Merge pull request #2355 from alusch/clone_on_ref_ptr_restriction

Fix #2048: Move `clone_on_ref_ptr` to the restriction lints

clippy_lints/src/methods.rs

@@ -361,9 +361,8 @@ declare_lint! {
 /// ```rust
 /// x.clone()
 /// ```
-declare_lint! {
+declare_restriction_lint! {
     pub CLONE_ON_REF_PTR,
-    Warn,
     "using 'clone' on a ref-counted pointer"
 }
 
@@ -1013,24 +1012,26 @@ fn lint_clone_on_copy(cx: &LateContext, expr: &hir::Expr, arg: &hir::Expr, arg_t
 fn lint_clone_on_ref_ptr(cx: &LateContext, expr: &hir::Expr, arg: &hir::Expr) {
     let (obj_ty, _) = walk_ptrs_ty_depth(cx.tables.expr_ty(arg));
 
-    let caller_type = if match_type(cx, obj_ty, &paths::RC) {
-        "Rc"
-    } else if match_type(cx, obj_ty, &paths::ARC) {
-        "Arc"
-    } else if match_type(cx, obj_ty, &paths::WEAK_RC) || match_type(cx, obj_ty, &paths::WEAK_ARC) {
-        "Weak"
-    } else {
-        return;
-    };
+    if let ty::TyAdt(_, subst) = obj_ty.sty {
+        let caller_type = if match_type(cx, obj_ty, &paths::RC) {
+            "Rc"
+        } else if match_type(cx, obj_ty, &paths::ARC) {
+            "Arc"
+        } else if match_type(cx, obj_ty, &paths::WEAK_RC) || match_type(cx, obj_ty, &paths::WEAK_ARC) {
+            "Weak"
+        } else {
+            return;
+        };
 
-    span_lint_and_sugg(
-        cx,
-        CLONE_ON_REF_PTR,
-        expr.span,
-        "using '.clone()' on a ref-counted pointer",
-        "try this",
-        format!("{}::clone(&{})", caller_type, snippet(cx, arg.span, "_")),
-    );
+        span_lint_and_sugg(
+            cx,
+            CLONE_ON_REF_PTR,
+            expr.span,
+            "using '.clone()' on a ref-counted pointer",
+            "try this",
+            format!("{}::<{}>::clone(&{})", caller_type, subst.type_at(0), snippet(cx, arg.span, "_")),
+        );
+    }
 }
 
 

tests/ui/unnecessary_clone.rs

@@ -1,3 +1,4 @@
+#![warn(clone_on_ref_ptr)]
 #![allow(unused)]
 
 use std::collections::HashSet;
@@ -5,6 +6,10 @@ use std::collections::VecDeque;
 use std::rc::{self, Rc};
 use std::sync::{self, Arc};
 
+trait SomeTrait {}
+struct SomeImpl;
+impl SomeTrait for SomeImpl {}
+
 fn main() {}
 
 fn clone_on_copy() {
@@ -34,7 +39,8 @@ fn clone_on_ref_ptr() {
     arc_weak.clone();
     sync::Weak::clone(&arc_weak);
 
-
+    let x = Arc::new(SomeImpl);
+    let _: Arc<SomeTrait> = x.clone(); 
 }
 
 fn clone_on_copy_generic<T: Copy>(t: T) {

tests/ui/unnecessary_clone.stderr

@@ -1,75 +1,81 @@
 error: using `clone` on a `Copy` type
-  --> $DIR/unnecessary_clone.rs:11:5
+  --> $DIR/unnecessary_clone.rs:16:5
    |
-11 |     42.clone();
+16 |     42.clone();
    |     ^^^^^^^^^^ help: try removing the `clone` call: `42`
    |
    = note: `-D clone-on-copy` implied by `-D warnings`
 
 error: using `clone` on a `Copy` type
-  --> $DIR/unnecessary_clone.rs:15:5
+  --> $DIR/unnecessary_clone.rs:20:5
    |
-15 |     (&42).clone();
+20 |     (&42).clone();
    |     ^^^^^^^^^^^^^ help: try dereferencing it: `*(&42)`
 
 error: using '.clone()' on a ref-counted pointer
-  --> $DIR/unnecessary_clone.rs:25:5
+  --> $DIR/unnecessary_clone.rs:30:5
    |
-25 |     rc.clone();
-   |     ^^^^^^^^^^ help: try this: `Rc::clone(&rc)`
+30 |     rc.clone();
+   |     ^^^^^^^^^^ help: try this: `Rc::<bool>::clone(&rc)`
    |
    = note: `-D clone-on-ref-ptr` implied by `-D warnings`
 
 error: using '.clone()' on a ref-counted pointer
-  --> $DIR/unnecessary_clone.rs:28:5
+  --> $DIR/unnecessary_clone.rs:33:5
    |
-28 |     arc.clone();
-   |     ^^^^^^^^^^^ help: try this: `Arc::clone(&arc)`
+33 |     arc.clone();
+   |     ^^^^^^^^^^^ help: try this: `Arc::<bool>::clone(&arc)`
 
 error: using '.clone()' on a ref-counted pointer
-  --> $DIR/unnecessary_clone.rs:31:5
+  --> $DIR/unnecessary_clone.rs:36:5
    |
-31 |     rcweak.clone();
-   |     ^^^^^^^^^^^^^^ help: try this: `Weak::clone(&rcweak)`
+36 |     rcweak.clone();
+   |     ^^^^^^^^^^^^^^ help: try this: `Weak::<bool>::clone(&rcweak)`
 
 error: using '.clone()' on a ref-counted pointer
-  --> $DIR/unnecessary_clone.rs:34:5
+  --> $DIR/unnecessary_clone.rs:39:5
    |
-34 |     arc_weak.clone();
-   |     ^^^^^^^^^^^^^^^^ help: try this: `Weak::clone(&arc_weak)`
+39 |     arc_weak.clone();
+   |     ^^^^^^^^^^^^^^^^ help: try this: `Weak::<bool>::clone(&arc_weak)`
+
+error: using '.clone()' on a ref-counted pointer
+  --> $DIR/unnecessary_clone.rs:43:29
+   |
+43 |     let _: Arc<SomeTrait> = x.clone(); 
+   |                             ^^^^^^^^^ help: try this: `Arc::<SomeImpl>::clone(&x)`
 
 error: using `clone` on a `Copy` type
-  --> $DIR/unnecessary_clone.rs:41:5
+  --> $DIR/unnecessary_clone.rs:47:5
    |
-41 |     t.clone();
+47 |     t.clone();
    |     ^^^^^^^^^ help: try removing the `clone` call: `t`
 
 error: using `clone` on a `Copy` type
-  --> $DIR/unnecessary_clone.rs:43:5
+  --> $DIR/unnecessary_clone.rs:49:5
    |
-43 |     Some(t).clone();
+49 |     Some(t).clone();
    |     ^^^^^^^^^^^^^^^ help: try removing the `clone` call: `Some(t)`
 
 error: using `clone` on a double-reference; this will copy the reference instead of cloning the inner type
-  --> $DIR/unnecessary_clone.rs:49:22
+  --> $DIR/unnecessary_clone.rs:55:22
    |
-49 |     let z: &Vec<_> = y.clone();
+55 |     let z: &Vec<_> = y.clone();
    |                      ^^^^^^^^^
    |
    = note: `-D clone-double-ref` implied by `-D warnings`
 help: try dereferencing it
    |
-49 |     let z: &Vec<_> = &(*y).clone();
+55 |     let z: &Vec<_> = &(*y).clone();
    |                      ^^^^^^^^^^^^^
 help: or try being explicit about what type to clone
    |
-49 |     let z: &Vec<_> = &std::vec::Vec<i32>::clone(y);
+55 |     let z: &Vec<_> = &std::vec::Vec<i32>::clone(y);
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: called `cloned().collect()` on a slice to create a `Vec`. Calling `to_vec()` is both faster and more readable
-  --> $DIR/unnecessary_clone.rs:56:27
+  --> $DIR/unnecessary_clone.rs:62:27
    |
-56 |     let v2 : Vec<isize> = v.iter().cloned().collect();
+62 |     let v2 : Vec<isize> = v.iter().cloned().collect();
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `-D iter-cloned-collect` implied by `-D warnings`