290 lines
12 KiB
Rust
290 lines
12 KiB
Rust
use clippy_config::msrvs::{self, Msrv};
|
|
use clippy_utils::diagnostics::span_lint_and_sugg;
|
|
use clippy_utils::source::snippet;
|
|
use clippy_utils::ty::{is_type_diagnostic_item, is_type_lang_item};
|
|
use clippy_utils::{match_def_path, paths, SpanlessEq};
|
|
use rustc_errors::Applicability;
|
|
use rustc_hir as hir;
|
|
use rustc_hir::def_id::DefId;
|
|
use rustc_hir::ExprKind::Assign;
|
|
use rustc_lint::{LateContext, LateLintPass};
|
|
use rustc_semver::RustcVersion;
|
|
use rustc_session::impl_lint_pass;
|
|
use rustc_span::symbol::sym;
|
|
use rustc_span::Span;
|
|
|
|
const ACCEPTABLE_METHODS: [&[&str]; 5] = [
|
|
&paths::BINARYHEAP_ITER,
|
|
&paths::HASHSET_ITER,
|
|
&paths::BTREESET_ITER,
|
|
&paths::SLICE_INTO,
|
|
&paths::VEC_DEQUE_ITER,
|
|
];
|
|
const ACCEPTABLE_TYPES: [(rustc_span::Symbol, Option<RustcVersion>); 7] = [
|
|
(sym::BinaryHeap, Some(msrvs::BINARY_HEAP_RETAIN)),
|
|
(sym::BTreeSet, Some(msrvs::BTREE_SET_RETAIN)),
|
|
(sym::BTreeMap, Some(msrvs::BTREE_MAP_RETAIN)),
|
|
(sym::HashSet, Some(msrvs::HASH_SET_RETAIN)),
|
|
(sym::HashMap, Some(msrvs::HASH_MAP_RETAIN)),
|
|
(sym::Vec, None),
|
|
(sym::VecDeque, None),
|
|
];
|
|
const MAP_TYPES: [rustc_span::Symbol; 2] = [sym::BTreeMap, sym::HashMap];
|
|
|
|
declare_clippy_lint! {
|
|
/// ### What it does
|
|
/// Checks for code to be replaced by `.retain()`.
|
|
/// ### Why is this bad?
|
|
/// `.retain()` is simpler and avoids needless allocation.
|
|
/// ### Example
|
|
/// ```no_run
|
|
/// let mut vec = vec![0, 1, 2];
|
|
/// vec = vec.iter().filter(|&x| x % 2 == 0).copied().collect();
|
|
/// vec = vec.into_iter().filter(|x| x % 2 == 0).collect();
|
|
/// ```
|
|
/// Use instead:
|
|
/// ```no_run
|
|
/// let mut vec = vec![0, 1, 2];
|
|
/// vec.retain(|x| x % 2 == 0);
|
|
/// vec.retain(|x| x % 2 == 0);
|
|
/// ```
|
|
#[clippy::version = "1.64.0"]
|
|
pub MANUAL_RETAIN,
|
|
perf,
|
|
"`retain()` is simpler and the same functionalities"
|
|
}
|
|
|
|
pub struct ManualRetain {
|
|
msrv: Msrv,
|
|
}
|
|
|
|
impl ManualRetain {
|
|
#[must_use]
|
|
pub fn new(msrv: Msrv) -> Self {
|
|
Self { msrv }
|
|
}
|
|
}
|
|
|
|
impl_lint_pass!(ManualRetain => [MANUAL_RETAIN]);
|
|
|
|
impl<'tcx> LateLintPass<'tcx> for ManualRetain {
|
|
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
|
|
if let Assign(left_expr, collect_expr, _) = &expr.kind
|
|
&& let hir::ExprKind::MethodCall(seg, ..) = &collect_expr.kind
|
|
&& seg.args.is_none()
|
|
&& let hir::ExprKind::MethodCall(_, target_expr, [], _) = &collect_expr.kind
|
|
&& let Some(collect_def_id) = cx.typeck_results().type_dependent_def_id(collect_expr.hir_id)
|
|
&& cx.tcx.is_diagnostic_item(sym::iterator_collect_fn, collect_def_id)
|
|
{
|
|
check_into_iter(cx, left_expr, target_expr, expr.span, &self.msrv);
|
|
check_iter(cx, left_expr, target_expr, expr.span, &self.msrv);
|
|
check_to_owned(cx, left_expr, target_expr, expr.span, &self.msrv);
|
|
}
|
|
}
|
|
|
|
extract_msrv_attr!(LateContext);
|
|
}
|
|
|
|
fn check_into_iter(
|
|
cx: &LateContext<'_>,
|
|
left_expr: &hir::Expr<'_>,
|
|
target_expr: &hir::Expr<'_>,
|
|
parent_expr_span: Span,
|
|
msrv: &Msrv,
|
|
) {
|
|
if let hir::ExprKind::MethodCall(_, into_iter_expr, [_], _) = &target_expr.kind
|
|
&& let Some(filter_def_id) = cx.typeck_results().type_dependent_def_id(target_expr.hir_id)
|
|
&& match_def_path(cx, filter_def_id, &paths::CORE_ITER_FILTER)
|
|
&& let hir::ExprKind::MethodCall(_, struct_expr, [], _) = &into_iter_expr.kind
|
|
&& let Some(into_iter_def_id) = cx.typeck_results().type_dependent_def_id(into_iter_expr.hir_id)
|
|
&& Some(into_iter_def_id) == cx.tcx.lang_items().into_iter_fn()
|
|
&& match_acceptable_type(cx, left_expr, msrv)
|
|
&& SpanlessEq::new(cx).eq_expr(left_expr, struct_expr)
|
|
&& let hir::ExprKind::MethodCall(_, _, [closure_expr], _) = target_expr.kind
|
|
&& let hir::ExprKind::Closure(closure) = closure_expr.kind
|
|
&& let filter_body = cx.tcx.hir().body(closure.body)
|
|
&& let [filter_params] = filter_body.params
|
|
{
|
|
if match_map_type(cx, left_expr) {
|
|
if let hir::PatKind::Tuple([key_pat, value_pat], _) = filter_params.pat.kind {
|
|
if let Some(sugg) = make_sugg(cx, key_pat, value_pat, left_expr, filter_body) {
|
|
make_span_lint_and_sugg(cx, parent_expr_span, sugg);
|
|
}
|
|
}
|
|
// Cannot lint other cases because `retain` requires two parameters
|
|
} else {
|
|
// Can always move because `retain` and `filter` have the same bound on the predicate
|
|
// for other types
|
|
make_span_lint_and_sugg(
|
|
cx,
|
|
parent_expr_span,
|
|
format!(
|
|
"{}.retain({})",
|
|
snippet(cx, left_expr.span, ".."),
|
|
snippet(cx, closure_expr.span, "..")
|
|
),
|
|
);
|
|
}
|
|
}
|
|
}
|
|
|
|
fn check_iter(
|
|
cx: &LateContext<'_>,
|
|
left_expr: &hir::Expr<'_>,
|
|
target_expr: &hir::Expr<'_>,
|
|
parent_expr_span: Span,
|
|
msrv: &Msrv,
|
|
) {
|
|
if let hir::ExprKind::MethodCall(_, filter_expr, [], _) = &target_expr.kind
|
|
&& let Some(copied_def_id) = cx.typeck_results().type_dependent_def_id(target_expr.hir_id)
|
|
&& (match_def_path(cx, copied_def_id, &paths::CORE_ITER_COPIED)
|
|
|| match_def_path(cx, copied_def_id, &paths::CORE_ITER_CLONED))
|
|
&& let hir::ExprKind::MethodCall(_, iter_expr, [_], _) = &filter_expr.kind
|
|
&& let Some(filter_def_id) = cx.typeck_results().type_dependent_def_id(filter_expr.hir_id)
|
|
&& match_def_path(cx, filter_def_id, &paths::CORE_ITER_FILTER)
|
|
&& let hir::ExprKind::MethodCall(_, struct_expr, [], _) = &iter_expr.kind
|
|
&& let Some(iter_expr_def_id) = cx.typeck_results().type_dependent_def_id(iter_expr.hir_id)
|
|
&& match_acceptable_def_path(cx, iter_expr_def_id)
|
|
&& match_acceptable_type(cx, left_expr, msrv)
|
|
&& SpanlessEq::new(cx).eq_expr(left_expr, struct_expr)
|
|
&& let hir::ExprKind::MethodCall(_, _, [closure_expr], _) = filter_expr.kind
|
|
&& let hir::ExprKind::Closure(closure) = closure_expr.kind
|
|
&& let filter_body = cx.tcx.hir().body(closure.body)
|
|
&& let [filter_params] = filter_body.params
|
|
{
|
|
match filter_params.pat.kind {
|
|
// hir::PatKind::Binding(_, _, _, None) => {
|
|
// // Be conservative now. Do nothing here.
|
|
// // TODO: Ideally, we can rewrite the lambda by stripping one level of reference
|
|
// },
|
|
hir::PatKind::Tuple([_, _], _) => {
|
|
// the `&&` reference for the `filter` method will be auto derefed to `ref`
|
|
// so, we can directly use the lambda
|
|
// https://doc.rust-lang.org/reference/patterns.html#binding-modes
|
|
make_span_lint_and_sugg(
|
|
cx,
|
|
parent_expr_span,
|
|
format!(
|
|
"{}.retain({})",
|
|
snippet(cx, left_expr.span, ".."),
|
|
snippet(cx, closure_expr.span, "..")
|
|
),
|
|
);
|
|
},
|
|
hir::PatKind::Ref(pat, _) => make_span_lint_and_sugg(
|
|
cx,
|
|
parent_expr_span,
|
|
format!(
|
|
"{}.retain(|{}| {})",
|
|
snippet(cx, left_expr.span, ".."),
|
|
snippet(cx, pat.span, ".."),
|
|
snippet(cx, filter_body.value.span, "..")
|
|
),
|
|
),
|
|
_ => {},
|
|
}
|
|
}
|
|
}
|
|
|
|
fn check_to_owned(
|
|
cx: &LateContext<'_>,
|
|
left_expr: &hir::Expr<'_>,
|
|
target_expr: &hir::Expr<'_>,
|
|
parent_expr_span: Span,
|
|
msrv: &Msrv,
|
|
) {
|
|
if msrv.meets(msrvs::STRING_RETAIN)
|
|
&& let hir::ExprKind::MethodCall(_, filter_expr, [], _) = &target_expr.kind
|
|
&& let Some(to_owned_def_id) = cx.typeck_results().type_dependent_def_id(target_expr.hir_id)
|
|
&& cx.tcx.is_diagnostic_item(sym::to_owned_method, to_owned_def_id)
|
|
&& let hir::ExprKind::MethodCall(_, chars_expr, [_], _) = &filter_expr.kind
|
|
&& let Some(filter_def_id) = cx.typeck_results().type_dependent_def_id(filter_expr.hir_id)
|
|
&& match_def_path(cx, filter_def_id, &paths::CORE_ITER_FILTER)
|
|
&& let hir::ExprKind::MethodCall(_, str_expr, [], _) = &chars_expr.kind
|
|
&& let Some(chars_expr_def_id) = cx.typeck_results().type_dependent_def_id(chars_expr.hir_id)
|
|
&& match_def_path(cx, chars_expr_def_id, &paths::STR_CHARS)
|
|
&& let ty = cx.typeck_results().expr_ty(str_expr).peel_refs()
|
|
&& is_type_lang_item(cx, ty, hir::LangItem::String)
|
|
&& SpanlessEq::new(cx).eq_expr(left_expr, str_expr)
|
|
&& let hir::ExprKind::MethodCall(_, _, [closure_expr], _) = filter_expr.kind
|
|
&& let hir::ExprKind::Closure(closure) = closure_expr.kind
|
|
&& let filter_body = cx.tcx.hir().body(closure.body)
|
|
&& let [filter_params] = filter_body.params
|
|
{
|
|
if let hir::PatKind::Ref(pat, _) = filter_params.pat.kind {
|
|
make_span_lint_and_sugg(
|
|
cx,
|
|
parent_expr_span,
|
|
format!(
|
|
"{}.retain(|{}| {})",
|
|
snippet(cx, left_expr.span, ".."),
|
|
snippet(cx, pat.span, ".."),
|
|
snippet(cx, filter_body.value.span, "..")
|
|
),
|
|
);
|
|
}
|
|
// Be conservative now. Do nothing for the `Binding` case.
|
|
// TODO: Ideally, we can rewrite the lambda by stripping one level of reference
|
|
}
|
|
}
|
|
|
|
fn make_sugg(
|
|
cx: &LateContext<'_>,
|
|
key_pat: &rustc_hir::Pat<'_>,
|
|
value_pat: &rustc_hir::Pat<'_>,
|
|
left_expr: &hir::Expr<'_>,
|
|
filter_body: &hir::Body<'_>,
|
|
) -> Option<String> {
|
|
match (&key_pat.kind, &value_pat.kind) {
|
|
(hir::PatKind::Binding(_, _, key_param_ident, None), hir::PatKind::Binding(_, _, value_param_ident, None)) => {
|
|
Some(format!(
|
|
"{}.retain(|{key_param_ident}, &mut {value_param_ident}| {})",
|
|
snippet(cx, left_expr.span, ".."),
|
|
snippet(cx, filter_body.value.span, "..")
|
|
))
|
|
},
|
|
(hir::PatKind::Binding(_, _, key_param_ident, None), hir::PatKind::Wild) => Some(format!(
|
|
"{}.retain(|{key_param_ident}, _| {})",
|
|
snippet(cx, left_expr.span, ".."),
|
|
snippet(cx, filter_body.value.span, "..")
|
|
)),
|
|
(hir::PatKind::Wild, hir::PatKind::Binding(_, _, value_param_ident, None)) => Some(format!(
|
|
"{}.retain(|_, &mut {value_param_ident}| {})",
|
|
snippet(cx, left_expr.span, ".."),
|
|
snippet(cx, filter_body.value.span, "..")
|
|
)),
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
fn match_acceptable_def_path(cx: &LateContext<'_>, collect_def_id: DefId) -> bool {
|
|
ACCEPTABLE_METHODS
|
|
.iter()
|
|
.any(|&method| match_def_path(cx, collect_def_id, method))
|
|
}
|
|
|
|
fn match_acceptable_type(cx: &LateContext<'_>, expr: &hir::Expr<'_>, msrv: &Msrv) -> bool {
|
|
let expr_ty = cx.typeck_results().expr_ty(expr).peel_refs();
|
|
ACCEPTABLE_TYPES.iter().any(|(ty, acceptable_msrv)| {
|
|
is_type_diagnostic_item(cx, expr_ty, *ty)
|
|
&& acceptable_msrv.map_or(true, |acceptable_msrv| msrv.meets(acceptable_msrv))
|
|
})
|
|
}
|
|
|
|
fn match_map_type(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> bool {
|
|
let expr_ty = cx.typeck_results().expr_ty(expr).peel_refs();
|
|
MAP_TYPES.iter().any(|ty| is_type_diagnostic_item(cx, expr_ty, *ty))
|
|
}
|
|
|
|
fn make_span_lint_and_sugg(cx: &LateContext<'_>, span: Span, sugg: String) {
|
|
span_lint_and_sugg(
|
|
cx,
|
|
MANUAL_RETAIN,
|
|
span,
|
|
"this expression can be written more simply using `.retain()`",
|
|
"consider calling `.retain()` instead",
|
|
sugg,
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|