From b9035c48fceed2a243d91d84554d6c019d863bc1 Mon Sep 17 00:00:00 2001 From: flip1995 Date: Tue, 12 Apr 2022 15:27:28 +0200 Subject: [PATCH 1/2] Prevent infinite (exponential) recursion in only_used_in_recursion This simplifies the visitor code a bit and prevents checking expressions multiple times. I still think this lint should be removed for now, because its code isn't really tested. --- .../src/only_used_in_recursion.rs | 47 +++++++------------ 1 file changed, 16 insertions(+), 31 deletions(-) diff --git a/src/tools/clippy/clippy_lints/src/only_used_in_recursion.rs b/src/tools/clippy/clippy_lints/src/only_used_in_recursion.rs index 8e61f2347767d..f946fc1119281 100644 --- a/src/tools/clippy/clippy_lints/src/only_used_in_recursion.rs +++ b/src/tools/clippy/clippy_lints/src/only_used_in_recursion.rs @@ -8,7 +8,7 @@ use rustc_errors::Applicability; use rustc_hir::def::{DefKind, Res}; use rustc_hir::def_id::DefId; use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData}; -use rustc_hir::intravisit::{walk_expr, FnKind, Visitor}; +use rustc_hir::intravisit::{walk_expr, walk_stmt, FnKind, Visitor}; use rustc_hir::{ Arm, Block, Body, Expr, ExprKind, Guard, HirId, ImplicitSelfKind, Let, Local, Pat, PatKind, Path, PathSegment, QPath, Stmt, StmtKind, TyKind, UnOp, @@ -145,7 +145,8 @@ impl<'tcx> LateLintPass<'tcx> for OnlyUsedInRecursion { is_method: matches!(kind, FnKind::Method(..)), has_self, ty_res, - ty_ctx: cx.tcx, + tcx: cx.tcx, + visited_exprs: FxHashSet::default(), }; visitor.visit_expr(&body.value); @@ -206,19 +207,13 @@ impl<'tcx> LateLintPass<'tcx> for OnlyUsedInRecursion { } pub fn is_primitive(ty: Ty<'_>) -> bool { - match ty.kind() { - ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Str => true, - ty::Ref(_, t, _) => is_primitive(*t), - _ => false, - } + let ty = ty.peel_refs(); + ty.is_primitive() || ty.is_str() } pub fn is_array(ty: Ty<'_>) -> bool { - match ty.kind() { - ty::Array(..) | ty::Slice(..) => true, - ty::Ref(_, t, _) => is_array(*t), - _ => false, - } + let ty = ty.peel_refs(); + ty.is_array() || ty.is_array_slice() } /// This builds the graph of side effect. @@ -250,40 +245,30 @@ pub struct SideEffectVisit<'tcx> { is_method: bool, has_self: bool, ty_res: &'tcx TypeckResults<'tcx>, - ty_ctx: TyCtxt<'tcx>, + tcx: TyCtxt<'tcx>, + visited_exprs: FxHashSet, } impl<'tcx> Visitor<'tcx> for SideEffectVisit<'tcx> { - fn visit_block(&mut self, b: &'tcx Block<'tcx>) { - b.stmts.iter().for_each(|stmt| { - self.visit_stmt(stmt); - self.ret_vars.clear(); - }); - walk_list!(self, visit_expr, b.expr); - } - fn visit_stmt(&mut self, s: &'tcx Stmt<'tcx>) { match s.kind { StmtKind::Local(Local { pat, init: Some(init), .. }) => { self.visit_pat_expr(pat, init, false); - self.ret_vars.clear(); }, - StmtKind::Item(i) => { - let item = self.ty_ctx.hir().item(i); - self.visit_item(item); - self.ret_vars.clear(); - }, - StmtKind::Expr(e) | StmtKind::Semi(e) => { - self.visit_expr(e); - self.ret_vars.clear(); + StmtKind::Item(_) | StmtKind::Expr(_) | StmtKind::Semi(_) => { + walk_stmt(self, s); }, StmtKind::Local(_) => {}, } + self.ret_vars.clear(); } fn visit_expr(&mut self, ex: &'tcx Expr<'tcx>) { + if !self.visited_exprs.insert(ex.hir_id) { + return; + } match ex.kind { ExprKind::Array(exprs) | ExprKind::Tup(exprs) => { self.ret_vars = exprs @@ -307,7 +292,7 @@ impl<'tcx> Visitor<'tcx> for SideEffectVisit<'tcx> { ExprKind::Match(expr, arms, _) => self.visit_match(expr, arms), // since analysing the closure is not easy, just set all variables in it to side-effect ExprKind::Closure(_, _, body_id, _, _) => { - let body = self.ty_ctx.hir().body(body_id); + let body = self.tcx.hir().body(body_id); self.visit_body(body); let vars = std::mem::take(&mut self.ret_vars); self.add_side_effect(vars); From 53074f559f61394a815b690042577eed871f4770 Mon Sep 17 00:00:00 2001 From: flip1995 Date: Tue, 3 May 2022 16:41:12 +0100 Subject: [PATCH 2/2] Move only_used_in_recursion to nursery --- src/tools/clippy/clippy_lints/src/lib.register_all.rs | 1 - .../clippy/clippy_lints/src/lib.register_complexity.rs | 1 - .../clippy/clippy_lints/src/lib.register_nursery.rs | 1 + .../clippy/clippy_lints/src/only_used_in_recursion.rs | 9 ++++++++- 4 files changed, 9 insertions(+), 3 deletions(-) diff --git a/src/tools/clippy/clippy_lints/src/lib.register_all.rs b/src/tools/clippy/clippy_lints/src/lib.register_all.rs index 132a466267626..4cd19d99c0856 100644 --- a/src/tools/clippy/clippy_lints/src/lib.register_all.rs +++ b/src/tools/clippy/clippy_lints/src/lib.register_all.rs @@ -237,7 +237,6 @@ store.register_group(true, "clippy::all", Some("clippy_all"), vec![ LintId::of(non_expressive_names::JUST_UNDERSCORES_AND_DIGITS), LintId::of(non_octal_unix_permissions::NON_OCTAL_UNIX_PERMISSIONS), LintId::of(octal_escapes::OCTAL_ESCAPES), - LintId::of(only_used_in_recursion::ONLY_USED_IN_RECURSION), LintId::of(open_options::NONSENSICAL_OPEN_OPTIONS), LintId::of(option_env_unwrap::OPTION_ENV_UNWRAP), LintId::of(overflow_check_conditional::OVERFLOW_CHECK_CONDITIONAL), diff --git a/src/tools/clippy/clippy_lints/src/lib.register_complexity.rs b/src/tools/clippy/clippy_lints/src/lib.register_complexity.rs index a2ce69065f94d..24658f02b052d 100644 --- a/src/tools/clippy/clippy_lints/src/lib.register_complexity.rs +++ b/src/tools/clippy/clippy_lints/src/lib.register_complexity.rs @@ -66,7 +66,6 @@ store.register_group(true, "clippy::complexity", Some("clippy_complexity"), vec! LintId::of(neg_cmp_op_on_partial_ord::NEG_CMP_OP_ON_PARTIAL_ORD), LintId::of(no_effect::NO_EFFECT), LintId::of(no_effect::UNNECESSARY_OPERATION), - LintId::of(only_used_in_recursion::ONLY_USED_IN_RECURSION), LintId::of(overflow_check_conditional::OVERFLOW_CHECK_CONDITIONAL), LintId::of(partialeq_ne_impl::PARTIALEQ_NE_IMPL), LintId::of(precedence::PRECEDENCE), diff --git a/src/tools/clippy/clippy_lints/src/lib.register_nursery.rs b/src/tools/clippy/clippy_lints/src/lib.register_nursery.rs index c2fc67afba517..18904a9453890 100644 --- a/src/tools/clippy/clippy_lints/src/lib.register_nursery.rs +++ b/src/tools/clippy/clippy_lints/src/lib.register_nursery.rs @@ -20,6 +20,7 @@ store.register_group(true, "clippy::nursery", Some("clippy_nursery"), vec![ LintId::of(mutex_atomic::MUTEX_INTEGER), LintId::of(non_send_fields_in_send_ty::NON_SEND_FIELDS_IN_SEND_TY), LintId::of(nonstandard_macro_braces::NONSTANDARD_MACRO_BRACES), + LintId::of(only_used_in_recursion::ONLY_USED_IN_RECURSION), LintId::of(option_if_let_else::OPTION_IF_LET_ELSE), LintId::of(path_buf_push_overwrite::PATH_BUF_PUSH_OVERWRITE), LintId::of(redundant_pub_crate::REDUNDANT_PUB_CRATE), diff --git a/src/tools/clippy/clippy_lints/src/only_used_in_recursion.rs b/src/tools/clippy/clippy_lints/src/only_used_in_recursion.rs index f946fc1119281..beb812793f81c 100644 --- a/src/tools/clippy/clippy_lints/src/only_used_in_recursion.rs +++ b/src/tools/clippy/clippy_lints/src/only_used_in_recursion.rs @@ -1,6 +1,7 @@ use std::collections::VecDeque; use clippy_utils::diagnostics::span_lint_and_sugg; +use clippy_utils::is_lint_allowed; use itertools::{izip, Itertools}; use rustc_ast::{walk_list, Label, Mutability}; use rustc_data_structures::fx::{FxHashMap, FxHashSet}; @@ -33,6 +34,9 @@ declare_clippy_lint! { /// and the assigned variables are also only in recursion, it is useless. /// /// ### Known problems + /// Too many code paths in the linting code are currently untested and prone to produce false + /// positives or are prone to have performance implications. + /// /// In some cases, this would not catch all useless arguments. /// /// ```rust @@ -85,7 +89,7 @@ declare_clippy_lint! { /// ``` #[clippy::version = "1.60.0"] pub ONLY_USED_IN_RECURSION, - complexity, + nursery, "arguments that is only used in recursion can be removed" } declare_lint_pass!(OnlyUsedInRecursion => [ONLY_USED_IN_RECURSION]); @@ -100,6 +104,9 @@ impl<'tcx> LateLintPass<'tcx> for OnlyUsedInRecursion { _: Span, id: HirId, ) { + if is_lint_allowed(cx, ONLY_USED_IN_RECURSION, id) { + return; + } if let FnKind::ItemFn(ident, ..) | FnKind::Method(ident, ..) = kind { let def_id = id.owner.to_def_id(); let data = cx.tcx.def_path(def_id).data;