diff --git a/CHANGELOG.md b/CHANGELOG.md index 579968021821..47af42e14ca9 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -2389,6 +2389,7 @@ Released 2018-09-13 [`op_ref`]: https://rust-lang.github.io/rust-clippy/master/index.html#op_ref [`option_as_ref_deref`]: https://rust-lang.github.io/rust-clippy/master/index.html#option_as_ref_deref [`option_env_unwrap`]: https://rust-lang.github.io/rust-clippy/master/index.html#option_env_unwrap +[`option_filter_map`]: https://rust-lang.github.io/rust-clippy/master/index.html#option_filter_map [`option_if_let_else`]: https://rust-lang.github.io/rust-clippy/master/index.html#option_if_let_else [`option_map_or_none`]: https://rust-lang.github.io/rust-clippy/master/index.html#option_map_or_none [`option_map_unit_fn`]: https://rust-lang.github.io/rust-clippy/master/index.html#option_map_unit_fn diff --git a/README.md b/README.md index 63057609bb6f..8c0c16c443df 100644 --- a/README.md +++ b/README.md @@ -5,7 +5,7 @@ A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code. -[There are over 400 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html) +[There are over 450 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html) Lints are divided into categories, each with a default [lint level](https://doc.rust-lang.org/rustc/lints/levels.html). You can choose how much Clippy is supposed to ~~annoy~~ help you by changing the lint level by category. diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs index f013613119cf..82abd4803db3 100644 --- a/clippy_lints/src/lib.rs +++ b/clippy_lints/src/lib.rs @@ -804,6 +804,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: &methods::NEW_RET_NO_SELF, &methods::OK_EXPECT, &methods::OPTION_AS_REF_DEREF, + &methods::OPTION_FILTER_MAP, &methods::OPTION_MAP_OR_NONE, &methods::OR_FUN_CALL, &methods::RESULT_MAP_OR_INTO_OPTION, @@ -1596,6 +1597,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: LintId::of(&methods::NEW_RET_NO_SELF), LintId::of(&methods::OK_EXPECT), LintId::of(&methods::OPTION_AS_REF_DEREF), + LintId::of(&methods::OPTION_FILTER_MAP), LintId::of(&methods::OPTION_MAP_OR_NONE), LintId::of(&methods::OR_FUN_CALL), LintId::of(&methods::RESULT_MAP_OR_INTO_OPTION), @@ -1891,6 +1893,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: LintId::of(&methods::MANUAL_FILTER_MAP), LintId::of(&methods::MANUAL_FIND_MAP), LintId::of(&methods::OPTION_AS_REF_DEREF), + LintId::of(&methods::OPTION_FILTER_MAP), LintId::of(&methods::SEARCH_IS_SOME), LintId::of(&methods::SKIP_WHILE_NEXT), LintId::of(&methods::SUSPICIOUS_MAP), diff --git a/clippy_lints/src/methods/filter_map.rs b/clippy_lints/src/methods/filter_map.rs index 2cb476acb2b3..68f8480dc51b 100644 --- a/clippy_lints/src/methods/filter_map.rs +++ b/clippy_lints/src/methods/filter_map.rs @@ -1,87 +1,166 @@ use clippy_utils::diagnostics::span_lint_and_sugg; -use clippy_utils::source::snippet; -use clippy_utils::{is_trait_method, path_to_local_id, SpanlessEq}; +use clippy_utils::source::{indent_of, reindent_multiline, snippet}; +use clippy_utils::ty::is_type_diagnostic_item; +use clippy_utils::{is_trait_method, path_to_local_id, remove_blocks, SpanlessEq}; use if_chain::if_chain; use rustc_errors::Applicability; use rustc_hir as hir; -use rustc_hir::{Expr, ExprKind, PatKind, UnOp}; +use rustc_hir::def::Res; +use rustc_hir::{Expr, ExprKind, PatKind, QPath, UnOp}; use rustc_lint::LateContext; use rustc_middle::ty::TyS; -use rustc_span::symbol::sym; +use rustc_span::source_map::Span; +use rustc_span::symbol::{sym, Symbol}; +use std::borrow::Cow; use super::MANUAL_FILTER_MAP; use super::MANUAL_FIND_MAP; +use super::OPTION_FILTER_MAP; + +fn is_method<'tcx>(cx: &LateContext<'tcx>, expr: &hir::Expr<'_>, method_name: Symbol) -> bool { + match &expr.kind { + hir::ExprKind::Path(QPath::TypeRelative(_, ref mname)) => mname.ident.name == method_name, + hir::ExprKind::Path(QPath::Resolved(_, segments)) => { + segments.segments.last().unwrap().ident.name == method_name + }, + hir::ExprKind::Closure(_, _, c, _, _) => { + let body = cx.tcx.hir().body(*c); + let closure_expr = remove_blocks(&body.value); + let arg_id = body.params[0].pat.hir_id; + match closure_expr.kind { + hir::ExprKind::MethodCall(hir::PathSegment { ident, .. }, _, ref args, _) => { + if_chain! { + if ident.name == method_name; + if let hir::ExprKind::Path(path) = &args[0].kind; + if let Res::Local(ref local) = cx.qpath_res(path, args[0].hir_id); + then { + return arg_id == *local + } + } + false + }, + _ => false, + } + }, + _ => false, + } +} + +fn is_option_filter_map<'tcx>( + cx: &LateContext<'tcx>, + filter_arg: &'tcx hir::Expr<'_>, + map_arg: &'tcx hir::Expr<'_>, +) -> bool { + is_method(cx, map_arg, sym::unwrap) && is_method(cx, filter_arg, sym!(is_some)) +} + +/// lint use of `filter().map()` for `Iterators` +fn lint_filter_some_map_unwrap<'tcx>( + cx: &LateContext<'tcx>, + expr: &'tcx hir::Expr<'_>, + filter_recv: &'tcx hir::Expr<'_>, + filter_arg: &'tcx hir::Expr<'_>, + map_arg: &'tcx hir::Expr<'_>, + target_span: Span, + methods_span: Span, +) { + let iterator = is_trait_method(cx, expr, sym::Iterator); + let option = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&filter_recv), sym::option_type); + if (iterator || option) && is_option_filter_map(cx, filter_arg, map_arg) { + let msg = "`filter` for `Some` followed by `unwrap`"; + let help = "consider using `flatten` instead"; + let sugg = format!( + "{}", + reindent_multiline(Cow::Borrowed("flatten()"), true, indent_of(cx, target_span),) + ); + span_lint_and_sugg( + cx, + OPTION_FILTER_MAP, + methods_span, + msg, + help, + sugg, + Applicability::MachineApplicable, + ); + } +} /// lint use of `filter().map()` or `find().map()` for `Iterators` -pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>, is_find: bool) { +pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>, is_find: bool, target_span: Span) { 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 is_trait_method(cx, map_recv, sym::Iterator); + if let ExprKind::MethodCall(_, _, [map_recv, map_arg], map_span) = expr.kind; + if let ExprKind::MethodCall(_, _, [filter_recv, filter_arg], filter_span) = map_recv.kind; + then { + lint_filter_some_map_unwrap(cx, expr, filter_recv, filter_arg, + map_arg, target_span, filter_span.to(map_span)); + if_chain! { + if is_trait_method(cx, map_recv, sym::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" }; + // 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); + // ...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::Deref, expr_path) = a.kind; - then { expr_path } else { a } - }; - // let the filter closure arg and the map closure arg be equal - if_chain! { - if path_to_local_id(a_path, filter_param_id); - if path_to_local_id(b, map_param_id); - if TyS::same_type(cx.typeck_results().expr_ty_adjusted(a), cx.typeck_results().expr_ty_adjusted(b)); - then { - return true; + 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::Deref, expr_path) = a.kind; + then { expr_path } else { a } + }; + // let the filter closure arg and the map closure arg be equal + if_chain! { + if path_to_local_id(a_path, filter_param_id); + if path_to_local_id(b, 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 (filter_name, lint) = if is_find { - ("find", MANUAL_FIND_MAP) - } else { - ("filter", MANUAL_FILTER_MAP) + false }; - let msg = format!("`{}(..).map(..)` can be simplified as `{0}_map(..)`", filter_name); - let to_opt = if is_result { ".ok()" } else { "" }; - let sugg = format!("{}_map(|{}| {}{})", filter_name, map_param_ident, - snippet(cx, map_arg.span, ".."), to_opt); - span_lint_and_sugg(cx, lint, span, &msg, "try", sugg, Applicability::MachineApplicable); + if SpanlessEq::new(cx).expr_fallback(eq_fallback).eq_expr(filter_arg, map_arg); + then { + let span = filter_span.to(map_span); + let (filter_name, lint) = if is_find { + ("find", MANUAL_FIND_MAP) + } else { + ("filter", MANUAL_FILTER_MAP) + }; + let msg = format!("`{}(..).map(..)` can be simplified as `{0}_map(..)`", filter_name); + let to_opt = if is_result { ".ok()" } else { "" }; + let sugg = format!("{}_map(|{}| {}{})", filter_name, map_param_ident, + snippet(cx, map_arg.span, ".."), to_opt); + span_lint_and_sugg(cx, lint, span, &msg, "try", sugg, Applicability::MachineApplicable); + } + } } } } diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs index fccdee078778..8a04fd0060d9 100644 --- a/clippy_lints/src/methods/mod.rs +++ b/clippy_lints/src/methods/mod.rs @@ -896,6 +896,28 @@ declare_clippy_lint! { "using `Iterator::step_by(0)`, which will panic at runtime" } +declare_clippy_lint! { + /// **What it does:** Checks for indirect collection of populated `Option` + /// + /// **Why is this bad?** `Option` is like a collection of 0-1 things, so `flatten` + /// automatically does this without suspicious-looking `unwrap` calls. + /// + /// **Known problems:** None. + /// + /// **Example:** + /// + /// ```rust + /// let _ = std::iter::empty::>().filter(Option::is_some).map(Option::unwrap); + /// ``` + /// Use instead: + /// ```rust + /// let _ = std::iter::empty::>().flatten(); + /// ``` + pub OPTION_FILTER_MAP, + complexity, + "filtering `Option` for `Some` then force-unwrapping, which can be one type-safe operation" +} + declare_clippy_lint! { /// **What it does:** Checks for the use of `iter.nth(0)`. /// @@ -1651,6 +1673,7 @@ impl_lint_pass!(Methods => [ FILTER_MAP_IDENTITY, MANUAL_FILTER_MAP, MANUAL_FIND_MAP, + OPTION_FILTER_MAP, FILTER_MAP_NEXT, FLAT_MAP_IDENTITY, MAP_FLATTEN, @@ -1720,10 +1743,10 @@ impl<'tcx> LateLintPass<'tcx> for Methods { ["next", "filter"] => filter_next::check(cx, expr, arg_lists[1]), ["next", "skip_while"] => skip_while_next::check(cx, expr, arg_lists[1]), ["next", "iter"] => iter_next_slice::check(cx, expr, arg_lists[1]), - ["map", "filter"] => filter_map::check(cx, expr, false), + ["map", "filter"] => filter_map::check(cx, expr, false, method_spans[0]), ["map", "filter_map"] => filter_map_map::check(cx, expr), ["next", "filter_map"] => filter_map_next::check(cx, expr, arg_lists[1], self.msrv.as_ref()), - ["map", "find"] => filter_map::check(cx, expr, true), + ["map", "find"] => filter_map::check(cx, expr, true, method_spans[0]), ["flat_map", "filter"] => filter_flat_map::check(cx, expr), ["flat_map", "filter_map"] => filter_map_flat_map::check(cx, expr), ["flat_map", ..] => flat_map_identity::check(cx, expr, arg_lists[0], method_spans[0]), diff --git a/tests/ui/option_filter_map.fixed b/tests/ui/option_filter_map.fixed new file mode 100644 index 000000000000..f9d1825ade05 --- /dev/null +++ b/tests/ui/option_filter_map.fixed @@ -0,0 +1,23 @@ +#![warn(clippy::option_filter_map)] +// run-rustfix +fn odds_out(x: i32) -> Option { + if x % 2 == 0 { Some(x) } else { None } +} + +fn main() { + let _ = Some(Some(1)).flatten(); + let _ = Some(Some(1)).flatten(); + let _ = Some(1).map(odds_out).flatten(); + let _ = Some(1).map(odds_out).flatten(); + + let _ = vec![Some(1)].into_iter().flatten(); + let _ = vec![Some(1)].into_iter().flatten(); + let _ = vec![1] + .into_iter() + .map(odds_out) + .flatten(); + let _ = vec![1] + .into_iter() + .map(odds_out) + .flatten(); +} diff --git a/tests/ui/option_filter_map.rs b/tests/ui/option_filter_map.rs new file mode 100644 index 000000000000..588e1ccccce2 --- /dev/null +++ b/tests/ui/option_filter_map.rs @@ -0,0 +1,25 @@ +#![warn(clippy::option_filter_map)] +// run-rustfix +fn odds_out(x: i32) -> Option { + if x % 2 == 0 { Some(x) } else { None } +} + +fn main() { + let _ = Some(Some(1)).filter(Option::is_some).map(Option::unwrap); + let _ = Some(Some(1)).filter(|o| o.is_some()).map(|o| o.unwrap()); + let _ = Some(1).map(odds_out).filter(Option::is_some).map(Option::unwrap); + let _ = Some(1).map(odds_out).filter(|o| o.is_some()).map(|o| o.unwrap()); + + let _ = vec![Some(1)].into_iter().filter(Option::is_some).map(Option::unwrap); + let _ = vec![Some(1)].into_iter().filter(|o| o.is_some()).map(|o| o.unwrap()); + let _ = vec![1] + .into_iter() + .map(odds_out) + .filter(Option::is_some) + .map(Option::unwrap); + let _ = vec![1] + .into_iter() + .map(odds_out) + .filter(|o| o.is_some()) + .map(|o| o.unwrap()); +} diff --git a/tests/ui/option_filter_map.stderr b/tests/ui/option_filter_map.stderr new file mode 100644 index 000000000000..31a82969d5a1 --- /dev/null +++ b/tests/ui/option_filter_map.stderr @@ -0,0 +1,56 @@ +error: `filter` for `Some` followed by `unwrap` + --> $DIR/option_filter_map.rs:8:27 + | +LL | let _ = Some(Some(1)).filter(Option::is_some).map(Option::unwrap); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `flatten` instead: `flatten()` + | + = note: `-D clippy::option-filter-map` implied by `-D warnings` + +error: `filter` for `Some` followed by `unwrap` + --> $DIR/option_filter_map.rs:9:27 + | +LL | let _ = Some(Some(1)).filter(|o| o.is_some()).map(|o| o.unwrap()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `flatten` instead: `flatten()` + +error: `filter` for `Some` followed by `unwrap` + --> $DIR/option_filter_map.rs:10:35 + | +LL | let _ = Some(1).map(odds_out).filter(Option::is_some).map(Option::unwrap); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `flatten` instead: `flatten()` + +error: `filter` for `Some` followed by `unwrap` + --> $DIR/option_filter_map.rs:11:35 + | +LL | let _ = Some(1).map(odds_out).filter(|o| o.is_some()).map(|o| o.unwrap()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `flatten` instead: `flatten()` + +error: `filter` for `Some` followed by `unwrap` + --> $DIR/option_filter_map.rs:13:39 + | +LL | let _ = vec![Some(1)].into_iter().filter(Option::is_some).map(Option::unwrap); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `flatten` instead: `flatten()` + +error: `filter` for `Some` followed by `unwrap` + --> $DIR/option_filter_map.rs:14:39 + | +LL | let _ = vec![Some(1)].into_iter().filter(|o| o.is_some()).map(|o| o.unwrap()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `flatten` instead: `flatten()` + +error: `filter` for `Some` followed by `unwrap` + --> $DIR/option_filter_map.rs:18:10 + | +LL | .filter(Option::is_some) + | __________^ +LL | | .map(Option::unwrap); + | |____________________________^ help: consider using `flatten` instead: `flatten()` + +error: `filter` for `Some` followed by `unwrap` + --> $DIR/option_filter_map.rs:23:10 + | +LL | .filter(|o| o.is_some()) + | __________^ +LL | | .map(|o| o.unwrap()); + | |____________________________^ help: consider using `flatten` instead: `flatten()` + +error: aborting due to 8 previous errors +