diff options
| -rw-r--r-- | clippy_lints/src/loops/mod.rs | 282 | ||||
| -rw-r--r-- | clippy_lints/src/loops/needless_collect.rs | 282 |
2 files changed, 289 insertions, 275 deletions
diff --git a/clippy_lints/src/loops/mod.rs b/clippy_lints/src/loops/mod.rs index 6adfbb6b955..043bbc9d1c5 100644 --- a/clippy_lints/src/loops/mod.rs +++ b/clippy_lints/src/loops/mod.rs @@ -6,6 +6,7 @@ mod for_mut_range_bound; mod for_single_element_loop; mod infinite_loop; mod manual_flatten; +mod needless_collect; mod utils; use crate::utils::sugg::Sugg; @@ -13,8 +14,8 @@ use crate::utils::usage::mutated_variables; use crate::utils::{ get_enclosing_block, get_parent_expr, get_trait_def_id, higher, implements_trait, is_in_panic_handler, is_integer_const, is_no_std_crate, is_refutable, is_type_diagnostic_item, last_path_segment, match_trait_method, - match_type, path_to_local, path_to_local_id, paths, snippet, snippet_with_applicability, - snippet_with_macro_callsite, span_lint, span_lint_and_help, span_lint_and_sugg, span_lint_and_then, sugg, + path_to_local, path_to_local_id, paths, snippet, snippet_with_applicability, snippet_with_macro_callsite, + span_lint, span_lint_and_help, span_lint_and_sugg, sugg, }; use if_chain::if_chain; use rustc_ast::ast; @@ -23,8 +24,8 @@ use rustc_errors::Applicability; use rustc_hir::def::{DefKind, Res}; use rustc_hir::intravisit::{walk_block, walk_expr, walk_pat, walk_stmt, NestedVisitorMap, Visitor}; use rustc_hir::{ - BinOpKind, BindingAnnotation, Block, BorrowKind, Expr, ExprKind, GenericArg, HirId, InlineAsmOperand, Local, - LoopSource, MatchSource, Mutability, Node, Pat, PatKind, QPath, Stmt, StmtKind, + BinOpKind, BindingAnnotation, Block, BorrowKind, Expr, ExprKind, HirId, InlineAsmOperand, LoopSource, MatchSource, + Mutability, Node, Pat, PatKind, Stmt, StmtKind, }; use rustc_lint::{LateContext, LateLintPass, LintContext}; use rustc_middle::hir::map::Map; @@ -32,7 +33,7 @@ use rustc_middle::lint::in_external_macro; use rustc_middle::ty::{self, Ty}; use rustc_session::{declare_lint_pass, declare_tool_lint}; use rustc_span::source_map::Span; -use rustc_span::symbol::{sym, Ident, Symbol}; +use rustc_span::symbol::{sym, Symbol}; use std::iter::{once, Iterator}; use utils::{get_span_of_entire_for_loop, make_iterator_snippet}; @@ -686,7 +687,7 @@ impl<'tcx> LateLintPass<'tcx> for Loops { infinite_loop::check_infinite_loop(cx, cond, body); } - check_needless_collect(expr, cx); + needless_collect::check_needless_collect(expr, cx); } } @@ -1894,272 +1895,3 @@ impl<'tcx> Visitor<'tcx> for LoopNestVisitor { NestedVisitorMap::None } } - -const NEEDLESS_COLLECT_MSG: &str = "avoid using `collect()` when not needed"; - -fn check_needless_collect<'tcx>(expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) { - check_needless_collect_direct_usage(expr, cx); - check_needless_collect_indirect_usage(expr, cx); -} -fn check_needless_collect_direct_usage<'tcx>(expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) { - if_chain! { - if let ExprKind::MethodCall(ref method, _, ref args, _) = expr.kind; - if let ExprKind::MethodCall(ref chain_method, _, _, _) = args[0].kind; - if chain_method.ident.name == sym!(collect) && match_trait_method(cx, &args[0], &paths::ITERATOR); - if let Some(ref generic_args) = chain_method.args; - if let Some(GenericArg::Type(ref ty)) = generic_args.args.get(0); - then { - let ty = cx.typeck_results().node_type(ty.hir_id); - if is_type_diagnostic_item(cx, ty, sym::vec_type) || - is_type_diagnostic_item(cx, ty, sym!(vecdeque_type)) || - match_type(cx, ty, &paths::BTREEMAP) || - is_type_diagnostic_item(cx, ty, sym!(hashmap_type)) { - if method.ident.name == sym!(len) { - let span = shorten_needless_collect_span(expr); - span_lint_and_sugg( - cx, - NEEDLESS_COLLECT, - span, - NEEDLESS_COLLECT_MSG, - "replace with", - "count()".to_string(), - Applicability::MachineApplicable, - ); - } - if method.ident.name == sym!(is_empty) { - let span = shorten_needless_collect_span(expr); - span_lint_and_sugg( - cx, - NEEDLESS_COLLECT, - span, - NEEDLESS_COLLECT_MSG, - "replace with", - "next().is_none()".to_string(), - Applicability::MachineApplicable, - ); - } - if method.ident.name == sym!(contains) { - let contains_arg = snippet(cx, args[1].span, "??"); - let span = shorten_needless_collect_span(expr); - span_lint_and_then( - cx, - NEEDLESS_COLLECT, - span, - NEEDLESS_COLLECT_MSG, - |diag| { - let (arg, pred) = contains_arg - .strip_prefix('&') - .map_or(("&x", &*contains_arg), |s| ("x", s)); - diag.span_suggestion( - span, - "replace with", - format!( - "any(|{}| x == {})", - arg, pred - ), - Applicability::MachineApplicable, - ); - } - ); - } - } - } - } -} - -fn check_needless_collect_indirect_usage<'tcx>(expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) { - if let ExprKind::Block(ref block, _) = expr.kind { - for ref stmt in block.stmts { - if_chain! { - if let StmtKind::Local( - Local { pat: Pat { hir_id: pat_id, kind: PatKind::Binding(_, _, ident, .. ), .. }, - init: Some(ref init_expr), .. } - ) = stmt.kind; - if let ExprKind::MethodCall(ref method_name, _, &[ref iter_source], ..) = init_expr.kind; - if method_name.ident.name == sym!(collect) && match_trait_method(cx, &init_expr, &paths::ITERATOR); - if let Some(ref generic_args) = method_name.args; - if let Some(GenericArg::Type(ref ty)) = generic_args.args.get(0); - if let ty = cx.typeck_results().node_type(ty.hir_id); - if is_type_diagnostic_item(cx, ty, sym::vec_type) || - is_type_diagnostic_item(cx, ty, sym!(vecdeque_type)) || - match_type(cx, ty, &paths::LINKED_LIST); - if let Some(iter_calls) = detect_iter_and_into_iters(block, *ident); - if iter_calls.len() == 1; - then { - let mut used_count_visitor = UsedCountVisitor { - cx, - id: *pat_id, - count: 0, - }; - walk_block(&mut used_count_visitor, block); - if used_count_visitor.count > 1 { - return; - } - - // Suggest replacing iter_call with iter_replacement, and removing stmt - let iter_call = &iter_calls[0]; - span_lint_and_then( - cx, - NEEDLESS_COLLECT, - stmt.span.until(iter_call.span), - NEEDLESS_COLLECT_MSG, - |diag| { - let iter_replacement = format!("{}{}", Sugg::hir(cx, iter_source, ".."), iter_call.get_iter_method(cx)); - diag.multipart_suggestion( - iter_call.get_suggestion_text(), - vec![ - (stmt.span, String::new()), - (iter_call.span, iter_replacement) - ], - Applicability::MachineApplicable,// MaybeIncorrect, - ).emit(); - }, - ); - } - } - } - } -} - -struct IterFunction { - func: IterFunctionKind, - span: Span, -} -impl IterFunction { - fn get_iter_method(&self, cx: &LateContext<'_>) -> String { - match &self.func { - IterFunctionKind::IntoIter => String::new(), - IterFunctionKind::Len => String::from(".count()"), - IterFunctionKind::IsEmpty => String::from(".next().is_none()"), - IterFunctionKind::Contains(span) => { - let s = snippet(cx, *span, ".."); - if let Some(stripped) = s.strip_prefix('&') { - format!(".any(|x| x == {})", stripped) - } else { - format!(".any(|x| x == *{})", s) - } - }, - } - } - fn get_suggestion_text(&self) -> &'static str { - match &self.func { - IterFunctionKind::IntoIter => { - "use the original Iterator instead of collecting it and then producing a new one" - }, - IterFunctionKind::Len => { - "take the original Iterator's count instead of collecting it and finding the length" - }, - IterFunctionKind::IsEmpty => { - "check if the original Iterator has anything instead of collecting it and seeing if it's empty" - }, - IterFunctionKind::Contains(_) => { - "check if the original Iterator contains an element instead of collecting then checking" - }, - } - } -} -enum IterFunctionKind { - IntoIter, - Len, - IsEmpty, - Contains(Span), -} - -struct IterFunctionVisitor { - uses: Vec<IterFunction>, - seen_other: bool, - target: Ident, -} -impl<'tcx> Visitor<'tcx> for IterFunctionVisitor { - fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) { - // Check function calls on our collection - if_chain! { - if let ExprKind::MethodCall(method_name, _, ref args, _) = &expr.kind; - if let Some(Expr { kind: ExprKind::Path(QPath::Resolved(_, ref path)), .. }) = args.get(0); - if let &[name] = &path.segments; - if name.ident == self.target; - then { - let len = sym!(len); - let is_empty = sym!(is_empty); - let contains = sym!(contains); - match method_name.ident.name { - sym::into_iter => self.uses.push( - IterFunction { func: IterFunctionKind::IntoIter, span: expr.span } - ), - name if name == len => self.uses.push( - IterFunction { func: IterFunctionKind::Len, span: expr.span } - ), - name if name == is_empty => self.uses.push( - IterFunction { func: IterFunctionKind::IsEmpty, span: expr.span } - ), - name if name == contains => self.uses.push( - IterFunction { func: IterFunctionKind::Contains(args[1].span), span: expr.span } - ), - _ => self.seen_other = true, - } - return - } - } - // Check if the collection is used for anything else - if_chain! { - if let Expr { kind: ExprKind::Path(QPath::Resolved(_, ref path)), .. } = expr; - if let &[name] = &path.segments; - if name.ident == self.target; - then { - self.seen_other = true; - } else { - walk_expr(self, expr); - } - } - } - - type Map = Map<'tcx>; - fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> { - NestedVisitorMap::None - } -} - -struct UsedCountVisitor<'a, 'tcx> { - cx: &'a LateContext<'tcx>, - id: HirId, - count: usize, -} - -impl<'a, 'tcx> Visitor<'tcx> for UsedCountVisitor<'a, 'tcx> { - type Map = Map<'tcx>; - - fn visit_expr(&mut self, expr: &'tcx Expr<'_>) { - if path_to_local_id(expr, self.id) { - self.count += 1; - } else { - walk_expr(self, expr); - } - } - - fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> { - NestedVisitorMap::OnlyBodies(self.cx.tcx.hir()) - } -} - -/// Detect the occurrences of calls to `iter` or `into_iter` for the -/// given identifier -fn detect_iter_and_into_iters<'tcx>(block: &'tcx Block<'tcx>, identifier: Ident) -> Option<Vec<IterFunction>> { - let mut visitor = IterFunctionVisitor { - uses: Vec::new(), - target: identifier, - seen_other: false, - }; - visitor.visit_block(block); - if visitor.seen_other { None } else { Some(visitor.uses) } -} - -fn shorten_needless_collect_span(expr: &Expr<'_>) -> Span { - if_chain! { - if let ExprKind::MethodCall(.., args, _) = &expr.kind; - if let ExprKind::MethodCall(_, span, ..) = &args[0].kind; - then { - return expr.span.with_lo(span.lo()); - } - } - unreachable!(); -} diff --git a/clippy_lints/src/loops/needless_collect.rs b/clippy_lints/src/loops/needless_collect.rs new file mode 100644 index 00000000000..cc2e2975492 --- /dev/null +++ b/clippy_lints/src/loops/needless_collect.rs @@ -0,0 +1,282 @@ +use crate::utils::sugg::Sugg; +use crate::utils::{ + is_type_diagnostic_item, match_trait_method, match_type, path_to_local_id, paths, snippet, span_lint_and_sugg, + span_lint_and_then, +}; +use if_chain::if_chain; +use rustc_errors::Applicability; +use rustc_hir::intravisit::{walk_block, walk_expr, NestedVisitorMap, Visitor}; +use rustc_hir::{Block, Expr, ExprKind, GenericArg, HirId, Local, Pat, PatKind, QPath, StmtKind}; +use rustc_lint::LateContext; +use rustc_middle::hir::map::Map; +use rustc_span::source_map::Span; +use rustc_span::symbol::{sym, Ident}; + +const NEEDLESS_COLLECT_MSG: &str = "avoid using `collect()` when not needed"; + +pub(super) fn check_needless_collect<'tcx>(expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) { + check_needless_collect_direct_usage(expr, cx); + check_needless_collect_indirect_usage(expr, cx); +} +fn check_needless_collect_direct_usage<'tcx>(expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) { + if_chain! { + if let ExprKind::MethodCall(ref method, _, ref args, _) = expr.kind; + if let ExprKind::MethodCall(ref chain_method, _, _, _) = args[0].kind; + if chain_method.ident.name == sym!(collect) && match_trait_method(cx, &args[0], &paths::ITERATOR); + if let Some(ref generic_args) = chain_method.args; + if let Some(GenericArg::Type(ref ty)) = generic_args.args.get(0); + then { + let ty = cx.typeck_results().node_type(ty.hir_id); + if is_type_diagnostic_item(cx, ty, sym::vec_type) || + is_type_diagnostic_item(cx, ty, sym!(vecdeque_type)) || + match_type(cx, ty, &paths::BTREEMAP) || + is_type_diagnostic_item(cx, ty, sym!(hashmap_type)) { + if method.ident.name == sym!(len) { + let span = shorten_needless_collect_span(expr); + span_lint_and_sugg( + cx, + super::NEEDLESS_COLLECT, + span, + NEEDLESS_COLLECT_MSG, + "replace with", + "count()".to_string(), + Applicability::MachineApplicable, + ); + } + if method.ident.name == sym!(is_empty) { + let span = shorten_needless_collect_span(expr); + span_lint_and_sugg( + cx, + super::NEEDLESS_COLLECT, + span, + NEEDLESS_COLLECT_MSG, + "replace with", + "next().is_none()".to_string(), + Applicability::MachineApplicable, + ); + } + if method.ident.name == sym!(contains) { + let contains_arg = snippet(cx, args[1].span, "??"); + let span = shorten_needless_collect_span(expr); + span_lint_and_then( + cx, + super::NEEDLESS_COLLECT, + span, + NEEDLESS_COLLECT_MSG, + |diag| { + let (arg, pred) = contains_arg + .strip_prefix('&') + .map_or(("&x", &*contains_arg), |s| ("x", s)); + diag.span_suggestion( + span, + "replace with", + format!( + "any(|{}| x == {})", + arg, pred + ), + Applicability::MachineApplicable, + ); + } + ); + } + } + } + } +} + +fn check_needless_collect_indirect_usage<'tcx>(expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) { + if let ExprKind::Block(ref block, _) = expr.kind { + for ref stmt in block.stmts { + if_chain! { + if let StmtKind::Local( + Local { pat: Pat { hir_id: pat_id, kind: PatKind::Binding(_, _, ident, .. ), .. }, + init: Some(ref init_expr), .. } + ) = stmt.kind; + if let ExprKind::MethodCall(ref method_name, _, &[ref iter_source], ..) = init_expr.kind; + if method_name.ident.name == sym!(collect) && match_trait_method(cx, &init_expr, &paths::ITERATOR); + if let Some(ref generic_args) = method_name.args; + if let Some(GenericArg::Type(ref ty)) = generic_args.args.get(0); + if let ty = cx.typeck_results().node_type(ty.hir_id); + if is_type_diagnostic_item(cx, ty, sym::vec_type) || + is_type_diagnostic_item(cx, ty, sym!(vecdeque_type)) || + match_type(cx, ty, &paths::LINKED_LIST); + if let Some(iter_calls) = detect_iter_and_into_iters(block, *ident); + if iter_calls.len() == 1; + then { + let mut used_count_visitor = UsedCountVisitor { + cx, + id: *pat_id, + count: 0, + }; + walk_block(&mut used_count_visitor, block); + if used_count_visitor.count > 1 { + return; + } + + // Suggest replacing iter_call with iter_replacement, and removing stmt + let iter_call = &iter_calls[0]; + span_lint_and_then( + cx, + super::NEEDLESS_COLLECT, + stmt.span.until(iter_call.span), + NEEDLESS_COLLECT_MSG, + |diag| { + let iter_replacement = format!("{}{}", Sugg::hir(cx, iter_source, ".."), iter_call.get_iter_method(cx)); + diag.multipart_suggestion( + iter_call.get_suggestion_text(), + vec![ + (stmt.span, String::new()), + (iter_call.span, iter_replacement) + ], + Applicability::MachineApplicable,// MaybeIncorrect, + ).emit(); + }, + ); + } + } + } + } +} + +struct IterFunction { + func: IterFunctionKind, + span: Span, +} +impl IterFunction { + fn get_iter_method(&self, cx: &LateContext<'_>) -> String { + match &self.func { + IterFunctionKind::IntoIter => String::new(), + IterFunctionKind::Len => String::from(".count()"), + IterFunctionKind::IsEmpty => String::from(".next().is_none()"), + IterFunctionKind::Contains(span) => { + let s = snippet(cx, *span, ".."); + if let Some(stripped) = s.strip_prefix('&') { + format!(".any(|x| x == {})", stripped) + } else { + format!(".any(|x| x == *{})", s) + } + }, + } + } + fn get_suggestion_text(&self) -> &'static str { + match &self.func { + IterFunctionKind::IntoIter => { + "use the original Iterator instead of collecting it and then producing a new one" + }, + IterFunctionKind::Len => { + "take the original Iterator's count instead of collecting it and finding the length" + }, + IterFunctionKind::IsEmpty => { + "check if the original Iterator has anything instead of collecting it and seeing if it's empty" + }, + IterFunctionKind::Contains(_) => { + "check if the original Iterator contains an element instead of collecting then checking" + }, + } + } +} +enum IterFunctionKind { + IntoIter, + Len, + IsEmpty, + Contains(Span), +} + +struct IterFunctionVisitor { + uses: Vec<IterFunction>, + seen_other: bool, + target: Ident, +} +impl<'tcx> Visitor<'tcx> for IterFunctionVisitor { + fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) { + // Check function calls on our collection + if_chain! { + if let ExprKind::MethodCall(method_name, _, ref args, _) = &expr.kind; + if let Some(Expr { kind: ExprKind::Path(QPath::Resolved(_, ref path)), .. }) = args.get(0); + if let &[name] = &path.segments; + if name.ident == self.target; + then { + let len = sym!(len); + let is_empty = sym!(is_empty); + let contains = sym!(contains); + match method_name.ident.name { + sym::into_iter => self.uses.push( + IterFunction { func: IterFunctionKind::IntoIter, span: expr.span } + ), + name if name == len => self.uses.push( + IterFunction { func: IterFunctionKind::Len, span: expr.span } + ), + name if name == is_empty => self.uses.push( + IterFunction { func: IterFunctionKind::IsEmpty, span: expr.span } + ), + name if name == contains => self.uses.push( + IterFunction { func: IterFunctionKind::Contains(args[1].span), span: expr.span } + ), + _ => self.seen_other = true, + } + return + } + } + // Check if the collection is used for anything else + if_chain! { + if let Expr { kind: ExprKind::Path(QPath::Resolved(_, ref path)), .. } = expr; + if let &[name] = &path.segments; + if name.ident == self.target; + then { + self.seen_other = true; + } else { + walk_expr(self, expr); + } + } + } + + type Map = Map<'tcx>; + fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> { + NestedVisitorMap::None + } +} + +struct UsedCountVisitor<'a, 'tcx> { + cx: &'a LateContext<'tcx>, + id: HirId, + count: usize, +} + +impl<'a, 'tcx> Visitor<'tcx> for UsedCountVisitor<'a, 'tcx> { + type Map = Map<'tcx>; + + fn visit_expr(&mut self, expr: &'tcx Expr<'_>) { + if path_to_local_id(expr, self.id) { + self.count += 1; + } else { + walk_expr(self, expr); + } + } + + fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> { + NestedVisitorMap::OnlyBodies(self.cx.tcx.hir()) + } +} + +/// Detect the occurrences of calls to `iter` or `into_iter` for the +/// given identifier +fn detect_iter_and_into_iters<'tcx>(block: &'tcx Block<'tcx>, identifier: Ident) -> Option<Vec<IterFunction>> { + let mut visitor = IterFunctionVisitor { + uses: Vec::new(), + target: identifier, + seen_other: false, + }; + visitor.visit_block(block); + if visitor.seen_other { None } else { Some(visitor.uses) } +} + +fn shorten_needless_collect_span(expr: &Expr<'_>) -> Span { + if_chain! { + if let ExprKind::MethodCall(.., args, _) = &expr.kind; + if let ExprKind::MethodCall(_, span, ..) = &args[0].kind; + then { + return expr.span.with_lo(span.lo()); + } + } + unreachable!(); +} |