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Auto merge of rust-lang#8972 - kyoto7250:use_retain, r=llogiq
feat(new lint): new lint `manual_retain` close rust-lang#8097 This PR is a new lint implementation. This lint checks if the `retain` method is available. Thank you in advance. changelog: add new ``[`manual_retain`]`` lint
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,228 @@ | ||
| use clippy_utils::diagnostics::span_lint_and_sugg; | ||
| use clippy_utils::source::snippet; | ||
| use clippy_utils::ty::is_type_diagnostic_item; | ||
| use clippy_utils::{get_parent_expr, match_def_path, paths, SpanlessEq}; | ||
| use clippy_utils::{meets_msrv, msrvs}; | ||
| 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::{declare_tool_lint, impl_lint_pass}; | ||
| use rustc_span::symbol::sym; | ||
|
|
||
| const ACCEPTABLE_METHODS: [&[&str]; 4] = [ | ||
| &paths::HASHSET_ITER, | ||
| &paths::BTREESET_ITER, | ||
| &paths::SLICE_INTO, | ||
| &paths::VEC_DEQUE_ITER, | ||
| ]; | ||
| const ACCEPTABLE_TYPES: [(rustc_span::Symbol, Option<RustcVersion>); 6] = [ | ||
| (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), | ||
| ]; | ||
|
|
||
| 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 | ||
| /// ```rust | ||
| /// 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: | ||
| /// ```rust | ||
| /// let mut vec = vec![0, 1, 2]; | ||
| /// vec.retain(|x| x % 2 == 0); | ||
| /// ``` | ||
| #[clippy::version = "1.63.0"] | ||
| pub MANUAL_RETAIN, | ||
| perf, | ||
| "`retain()` is simpler and the same functionalitys" | ||
| } | ||
|
|
||
| pub struct ManualRetain { | ||
| msrv: Option<RustcVersion>, | ||
| } | ||
|
|
||
| impl ManualRetain { | ||
| #[must_use] | ||
| pub fn new(msrv: Option<RustcVersion>) -> 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 Some(parent_expr) = get_parent_expr(cx, expr) | ||
| && let Assign(left_expr, collect_expr, _) = &parent_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) | ||
| && match_def_path(cx, collect_def_id, &paths::CORE_ITER_COLLECT) { | ||
| check_into_iter(cx, parent_expr, left_expr, target_expr, self.msrv); | ||
| check_iter(cx, parent_expr, left_expr, target_expr, self.msrv); | ||
| check_to_owned(cx, parent_expr, left_expr, target_expr, self.msrv); | ||
| } | ||
| } | ||
|
|
||
| extract_msrv_attr!(LateContext); | ||
| } | ||
|
|
||
| fn check_into_iter( | ||
| cx: &LateContext<'_>, | ||
| parent_expr: &hir::Expr<'_>, | ||
| left_expr: &hir::Expr<'_>, | ||
| target_expr: &hir::Expr<'_>, | ||
| msrv: Option<RustcVersion>, | ||
| ) { | ||
| 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) | ||
| && match_def_path(cx, into_iter_def_id, &paths::CORE_ITER_INTO_ITER) | ||
| && match_acceptable_type(cx, left_expr, msrv) | ||
| && SpanlessEq::new(cx).eq_expr(left_expr, struct_expr) { | ||
| suggest(cx, parent_expr, left_expr, target_expr); | ||
| } | ||
| } | ||
|
|
||
| fn check_iter( | ||
| cx: &LateContext<'_>, | ||
| parent_expr: &hir::Expr<'_>, | ||
| left_expr: &hir::Expr<'_>, | ||
| target_expr: &hir::Expr<'_>, | ||
| msrv: Option<RustcVersion>, | ||
| ) { | ||
| 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) { | ||
| suggest(cx, parent_expr, left_expr, filter_expr); | ||
| } | ||
| } | ||
|
|
||
| fn check_to_owned( | ||
| cx: &LateContext<'_>, | ||
| parent_expr: &hir::Expr<'_>, | ||
| left_expr: &hir::Expr<'_>, | ||
| target_expr: &hir::Expr<'_>, | ||
| msrv: Option<RustcVersion>, | ||
| ) { | ||
| if meets_msrv(msrv, 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) | ||
| && match_def_path(cx, to_owned_def_id, &paths::TO_OWNED_METHOD) | ||
| && 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_diagnostic_item(cx, ty, sym::String) | ||
| && SpanlessEq::new(cx).eq_expr(left_expr, str_expr) { | ||
| suggest(cx, parent_expr, left_expr, filter_expr); | ||
| } | ||
| } | ||
|
|
||
| fn suggest(cx: &LateContext<'_>, parent_expr: &hir::Expr<'_>, left_expr: &hir::Expr<'_>, filter_expr: &hir::Expr<'_>) { | ||
| if let hir::ExprKind::MethodCall(_, [_, closure], _) = filter_expr.kind | ||
| && let hir::ExprKind::Closure{ body, ..} = closure.kind | ||
| && let filter_body = cx.tcx.hir().body(body) | ||
| && let [filter_params] = filter_body.params | ||
| && let Some(sugg) = match filter_params.pat.kind { | ||
| hir::PatKind::Binding(_, _, filter_param_ident, None) => { | ||
| Some(format!("{}.retain(|{}| {})", snippet(cx, left_expr.span, ".."), filter_param_ident, snippet(cx, filter_body.value.span, ".."))) | ||
| }, | ||
| hir::PatKind::Tuple([key_pat, value_pat], _) => { | ||
| make_sugg(cx, key_pat, value_pat, left_expr, filter_body) | ||
| }, | ||
| hir::PatKind::Ref(pat, _) => { | ||
| match pat.kind { | ||
| hir::PatKind::Binding(_, _, filter_param_ident, None) => { | ||
| Some(format!("{}.retain(|{}| {})", snippet(cx, left_expr.span, ".."), filter_param_ident, snippet(cx, filter_body.value.span, ".."))) | ||
| }, | ||
| _ => None | ||
| } | ||
| }, | ||
| _ => None | ||
| } { | ||
| span_lint_and_sugg( | ||
| cx, | ||
| MANUAL_RETAIN, | ||
| parent_expr.span, | ||
| "this expression can be written more simply using `.retain()`", | ||
| "consider calling `.retain()` instead", | ||
| sugg, | ||
| Applicability::MachineApplicable | ||
| ); | ||
| } | ||
| } | ||
|
|
||
| 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(|{}, &mut {}| {})", | ||
| snippet(cx, left_expr.span, ".."), | ||
| key_param_ident, | ||
| value_param_ident, | ||
| snippet(cx, filter_body.value.span, "..") | ||
| )) | ||
| }, | ||
| (hir::PatKind::Binding(_, _, key_param_ident, None), hir::PatKind::Wild) => Some(format!( | ||
| "{}.retain(|{}, _| {})", | ||
| snippet(cx, left_expr.span, ".."), | ||
| key_param_ident, | ||
| snippet(cx, filter_body.value.span, "..") | ||
| )), | ||
| (hir::PatKind::Wild, hir::PatKind::Binding(_, _, value_param_ident, None)) => Some(format!( | ||
| "{}.retain(|_, &mut {}| {})", | ||
| snippet(cx, left_expr.span, ".."), | ||
| value_param_ident, | ||
| 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: Option<RustcVersion>) -> 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| meets_msrv(msrv, acceptable_msrv)) | ||
| }) | ||
| } |
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