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Add check_infinite_loop to its own module
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,138 @@ | ||
| use crate::consts::constant; | ||
| use crate::utils::span_lint_and_then; | ||
| use crate::utils::usage::mutated_variables; | ||
| use if_chain::if_chain; | ||
| use rustc_data_structures::fx::{FxHashMap, FxHashSet}; | ||
| use rustc_hir::def::{DefKind, Res}; | ||
| use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor}; | ||
| use rustc_hir::{def_id, Expr, ExprKind, HirId, QPath}; | ||
| use rustc_lint::LateContext; | ||
| use rustc_middle::hir::map::Map; | ||
| use std::iter::Iterator; | ||
|
|
||
| pub(super) fn check_infinite_loop<'tcx>(cx: &LateContext<'tcx>, cond: &'tcx Expr<'_>, expr: &'tcx Expr<'_>) { | ||
| if constant(cx, cx.typeck_results(), cond).is_some() { | ||
| // A pure constant condition (e.g., `while false`) is not linted. | ||
| return; | ||
| } | ||
|
|
||
| let mut var_visitor = VarCollectorVisitor { | ||
| cx, | ||
| ids: FxHashSet::default(), | ||
| def_ids: FxHashMap::default(), | ||
| skip: false, | ||
| }; | ||
| var_visitor.visit_expr(cond); | ||
| if var_visitor.skip { | ||
| return; | ||
| } | ||
| let used_in_condition = &var_visitor.ids; | ||
| let no_cond_variable_mutated = if let Some(used_mutably) = mutated_variables(expr, cx) { | ||
| used_in_condition.is_disjoint(&used_mutably) | ||
| } else { | ||
| return; | ||
| }; | ||
| let mutable_static_in_cond = var_visitor.def_ids.iter().any(|(_, v)| *v); | ||
|
|
||
| let mut has_break_or_return_visitor = HasBreakOrReturnVisitor { | ||
| has_break_or_return: false, | ||
| }; | ||
| has_break_or_return_visitor.visit_expr(expr); | ||
| let has_break_or_return = has_break_or_return_visitor.has_break_or_return; | ||
|
|
||
| if no_cond_variable_mutated && !mutable_static_in_cond { | ||
| span_lint_and_then( | ||
| cx, | ||
| super::WHILE_IMMUTABLE_CONDITION, | ||
| cond.span, | ||
| "variables in the condition are not mutated in the loop body", | ||
| |diag| { | ||
| diag.note("this may lead to an infinite or to a never running loop"); | ||
|
|
||
| if has_break_or_return { | ||
| diag.note("this loop contains `return`s or `break`s"); | ||
| diag.help("rewrite it as `if cond { loop { } }`"); | ||
| } | ||
| }, | ||
| ); | ||
| } | ||
| } | ||
|
|
||
| struct HasBreakOrReturnVisitor { | ||
| has_break_or_return: bool, | ||
| } | ||
|
|
||
| impl<'tcx> Visitor<'tcx> for HasBreakOrReturnVisitor { | ||
| type Map = Map<'tcx>; | ||
|
|
||
| fn visit_expr(&mut self, expr: &'tcx Expr<'_>) { | ||
| if self.has_break_or_return { | ||
| return; | ||
| } | ||
|
|
||
| match expr.kind { | ||
| ExprKind::Ret(_) | ExprKind::Break(_, _) => { | ||
| self.has_break_or_return = true; | ||
| return; | ||
| }, | ||
| _ => {}, | ||
| } | ||
|
|
||
| walk_expr(self, expr); | ||
| } | ||
|
|
||
| fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> { | ||
| NestedVisitorMap::None | ||
| } | ||
| } | ||
|
|
||
| /// Collects the set of variables in an expression | ||
| /// Stops analysis if a function call is found | ||
| /// Note: In some cases such as `self`, there are no mutable annotation, | ||
| /// All variables definition IDs are collected | ||
| struct VarCollectorVisitor<'a, 'tcx> { | ||
| cx: &'a LateContext<'tcx>, | ||
| ids: FxHashSet<HirId>, | ||
| def_ids: FxHashMap<def_id::DefId, bool>, | ||
| skip: bool, | ||
| } | ||
|
|
||
| impl<'a, 'tcx> VarCollectorVisitor<'a, 'tcx> { | ||
| fn insert_def_id(&mut self, ex: &'tcx Expr<'_>) { | ||
| if_chain! { | ||
| if let ExprKind::Path(ref qpath) = ex.kind; | ||
| if let QPath::Resolved(None, _) = *qpath; | ||
| let res = self.cx.qpath_res(qpath, ex.hir_id); | ||
| then { | ||
| match res { | ||
| Res::Local(hir_id) => { | ||
| self.ids.insert(hir_id); | ||
| }, | ||
| Res::Def(DefKind::Static, def_id) => { | ||
| let mutable = self.cx.tcx.is_mutable_static(def_id); | ||
| self.def_ids.insert(def_id, mutable); | ||
| }, | ||
| _ => {}, | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
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| impl<'a, 'tcx> Visitor<'tcx> for VarCollectorVisitor<'a, 'tcx> { | ||
| type Map = Map<'tcx>; | ||
|
|
||
| fn visit_expr(&mut self, ex: &'tcx Expr<'_>) { | ||
| match ex.kind { | ||
| ExprKind::Path(_) => self.insert_def_id(ex), | ||
| // If there is any function/method call… we just stop analysis | ||
| ExprKind::Call(..) | ExprKind::MethodCall(..) => self.skip = true, | ||
|
|
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| _ => walk_expr(self, ex), | ||
| } | ||
| } | ||
|
|
||
| fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> { | ||
| NestedVisitorMap::None | ||
| } | ||
| } |
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