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Refactor dereference.rs

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Merge `Position` and `AutoDerefStability`
This commit is contained in:
Jason Newcomb 2022-01-29 18:06:14 -05:00
parent 0204b95357
commit 0b4ba734cb
4 changed files with 120 additions and 124 deletions
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174
clippy_lints/src/dereference.rs
View file

@ -2,7 +2,7 @@ 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, variant_of_res};
use clippy_utils::{get_parent_expr, get_parent_node, is_lint_allowed, path_to_local, walk_to_expr_usage};
use clippy_utils::{get_parent_expr, is_lint_allowed, 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;
@ -15,7 +15,7 @@ use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow, AutoBorrowMutability};
use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeckResults};
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::{symbol::sym, Span, Symbol, SyntaxContext};
use rustc_span::{symbol::sym, Span, Symbol};
declare_clippy_lint! {
/// ### What it does
@ -167,7 +167,6 @@ struct DerefedBorrow {
count: usize,
required_precedence: i8,
msg: &'static str,
stability: AutoDerefStability,
position: Position,
}
@ -249,8 +248,7 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
match (self.state.take(), kind) {
(None, kind) => {
let expr_ty = typeck.expr_ty(expr);
let (position, parent_ctxt) = get_expr_position(cx, expr);
let (stability, adjustments) = walk_parents(cx, expr);
let (position, adjustments) = walk_parents(cx, expr);
match kind {
RefOp::Deref => {
@ -261,7 +259,7 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
State::ExplicitDerefField { name },
StateData { span: expr.span, hir_id: expr.hir_id },
));
} else if stability.is_deref_stable() {
} else if position.is_deref_stable() {
self.state = Some((
State::ExplicitDeref { deref_span: expr.span, deref_hir_id: expr.hir_id },
StateData { span: expr.span, hir_id: expr.hir_id },
@ -270,7 +268,7 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
}
RefOp::Method(target_mut)
if !is_lint_allowed(cx, EXPLICIT_DEREF_METHODS, expr.hir_id)
&& (position.lint_explicit_deref() || parent_ctxt != expr.span.ctxt()) =>
&& position.lint_explicit_deref() =>
{
self.state = Some((
State::DerefMethod {
@ -336,7 +334,7 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
} else if let Some(&Adjust::Borrow(AutoBorrow::Ref(_, mutability))) =
next_adjust.map(|a| &a.kind)
{
if matches!(mutability, AutoBorrowMutability::Mut { .. }) && !stability.is_reborrow_stable()
if matches!(mutability, AutoBorrowMutability::Mut { .. }) && !position.is_reborrow_stable()
{
(3, 0, deref_msg)
} else {
@ -354,12 +352,11 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
count: deref_count - required_refs,
required_precedence,
msg,
stability,
position,
}),
StateData { span: expr.span, hir_id: expr.hir_id },
));
} else if stability.is_deref_stable() {
} else if position.is_deref_stable() {
self.state = Some((
State::Borrow,
StateData {
@ -406,9 +403,9 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
));
},
(Some((State::DerefedBorrow(state), data)), RefOp::AddrOf) => {
let stability = state.stability;
let position = state.position;
report(cx, expr, State::DerefedBorrow(state), data);
if stability.is_deref_stable() {
if position.is_deref_stable() {
self.state = Some((
State::Borrow,
StateData {
@ -419,7 +416,6 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
}
},
(Some((State::DerefedBorrow(state), data)), RefOp::Deref) => {
let stability = state.stability;
let position = state.position;
report(cx, expr, State::DerefedBorrow(state), data);
if let Position::FieldAccess(name) = position
@ -429,7 +425,7 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
State::ExplicitDerefField { name },
StateData { span: expr.span, hir_id: expr.hir_id },
));
} else if stability.is_deref_stable() {
} else if position.is_deref_stable() {
self.state = Some((
State::ExplicitDeref { deref_span: expr.span, deref_hir_id: expr.hir_id },
StateData { span: expr.span, hir_id: expr.hir_id },
@ -601,61 +597,35 @@ fn deref_method_same_type<'tcx>(result_ty: Ty<'tcx>, arg_ty: Ty<'tcx>) -> bool {
}
}
/// The position of an expression relative to it's parent.
#[derive(Clone, Copy)]
enum Position {
MethodReceiver,
FieldAccess(Symbol),
Callee,
FieldAccess(Symbol),
Postfix,
Deref,
/// Any other location which will trigger auto-deref to a specific time.
DerefStable,
/// Any other location which will trigger auto-reborrowing.
ReborrowStable,
Other,
}
impl Position {
fn is_deref_stable(self) -> bool {
matches!(self, Self::DerefStable)
}
fn is_reborrow_stable(self) -> bool {
matches!(self, Self::DerefStable | Self::ReborrowStable)
}
fn can_auto_borrow(self) -> bool {
matches!(self, Self::MethodReceiver | Self::FieldAccess(_) | Self::Callee)
}
fn lint_explicit_deref(self) -> bool {
matches!(self, Self::Other)
}
}
/// Get which position an expression is in relative to it's parent.
fn get_expr_position(cx: &LateContext<'_>, e: &Expr<'_>) -> (Position, SyntaxContext) {
if let Some(Node::Expr(parent)) = get_parent_node(cx.tcx, e.hir_id) {
let pos = match parent.kind {
ExprKind::MethodCall(_, [self_arg, ..], _) if self_arg.hir_id == e.hir_id => Position::MethodReceiver,
ExprKind::Field(_, name) => Position::FieldAccess(name.name),
ExprKind::Call(f, _) if f.hir_id == e.hir_id => Position::Callee,
ExprKind::Unary(UnOp::Deref, _) => Position::Deref,
ExprKind::Match(_, _, MatchSource::TryDesugar | MatchSource::AwaitDesugar) | ExprKind::Index(..) => {
Position::Postfix
},
_ => Position::Other,
};
(pos, parent.span.ctxt())
} else {
(Position::Other, SyntaxContext::root())
}
}
/// How stable the result of auto-deref is.
#[derive(Clone, Copy)]
enum AutoDerefStability {
/// Auto-deref will always choose the same type.
Deref,
/// Auto-deref will always reborrow a reference.
Reborrow,
/// Auto-deref will not occur, or it may select a different type.
None,
}
impl AutoDerefStability {
fn is_deref_stable(self) -> bool {
matches!(self, Self::Deref)
}
fn is_reborrow_stable(self) -> bool {
matches!(self, Self::Deref | Self::Reborrow)
matches!(self, Self::Other | Self::DerefStable | Self::ReborrowStable)
}
}
@ -663,64 +633,73 @@ impl AutoDerefStability {
/// 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<'_>) -> (AutoDerefStability, &'tcx [Adjustment<'tcx>]) {
fn walk_parents<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> (Position, &'tcx [Adjustment<'tcx>]) {
let mut adjustments = [].as_slice();
let stability = walk_to_expr_usage(cx, e, &mut |node, child_id| {
let ctxt = e.span.ctxt();
let position = walk_to_expr_usage(cx, e, &mut |parent, child_id| {
// LocalTableInContext returns the wrong lifetime, so go use `expr_adjustments` instead.
if adjustments.is_empty() && let Node::Expr(e) = cx.tcx.hir().get(child_id) {
adjustments = cx.typeck_results().expr_adjustments(e);
}
match node {
Node::Local(Local { ty: Some(ty), .. }) => Some(binding_ty_auto_deref_stability(ty)),
match parent {
Node::Local(Local { ty: Some(ty), span, .. }) if span.ctxt() == ctxt => {
Some(binding_ty_auto_deref_stability(ty))
},
Node::Item(&Item {
kind: ItemKind::Static(..) | ItemKind::Const(..),
def_id,
span,
..
})
| Node::TraitItem(&TraitItem {
kind: TraitItemKind::Const(..),
def_id,
span,
..
})
| Node::ImplItem(&ImplItem {
kind: ImplItemKind::Const(..),
def_id,
span,
..
}) => {
}) if span.ctxt() == ctxt => {
let ty = cx.tcx.type_of(def_id);
Some(if ty.is_ref() {
AutoDerefStability::None
Position::Other
} else {
AutoDerefStability::Deref
Position::DerefStable
})
},
Node::Item(&Item {
kind: ItemKind::Fn(..),
def_id,
span,
..
})
| Node::TraitItem(&TraitItem {
kind: TraitItemKind::Fn(..),
def_id,
span,
..
})
| Node::ImplItem(&ImplItem {
kind: ImplItemKind::Fn(..),
def_id,
span,
..
}) => {
}) if span.ctxt() == ctxt => {
let output = cx.tcx.fn_sig(def_id.to_def_id()).skip_binder().output();
Some(if !output.is_ref() {
AutoDerefStability::None
Position::Other
} else if output.has_placeholders() || output.has_opaque_types() {
AutoDerefStability::Reborrow
Position::ReborrowStable
} else {
AutoDerefStability::Deref
Position::DerefStable
})
},
Node::Expr(e) => match e.kind {
Node::Expr(parent) if parent.span.ctxt() == ctxt => match parent.kind {
ExprKind::Ret(_) => {
let output = cx
.tcx
@ -728,13 +707,14 @@ fn walk_parents<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> (AutoDerefSt
.skip_binder()
.output();
Some(if !output.is_ref() {
AutoDerefStability::None
Position::Other
} else if output.has_placeholders() || output.has_opaque_types() {
AutoDerefStability::Reborrow
Position::ReborrowStable
} else {
AutoDerefStability::Deref
Position::DerefStable
})
},
ExprKind::Call(func, _) if func.hir_id == child_id => (child_id == e.hir_id).then(|| Position::Callee),
ExprKind::Call(func, args) => args
.iter()
.position(|arg| arg.hir_id == child_id)
@ -746,16 +726,22 @@ fn walk_parents<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> (AutoDerefSt
Some(ty) => binding_ty_auto_deref_stability(ty),
None => param_auto_deref_stability(ty.skip_binder()),
}),
ExprKind::MethodCall(_, [_, args @ ..], _) => {
let id = cx.typeck_results().type_dependent_def_id(e.hir_id).unwrap();
ExprKind::MethodCall(_, args, _) => {
let id = cx.typeck_results().type_dependent_def_id(parent.hir_id).unwrap();
args.iter().position(|arg| arg.hir_id == child_id).map(|i| {
let arg = cx.tcx.fn_sig(id).skip_binder().inputs()[i + 1];
param_auto_deref_stability(arg)
if i == 0 {
if e.hir_id == child_id {
Position::MethodReceiver
} else {
Position::ReborrowStable
}
} else {
param_auto_deref_stability(cx.tcx.fn_sig(id).skip_binder().inputs()[i])
}
})
},
ExprKind::MethodCall(..) => Some(AutoDerefStability::Reborrow),
ExprKind::Struct(path, fields, _) => {
let variant = variant_of_res(cx, cx.qpath_res(path, e.hir_id));
let variant = variant_of_res(cx, cx.qpath_res(path, parent.hir_id));
fields
.iter()
.find(|f| f.expr.hir_id == child_id)
@ -763,13 +749,21 @@ fn walk_parents<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> (AutoDerefSt
.and_then(|(field, variant)| variant.fields.iter().find(|f| f.name == field.ident.name))
.map(|field| param_auto_deref_stability(cx.tcx.type_of(field.did)))
},
ExprKind::Field(child, name) if child.hir_id == e.hir_id => Some(Position::FieldAccess(name.name)),
ExprKind::Unary(UnOp::Deref, child) if child.hir_id == e.hir_id => Some(Position::Deref),
ExprKind::Match(child, _, MatchSource::TryDesugar | MatchSource::AwaitDesugar)
| ExprKind::Index(child, _)
if child.hir_id == e.hir_id =>
{
Some(Position::Postfix)
},
_ => None,
},
_ => None,
}
})
.unwrap_or(AutoDerefStability::None);
(stability, adjustments)
.unwrap_or(Position::Other);
(position, adjustments)
}
// Checks the stability of auto-deref when assigned to a binding with the given explicit type.
@ -781,9 +775,9 @@ fn walk_parents<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> (AutoDerefSt
//
// Here `y1` and `y2` would resolve to different types, so the type `&Box<_>` is not stable when
// switching to auto-dereferencing.
fn binding_ty_auto_deref_stability(ty: &hir::Ty<'_>) -> AutoDerefStability {
fn binding_ty_auto_deref_stability(ty: &hir::Ty<'_>) -> Position {
let TyKind::Rptr(_, ty) = &ty.kind else {
return AutoDerefStability::None;
return Position::Other;
};
let mut ty = ty;
@ -809,9 +803,9 @@ fn binding_ty_auto_deref_stability(ty: &hir::Ty<'_>) -> AutoDerefStability {
_ => false,
})
{
AutoDerefStability::Reborrow
Position::ReborrowStable
} else {
AutoDerefStability::Deref
Position::DerefStable
}
},
TyKind::Slice(_)
@ -821,8 +815,8 @@ fn binding_ty_auto_deref_stability(ty: &hir::Ty<'_>) -> AutoDerefStability {
| TyKind::Tup(_)
| TyKind::Ptr(_)
| TyKind::TraitObject(..)
| TyKind::Path(_) => AutoDerefStability::Deref,
TyKind::OpaqueDef(..) | TyKind::Infer | TyKind::Typeof(..) | TyKind::Err => AutoDerefStability::Reborrow,
| TyKind::Path(_) => Position::DerefStable,
TyKind::OpaqueDef(..) | TyKind::Infer | TyKind::Typeof(..) | TyKind::Err => Position::ReborrowStable,
};
}
}
@ -865,9 +859,9 @@ fn ty_contains_infer(ty: &hir::Ty<'_>) -> bool {
}
// Checks whether a type is stable when switching to auto dereferencing,
fn param_auto_deref_stability(ty: Ty<'_>) -> AutoDerefStability {
fn param_auto_deref_stability(ty: Ty<'_>) -> Position {
let ty::Ref(_, mut ty, _) = *ty.kind() else {
return AutoDerefStability::None;
return Position::Other;
};
loop {
@ -893,16 +887,16 @@ fn param_auto_deref_stability(ty: Ty<'_>) -> AutoDerefStability {
| ty::GeneratorWitness(..)
| ty::Never
| ty::Tuple(_)
| ty::Projection(_) => AutoDerefStability::Deref,
| ty::Projection(_) => Position::DerefStable,
ty::Infer(_)
| ty::Error(_)
| ty::Param(_)
| ty::Bound(..)
| ty::Opaque(..)
| ty::Placeholder(_)
| ty::Dynamic(..) => AutoDerefStability::Reborrow,
ty::Adt(..) if ty.has_placeholders() || ty.has_param_types_or_consts() => AutoDerefStability::Reborrow,
ty::Adt(..) => AutoDerefStability::Deref,
| ty::Dynamic(..) => Position::ReborrowStable,
ty::Adt(..) if ty.has_placeholders() || ty.has_param_types_or_consts() => Position::ReborrowStable,
ty::Adt(..) => Position::DerefStable,
};
}
}

3
tests/ui/explicit_auto_deref.fixed
View file

@ -10,7 +10,8 @@
clippy::ptr_arg,
clippy::redundant_field_names,
clippy::too_many_arguments,
clippy::borrow_deref_ref
clippy::borrow_deref_ref,
clippy::let_unit_value
)]
trait CallableStr {

3
tests/ui/explicit_auto_deref.rs
View file

@ -10,7 +10,8 @@
clippy::ptr_arg,
clippy::redundant_field_names,
clippy::too_many_arguments,
clippy::borrow_deref_ref
clippy::borrow_deref_ref,
clippy::let_unit_value
)]
trait CallableStr {

64
tests/ui/explicit_auto_deref.stderr
View file

@ -1,5 +1,5 @@
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:63:20
--> $DIR/explicit_auto_deref.rs:65:20
|
LL | let _: &str = &*s;
| ^^ help: try this: `s`
@ -7,187 +7,187 @@ LL | let _: &str = &*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:67:12
--> $DIR/explicit_auto_deref.rs:69:12
|
LL | f_str(&*s);
| ^^ help: try this: `s`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:71:14
--> $DIR/explicit_auto_deref.rs:73:14
|
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:74:25
--> $DIR/explicit_auto_deref.rs:76:25
|
LL | let _: &Box<i32> = &**b;
| ^^^ help: try this: `b`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:80:8
--> $DIR/explicit_auto_deref.rs:82:8
|
LL | c(&*s);
| ^^ help: try this: `s`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:86:9
--> $DIR/explicit_auto_deref.rs:88:9
|
LL | &**x
| ^^^^ help: try this: `x`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:90:11
--> $DIR/explicit_auto_deref.rs:92:11
|
LL | { &**x }
| ^^^^ help: try this: `x`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:94:9
--> $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:98:9
--> $DIR/explicit_auto_deref.rs:100:9
|
LL | &***x
| ^^^^^ help: try this: `x`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:115:13
--> $DIR/explicit_auto_deref.rs:117:13
|
LL | f1(&*x);
| ^^ help: try this: `x`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:116:13
--> $DIR/explicit_auto_deref.rs:118:13
|
LL | f2(&*x);
| ^^ help: try this: `x`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:117:13
--> $DIR/explicit_auto_deref.rs:119:13
|
LL | f3(&*x);
| ^^ help: try this: `x`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:118:28
--> $DIR/explicit_auto_deref.rs:120:28
|
LL | f4.callable_str()(&*x);
| ^^ help: try this: `x`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:119:13
--> $DIR/explicit_auto_deref.rs:121:13
|
LL | f5(&*x);
| ^^ help: try this: `x`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:120:13
--> $DIR/explicit_auto_deref.rs:122:13
|
LL | f6(&*x);
| ^^ help: try this: `x`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:121:28
--> $DIR/explicit_auto_deref.rs:123:28
|
LL | f7.callable_str()(&*x);
| ^^ help: try this: `x`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:122:26
--> $DIR/explicit_auto_deref.rs:124:26
|
LL | f8.callable_t()(&*x);
| ^^ help: try this: `x`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:123:13
--> $DIR/explicit_auto_deref.rs:125:13
|
LL | f9(&*x);
| ^^ help: try this: `x`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:124:14
--> $DIR/explicit_auto_deref.rs:126:14
|
LL | f10(&*x);
| ^^ help: try this: `x`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:125:27
--> $DIR/explicit_auto_deref.rs:127:27
|
LL | f11.callable_t()(&*x);
| ^^ help: try this: `x`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:129:17
--> $DIR/explicit_auto_deref.rs:131:17
|
LL | let _ = S1(&*s);
| ^^ help: try this: `s`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:134:22
--> $DIR/explicit_auto_deref.rs:136:22
|
LL | let _ = S2 { s: &*s };
| ^^ help: try this: `s`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:150:30
--> $DIR/explicit_auto_deref.rs:152:30
|
LL | let _ = Self::S1(&**s);
| ^^^^ help: try this: `s`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:151:35
--> $DIR/explicit_auto_deref.rs:153:35
|
LL | let _ = Self::S2 { s: &**s };
| ^^^^ help: try this: `s`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:154:21
--> $DIR/explicit_auto_deref.rs:156:21
|
LL | let _ = E1::S1(&*s);
| ^^ help: try this: `s`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:155:26
--> $DIR/explicit_auto_deref.rs:157:26
|
LL | let _ = E1::S2 { s: &*s };
| ^^ help: try this: `s`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:173:13
--> $DIR/explicit_auto_deref.rs:175:13
|
LL | let _ = (*b).foo;
| ^^^^ help: try this: `b`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:174:13
--> $DIR/explicit_auto_deref.rs:176:13
|
LL | let _ = (**b).foo;
| ^^^^^ help: try this: `b`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:189:19
--> $DIR/explicit_auto_deref.rs:191:19
|
LL | let _ = f_str(*ref_str);
| ^^^^^^^^ help: try this: `ref_str`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:191:19
--> $DIR/explicit_auto_deref.rs:193:19
|
LL | let _ = f_str(**ref_ref_str);
| ^^^^^^^^^^^^^ help: try this: `ref_ref_str`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:201:13
--> $DIR/explicit_auto_deref.rs:203:13
|
LL | f_str(&&*ref_str); // `needless_borrow` will suggest removing both references
| ^^^^^^^^ help: try this: `ref_str`
error: deref which would be done by auto-deref
--> $DIR/explicit_auto_deref.rs:202:12
--> $DIR/explicit_auto_deref.rs:204:12
|
LL | f_str(&&**ref_str); // `needless_borrow` will suggest removing only one reference
| ^^^^^^^^^^ help: try this: `ref_str`