diff options
| -rw-r--r-- | CHANGELOG.md | 1 | ||||
| -rw-r--r-- | clippy_lints/src/lib.rs | 3 | ||||
| -rw-r--r-- | clippy_lints/src/methods/mod.rs | 109 | ||||
| -rw-r--r-- | tests/ui/filter_methods.stderr | 12 | ||||
| -rw-r--r-- | tests/ui/manual_filter_map.fixed | 37 | ||||
| -rw-r--r-- | tests/ui/manual_filter_map.rs | 37 | ||||
| -rw-r--r-- | tests/ui/manual_filter_map.stderr | 22 |
7 files changed, 198 insertions, 23 deletions
diff --git a/CHANGELOG.md b/CHANGELOG.md index 04f042b2deb..8feb1a148af 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -2035,6 +2035,7 @@ Released 2018-09-13 [`macro_use_imports`]: https://rust-lang.github.io/rust-clippy/master/index.html#macro_use_imports [`main_recursion`]: https://rust-lang.github.io/rust-clippy/master/index.html#main_recursion [`manual_async_fn`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_async_fn +[`manual_filter_map`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_filter_map [`manual_memcpy`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_memcpy [`manual_non_exhaustive`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_non_exhaustive [`manual_ok_or`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_ok_or diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs index 53764bb7390..bde9c630c6c 100644 --- a/clippy_lints/src/lib.rs +++ b/clippy_lints/src/lib.rs @@ -745,6 +745,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: &methods::ITER_NTH, &methods::ITER_NTH_ZERO, &methods::ITER_SKIP_NEXT, + &methods::MANUAL_FILTER_MAP, &methods::MANUAL_SATURATING_ARITHMETIC, &methods::MAP_COLLECT_RESULT_UNIT, &methods::MAP_FLATTEN, @@ -1526,6 +1527,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: LintId::of(&methods::ITER_NTH), LintId::of(&methods::ITER_NTH_ZERO), LintId::of(&methods::ITER_SKIP_NEXT), + LintId::of(&methods::MANUAL_FILTER_MAP), LintId::of(&methods::MANUAL_SATURATING_ARITHMETIC), LintId::of(&methods::MAP_COLLECT_RESULT_UNIT), LintId::of(&methods::NEW_RET_NO_SELF), @@ -1823,6 +1825,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: LintId::of(&methods::FILTER_NEXT), LintId::of(&methods::FLAT_MAP_IDENTITY), LintId::of(&methods::INSPECT_FOR_EACH), + LintId::of(&methods::MANUAL_FILTER_MAP), LintId::of(&methods::OPTION_AS_REF_DEREF), LintId::of(&methods::SEARCH_IS_SOME), LintId::of(&methods::SKIP_WHILE_NEXT), diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs index c8b69f4fbae..518d2e67ad1 100644 --- a/clippy_lints/src/methods/mod.rs +++ b/clippy_lints/src/methods/mod.rs @@ -15,7 +15,8 @@ use if_chain::if_chain; use rustc_ast::ast; use rustc_errors::Applicability; use rustc_hir as hir; -use rustc_hir::{TraitItem, TraitItemKind}; +use rustc_hir::def::Res; +use rustc_hir::{Expr, ExprKind, PatKind, QPath, TraitItem, TraitItemKind, UnOp}; use rustc_lint::{LateContext, LateLintPass, Lint, LintContext}; use rustc_middle::lint::in_external_macro; use rustc_middle::ty::{self, TraitRef, Ty, TyS}; @@ -451,6 +452,32 @@ declare_clippy_lint! { } declare_clippy_lint! { + /// **What it does:** Checks for usage of `_.filter(_).map(_)` that can be written more simply + /// as `filter_map(_)`. + /// + /// **Why is this bad?** Redundant code in the `filter` and `map` operations is poor style and + /// less performant. + /// + /// **Known problems:** None. + /// + /// **Example:** + /// Bad: + /// ```rust + /// (0_i32..10) + /// .filter(|n| n.checked_add(1).is_some()) + /// .map(|n| n.checked_add(1).unwrap()); + /// ``` + /// + /// Good: + /// ```rust + /// (0_i32..10).filter_map(|n| n.checked_add(1)); + /// ``` + pub MANUAL_FILTER_MAP, + complexity, + "using `_.filter(_).map(_)` in a way that can be written more simply as `filter_map(_)`" +} + +declare_clippy_lint! { /// **What it does:** Checks for usage of `_.filter_map(_).next()`. /// /// **Why is this bad?** Readability, this can be written more concisely as @@ -1473,6 +1500,7 @@ impl_lint_pass!(Methods => [ FILTER_NEXT, SKIP_WHILE_NEXT, FILTER_MAP, + MANUAL_FILTER_MAP, FILTER_MAP_NEXT, FLAT_MAP_IDENTITY, FIND_MAP, @@ -1540,7 +1568,7 @@ impl<'tcx> LateLintPass<'tcx> for Methods { ["next", "filter"] => lint_filter_next(cx, expr, arg_lists[1]), ["next", "skip_while"] => lint_skip_while_next(cx, expr, arg_lists[1]), ["next", "iter"] => lint_iter_next(cx, expr, arg_lists[1]), - ["map", "filter"] => lint_filter_map(cx, expr, arg_lists[1], arg_lists[0]), + ["map", "filter"] => lint_filter_map(cx, expr), ["map", "filter_map"] => lint_filter_map_map(cx, expr, arg_lists[1], arg_lists[0]), ["next", "filter_map"] => lint_filter_map_next(cx, expr, arg_lists[1], self.msrv.as_ref()), ["map", "find"] => lint_find_map(cx, expr, arg_lists[1], arg_lists[0]), @@ -2989,17 +3017,72 @@ fn lint_skip_while_next<'tcx>( } /// lint use of `filter().map()` for `Iterators` -fn lint_filter_map<'tcx>( - cx: &LateContext<'tcx>, - expr: &'tcx hir::Expr<'_>, - _filter_args: &'tcx [hir::Expr<'_>], - _map_args: &'tcx [hir::Expr<'_>], -) { - // lint if caller of `.filter().map()` is an Iterator - if match_trait_method(cx, expr, &paths::ITERATOR) { - let msg = "called `filter(..).map(..)` on an `Iterator`"; - let hint = "this is more succinctly expressed by calling `.filter_map(..)` instead"; - span_lint_and_help(cx, FILTER_MAP, expr.span, msg, None, hint); +fn lint_filter_map<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) { + if_chain! { + if let ExprKind::MethodCall(_, _, [map_recv, map_arg], map_span) = expr.kind; + if let ExprKind::MethodCall(_, _, [_, filter_arg], filter_span) = map_recv.kind; + if match_trait_method(cx, expr, &paths::ITERATOR); + + // filter(|x| ...is_some())... + if let ExprKind::Closure(_, _, filter_body_id, ..) = filter_arg.kind; + let filter_body = cx.tcx.hir().body(filter_body_id); + if let [filter_param] = filter_body.params; + // optional ref pattern: `filter(|&x| ..)` + let (filter_pat, is_filter_param_ref) = if let PatKind::Ref(ref_pat, _) = filter_param.pat.kind { + (ref_pat, true) + } else { + (filter_param.pat, false) + }; + // closure ends with is_some() or is_ok() + if let PatKind::Binding(_, filter_param_id, _, None) = filter_pat.kind; + if let ExprKind::MethodCall(path, _, [filter_arg], _) = filter_body.value.kind; + if let Some(opt_ty) = cx.typeck_results().expr_ty(filter_arg).ty_adt_def(); + if let Some(is_result) = if cx.tcx.is_diagnostic_item(sym::option_type, opt_ty.did) { + Some(false) + } else if cx.tcx.is_diagnostic_item(sym::result_type, opt_ty.did) { + Some(true) + } else { + None + }; + if path.ident.name.as_str() == if is_result { "is_ok" } else { "is_some" }; + + // ...map(|x| ...unwrap()) + if let ExprKind::Closure(_, _, map_body_id, ..) = map_arg.kind; + let map_body = cx.tcx.hir().body(map_body_id); + if let [map_param] = map_body.params; + if let PatKind::Binding(_, map_param_id, map_param_ident, None) = map_param.pat.kind; + // closure ends with expect() or unwrap() + if let ExprKind::MethodCall(seg, _, [map_arg, ..], _) = map_body.value.kind; + if matches!(seg.ident.name, sym::expect | sym::unwrap | sym::unwrap_or); + + let eq_fallback = |a: &Expr<'_>, b: &Expr<'_>| { + // in `filter(|x| ..)`, replace `*x` with `x` + let a_path = if_chain! { + if !is_filter_param_ref; + if let ExprKind::Unary(UnOp::UnDeref, expr_path) = a.kind; + then { expr_path } else { a } + }; + // let the filter closure arg and the map closure arg be equal + if_chain! { + if let ExprKind::Path(QPath::Resolved(None, a_path)) = a_path.kind; + if let ExprKind::Path(QPath::Resolved(None, b_path)) = b.kind; + if a_path.res == Res::Local(filter_param_id); + if b_path.res == Res::Local(map_param_id); + if TyS::same_type(cx.typeck_results().expr_ty_adjusted(a), cx.typeck_results().expr_ty_adjusted(b)); + then { + return true; + } + } + false + }; + if SpanlessEq::new(cx).expr_fallback(eq_fallback).eq_expr(filter_arg, map_arg); + then { + let span = filter_span.to(map_span); + let msg = "`filter(..).map(..)` can be simplified as `filter_map(..)`"; + let to_opt = if is_result { ".ok()" } else { "" }; + let sugg = format!("filter_map(|{}| {}{})", map_param_ident, snippet(cx, map_arg.span, ".."), to_opt); + span_lint_and_sugg(cx, MANUAL_FILTER_MAP, span, msg, "try", sugg, Applicability::MachineApplicable); + } } } diff --git a/tests/ui/filter_methods.stderr b/tests/ui/filter_methods.stderr index 11922681379..c7b4f28be3a 100644 --- a/tests/ui/filter_methods.stderr +++ b/tests/ui/filter_methods.stderr @@ -1,12 +1,3 @@ -error: called `filter(..).map(..)` on an `Iterator` - --> $DIR/filter_methods.rs:6:21 - | -LL | let _: Vec<_> = vec![5; 6].into_iter().filter(|&x| x == 0).map(|x| x * 2).collect(); - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - | - = note: `-D clippy::filter-map` implied by `-D warnings` - = help: this is more succinctly expressed by calling `.filter_map(..)` instead - error: called `filter(..).flat_map(..)` on an `Iterator` --> $DIR/filter_methods.rs:8:21 | @@ -17,6 +8,7 @@ LL | | .filter(|&x| x == 0) LL | | .flat_map(|x| x.checked_mul(2)) | |_______________________________________^ | + = note: `-D clippy::filter-map` implied by `-D warnings` = help: this is more succinctly expressed by calling `.flat_map(..)` and filtering by returning `iter::empty()` error: called `filter_map(..).flat_map(..)` on an `Iterator` @@ -43,5 +35,5 @@ LL | | .map(|x| x.checked_mul(2)) | = help: this is more succinctly expressed by only calling `.filter_map(..)` instead -error: aborting due to 4 previous errors +error: aborting due to 3 previous errors diff --git a/tests/ui/manual_filter_map.fixed b/tests/ui/manual_filter_map.fixed new file mode 100644 index 00000000000..fc8f58f8ea5 --- /dev/null +++ b/tests/ui/manual_filter_map.fixed @@ -0,0 +1,37 @@ +// run-rustfix +#![allow(dead_code)] +#![warn(clippy::manual_filter_map)] +#![allow(clippy::redundant_closure)] // FIXME suggestion may have redundant closure + +fn main() { + // is_some(), unwrap() + let _ = (0..).filter_map(|a| to_opt(a)); + + // ref pattern, expect() + let _ = (0..).filter_map(|a| to_opt(a)); + + // is_ok(), unwrap_or() + let _ = (0..).filter_map(|a| to_res(a).ok()); +} + +fn no_lint() { + // no shared code + let _ = (0..).filter(|n| *n > 1).map(|n| n + 1); + + // very close but different since filter() provides a reference + let _ = (0..).filter(|n| to_opt(n).is_some()).map(|a| to_opt(a).unwrap()); + + // similar but different + let _ = (0..).filter(|n| to_opt(n).is_some()).map(|n| to_res(n).unwrap()); + let _ = (0..) + .filter(|n| to_opt(n).map(|n| n + 1).is_some()) + .map(|a| to_opt(a).unwrap()); +} + +fn to_opt<T>(_: T) -> Option<T> { + unimplemented!() +} + +fn to_res<T>(_: T) -> Result<T, ()> { + unimplemented!() +} diff --git a/tests/ui/manual_filter_map.rs b/tests/ui/manual_filter_map.rs new file mode 100644 index 00000000000..3af4bbee3bf --- /dev/null +++ b/tests/ui/manual_filter_map.rs @@ -0,0 +1,37 @@ +// run-rustfix +#![allow(dead_code)] +#![warn(clippy::manual_filter_map)] +#![allow(clippy::redundant_closure)] // FIXME suggestion may have redundant closure + +fn main() { + // is_some(), unwrap() + let _ = (0..).filter(|n| to_opt(*n).is_some()).map(|a| to_opt(a).unwrap()); + + // ref pattern, expect() + let _ = (0..).filter(|&n| to_opt(n).is_some()).map(|a| to_opt(a).expect("hi")); + + // is_ok(), unwrap_or() + let _ = (0..).filter(|&n| to_res(n).is_ok()).map(|a| to_res(a).unwrap_or(1)); +} + +fn no_lint() { + // no shared code + let _ = (0..).filter(|n| *n > 1).map(|n| n + 1); + + // very close but different since filter() provides a reference + let _ = (0..).filter(|n| to_opt(n).is_some()).map(|a| to_opt(a).unwrap()); + + // similar but different + let _ = (0..).filter(|n| to_opt(n).is_some()).map(|n| to_res(n).unwrap()); + let _ = (0..) + .filter(|n| to_opt(n).map(|n| n + 1).is_some()) + .map(|a| to_opt(a).unwrap()); +} + +fn to_opt<T>(_: T) -> Option<T> { + unimplemented!() +} + +fn to_res<T>(_: T) -> Result<T, ()> { + unimplemented!() +} diff --git a/tests/ui/manual_filter_map.stderr b/tests/ui/manual_filter_map.stderr new file mode 100644 index 00000000000..4d4e2d5c12f --- /dev/null +++ b/tests/ui/manual_filter_map.stderr @@ -0,0 +1,22 @@ +error: `filter(..).map(..)` can be simplified as `filter_map(..)` + --> $DIR/manual_filter_map.rs:8:19 + | +LL | let _ = (0..).filter(|n| to_opt(*n).is_some()).map(|a| to_opt(a).unwrap()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `filter_map(|a| to_opt(a))` + | + = note: `-D clippy::manual-filter-map` implied by `-D warnings` + +error: `filter(..).map(..)` can be simplified as `filter_map(..)` + --> $DIR/manual_filter_map.rs:11:19 + | +LL | let _ = (0..).filter(|&n| to_opt(n).is_some()).map(|a| to_opt(a).expect("hi")); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `filter_map(|a| to_opt(a))` + +error: `filter(..).map(..)` can be simplified as `filter_map(..)` + --> $DIR/manual_filter_map.rs:14:19 + | +LL | let _ = (0..).filter(|&n| to_res(n).is_ok()).map(|a| to_res(a).unwrap_or(1)); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `filter_map(|a| to_res(a).ok())` + +error: aborting due to 3 previous errors + |