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