--- /dev/null
+use super::MUT_RANGE_BOUND;
+use crate::utils::{higher, path_to_local, span_lint};
+use if_chain::if_chain;
+use rustc_hir::{BindingAnnotation, Expr, HirId, Node, PatKind};
+use rustc_infer::infer::TyCtxtInferExt;
+use rustc_lint::LateContext;
+use rustc_middle::mir::FakeReadCause;
+use rustc_middle::ty;
+use rustc_span::source_map::Span;
+use rustc_typeck::expr_use_visitor::{ConsumeMode, 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(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);
+ mut_warn_with_span(cx, span_low);
+ mut_warn_with_span(cx, span_high);
+ }
+ }
+}
+
+fn mut_warn_with_span(cx: &LateContext<'_>, span: Option<Span>) {
+ if let Some(sp) = span {
+ span_lint(
+ cx,
+ MUT_RANGE_BOUND,
+ sp,
+ "attempt to mutate range bound within loop; note that the range of the loop is unchanged",
+ );
+ }
+}
+
+fn check_for_mutability(cx: &LateContext<'_>, bound: &Expr<'_>) -> Option<HirId> {
+ if_chain! {
+ if let Some(hir_id) = path_to_local(bound);
+ if let Node::Binding(pat) = cx.tcx.hir().get(hir_id);
+ if let PatKind::Binding(BindingAnnotation::Mutable, ..) = pat.kind;
+ then {
+ return Some(hir_id);
+ }
+ }
+ None
+}
+
+fn check_for_mutation<'tcx>(
+ cx: &LateContext<'tcx>,
+ body: &Expr<'_>,
+ bound_ids: &[Option<HirId>],
+) -> (Option<Span>, Option<Span>) {
+ let mut delegate = MutatePairDelegate {
+ cx,
+ hir_id_low: bound_ids[0],
+ hir_id_high: bound_ids[1],
+ span_low: None,
+ span_high: None,
+ };
+ cx.tcx.infer_ctxt().enter(|infcx| {
+ ExprUseVisitor::new(
+ &mut delegate,
+ &infcx,
+ body.hir_id.owner,
+ cx.param_env,
+ cx.typeck_results(),
+ )
+ .walk_expr(body);
+ });
+ delegate.mutation_span()
+}
+
+struct MutatePairDelegate<'a, 'tcx> {
+ cx: &'a LateContext<'tcx>,
+ hir_id_low: Option<HirId>,
+ hir_id_high: Option<HirId>,
+ span_low: Option<Span>,
+ span_high: Option<Span>,
+}
+
+impl<'tcx> Delegate<'tcx> for MutatePairDelegate<'_, 'tcx> {
+ fn consume(&mut self, _: &PlaceWithHirId<'tcx>, _: HirId, _: ConsumeMode) {}
+
+ 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 {
+ self.span_low = Some(self.cx.tcx.hir().span(diag_expr_id))
+ }
+ if Some(id) == self.hir_id_high {
+ self.span_high = Some(self.cx.tcx.hir().span(diag_expr_id))
+ }
+ }
+ }
+ }
+
+ 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 {
+ self.span_low = Some(self.cx.tcx.hir().span(diag_expr_id))
+ }
+ if Some(id) == self.hir_id_high {
+ self.span_high = Some(self.cx.tcx.hir().span(diag_expr_id))
+ }
+ }
+ }
+
+ fn fake_read(&mut self, _: rustc_typeck::expr_use_visitor::Place<'tcx>, _: FakeReadCause, _:HirId) { }
+}
+
+impl MutatePairDelegate<'_, '_> {
+ fn mutation_span(&self) -> (Option<Span>, Option<Span>) {
+ (self.span_low, self.span_high)
+ }
+}