2021-12-17 12:40:22 +00:00
|
|
|
use super::implicit_clone::is_clone_like;
|
|
|
|
use super::unnecessary_iter_cloned::{self, is_into_iter};
|
|
|
|
use clippy_utils::diagnostics::span_lint_and_sugg;
|
|
|
|
use clippy_utils::source::snippet_opt;
|
|
|
|
use clippy_utils::ty::{get_associated_type, get_iterator_item_ty, implements_trait, is_copy, peel_mid_ty_refs};
|
|
|
|
use clippy_utils::{fn_def_id, get_parent_expr, is_diag_item_method, is_diag_trait_item};
|
|
|
|
use rustc_errors::Applicability;
|
|
|
|
use rustc_hir::{def_id::DefId, BorrowKind, Expr, ExprKind};
|
|
|
|
use rustc_lint::LateContext;
|
|
|
|
use rustc_middle::mir::Mutability;
|
|
|
|
use rustc_middle::ty::adjustment::{Adjust, Adjustment, OverloadedDeref};
|
|
|
|
use rustc_middle::ty::subst::{GenericArg, GenericArgKind, SubstsRef};
|
|
|
|
use rustc_middle::ty::{self, PredicateKind, ProjectionPredicate, TraitPredicate, Ty};
|
|
|
|
use rustc_span::{sym, Symbol};
|
|
|
|
use std::cmp::max;
|
|
|
|
|
|
|
|
use super::UNNECESSARY_TO_OWNED;
|
|
|
|
|
2022-01-13 12:18:19 +00:00
|
|
|
pub fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>, method_name: Symbol, args: &'tcx [Expr<'tcx>]) {
|
2021-12-17 12:40:22 +00:00
|
|
|
if_chain! {
|
|
|
|
if let Some(method_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id);
|
|
|
|
if let [receiver] = args;
|
|
|
|
then {
|
|
|
|
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, method_name, method_def_id) {
|
|
|
|
// 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) {
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
check_other_call_arg(cx, expr, method_name, receiver);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/// 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(
|
2022-01-13 12:18:19 +00:00
|
|
|
cx: &LateContext<'_>,
|
|
|
|
expr: &Expr<'_>,
|
2021-12-17 12:40:22 +00:00
|
|
|
method_name: Symbol,
|
|
|
|
method_def_id: DefId,
|
2022-01-13 12:18:19 +00:00
|
|
|
receiver: &Expr<'_>,
|
2021-12-17 12:40:22 +00:00
|
|
|
) -> bool {
|
|
|
|
if_chain! {
|
|
|
|
if let Some(parent) = get_parent_expr(cx, expr);
|
|
|
|
if let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, _) = parent.kind;
|
|
|
|
let adjustments = cx.typeck_results().expr_adjustments(parent).iter().collect::<Vec<_>>();
|
|
|
|
if let Some(target_ty) = match adjustments[..]
|
|
|
|
{
|
|
|
|
// For matching uses of `Cow::from`
|
|
|
|
[
|
|
|
|
Adjustment {
|
|
|
|
kind: Adjust::Deref(None),
|
|
|
|
..
|
|
|
|
},
|
|
|
|
Adjustment {
|
|
|
|
kind: Adjust::Borrow(_),
|
|
|
|
target: target_ty,
|
|
|
|
},
|
|
|
|
]
|
|
|
|
// For matching uses of arrays
|
|
|
|
| [
|
|
|
|
Adjustment {
|
|
|
|
kind: Adjust::Deref(None),
|
|
|
|
..
|
|
|
|
},
|
|
|
|
Adjustment {
|
|
|
|
kind: Adjust::Borrow(_),
|
|
|
|
..
|
|
|
|
},
|
|
|
|
Adjustment {
|
|
|
|
kind: Adjust::Pointer(_),
|
|
|
|
target: target_ty,
|
|
|
|
},
|
|
|
|
]
|
|
|
|
// For matching everything else
|
|
|
|
| [
|
|
|
|
Adjustment {
|
|
|
|
kind: Adjust::Deref(None),
|
|
|
|
..
|
|
|
|
},
|
|
|
|
Adjustment {
|
|
|
|
kind: Adjust::Deref(Some(OverloadedDeref { .. })),
|
|
|
|
..
|
|
|
|
},
|
|
|
|
Adjustment {
|
|
|
|
kind: Adjust::Borrow(_),
|
|
|
|
target: target_ty,
|
|
|
|
},
|
|
|
|
] => Some(target_ty),
|
|
|
|
_ => None,
|
|
|
|
};
|
|
|
|
let receiver_ty = cx.typeck_results().expr_ty(receiver);
|
|
|
|
// Only flag cases where the receiver is copyable or the method is `Cow::into_owned`. This
|
|
|
|
// restriction is to ensure there is not overlap between `redundant_clone` and this lint.
|
|
|
|
if is_copy(cx, receiver_ty) || is_cow_into_owned(cx, method_name, method_def_id);
|
|
|
|
if let Some(receiver_snippet) = snippet_opt(cx, receiver.span);
|
|
|
|
then {
|
|
|
|
let (target_ty, n_target_refs) = peel_mid_ty_refs(target_ty);
|
|
|
|
let (receiver_ty, n_receiver_refs) = peel_mid_ty_refs(receiver_ty);
|
|
|
|
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_chain! {
|
|
|
|
if let Some(deref_trait_id) = cx.tcx.get_diagnostic_item(sym::Deref);
|
|
|
|
if implements_trait(cx, receiver_ty, deref_trait_id, &[]);
|
|
|
|
if get_associated_type(cx, receiver_ty, deref_trait_id, "Target") == Some(target_ty);
|
|
|
|
then {
|
|
|
|
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_chain! {
|
|
|
|
if let Some(as_ref_trait_id) = cx.tcx.get_diagnostic_item(sym::AsRef);
|
|
|
|
if implements_trait(cx, receiver_ty, as_ref_trait_id, &[GenericArg::from(target_ty)]);
|
|
|
|
then {
|
|
|
|
span_lint_and_sugg(
|
|
|
|
cx,
|
|
|
|
UNNECESSARY_TO_OWNED,
|
|
|
|
parent.span,
|
|
|
|
&format!("unnecessary use of `{}`", method_name),
|
|
|
|
"use",
|
|
|
|
format!("{}.as_ref()", receiver_snippet),
|
|
|
|
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.
|
2022-01-13 12:18:19 +00:00
|
|
|
fn check_into_iter_call_arg(cx: &LateContext<'_>, expr: &Expr<'_>, method_name: Symbol, receiver: &Expr<'_>) -> bool {
|
2021-12-17 12:40:22 +00:00
|
|
|
if_chain! {
|
|
|
|
if let Some(parent) = get_parent_expr(cx, expr);
|
|
|
|
if let Some(callee_def_id) = fn_def_id(cx, parent);
|
|
|
|
if is_into_iter(cx, callee_def_id);
|
|
|
|
if let Some(iterator_trait_id) = cx.tcx.get_diagnostic_item(sym::Iterator);
|
|
|
|
let parent_ty = cx.typeck_results().expr_ty(parent);
|
|
|
|
if implements_trait(cx, parent_ty, iterator_trait_id, &[]);
|
|
|
|
if let Some(item_ty) = get_iterator_item_ty(cx, parent_ty);
|
|
|
|
if let Some(receiver_snippet) = snippet_opt(cx, receiver.span);
|
|
|
|
then {
|
2022-01-13 12:18:19 +00:00
|
|
|
if unnecessary_iter_cloned::check_for_loop_iter(
|
|
|
|
cx,
|
|
|
|
parent,
|
|
|
|
method_name,
|
|
|
|
receiver,
|
|
|
|
true,
|
|
|
|
) {
|
2021-12-17 12:40:22 +00:00
|
|
|
return true;
|
|
|
|
}
|
|
|
|
let cloned_or_copied = if is_copy(cx, item_ty) {
|
|
|
|
"copied"
|
|
|
|
} else {
|
|
|
|
"cloned"
|
|
|
|
};
|
2022-01-13 12:18:19 +00:00
|
|
|
// 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.
|
2021-12-17 12:40:22 +00:00
|
|
|
span_lint_and_sugg(
|
|
|
|
cx,
|
|
|
|
UNNECESSARY_TO_OWNED,
|
|
|
|
parent.span,
|
|
|
|
&format!("unnecessary use of `{}`", method_name),
|
|
|
|
"use",
|
|
|
|
format!("{}.iter().{}()", receiver_snippet, cloned_or_copied),
|
2022-01-13 12:18:19 +00:00
|
|
|
Applicability::MaybeIncorrect,
|
2021-12-17 12:40:22 +00:00
|
|
|
);
|
|
|
|
return true;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
false
|
|
|
|
}
|
|
|
|
|
|
|
|
/// 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.
|
2022-01-13 12:18:19 +00:00
|
|
|
fn check_other_call_arg<'tcx>(
|
2021-12-17 12:40:22 +00:00
|
|
|
cx: &LateContext<'tcx>,
|
|
|
|
expr: &'tcx Expr<'tcx>,
|
|
|
|
method_name: Symbol,
|
|
|
|
receiver: &'tcx Expr<'tcx>,
|
|
|
|
) -> bool {
|
|
|
|
if_chain! {
|
|
|
|
if let Some((maybe_call, maybe_arg)) = skip_addr_of_ancestors(cx, expr);
|
|
|
|
if let Some((callee_def_id, call_substs, call_args)) = get_callee_substs_and_args(cx, maybe_call);
|
|
|
|
let fn_sig = cx.tcx.fn_sig(callee_def_id).skip_binder();
|
|
|
|
if let Some(i) = call_args.iter().position(|arg| arg.hir_id == maybe_arg.hir_id);
|
|
|
|
if let Some(input) = fn_sig.inputs().get(i);
|
|
|
|
let (input, n_refs) = peel_mid_ty_refs(input);
|
|
|
|
if let (trait_predicates, projection_predicates) = get_input_traits_and_projections(cx, callee_def_id, input);
|
|
|
|
if let Some(sized_def_id) = cx.tcx.lang_items().sized_trait();
|
|
|
|
if let [trait_predicate] = trait_predicates
|
|
|
|
.iter()
|
|
|
|
.filter(|trait_predicate| trait_predicate.def_id() != sized_def_id)
|
|
|
|
.collect::<Vec<_>>()[..];
|
|
|
|
if let Some(deref_trait_id) = cx.tcx.get_diagnostic_item(sym::Deref);
|
|
|
|
if let Some(as_ref_trait_id) = cx.tcx.get_diagnostic_item(sym::AsRef);
|
|
|
|
let receiver_ty = cx.typeck_results().expr_ty(receiver);
|
|
|
|
// If the callee has type parameters, they could appear in `projection_predicate.ty` or the
|
|
|
|
// types of `trait_predicate.trait_ref.substs`.
|
|
|
|
if if trait_predicate.def_id() == deref_trait_id {
|
|
|
|
if let [projection_predicate] = projection_predicates[..] {
|
|
|
|
let normalized_ty =
|
2022-01-08 09:28:12 +00:00
|
|
|
cx.tcx.subst_and_normalize_erasing_regions(call_substs, cx.param_env, projection_predicate.term.ty());
|
2021-12-17 12:40:22 +00:00
|
|
|
implements_trait(cx, receiver_ty, deref_trait_id, &[])
|
|
|
|
&& get_associated_type(cx, receiver_ty, deref_trait_id, "Target") == Some(normalized_ty)
|
|
|
|
} else {
|
|
|
|
false
|
|
|
|
}
|
|
|
|
} else if trait_predicate.def_id() == as_ref_trait_id {
|
|
|
|
let composed_substs = compose_substs(
|
|
|
|
cx,
|
|
|
|
&trait_predicate.trait_ref.substs.iter().skip(1).collect::<Vec<_>>()[..],
|
|
|
|
call_substs
|
|
|
|
);
|
|
|
|
implements_trait(cx, receiver_ty, as_ref_trait_id, &composed_substs)
|
|
|
|
} else {
|
|
|
|
false
|
|
|
|
};
|
|
|
|
// We can't add an `&` when the trait is `Deref` because `Target = &T` won't match
|
|
|
|
// `Target = T`.
|
|
|
|
if n_refs > 0 || is_copy(cx, receiver_ty) || trait_predicate.def_id() != deref_trait_id;
|
|
|
|
let n_refs = max(n_refs, if is_copy(cx, receiver_ty) { 0 } else { 1 });
|
|
|
|
if let Some(receiver_snippet) = snippet_opt(cx, receiver.span);
|
|
|
|
then {
|
|
|
|
span_lint_and_sugg(
|
|
|
|
cx,
|
|
|
|
UNNECESSARY_TO_OWNED,
|
|
|
|
maybe_arg.span,
|
|
|
|
&format!("unnecessary use of `{}`", method_name),
|
|
|
|
"use",
|
|
|
|
format!("{:&>width$}{}", "", receiver_snippet, width = n_refs),
|
|
|
|
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.
|
2022-01-13 12:18:19 +00:00
|
|
|
fn skip_addr_of_ancestors<'tcx>(
|
2021-12-17 12:40:22 +00:00
|
|
|
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`,
|
|
|
|
/// `Substs`, and arguments.
|
2022-01-13 12:18:19 +00:00
|
|
|
fn get_callee_substs_and_args<'tcx>(
|
2021-12-17 12:40:22 +00:00
|
|
|
cx: &LateContext<'tcx>,
|
|
|
|
expr: &'tcx Expr<'tcx>,
|
|
|
|
) -> Option<(DefId, SubstsRef<'tcx>, &'tcx [Expr<'tcx>])> {
|
|
|
|
if_chain! {
|
|
|
|
if let ExprKind::Call(callee, args) = expr.kind;
|
|
|
|
let callee_ty = cx.typeck_results().expr_ty(callee);
|
|
|
|
if let ty::FnDef(callee_def_id, _) = callee_ty.kind();
|
|
|
|
then {
|
|
|
|
let substs = cx.typeck_results().node_substs(callee.hir_id);
|
|
|
|
return Some((*callee_def_id, substs, args));
|
|
|
|
}
|
|
|
|
}
|
|
|
|
if_chain! {
|
|
|
|
if let ExprKind::MethodCall(_, _, args, _) = expr.kind;
|
|
|
|
if let Some(method_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id);
|
|
|
|
then {
|
|
|
|
let substs = cx.typeck_results().node_substs(expr.hir_id);
|
|
|
|
return Some((method_def_id, substs, args));
|
|
|
|
}
|
|
|
|
}
|
|
|
|
None
|
|
|
|
}
|
|
|
|
|
|
|
|
/// Returns the `TraitPredicate`s and `ProjectionPredicate`s for a function's input type.
|
2022-01-13 12:18:19 +00:00
|
|
|
fn get_input_traits_and_projections<'tcx>(
|
2021-12-17 12:40:22 +00:00
|
|
|
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.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
|
|
|
|
}
|
|
|
|
}
|
|
|
|
};
|
|
|
|
match predicate.kind().skip_binder() {
|
|
|
|
PredicateKind::Trait(trait_predicate) => {
|
|
|
|
if is_input_substs(trait_predicate.trait_ref.substs) {
|
|
|
|
trait_predicates.push(trait_predicate);
|
|
|
|
}
|
|
|
|
},
|
|
|
|
PredicateKind::Projection(projection_predicate) => {
|
|
|
|
if is_input_substs(projection_predicate.projection_ty.substs) {
|
|
|
|
projection_predicates.push(projection_predicate);
|
|
|
|
}
|
|
|
|
},
|
|
|
|
_ => {},
|
|
|
|
}
|
|
|
|
}
|
|
|
|
(trait_predicates, projection_predicates)
|
|
|
|
}
|
|
|
|
|
|
|
|
/// Composes two substitutions by applying the latter to the types of the former.
|
2022-01-13 12:18:19 +00:00
|
|
|
fn compose_substs<'tcx>(
|
|
|
|
cx: &LateContext<'tcx>,
|
|
|
|
left: &[GenericArg<'tcx>],
|
|
|
|
right: SubstsRef<'tcx>,
|
|
|
|
) -> Vec<GenericArg<'tcx>> {
|
2021-12-17 12:40:22 +00:00
|
|
|
left.iter()
|
|
|
|
.map(|arg| {
|
|
|
|
if let GenericArgKind::Type(arg_ty) = arg.unpack() {
|
|
|
|
let normalized_ty = cx.tcx.subst_and_normalize_erasing_regions(right, cx.param_env, arg_ty);
|
|
|
|
GenericArg::from(normalized_ty)
|
|
|
|
} else {
|
|
|
|
*arg
|
|
|
|
}
|
|
|
|
})
|
|
|
|
.collect()
|
|
|
|
}
|
|
|
|
|
|
|
|
/// 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(cx: &LateContext<'_>, 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(cx, 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`.
|
|
|
|
fn is_to_string(cx: &LateContext<'_>, method_name: Symbol, method_def_id: DefId) -> bool {
|
|
|
|
method_name.as_str() == "to_string" && is_diag_trait_item(cx, method_def_id, sym::ToString)
|
|
|
|
}
|