//!
//! This lint is **warn** by default
-use crate::utils::sym;
-use crate::utils::{in_macro_or_desugar, snippet_opt, span_lint_and_then};
+use crate::utils::{is_automatically_derived, snippet_opt, span_lint_and_then};
use if_chain::if_chain;
-use rustc::hir::{BindingAnnotation, Expr, ExprKind, HirId, Item, MutImmutable, Pat, PatKind};
-use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use rustc::ty;
-use rustc::ty::adjustment::{Adjust, Adjustment};
-use rustc::{declare_tool_lint, impl_lint_pass};
use rustc_errors::Applicability;
+use rustc_hir::{BindingAnnotation, BorrowKind, Expr, ExprKind, Item, Mutability, Pat, PatKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty;
+use rustc_middle::ty::adjustment::{Adjust, Adjustment};
+use rustc_session::{declare_tool_lint, impl_lint_pass};
+use rustc_span::def_id::LocalDefId;
declare_clippy_lint! {
/// **What it does:** Checks for address of operations (`&`) that are going to
/// **Why is this bad?** Suggests that the receiver of the expression borrows
/// the expression.
///
+ /// **Known problems:** None.
+ ///
/// **Example:**
/// ```rust
+ /// // Bad
/// let x: &i32 = &&&&&&5;
- /// ```
///
- /// **Known problems:** None.
+ /// // Good
+ /// let x: &i32 = &5;
+ /// ```
pub NEEDLESS_BORROW,
nursery,
"taking a reference that is going to be automatically dereferenced"
#[derive(Default)]
pub struct NeedlessBorrow {
- derived_item: Option<HirId>,
+ derived_item: Option<LocalDefId>,
}
impl_lint_pass!(NeedlessBorrow => [NEEDLESS_BORROW]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NeedlessBorrow {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
- if in_macro_or_desugar(e.span) || self.derived_item.is_some() {
+impl<'tcx> LateLintPass<'tcx> for NeedlessBorrow {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
+ if e.span.from_expansion() || self.derived_item.is_some() {
return;
}
- if let ExprKind::AddrOf(MutImmutable, ref inner) = e.node {
- if let ty::Ref(..) = cx.tables.expr_ty(inner).sty {
- for adj3 in cx.tables.expr_adjustments(e).windows(3) {
+ if let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, ref inner) = e.kind {
+ if let ty::Ref(_, ty, _) = cx.typeck_results().expr_ty(inner).kind() {
+ for adj3 in cx.typeck_results().expr_adjustments(e).windows(3) {
if let [Adjustment {
kind: Adjust::Deref(_), ..
}, Adjustment {
cx,
NEEDLESS_BORROW,
e.span,
- "this expression borrows a reference that is immediately dereferenced \
+ &format!(
+ "this expression borrows a reference (`&{}`) that is immediately dereferenced \
by the compiler",
- |db| {
+ ty
+ ),
+ |diag| {
if let Some(snippet) = snippet_opt(cx, inner.span) {
- db.span_suggestion(
+ diag.span_suggestion(
e.span,
"change this to",
snippet,
}
}
}
- fn check_pat(&mut self, cx: &LateContext<'a, 'tcx>, pat: &'tcx Pat) {
- if in_macro_or_desugar(pat.span) || self.derived_item.is_some() {
+ fn check_pat(&mut self, cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>) {
+ if pat.span.from_expansion() || self.derived_item.is_some() {
return;
}
if_chain! {
- if let PatKind::Binding(BindingAnnotation::Ref, .., name, _) = pat.node;
- if let ty::Ref(_, tam, mutbl) = cx.tables.pat_ty(pat).sty;
- if mutbl == MutImmutable;
- if let ty::Ref(_, _, mutbl) = tam.sty;
+ if let PatKind::Binding(BindingAnnotation::Ref, .., name, _) = pat.kind;
+ if let ty::Ref(_, tam, mutbl) = *cx.typeck_results().pat_ty(pat).kind();
+ if mutbl == Mutability::Not;
+ if let ty::Ref(_, _, mutbl) = *tam.kind();
// only lint immutable refs, because borrowed `&mut T` cannot be moved out
- if mutbl == MutImmutable;
+ if mutbl == Mutability::Not;
then {
span_lint_and_then(
cx,
NEEDLESS_BORROW,
pat.span,
"this pattern creates a reference to a reference",
- |db| {
+ |diag| {
if let Some(snippet) = snippet_opt(cx, name.span) {
- db.span_suggestion(
+ diag.span_suggestion(
pat.span,
"change this to",
snippet,
}
}
- fn check_item(&mut self, _: &LateContext<'a, 'tcx>, item: &'tcx Item) {
- if item.attrs.iter().any(|a| a.check_name(*sym::automatically_derived)) {
+ fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
+ let attrs = cx.tcx.hir().attrs(item.hir_id());
+ if is_automatically_derived(attrs) {
debug_assert!(self.derived_item.is_none());
- self.derived_item = Some(item.hir_id);
+ self.derived_item = Some(item.def_id);
}
}
- fn check_item_post(&mut self, _: &LateContext<'a, 'tcx>, item: &'tcx Item) {
+ fn check_item_post(&mut self, _: &LateContext<'tcx>, item: &'tcx Item<'_>) {
if let Some(id) = self.derived_item {
- if item.hir_id == id {
+ if item.def_id == id {
self.derived_item = None;
}
}