add type in help of from over Into

clippy_lints/src/from_over_into.rs

@@ -73,7 +73,7 @@ fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
                     cx.tcx.sess.source_map().guess_head_span(item.span),
                     "an implementation of `From` is preferred since it gives you `Into<_>` for free where the reverse isn't true",
                     None,
-                    "consider to implement `From` instead",
+                    &format!("consider to implement `From<{}>` instead", impl_trait_ref.self_ty()),
                 );
             }
         }

tests/ui/from_over_into.stderr

@@ -5,7 +5,6 @@ LL | impl Into<StringWrapper> for String {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `-D clippy::from-over-into` implied by `-D warnings`
-   = help: consider to implement `From` instead
+   = help: consider to implement `From<std::string::String>` instead
 
 error: aborting due to previous error
-