only check ExprKind::Path

Author: lengyijun

clippy_lints/src/needless_deref.rs

@@ -54,11 +54,13 @@ impl LateLintPass<'_> for NeedlessDeref {
                     if span.from_expansion() {
                         return;
                     }
-                    let parent_node = map.find(parent_hir_id);
-                    if let Some(rustc_hir::Node::Expr(parent_expr)) = parent_node {
-                        if matches!(parent_expr.kind, ExprKind::Unary(UnOp::Deref, ..)) ||
-                           matches!(parent_expr.kind, ExprKind::AddrOf(..) ) {
-                            return;
+                    if matches!(deref_target.kind, ExprKind::Path(..) ){
+                        let parent_node = map.find(parent_hir_id);
+                        if let Some(rustc_hir::Node::Expr(parent_expr)) = parent_node {
+                            if matches!(parent_expr.kind, ExprKind::Unary(UnOp::Deref, ..)) ||
+                               matches!(parent_expr.kind, ExprKind::AddrOf(..) ) {
+                                return;
+                            }
                         }
                     }
                 }

tests/ui/needless_deref.rs

@@ -7,6 +7,13 @@ mod should_lint {
 
         let s = &String::new();
         let a: &str = &*s;
+
+        let a = &12;
+        let b = &mut &*bar(a);
+    }
+
+    fn bar(x: &u32) -> &u32 {
+        x
     }
 }
 

tests/ui/needless_deref.stderr

@@ -17,5 +17,14 @@ LL |         let a: &str = &*s;
    = help: consider using `&**s` if you would like to deref
    = help: consider using `s` if you would like to reborrow
 
-error: aborting due to 2 previous errors
+error: deref on an immutable reference
+  --> $DIR/needless_deref.rs:12:22
+   |
+LL |         let b = &mut &*bar(a);
+   |                      ^^^^^^^^
+   |
+   = help: consider using `&**bar(a)` if you would like to deref
+   = help: consider using `bar(a)` if you would like to reborrow
+
+error: aborting due to 3 previous errors