226 lines
9.2 KiB
Rust
226 lines
9.2 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::msrvs::{self, Msrv};
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use clippy_utils::source::snippet;
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use clippy_utils::ty::{is_type_diagnostic_item, is_type_lang_item};
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use clippy_utils::{get_parent_expr, match_def_path, paths, SpanlessEq};
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use rustc_errors::Applicability;
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use rustc_hir as hir;
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use rustc_hir::def_id::DefId;
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use rustc_hir::ExprKind::Assign;
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_semver::RustcVersion;
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use rustc_session::{declare_tool_lint, impl_lint_pass};
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use rustc_span::symbol::sym;
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const ACCEPTABLE_METHODS: [&[&str]; 4] = [
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&paths::HASHSET_ITER,
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&paths::BTREESET_ITER,
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&paths::SLICE_INTO,
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&paths::VEC_DEQUE_ITER,
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];
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const ACCEPTABLE_TYPES: [(rustc_span::Symbol, Option<RustcVersion>); 6] = [
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(sym::BTreeSet, Some(msrvs::BTREE_SET_RETAIN)),
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(sym::BTreeMap, Some(msrvs::BTREE_MAP_RETAIN)),
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(sym::HashSet, Some(msrvs::HASH_SET_RETAIN)),
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(sym::HashMap, Some(msrvs::HASH_MAP_RETAIN)),
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(sym::Vec, None),
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(sym::VecDeque, None),
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];
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for code to be replaced by `.retain()`.
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/// ### Why is this bad?
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/// `.retain()` is simpler and avoids needless allocation.
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/// ### Example
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/// ```rust
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/// let mut vec = vec![0, 1, 2];
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/// vec = vec.iter().filter(|&x| x % 2 == 0).copied().collect();
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/// vec = vec.into_iter().filter(|x| x % 2 == 0).collect();
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/// ```
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/// Use instead:
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/// ```rust
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/// let mut vec = vec![0, 1, 2];
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/// vec.retain(|x| x % 2 == 0);
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/// ```
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#[clippy::version = "1.64.0"]
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pub MANUAL_RETAIN,
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perf,
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"`retain()` is simpler and the same functionalitys"
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}
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pub struct ManualRetain {
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msrv: Msrv,
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}
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impl ManualRetain {
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#[must_use]
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pub fn new(msrv: Msrv) -> Self {
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Self { msrv }
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}
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}
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impl_lint_pass!(ManualRetain => [MANUAL_RETAIN]);
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impl<'tcx> LateLintPass<'tcx> for ManualRetain {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
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if let Some(parent_expr) = get_parent_expr(cx, expr)
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&& let Assign(left_expr, collect_expr, _) = &parent_expr.kind
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&& let hir::ExprKind::MethodCall(seg, ..) = &collect_expr.kind
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&& seg.args.is_none()
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&& let hir::ExprKind::MethodCall(_, target_expr, [], _) = &collect_expr.kind
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&& let Some(collect_def_id) = cx.typeck_results().type_dependent_def_id(collect_expr.hir_id)
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&& cx.tcx.is_diagnostic_item(sym::iterator_collect_fn, collect_def_id)
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{
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check_into_iter(cx, parent_expr, left_expr, target_expr, &self.msrv);
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check_iter(cx, parent_expr, left_expr, target_expr, &self.msrv);
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check_to_owned(cx, parent_expr, left_expr, target_expr, &self.msrv);
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}
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}
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extract_msrv_attr!(LateContext);
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}
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fn check_into_iter(
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cx: &LateContext<'_>,
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parent_expr: &hir::Expr<'_>,
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left_expr: &hir::Expr<'_>,
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target_expr: &hir::Expr<'_>,
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msrv: &Msrv,
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) {
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if let hir::ExprKind::MethodCall(_, into_iter_expr, [_], _) = &target_expr.kind
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&& let Some(filter_def_id) = cx.typeck_results().type_dependent_def_id(target_expr.hir_id)
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&& match_def_path(cx, filter_def_id, &paths::CORE_ITER_FILTER)
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&& let hir::ExprKind::MethodCall(_, struct_expr, [], _) = &into_iter_expr.kind
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&& let Some(into_iter_def_id) = cx.typeck_results().type_dependent_def_id(into_iter_expr.hir_id)
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&& Some(into_iter_def_id) == cx.tcx.lang_items().into_iter_fn()
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&& match_acceptable_type(cx, left_expr, msrv)
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&& SpanlessEq::new(cx).eq_expr(left_expr, struct_expr) {
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suggest(cx, parent_expr, left_expr, target_expr);
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}
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}
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fn check_iter(
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cx: &LateContext<'_>,
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parent_expr: &hir::Expr<'_>,
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left_expr: &hir::Expr<'_>,
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target_expr: &hir::Expr<'_>,
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msrv: &Msrv,
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) {
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if let hir::ExprKind::MethodCall(_, filter_expr, [], _) = &target_expr.kind
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&& let Some(copied_def_id) = cx.typeck_results().type_dependent_def_id(target_expr.hir_id)
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&& (match_def_path(cx, copied_def_id, &paths::CORE_ITER_COPIED)
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|| match_def_path(cx, copied_def_id, &paths::CORE_ITER_CLONED))
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&& let hir::ExprKind::MethodCall(_, iter_expr, [_], _) = &filter_expr.kind
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&& let Some(filter_def_id) = cx.typeck_results().type_dependent_def_id(filter_expr.hir_id)
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&& match_def_path(cx, filter_def_id, &paths::CORE_ITER_FILTER)
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&& let hir::ExprKind::MethodCall(_, struct_expr, [], _) = &iter_expr.kind
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&& let Some(iter_expr_def_id) = cx.typeck_results().type_dependent_def_id(iter_expr.hir_id)
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&& match_acceptable_def_path(cx, iter_expr_def_id)
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&& match_acceptable_type(cx, left_expr, msrv)
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&& SpanlessEq::new(cx).eq_expr(left_expr, struct_expr) {
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suggest(cx, parent_expr, left_expr, filter_expr);
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}
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}
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fn check_to_owned(
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cx: &LateContext<'_>,
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parent_expr: &hir::Expr<'_>,
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left_expr: &hir::Expr<'_>,
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target_expr: &hir::Expr<'_>,
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msrv: &Msrv,
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) {
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if msrv.meets(msrvs::STRING_RETAIN)
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&& let hir::ExprKind::MethodCall(_, filter_expr, [], _) = &target_expr.kind
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&& let Some(to_owned_def_id) = cx.typeck_results().type_dependent_def_id(target_expr.hir_id)
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&& match_def_path(cx, to_owned_def_id, &paths::TO_OWNED_METHOD)
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&& let hir::ExprKind::MethodCall(_, chars_expr, [_], _) = &filter_expr.kind
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&& let Some(filter_def_id) = cx.typeck_results().type_dependent_def_id(filter_expr.hir_id)
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&& match_def_path(cx, filter_def_id, &paths::CORE_ITER_FILTER)
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&& let hir::ExprKind::MethodCall(_, str_expr, [], _) = &chars_expr.kind
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&& let Some(chars_expr_def_id) = cx.typeck_results().type_dependent_def_id(chars_expr.hir_id)
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&& match_def_path(cx, chars_expr_def_id, &paths::STR_CHARS)
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&& let ty = cx.typeck_results().expr_ty(str_expr).peel_refs()
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&& is_type_lang_item(cx, ty, hir::LangItem::String)
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&& SpanlessEq::new(cx).eq_expr(left_expr, str_expr) {
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suggest(cx, parent_expr, left_expr, filter_expr);
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}
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}
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fn suggest(cx: &LateContext<'_>, parent_expr: &hir::Expr<'_>, left_expr: &hir::Expr<'_>, filter_expr: &hir::Expr<'_>) {
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if let hir::ExprKind::MethodCall(_, _, [closure], _) = filter_expr.kind
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&& let hir::ExprKind::Closure(&hir::Closure { body, ..}) = closure.kind
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&& let filter_body = cx.tcx.hir().body(body)
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&& let [filter_params] = filter_body.params
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&& let Some(sugg) = match filter_params.pat.kind {
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hir::PatKind::Binding(_, _, filter_param_ident, None) => {
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Some(format!("{}.retain(|{filter_param_ident}| {})", snippet(cx, left_expr.span, ".."), snippet(cx, filter_body.value.span, "..")))
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},
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hir::PatKind::Tuple([key_pat, value_pat], _) => {
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make_sugg(cx, key_pat, value_pat, left_expr, filter_body)
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},
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hir::PatKind::Ref(pat, _) => {
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match pat.kind {
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hir::PatKind::Binding(_, _, filter_param_ident, None) => {
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Some(format!("{}.retain(|{filter_param_ident}| {})", snippet(cx, left_expr.span, ".."), snippet(cx, filter_body.value.span, "..")))
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},
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_ => None
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}
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},
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_ => None
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} {
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span_lint_and_sugg(
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cx,
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MANUAL_RETAIN,
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parent_expr.span,
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"this expression can be written more simply using `.retain()`",
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"consider calling `.retain()` instead",
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sugg,
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Applicability::MachineApplicable
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);
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}
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}
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fn make_sugg(
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cx: &LateContext<'_>,
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key_pat: &rustc_hir::Pat<'_>,
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value_pat: &rustc_hir::Pat<'_>,
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left_expr: &hir::Expr<'_>,
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filter_body: &hir::Body<'_>,
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) -> Option<String> {
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match (&key_pat.kind, &value_pat.kind) {
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(hir::PatKind::Binding(_, _, key_param_ident, None), hir::PatKind::Binding(_, _, value_param_ident, None)) => {
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Some(format!(
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"{}.retain(|{key_param_ident}, &mut {value_param_ident}| {})",
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snippet(cx, left_expr.span, ".."),
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snippet(cx, filter_body.value.span, "..")
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))
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},
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(hir::PatKind::Binding(_, _, key_param_ident, None), hir::PatKind::Wild) => Some(format!(
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"{}.retain(|{key_param_ident}, _| {})",
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snippet(cx, left_expr.span, ".."),
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snippet(cx, filter_body.value.span, "..")
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)),
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(hir::PatKind::Wild, hir::PatKind::Binding(_, _, value_param_ident, None)) => Some(format!(
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"{}.retain(|_, &mut {value_param_ident}| {})",
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snippet(cx, left_expr.span, ".."),
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snippet(cx, filter_body.value.span, "..")
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)),
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_ => None,
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}
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}
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fn match_acceptable_def_path(cx: &LateContext<'_>, collect_def_id: DefId) -> bool {
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ACCEPTABLE_METHODS
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.iter()
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.any(|&method| match_def_path(cx, collect_def_id, method))
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}
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fn match_acceptable_type(cx: &LateContext<'_>, expr: &hir::Expr<'_>, msrv: &Msrv) -> bool {
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let expr_ty = cx.typeck_results().expr_ty(expr).peel_refs();
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ACCEPTABLE_TYPES.iter().any(|(ty, acceptable_msrv)| {
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is_type_diagnostic_item(cx, expr_ty, *ty)
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&& acceptable_msrv.map_or(true, |acceptable_msrv| msrv.meets(acceptable_msrv))
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})
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}
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