a/clippy_utils/src/ty.rs +++ b/clippy_utils/src/ty.rs @@ -6,16 +6,16 @@ use core::ops::ControlFlow; use rustc_ast::ast::Mutability; use rustc_data_structures::fx::{FxHashMap, FxHashSet}; use rustc_hir as hir; -use rustc_hir::def::{CtorKind, DefKind, Res}; +use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res}; use rustc_hir::def_id::DefId; -use rustc_hir::{Expr, LangItem, TyKind, Unsafety}; +use rustc_hir::{Expr, FnDecl, LangItem, TyKind, Unsafety}; use rustc_infer::infer::TyCtxtInferExt; use rustc_lint::LateContext; use rustc_middle::mir::interpret::{ConstValue, Scalar}; use rustc_middle::ty::subst::{GenericArg, GenericArgKind, Subst}; use rustc_middle::ty::{ - self, AdtDef, Binder, BoundRegion, FnSig, IntTy, ParamEnv, Predicate, PredicateKind, ProjectionTy, Region, - RegionKind, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable, TypeVisitor, UintTy, VariantDiscr, + self, AdtDef, Binder, BoundRegion, DefIdTree, FnSig, IntTy, ParamEnv, Predicate, PredicateKind, ProjectionTy, + Region, RegionKind, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable, TypeVisitor, UintTy, VariantDef, VariantDiscr, }; use rustc_span::symbol::Ident; use rustc_span::{sym, Span, Symbol, DUMMY_SP}; @@ -502,16 +502,46 @@ pub fn all_predicates_of(tcx: TyCtxt<'_>, id: DefId) -> impl Iterator { Sig(Binder<'tcx, FnSig<'tcx>>), - Closure(Binder<'tcx, FnSig<'tcx>>), + Closure(Option<&'tcx FnDecl<'tcx>>, Binder<'tcx, FnSig<'tcx>>), Trait(Binder<'tcx, Ty<'tcx>>, Option>>), } impl<'tcx> ExprFnSig<'tcx> { - /// Gets the argument type at the given offset. - pub fn input(self, i: usize) -> Binder<'tcx, Ty<'tcx>> { + /// Gets the argument type at the given offset. This will return `None` when the index is out of + /// bounds only for variadic functions, otherwise this will panic. + pub fn input(self, i: usize) -> Option>> { match self { - Self::Sig(sig) => sig.input(i), - Self::Closure(sig) => sig.input(0).map_bound(|ty| ty.tuple_fields()[i]), - Self::Trait(inputs, _) => inputs.map_bound(|ty| ty.tuple_fields()[i]), + Self::Sig(sig) => { + if sig.c_variadic() { + sig.inputs().map_bound(|inputs| inputs.get(i).copied()).transpose() + } else { + Some(sig.input(i)) + } + }, + Self::Closure(_, sig) => Some(sig.input(0).map_bound(|ty| ty.tuple_fields()[i])), + Self::Trait(inputs, _) => Some(inputs.map_bound(|ty| ty.tuple_fields()[i])), + } + } + + /// Gets the argument type at the given offset. For closures this will also get the type as + /// written. This will return `None` when the index is out of bounds only for variadic + /// functions, otherwise this will panic. + pub fn input_with_hir(self, i: usize) -> Option<(Option<&'tcx hir::Ty<'tcx>>, Binder<'tcx, Ty<'tcx>>)> { + match self { + Self::Sig(sig) => { + if sig.c_variadic() { + sig.inputs() + .map_bound(|inputs| inputs.get(i).copied()) + .transpose() + .map(|arg| (None, arg)) + } else { + Some((None, sig.input(i))) + } + }, + Self::Closure(decl, sig) => Some(( + decl.and_then(|decl| decl.inputs.get(i)), + sig.input(0).map_bound(|ty| ty.tuple_fields()[i]), + )), + Self::Trait(inputs, _) => Some((None, inputs.map_bound(|ty| ty.tuple_fields()[i]))), } } @@ -519,7 +549,7 @@ impl<'tcx> ExprFnSig<'tcx> { /// specified. pub fn output(self) -> Option>> { match self { - Self::Sig(sig) | Self::Closure(sig) => Some(sig.output()), + Self::Sig(sig) | Self::Closure(_, sig) => Some(sig.output()), Self::Trait(_, output) => output, } } @@ -536,7 +566,12 @@ pub fn expr_sig<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>) -> Option(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option> { match *ty.kind() { - ty::Closure(_, subs) => Some(ExprFnSig::Closure(subs.as_closure().sig())), + ty::Closure(id, subs) => { + let decl = id + .as_local() + .and_then(|id| cx.tcx.hir().fn_decl_by_hir_id(cx.tcx.hir().local_def_id_to_hir_id(id))); + Some(ExprFnSig::Closure(decl, subs.as_closure().sig())) + }, ty::FnDef(id, subs) => Some(ExprFnSig::Sig(cx.tcx.bound_fn_sig(id).subst(cx.tcx, subs))), ty::FnPtr(sig) => Some(ExprFnSig::Sig(sig)), ty::Dynamic(bounds, _) => { @@ -739,3 +774,17 @@ pub fn for_each_top_level_late_bound_region( } ty.visit_with(&mut V { index: 0, f }) } + +pub fn variant_of_res<'tcx>(cx: &LateContext<'tcx>, res: Res) -> Option<&'tcx VariantDef> { + match res { + Res::Def(DefKind::Struct, id) => Some(cx.tcx.adt_def(id).non_enum_variant()), + Res::Def(DefKind::Variant, id) => Some(cx.tcx.adt_def(cx.tcx.parent(id)).variant_with_id(id)), + Res::Def(DefKind::Ctor(CtorOf::Struct, _), id) => Some(cx.tcx.adt_def(cx.tcx.parent(id)).non_enum_variant()), + Res::Def(DefKind::Ctor(CtorOf::Variant, _), id) => { + let var_id = cx.tcx.parent(id); + Some(cx.tcx.adt_def(cx.tcx.parent(var_id)).variant_with_id(var_id)) + }, + Res::SelfCtor(id) => Some(cx.tcx.type_of(id).ty_adt_def().unwrap().non_enum_variant()), + _ => None, + } +} diff --git a/tests/ui/borrow_deref_ref_unfixable.rs b/tests/ui/borrow_deref_ref_unfixable.rs index a8e2bbfef0f..b4e93774436 100644 --- a/tests/ui/borrow_deref_ref_unfixable.rs +++ b/tests/ui/borrow_deref_ref_unfixable.rs @@ -1,4 +1,4 @@ -#![allow(dead_code, unused_variables)] +#![allow(dead_code, unused_variables, clippy::explicit_auto_deref)] fn main() {} diff --git a/tests/ui/explicit_auto_deref.fixed b/tests/ui/explicit_auto_deref.fixed new file mode 100644 index 00000000000..04039ca3154 --- /dev/null +++ b/tests/ui/explicit_auto_deref.fixed @@ -0,0 +1,161 @@ +// run-rustfix + +#![warn(clippy::explicit_auto_deref)] +#![allow( + dead_code, + unused_braces, + clippy::borrowed_box, + clippy::needless_borrow, + clippy::ptr_arg, + clippy::redundant_field_names, + clippy::too_many_arguments +)] + +trait CallableStr { + type T: Fn(&str); + fn callable_str(&self) -> Self::T; +} +impl CallableStr for () { + type T = fn(&str); + fn callable_str(&self) -> Self::T { + fn f(_: &str) {} + f + } +} +impl CallableStr for i32 { + type T = <() as CallableStr>::T; + fn callable_str(&self) -> Self::T { + ().callable_str() + } +} + +trait CallableT { + type T: Fn(&U); + fn callable_t(&self) -> Self::T; +} +impl CallableT for () { + type T = fn(&U); + fn callable_t(&self) -> Self::T { + fn f(_: &U) {} + f:: + } +} +impl CallableT for i32 { + type T = <() as CallableT>::T; + fn callable_t(&self) -> Self::T { + ().callable_t() + } +} + +fn f_str(_: &str) {} +fn f_t(_: T) {} +fn f_ref_t(_: &T) {} + +fn f_str_t(_: &str, _: T) {} + +fn f_box_t(_: &Box) {} + +fn main() { + let s = String::new(); + + let _: &str = &s; + let _ = &*s; // Don't lint. Inferred type would change. + let _: &_ = &*s; // Don't lint. Inferred type would change. + + f_str(&s); + f_t(&*s); // Don't lint. Inferred type would change. + f_ref_t(&*s); // Don't lint. Inferred type would change. + + f_str_t(&s, &*s); // Don't lint second param. + + let b = Box::new(Box::new(Box::new(5))); + let _: &Box = &b; + let _: &Box<_> = &**b; // Don't lint. Inferred type would change. + + f_box_t(&**b); // Don't lint. Inferred type would change. + + let c = |_x: &str| (); + c(&s); + + let c = |_x| (); + c(&*s); // Don't lint. Inferred type would change. + + fn _f(x: &String) -> &str { + x + } + + fn _f1(x: &String) -> &str { + { x } + } + + fn _f2(x: &String) -> &str { + { x } + } + + fn _f3(x: &Box>>) -> &Box { + x + } + + fn _f4( + x: String, + f1: impl Fn(&str), + f2: &dyn Fn(&str), + f3: fn(&str), + f4: impl CallableStr, + f5: <() as CallableStr>::T, + f6: ::T, + f7: &dyn CallableStr, + f8: impl CallableT, + f9: <() as CallableT>::T, + f10: >::T, + f11: &dyn CallableT, + ) { + f1(&x); + f2(&x); + f3(&x); + f4.callable_str()(&x); + f5(&x); + f6(&x); + f7.callable_str()(&x); + f8.callable_t()(&x); + f9(&x); + f10(&x); + f11.callable_t()(&x); + } + + struct S1<'a>(&'a str); + let _ = S1(&s); + + struct S2<'a> { + s: &'a str, + } + let _ = S2 { s: &s }; + + struct S3<'a, T: ?Sized>(&'a T); + let _ = S3(&*s); // Don't lint. Inferred type would change. + + struct S4<'a, T: ?Sized> { + s: &'a T, + } + let _ = S4 { s: &*s }; // Don't lint. Inferred type would change. + + enum E1<'a> { + S1(&'a str), + S2 { s: &'a str }, + } + impl<'a> E1<'a> { + fn m1(s: &'a String) { + let _ = Self::S1(s); + let _ = Self::S2 { s: s }; + } + } + let _ = E1::S1(&s); + let _ = E1::S2 { s: &s }; + + enum E2<'a, T: ?Sized> { + S1(&'a T), + S2 { s: &'a T }, + } + let _ = E2::S1(&*s); // Don't lint. Inferred type would change. + let _ = E2::S2 { s: &*s }; // Don't lint. Inferred type would change. +} diff --git a/tests/ui/explicit_auto_deref.rs b/tests/ui/explicit_auto_deref.rs new file mode 100644 index 00000000000..1cc77c1b08f --- /dev/null +++ b/tests/ui/explicit_auto_deref.rs @@ -0,0 +1,161 @@ +// run-rustfix + +#![warn(clippy::explicit_auto_deref)] +#![allow( + dead_code, + unused_braces, + clippy::borrowed_box, + clippy::needless_borrow, + clippy::ptr_arg, + clippy::redundant_field_names, + clippy::too_many_arguments +)] + +trait CallableStr { + type T: Fn(&str); + fn callable_str(&self) -> Self::T; +} +impl CallableStr for () { + type T = fn(&str); + fn callable_str(&self) -> Self::T { + fn f(_: &str) {} + f + } +} +impl CallableStr for i32 { + type T = <() as CallableStr>::T; + fn callable_str(&self) -> Self::T { + ().callable_str() + } +} + +trait CallableT { + type T: Fn(&U); + fn callable_t(&self) -> Self::T; +} +impl CallableT for () { + type T = fn(&U); + fn callable_t(&self) -> Self::T { + fn f(_: &U) {} + f:: + } +} +impl CallableT for i32 { + type T = <() as CallableT>::T; + fn callable_t(&self) -> Self::T { + ().callable_t() + } +} + +fn f_str(_: &str) {} +fn f_t(_: T) {} +fn f_ref_t(_: &T) {} + +fn f_str_t(_: &str, _: T) {} + +fn f_box_t(_: &Box) {} + +fn main() { + let s = String::new(); + + let _: &str = &*s; + let _ = &*s; // Don't lint. Inferred type would change. + let _: &_ = &*s; // Don't lint. Inferred type would change. + + f_str(&*s); + f_t(&*s); // Don't lint. Inferred type would change. + f_ref_t(&*s); // Don't lint. Inferred type would change. + + f_str_t(&*s, &*s); // Don't lint second param. + + let b = Box::new(Box::new(Box::new(5))); + let _: &Box = &**b; + let _: &Box<_> = &**b; // Don't lint. Inferred type would change. + + f_box_t(&**b); // Don't lint. Inferred type would change. + + let c = |_x: &str| (); + c(&*s); + + let c = |_x| (); + c(&*s); // Don't lint. Inferred type would change. + + fn _f(x: &String) -> &str { + &**x + } + + fn _f1(x: &String) -> &str { + { &**x } + } + + fn _f2(x: &String) -> &str { + &**{ x } + } + + fn _f3(x: &Box>>) -> &Box { + &***x + } + + fn _f4( + x: String, + f1: impl Fn(&str), + f2: &dyn Fn(&str), + f3: fn(&str), + f4: impl CallableStr, + f5: <() as CallableStr>::T, + f6: ::T, + f7: &dyn CallableStr, + f8: impl CallableT, + f9: <() as CallableT>::T, + f10: >::T, + f11: &dyn CallableT, + ) { + f1(&*x); + f2(&*x); + f3(&*x); + f4.callable_str()(&*x); + f5(&*x); + f6(&*x); + f7.callable_str()(&*x); + f8.callable_t()(&*x); + f9(&*x); + f10(&*x); + f11.callable_t()(&*x); + } + + struct S1<'a>(&'a str); + let _ = S1(&*s); + + struct S2<'a> { + s: &'a str, + } + let _ = S2 { s: &*s }; + + struct S3<'a, T: ?Sized>(&'a T); + let _ = S3(&*s); // Don't lint. Inferred type would change. + + struct S4<'a, T: ?Sized> { + s: &'a T, + } + let _ = S4 { s: &*s }; // Don't lint. Inferred type would change. + + enum E1<'a> { + S1(&'a str), + S2 { s: &'a str }, + } + impl<'a> E1<'a> { + fn m1(s: &'a String) { + let _ = Self::S1(&**s); + let _ = Self::S2 { s: &**s }; + } + } + let _ = E1::S1(&*s); + let _ = E1::S2 { s: &*s }; + + enum E2<'a, T: ?Sized> { + S1(&'a T), + S2 { s: &'a T }, + } + let _ = E2::S1(&*s); // Don't lint. Inferred type would change. + let _ = E2::S2 { s: &*s }; // Don't lint. Inferred type would change. +} diff --git a/tests/ui/explicit_auto_deref.stderr b/tests/ui/explicit_auto_deref.stderr new file mode 100644 index 00000000000..f3cceb6b889 --- /dev/null +++ b/tests/ui/explicit_auto_deref.stderr @@ -0,0 +1,160 @@ +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:61:20 + | +LL | let _: &str = &*s; + | ^^ help: try this: `s` + | + = note: `-D clippy::explicit-auto-deref` implied by `-D warnings` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:65:12 + | +LL | f_str(&*s); + | ^^ help: try this: `s` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:69:14 + | +LL | f_str_t(&*s, &*s); // Don't lint second param. + | ^^ help: try this: `s` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:72:25 + | +LL | let _: &Box = &**b; + | ^^^ help: try this: `b` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:78:8 + | +LL | c(&*s); + | ^^ help: try this: `s` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:84:9 + | +LL | &**x + | ^^^^ help: try this: `x` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:88:11 + | +LL | { &**x } + | ^^^^ help: try this: `x` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:92:9 + | +LL | &**{ x } + | ^^^^^^^^ help: try this: `{ x }` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:96:9 + | +LL | &***x + | ^^^^^ help: try this: `x` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:113:13 + | +LL | f1(&*x); + | ^^ help: try this: `x` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:114:13 + | +LL | f2(&*x); + | ^^ help: try this: `x` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:115:13 + | +LL | f3(&*x); + | ^^ help: try this: `x` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:116:28 + | +LL | f4.callable_str()(&*x); + | ^^ help: try this: `x` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:117:13 + | +LL | f5(&*x); + | ^^ help: try this: `x` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:118:13 + | +LL | f6(&*x); + | ^^ help: try this: `x` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:119:28 + | +LL | f7.callable_str()(&*x); + | ^^ help: try this: `x` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:120:26 + | +LL | f8.callable_t()(&*x); + | ^^ help: try this: `x` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:121:13 + | +LL | f9(&*x); + | ^^ help: try this: `x` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:122:14 + | +LL | f10(&*x); + | ^^ help: try this: `x` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:123:27 + | +LL | f11.callable_t()(&*x); + | ^^ help: try this: `x` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:127:17 + | +LL | let _ = S1(&*s); + | ^^ help: try this: `s` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:132:22 + | +LL | let _ = S2 { s: &*s }; + | ^^ help: try this: `s` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:148:30 + | +LL | let _ = Self::S1(&**s); + | ^^^^ help: try this: `s` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:149:35 + | +LL | let _ = Self::S2 { s: &**s }; + | ^^^^ help: try this: `s` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:152:21 + | +LL | let _ = E1::S1(&*s); + | ^^ help: try this: `s` + +error: deref which would be done by auto-deref + --> $DIR/explicit_auto_deref.rs:153:26 + | +LL | let _ = E1::S2 { s: &*s }; + | ^^ help: try this: `s` + +error: aborting due to 26 previous errors + diff --git a/tests/ui/explicit_deref_methods.fixed b/tests/ui/explicit_deref_methods.fixed index 92f27e68549..523cae183ee 100644 --- a/tests/ui/explicit_deref_methods.fixed +++ b/tests/ui/explicit_deref_methods.fixed @@ -4,7 +4,8 @@ unused_variables, clippy::clone_double_ref, clippy::needless_borrow, - clippy::borrow_deref_ref + clippy::borrow_deref_ref, + clippy::explicit_auto_deref )] #![warn(clippy::explicit_deref_methods)] diff --git a/tests/ui/explicit_deref_methods.rs b/tests/ui/explicit_deref_methods.rs index d118607f992..0bbc1ae57cd 100644 --- a/tests/ui/explicit_deref_methods.rs +++ b/tests/ui/explicit_deref_methods.rs @@ -4,7 +4,8 @@ unused_variables, clippy::clone_double_ref, clippy::needless_borrow, - clippy::borrow_deref_ref + clippy::borrow_deref_ref, + clippy::explicit_auto_deref )] #![warn(clippy::explicit_deref_methods)] diff --git a/tests/ui/explicit_deref_methods.stderr b/tests/ui/explicit_deref_methods.stderr index 8e8b358972b..4b10ed1377b 100644 --- a/tests/ui/explicit_deref_methods.stderr +++ b/tests/ui/explicit_deref_methods.stderr @@ -1,5 +1,5 @@ error: explicit `deref` method call - --> $DIR/explicit_deref_methods.rs:35:19 + --> $DIR/explicit_deref_methods.rs:36:19 | LL | let b: &str = a.deref(); | ^^^^^^^^^ help: try this: `&*a` @@ -7,67 +7,67 @@ LL | let b: &str = a.deref(); = note: `-D clippy::explicit-deref-methods` implied by `-D warnings` error: explicit `deref_mut` method call - --> $DIR/explicit_deref_methods.rs:37:23 + --> $DIR/explicit_deref_methods.rs:38:23 | LL | let b: &mut str = a.deref_mut(); | ^^^^^^^^^^^^^ help: try this: `&mut **a` error: explicit `deref` method call - --> $DIR/explicit_deref_methods.rs:40:39 + --> $DIR/explicit_deref_methods.rs:41:39 | LL | let b: String = format!("{}, {}", a.deref(), a.deref()); | ^^^^^^^^^ help: try this: `&*a` error: explicit `deref` method call - --> $DIR/explicit_deref_methods.rs:40:50 + --> $DIR/explicit_deref_methods.rs:41:50 | LL | let b: String = format!("{}, {}", a.deref(), a.deref()); | ^^^^^^^^^ help: try this: `&*a` error: explicit `deref` method call - --> $DIR/explicit_deref_methods.rs:42:20 + --> $DIR/explicit_deref_methods.rs:43:20 | LL | println!("{}", a.deref()); | ^^^^^^^^^ help: try this: `&*a` error: explicit `deref` method call - --> $DIR/explicit_deref_methods.rs:45:11 + --> $DIR/explicit_deref_methods.rs:46:11 | LL | match a.deref() { | ^^^^^^^^^ help: try this: `&*a` error: explicit `deref` method call - --> $DIR/explicit_deref_methods.rs:49:28 + --> $DIR/explicit_deref_methods.rs:50:28 | LL | let b: String = concat(a.deref()); | ^^^^^^^^^ help: try this: `&*a` error: explicit `deref` method call - --> $DIR/explicit_deref_methods.rs:51:13 + --> $DIR/explicit_deref_methods.rs:52:13 | LL | let b = just_return(a).deref(); | ^^^^^^^^^^^^^^^^^^^^^^ help: try this: `just_return(a)` error: explicit `deref` method call - --> $DIR/explicit_deref_methods.rs:53:28 + --> $DIR/explicit_deref_methods.rs:54:28 | LL | let b: String = concat(just_return(a).deref()); | ^^^^^^^^^^^^^^^^^^^^^^ help: try this: `just_return(a)` error: explicit `deref` method call - --> $DIR/explicit_deref_methods.rs:55:19 + --> $DIR/explicit_deref_methods.rs:56:19 | LL | let b: &str = a.deref().deref(); | ^^^^^^^^^^^^^^^^^ help: try this: `&**a` error: explicit `deref` method call - --> $DIR/explicit_deref_methods.rs:58:13 + --> $DIR/explicit_deref_methods.rs:59:13 | LL | let b = opt_a.unwrap().deref(); | ^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&*opt_a.unwrap()` error: explicit `deref` method call - --> $DIR/explicit_deref_methods.rs:84:31 + --> $DIR/explicit_deref_methods.rs:85:31 | LL | let b: &str = expr_deref!(a.deref()); | ^^^^^^^^^ help: try this: `&*a` diff --git a/tests/ui/useless_asref.fixed b/tests/ui/useless_asref.fixed index e431661d180..90cb8945e77 100644 --- a/tests/ui/useless_asref.fixed +++ b/tests/ui/useless_asref.fixed @@ -1,6 +1,7 @@ // run-rustfix #![deny(clippy::useless_asref)] +#![allow(clippy::explicit_auto_deref)] use std::fmt::Debug; diff --git a/tests/ui/useless_asref.rs b/tests/ui/useless_asref.rs index 6ae931d7aa4..cb9f8ae5909 100644 --- a/tests/ui/useless_asref.rs +++ b/tests/ui/useless_asref.rs @@ -1,6 +1,7 @@ // run-rustfix #![deny(clippy::useless_asref)] +#![allow(clippy::explicit_auto_deref)] use std::fmt::Debug; diff --git a/tests/ui/useless_asref.stderr b/tests/ui/useless_asref.stderr index 5876b54aca8..b21c67bb364 100644 --- a/tests/ui/useless_asref.stderr +++ b/tests/ui/useless_asref.stderr @@ -1,5 +1,5 @@ error: this call to `as_ref` does nothing - --> $DIR/useless_asref.rs:43:18 + --> $DIR/useless_asref.rs:44:18 | LL | foo_rstr(rstr.as_ref()); | ^^^^^^^^^^^^^ help: try this: `rstr` @@ -11,61 +11,61 @@ LL | #![deny(clippy::useless_asref)] | ^^^^^^^^^^^^^^^^^^^^^ error: this call to `as_ref` does nothing - --> $DIR/useless_asref.rs:45:20 + --> $DIR/useless_asref.rs:46:20 | LL | foo_rslice(rslice.as_ref()); | ^^^^^^^^^^^^^^^ help: try this: `rslice` error: this call to `as_mut` does nothing - --> $DIR/useless_asref.rs:49:21 + --> $DIR/useless_asref.rs:50:21 | LL | foo_mrslice(mrslice.as_mut()); | ^^^^^^^^^^^^^^^^ help: try this: `mrslice` error: this call to `as_ref` does nothing - --> $DIR/useless_asref.rs:51:20 + --> $DIR/useless_asref.rs:52:20 | LL | foo_rslice(mrslice.as_ref()); | ^^^^^^^^^^^^^^^^ help: try this: `mrslice` error: this call to `as_ref` does nothing - --> $DIR/useless_asref.rs:58:20 + --> $DIR/useless_asref.rs:59:20 | LL | foo_rslice(rrrrrslice.as_ref()); | ^^^^^^^^^^^^^^^^^^^ help: try this: `rrrrrslice` error: this call to `as_ref` does nothing - --> $DIR/useless_asref.rs:60:18 + --> $DIR/useless_asref.rs:61:18 | LL | foo_rstr(rrrrrstr.as_ref()); | ^^^^^^^^^^^^^^^^^ help: try this: `rrrrrstr` error: this call to `as_mut` does nothing - --> $DIR/useless_asref.rs:65:21 + --> $DIR/useless_asref.rs:66:21 | LL | foo_mrslice(mrrrrrslice.as_mut()); | ^^^^^^^^^^^^^^^^^^^^ help: try this: `mrrrrrslice` error: this call to `as_ref` does nothing - --> $DIR/useless_asref.rs:67:20 + --> $DIR/useless_asref.rs:68:20 | LL | foo_rslice(mrrrrrslice.as_ref()); | ^^^^^^^^^^^^^^^^^^^^ help: try this: `mrrrrrslice` error: this call to `as_ref` does nothing - --> $DIR/useless_asref.rs:71:16 + --> $DIR/useless_asref.rs:72:16 | LL | foo_rrrrmr((&&&&MoreRef).as_ref()); | ^^^^^^^^^^^^^^^^^^^^^^ help: try this: `(&&&&MoreRef)` error: this call to `as_mut` does nothing - --> $DIR/useless_asref.rs:121:13 + --> $DIR/useless_asref.rs:122:13 | LL | foo_mrt(mrt.as_mut()); | ^^^^^^^^^^^^ help: try this: `mrt` error: this call to `as_ref` does nothing - --> $DIR/useless_asref.rs:123:12 + --> $DIR/useless_asref.rs:124:12 | LL | foo_rt(mrt.as_ref()); | ^^^^^^^^^^^^ help: try this: `mrt`