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https://github.com/rust-lang/rust-clippy
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Add check_infinite_loop to its own module
This commit is contained in:
nahuakang
Yoshitomo Nakanishi
parent
1e5e541ac5
commit
9520cba554
2 changed files with 143 additions and 132 deletions
138
clippy_lints/src/loops/infinite_loop.rs
Normal file
138
clippy_lints/src/loops/infinite_loop.rs
Normal file
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@ -0,0 +1,138 @@
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use crate::consts::constant;
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use crate::utils::span_lint_and_then;
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use crate::utils::usage::mutated_variables;
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use if_chain::if_chain;
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use rustc_data_structures::fx::{FxHashMap, FxHashSet};
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use rustc_hir::def::{DefKind, Res};
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use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
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use rustc_hir::{def_id, Expr, ExprKind, HirId, QPath};
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use rustc_lint::LateContext;
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use rustc_middle::hir::map::Map;
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use std::iter::Iterator;
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pub(super) fn check_infinite_loop<'tcx>(cx: &LateContext<'tcx>, cond: &'tcx Expr<'_>, expr: &'tcx Expr<'_>) {
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if constant(cx, cx.typeck_results(), cond).is_some() {
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// A pure constant condition (e.g., `while false`) is not linted.
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return;
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}
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let mut var_visitor = VarCollectorVisitor {
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cx,
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ids: FxHashSet::default(),
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def_ids: FxHashMap::default(),
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skip: false,
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};
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var_visitor.visit_expr(cond);
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if var_visitor.skip {
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return;
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}
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let used_in_condition = &var_visitor.ids;
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let no_cond_variable_mutated = if let Some(used_mutably) = mutated_variables(expr, cx) {
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used_in_condition.is_disjoint(&used_mutably)
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} else {
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return;
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};
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let mutable_static_in_cond = var_visitor.def_ids.iter().any(|(_, v)| *v);
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let mut has_break_or_return_visitor = HasBreakOrReturnVisitor {
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has_break_or_return: false,
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};
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has_break_or_return_visitor.visit_expr(expr);
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let has_break_or_return = has_break_or_return_visitor.has_break_or_return;
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if no_cond_variable_mutated && !mutable_static_in_cond {
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span_lint_and_then(
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cx,
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super::WHILE_IMMUTABLE_CONDITION,
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cond.span,
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"variables in the condition are not mutated in the loop body",
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|diag| {
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diag.note("this may lead to an infinite or to a never running loop");
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if has_break_or_return {
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diag.note("this loop contains `return`s or `break`s");
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diag.help("rewrite it as `if cond { loop { } }`");
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}
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},
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);
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}
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}
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struct HasBreakOrReturnVisitor {
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has_break_or_return: bool,
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}
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impl<'tcx> Visitor<'tcx> for HasBreakOrReturnVisitor {
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type Map = Map<'tcx>;
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fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
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if self.has_break_or_return {
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return;
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}
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match expr.kind {
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ExprKind::Ret(_) | ExprKind::Break(_, _) => {
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self.has_break_or_return = true;
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return;
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},
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_ => {},
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}
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walk_expr(self, expr);
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}
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fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
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NestedVisitorMap::None
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}
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}
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/// Collects the set of variables in an expression
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/// Stops analysis if a function call is found
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/// Note: In some cases such as `self`, there are no mutable annotation,
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/// All variables definition IDs are collected
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struct VarCollectorVisitor<'a, 'tcx> {
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cx: &'a LateContext<'tcx>,
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ids: FxHashSet<HirId>,
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def_ids: FxHashMap<def_id::DefId, bool>,
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skip: bool,
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}
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impl<'a, 'tcx> VarCollectorVisitor<'a, 'tcx> {
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fn insert_def_id(&mut self, ex: &'tcx Expr<'_>) {
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if_chain! {
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if let ExprKind::Path(ref qpath) = ex.kind;
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if let QPath::Resolved(None, _) = *qpath;
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let res = self.cx.qpath_res(qpath, ex.hir_id);
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then {
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match res {
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Res::Local(hir_id) => {
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self.ids.insert(hir_id);
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},
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Res::Def(DefKind::Static, def_id) => {
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let mutable = self.cx.tcx.is_mutable_static(def_id);
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self.def_ids.insert(def_id, mutable);
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},
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_ => {},
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}
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}
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}
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}
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}
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impl<'a, 'tcx> Visitor<'tcx> for VarCollectorVisitor<'a, 'tcx> {
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type Map = Map<'tcx>;
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fn visit_expr(&mut self, ex: &'tcx Expr<'_>) {
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match ex.kind {
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ExprKind::Path(_) => self.insert_def_id(ex),
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// If there is any function/method call… we just stop analysis
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ExprKind::Call(..) | ExprKind::MethodCall(..) => self.skip = true,
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_ => walk_expr(self, ex),
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}
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}
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fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
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NestedVisitorMap::None
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}
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}
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@ -4,10 +4,10 @@ mod for_loop_over_map_kv;
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mod for_loop_range;
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mod for_mut_range_bound;
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mod for_single_element_loop;
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mod infinite_loop;
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mod manual_flatten;
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mod utils;
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use crate::consts::constant;
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use crate::utils::sugg::Sugg;
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use crate::utils::usage::mutated_variables;
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use crate::utils::{
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@ -18,13 +18,13 @@ use crate::utils::{
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};
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use if_chain::if_chain;
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use rustc_ast::ast;
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use rustc_data_structures::fx::{FxHashMap, FxHashSet};
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use rustc_data_structures::fx::FxHashMap;
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use rustc_errors::Applicability;
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use rustc_hir::def::{DefKind, Res};
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use rustc_hir::intravisit::{walk_block, walk_expr, walk_pat, walk_stmt, NestedVisitorMap, Visitor};
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use rustc_hir::{
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def_id, BinOpKind, BindingAnnotation, Block, BorrowKind, Expr, ExprKind, GenericArg, HirId, InlineAsmOperand,
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Local, LoopSource, MatchSource, Mutability, Node, Pat, PatKind, QPath, Stmt, StmtKind,
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BinOpKind, BindingAnnotation, Block, BorrowKind, Expr, ExprKind, GenericArg, HirId, InlineAsmOperand, Local,
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LoopSource, MatchSource, Mutability, Node, Pat, PatKind, QPath, Stmt, StmtKind,
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};
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use rustc_lint::{LateContext, LateLintPass, LintContext};
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use rustc_middle::hir::map::Map;
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@ -683,7 +683,7 @@ impl<'tcx> LateLintPass<'tcx> for Loops {
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}
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if let Some((cond, body)) = higher::while_loop(&expr) {
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check_infinite_loop(cx, cond, body);
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infinite_loop::check_infinite_loop(cx, cond, body);
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}
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check_needless_collect(expr, cx);
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@ -1895,133 +1895,6 @@ impl<'tcx> Visitor<'tcx> for LoopNestVisitor {
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}
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}
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fn check_infinite_loop<'tcx>(cx: &LateContext<'tcx>, cond: &'tcx Expr<'_>, expr: &'tcx Expr<'_>) {
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if constant(cx, cx.typeck_results(), cond).is_some() {
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// A pure constant condition (e.g., `while false`) is not linted.
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return;
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}
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let mut var_visitor = VarCollectorVisitor {
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cx,
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ids: FxHashSet::default(),
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def_ids: FxHashMap::default(),
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skip: false,
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};
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var_visitor.visit_expr(cond);
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if var_visitor.skip {
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return;
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}
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let used_in_condition = &var_visitor.ids;
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let no_cond_variable_mutated = if let Some(used_mutably) = mutated_variables(expr, cx) {
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used_in_condition.is_disjoint(&used_mutably)
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} else {
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return;
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};
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let mutable_static_in_cond = var_visitor.def_ids.iter().any(|(_, v)| *v);
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let mut has_break_or_return_visitor = HasBreakOrReturnVisitor {
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has_break_or_return: false,
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};
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has_break_or_return_visitor.visit_expr(expr);
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let has_break_or_return = has_break_or_return_visitor.has_break_or_return;
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if no_cond_variable_mutated && !mutable_static_in_cond {
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span_lint_and_then(
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cx,
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WHILE_IMMUTABLE_CONDITION,
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cond.span,
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"variables in the condition are not mutated in the loop body",
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|diag| {
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diag.note("this may lead to an infinite or to a never running loop");
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if has_break_or_return {
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diag.note("this loop contains `return`s or `break`s");
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diag.help("rewrite it as `if cond { loop { } }`");
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}
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},
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);
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}
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}
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struct HasBreakOrReturnVisitor {
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has_break_or_return: bool,
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}
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impl<'tcx> Visitor<'tcx> for HasBreakOrReturnVisitor {
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type Map = Map<'tcx>;
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fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
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if self.has_break_or_return {
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return;
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}
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match expr.kind {
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ExprKind::Ret(_) | ExprKind::Break(_, _) => {
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self.has_break_or_return = true;
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return;
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},
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_ => {},
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}
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walk_expr(self, expr);
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}
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fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
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NestedVisitorMap::None
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}
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}
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/// Collects the set of variables in an expression
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/// Stops analysis if a function call is found
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/// Note: In some cases such as `self`, there are no mutable annotation,
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/// All variables definition IDs are collected
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struct VarCollectorVisitor<'a, 'tcx> {
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cx: &'a LateContext<'tcx>,
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ids: FxHashSet<HirId>,
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def_ids: FxHashMap<def_id::DefId, bool>,
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skip: bool,
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}
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impl<'a, 'tcx> VarCollectorVisitor<'a, 'tcx> {
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fn insert_def_id(&mut self, ex: &'tcx Expr<'_>) {
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if_chain! {
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if let ExprKind::Path(ref qpath) = ex.kind;
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if let QPath::Resolved(None, _) = *qpath;
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let res = self.cx.qpath_res(qpath, ex.hir_id);
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then {
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match res {
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Res::Local(hir_id) => {
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self.ids.insert(hir_id);
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},
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Res::Def(DefKind::Static, def_id) => {
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let mutable = self.cx.tcx.is_mutable_static(def_id);
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self.def_ids.insert(def_id, mutable);
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},
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_ => {},
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}
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}
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}
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}
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}
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impl<'a, 'tcx> Visitor<'tcx> for VarCollectorVisitor<'a, 'tcx> {
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type Map = Map<'tcx>;
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fn visit_expr(&mut self, ex: &'tcx Expr<'_>) {
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match ex.kind {
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ExprKind::Path(_) => self.insert_def_id(ex),
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// If there is any function/method call… we just stop analysis
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ExprKind::Call(..) | ExprKind::MethodCall(..) => self.skip = true,
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_ => walk_expr(self, ex),
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}
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}
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fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
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NestedVisitorMap::None
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}
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}
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const NEEDLESS_COLLECT_MSG: &str = "avoid using `collect()` when not needed";
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fn check_needless_collect<'tcx>(expr: &'tcx Expr<'_>, cx: &LateContext<'tcx>) {
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