using full path in the suggestion of clone_on_ref_ptr (#15561)

Fix: rust-lang/rust-clippy#15258

changelog: suggest full path in [`clone_on_ref_ptr`] to avoid "failed to
resolve" error.

Author: y21

clippy_lints/src/methods/clone_on_ref_ptr.rs

@@ -24,9 +24,10 @@ pub(super) fn check(
         && let Some(name) = cx.tcx.get_diagnostic_name(adt.did())
     {
         let caller_type = match name {
-            sym::Rc => "Rc",
-            sym::Arc => "Arc",
-            sym::RcWeak | sym::ArcWeak => "Weak",
+            sym::Rc => "std::rc::Rc",
+            sym::Arc => "std::sync::Arc",
+            sym::RcWeak => "std::rc::Weak",
+            sym::ArcWeak => "std::sync::Weak",
             _ => return,
         };
         span_lint_and_then(

tests/ui/unnecessary_clone.stderr

@@ -2,7 +2,7 @@ error: using `.clone()` on a ref-counted pointer
   --> tests/ui/unnecessary_clone.rs:23:5
    |
 LL |     rc.clone();
-   |     ^^^^^^^^^^ help: try: `Rc::<bool>::clone(&rc)`
+   |     ^^^^^^^^^^ help: try: `std::rc::Rc::<bool>::clone(&rc)`
    |
    = note: `-D clippy::clone-on-ref-ptr` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::clone_on_ref_ptr)]`
@@ -11,25 +11,25 @@ error: using `.clone()` on a ref-counted pointer
   --> tests/ui/unnecessary_clone.rs:28:5
    |
 LL |     arc.clone();
-   |     ^^^^^^^^^^^ help: try: `Arc::<bool>::clone(&arc)`
+   |     ^^^^^^^^^^^ help: try: `std::sync::Arc::<bool>::clone(&arc)`
 
 error: using `.clone()` on a ref-counted pointer
   --> tests/ui/unnecessary_clone.rs:33:5
    |
 LL |     rcweak.clone();
-   |     ^^^^^^^^^^^^^^ help: try: `Weak::<bool>::clone(&rcweak)`
+   |     ^^^^^^^^^^^^^^ help: try: `std::rc::Weak::<bool>::clone(&rcweak)`
 
 error: using `.clone()` on a ref-counted pointer
   --> tests/ui/unnecessary_clone.rs:38:5
    |
 LL |     arc_weak.clone();
-   |     ^^^^^^^^^^^^^^^^ help: try: `Weak::<bool>::clone(&arc_weak)`
+   |     ^^^^^^^^^^^^^^^^ help: try: `std::sync::Weak::<bool>::clone(&arc_weak)`
 
 error: using `.clone()` on a ref-counted pointer
   --> tests/ui/unnecessary_clone.rs:44:33
    |
 LL |     let _: Arc<dyn SomeTrait> = x.clone();
-   |                                 ^^^^^^^^^ help: try: `Arc::<SomeImpl>::clone(&x)`
+   |                                 ^^^^^^^^^ help: try: `std::sync::Arc::<SomeImpl>::clone(&x)`
 
 error: using `clone` on type `T` which implements the `Copy` trait
   --> tests/ui/unnecessary_clone.rs:49:5
@@ -56,7 +56,7 @@ error: using `.clone()` on a ref-counted pointer
   --> tests/ui/unnecessary_clone.rs:108:14
    |
 LL |         Some(try_opt!(Some(rc)).clone())
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `Rc::<u8>::clone(&try_opt!(Some(rc)))`
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::rc::Rc::<u8>::clone(&try_opt!(Some(rc)))`
 
 error: aborting due to 9 previous errors