use BindingAnnotation instead of BindingMode

[rust.git] / clippy_lints / src / needless_borrow.rs

diff --git a/clippy_lints/src/needless_borrow.rs b/clippy_lints/src/needless_borrow.rs
index 033811841ce6f8b5401636bdfe58cb7537c7369e..385fcc86adb6a50f8fce8fe28cb89946c8da4737 100644 (file)
--- a/clippy_lints/src/needless_borrow.rs
+++ b/clippy_lints/src/needless_borrow.rs
@@ -3,18 +3,23 @@
 //! This lint is **warn** by default
 
 use rustc::lint::*;
-use rustc::hir::{ExprAddrOf, Expr, MutImmutable};
-use rustc::ty::TyRef;
+use rustc::hir::{ExprAddrOf, Expr, MutImmutable, Pat, PatKind, BindingAnnotation};
+use rustc::ty;
+use rustc::ty::adjustment::{Adjustment, Adjust};
 use utils::{span_lint, in_macro};
-use rustc::ty::adjustment::AutoAdjustment::AdjustDerefRef;
 
-/// **What it does:** This lint checks for address of operations (`&`) that are going to be dereferenced immediately by the compiler
+/// **What it does:** Checks for address of operations (`&`) that are going to
+/// be dereferenced immediately by the compiler.
 ///
-/// **Why is this bad?** Suggests that the receiver of the expression borrows the expression
+/// **Why is this bad?** Suggests that the receiver of the expression borrows
+/// the expression.
 ///
-/// **Known problems:**
+/// **Known problems:** None.
 ///
-/// **Example:** `let x: &i32 = &&&&&&5;`
+/// **Example:**
+/// ```rust
+/// let x: &i32 = &&&&&&5;
+/// ```
 declare_lint! {
     pub NEEDLESS_BORROW,
     Warn,
@@ -30,22 +35,42 @@ fn get_lints(&self) -> LintArray {
     }
 }
 
-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 TyRef(..) = cx.tcx.expr_ty(inner).sty {
-                if let Some(&AdjustDerefRef(ref deref)) = cx.tcx.tables.borrow().adjustments.get(&e.id) {
-                    if deref.autoderefs > 1 && deref.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,
-                                  "this expression borrows a reference that is immediately dereferenced by the compiler");
+                                  "this expression borrows a reference that is immediately dereferenced by the \
+                                   compiler");
                     }
                 }
             }
         }
     }
+    fn check_pat(&mut self, cx: &LateContext<'a, 'tcx>, pat: &'tcx Pat) {
+        if in_macro(pat.span) {
+            return;
+        }
+        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")
+        }}
+    }
 }