//! This lint is **warn** by default
use rustc::lint::*;
-use rustc::hir::{ExprAddrOf, Expr, MutImmutable, Pat, PatKind, BindingMode};
+use rustc::hir::{ExprAddrOf, Expr, MutImmutable, Pat, PatKind, BindingAnnotation};
use rustc::ty;
+use rustc::ty::adjustment::{Adjustment, Adjust};
use utils::{span_lint, in_macro};
/// **What it does:** Checks for address of operations (`&`) that are going to
}
}
-impl LateLintPass for NeedlessBorrow {
- fn check_expr(&mut self, cx: &LateContext, e: &Expr) {
- if in_macro(cx, e.span) {
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NeedlessBorrow {
+ fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
+ if in_macro(e.span) {
return;
}
if let ExprAddrOf(MutImmutable, ref inner) = e.node {
- if let ty::TyRef(..) = cx.tcx.tables().expr_ty(inner).sty {
- if let Some(&ty::adjustment::Adjust::DerefRef { autoderefs, autoref, .. }) = cx.tcx.tables.borrow().adjustments.get(&e.id).map(|a| &a.kind) {
- if autoderefs > 1 && autoref.is_some() {
+ if let ty::TyRef(..) = cx.tables.expr_ty(inner).sty {
+ for adj3 in cx.tables.expr_adjustments(e).windows(3) {
+ if let [
+ Adjustment { kind: Adjust::Deref(_), .. },
+ Adjustment { kind: Adjust::Deref(_), .. },
+ Adjustment { kind: Adjust::Borrow(_), .. }
+ ] = *adj3 {
span_lint(cx,
NEEDLESS_BORROW,
e.span,
}
}
}
- fn check_pat(&mut self, cx: &LateContext, pat: &Pat) {
- if in_macro(cx, pat.span) {
+ fn check_pat(&mut self, cx: &LateContext<'a, 'tcx>, pat: &'tcx Pat) {
+ if in_macro(pat.span) {
return;
}
- if let PatKind::Binding(BindingMode::BindByRef(MutImmutable), _, _, _) = pat.node {
- if let ty::TyRef(_, ref tam) = cx.tcx.tables().pat_ty(pat).sty {
- if tam.mutbl == MutImmutable {
- if let ty::TyRef(..) = tam.ty.sty {
- span_lint(cx,
- NEEDLESS_BORROW,
- pat.span,
- "this pattern creates a reference to a reference")
- }
- }
- }
- }
+ if_let_chain! {[
+ let PatKind::Binding(BindingAnnotation::Ref, _, _, _) = pat.node,
+ let ty::TyRef(_, ref tam) = cx.tables.pat_ty(pat).sty,
+ tam.mutbl == MutImmutable,
+ let ty::TyRef(_, ref tam) = tam.ty.sty,
+ // only lint immutable refs, because borrowed `&mut T` cannot be moved out
+ tam.mutbl == MutImmutable,
+ ], {
+ span_lint(cx, NEEDLESS_BORROW, pat.span, "this pattern creates a reference to a reference")
+ }}
}
}