diff --git a/clippy_lints/src/loops/mut_range_bound.rs b/clippy_lints/src/loops/mut_range_bound.rs index 344dc5074d3..358d53e8859 100644 --- a/clippy_lints/src/loops/mut_range_bound.rs +++ b/clippy_lints/src/loops/mut_range_bound.rs @@ -1,24 +1,27 @@ use super::MUT_RANGE_BOUND; -use clippy_utils::diagnostics::span_lint; -use clippy_utils::{higher, path_to_local}; +use clippy_utils::diagnostics::span_lint_and_note; +use clippy_utils::{get_enclosing_block, higher, path_to_local}; use if_chain::if_chain; -use rustc_hir::{BindingAnnotation, Expr, HirId, Node, PatKind}; +use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor}; +use rustc_hir::{BindingAnnotation, Expr, ExprKind, HirId, Node, PatKind}; use rustc_infer::infer::TyCtxtInferExt; use rustc_lint::LateContext; +use rustc_middle::hir::map::Map; use rustc_middle::{mir::FakeReadCause, ty}; use rustc_span::source_map::Span; use rustc_typeck::expr_use_visitor::{Delegate, ExprUseVisitor, PlaceBase, PlaceWithHirId}; pub(super) fn check(cx: &LateContext<'_>, arg: &Expr<'_>, body: &Expr<'_>) { - if let Some(higher::Range { - start: Some(start), - end: Some(end), - .. - }) = higher::Range::hir(arg) - { - let mut_ids = vec![check_for_mutability(cx, start), check_for_mutability(cx, end)]; - if mut_ids[0].is_some() || mut_ids[1].is_some() { - let (span_low, span_high) = check_for_mutation(cx, body, &mut_ids); + if_chain! { + if let Some(higher::Range { + start: Some(start), + end: Some(end), + .. + }) = higher::Range::hir(arg); + let (mut_id_start, mut_id_end) = (check_for_mutability(cx, start), check_for_mutability(cx, end)); + if mut_id_start.is_some() || mut_id_end.is_some(); + then { + let (span_low, span_high) = check_for_mutation(cx, body, mut_id_start, mut_id_end); mut_warn_with_span(cx, span_low); mut_warn_with_span(cx, span_high); } @@ -27,11 +30,13 @@ pub(super) fn check(cx: &LateContext<'_>, arg: &Expr<'_>, body: &Expr<'_>) { fn mut_warn_with_span(cx: &LateContext<'_>, span: Option) { if let Some(sp) = span { - span_lint( + span_lint_and_note( cx, MUT_RANGE_BOUND, sp, - "attempt to mutate range bound within loop; note that the range of the loop is unchanged", + "attempt to mutate range bound within loop", + None, + "the range of the loop is unchanged", ); } } @@ -51,12 +56,13 @@ fn check_for_mutability(cx: &LateContext<'_>, bound: &Expr<'_>) -> Option fn check_for_mutation<'tcx>( cx: &LateContext<'tcx>, body: &Expr<'_>, - bound_ids: &[Option], + bound_id_start: Option, + bound_id_end: Option, ) -> (Option, Option) { let mut delegate = MutatePairDelegate { cx, - hir_id_low: bound_ids[0], - hir_id_high: bound_ids[1], + hir_id_low: bound_id_start, + hir_id_high: bound_id_end, span_low: None, span_high: None, }; @@ -70,6 +76,7 @@ fn check_for_mutation<'tcx>( ) .walk_expr(body); }); + delegate.mutation_span() } @@ -87,10 +94,10 @@ impl<'tcx> Delegate<'tcx> for MutatePairDelegate<'_, 'tcx> { fn borrow(&mut self, cmt: &PlaceWithHirId<'tcx>, diag_expr_id: HirId, bk: ty::BorrowKind) { if let ty::BorrowKind::MutBorrow = bk { if let PlaceBase::Local(id) = cmt.place.base { - if Some(id) == self.hir_id_low { + if Some(id) == self.hir_id_low && !BreakAfterExprVisitor::is_found(self.cx, diag_expr_id) { self.span_low = Some(self.cx.tcx.hir().span(diag_expr_id)); } - if Some(id) == self.hir_id_high { + if Some(id) == self.hir_id_high && !BreakAfterExprVisitor::is_found(self.cx, diag_expr_id) { self.span_high = Some(self.cx.tcx.hir().span(diag_expr_id)); } } @@ -99,10 +106,10 @@ impl<'tcx> Delegate<'tcx> for MutatePairDelegate<'_, 'tcx> { fn mutate(&mut self, cmt: &PlaceWithHirId<'tcx>, diag_expr_id: HirId) { if let PlaceBase::Local(id) = cmt.place.base { - if Some(id) == self.hir_id_low { + if Some(id) == self.hir_id_low && !BreakAfterExprVisitor::is_found(self.cx, diag_expr_id) { self.span_low = Some(self.cx.tcx.hir().span(diag_expr_id)); } - if Some(id) == self.hir_id_high { + if Some(id) == self.hir_id_high && !BreakAfterExprVisitor::is_found(self.cx, diag_expr_id) { self.span_high = Some(self.cx.tcx.hir().span(diag_expr_id)); } } @@ -116,3 +123,52 @@ impl MutatePairDelegate<'_, '_> { (self.span_low, self.span_high) } } + +struct BreakAfterExprVisitor { + hir_id: HirId, + past_expr: bool, + past_candidate: bool, + break_after_expr: bool, +} + +impl BreakAfterExprVisitor { + pub fn is_found(cx: &LateContext<'_>, hir_id: HirId) -> bool { + let mut visitor = BreakAfterExprVisitor { + hir_id, + past_expr: false, + past_candidate: false, + break_after_expr: false, + }; + + get_enclosing_block(cx, hir_id).map_or(false, |block| { + visitor.visit_block(block); + visitor.break_after_expr + }) + } +} + +impl intravisit::Visitor<'tcx> for BreakAfterExprVisitor { + type Map = Map<'tcx>; + + fn nested_visit_map(&mut self) -> NestedVisitorMap { + NestedVisitorMap::None + } + + fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) { + if self.past_candidate { + return; + } + + if expr.hir_id == self.hir_id { + self.past_expr = true; + } else if self.past_expr { + if matches!(&expr.kind, ExprKind::Break(..)) { + self.break_after_expr = true; + } + + self.past_candidate = true; + } else { + intravisit::walk_expr(self, expr); + } + } +}