Auto merge of #113365 - dima74:diralik/add-deprecated-suggestions, r=workingjubilee

Add `suggestion` for some `#[deprecated]` items

Consider code:
```rust
fn main() {
    let _ = ["a", "b"].connect(" ");
}
```

Currently it shows deprecated warning:
```rust
warning: use of deprecated method `std::slice::<impl [T]>::connect`: renamed to join
 --> src/main.rs:2:24
  |
2 |     let _ = ["a", "b"].connect(" ");
  |                        ^^^^^^^
  |
  = note: `#[warn(deprecated)]` on by default
```

This PR adds `suggestion` for `connect` and some other deprecated items, so the warning will be changed to this:
```rust
warning: use of deprecated method `std::slice::<impl [T]>::connect`: renamed to join
 --> src/main.rs:2:24
  |
2 |     let _ = ["a", "b"].connect(" ");
  |                        ^^^^^^^
  |
  = note: `#[warn(deprecated)]` on by default
help: replace the use of the deprecated method
  |
2 |     let _ = ["a", "b"].join(" ");
  |                        ^^^^
```

2 files changed, 2 insertions, 1 deletions

diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
index ffe6d637387..efe8f5a8bcf 100644
--- a/library/alloc/src/lib.rs
+++ b/library/alloc/src/lib.rs
@@ -120,6 +120,7 @@
 #![feature(const_waker)]
 #![feature(core_intrinsics)]
 #![feature(core_panic)]
+#![feature(deprecated_suggestion)]
 #![feature(dispatch_from_dyn)]
 #![feature(error_generic_member_access)]
 #![feature(error_in_core)]
diff --git a/library/alloc/src/slice.rs b/library/alloc/src/slice.rs
index 093dcbbe8bf..aa3b7b7e191 100644
--- a/library/alloc/src/slice.rs
+++ b/library/alloc/src/slice.rs
@@ -592,7 +592,7 @@ impl<T> [T] {
     /// ```
     #[rustc_allow_incoherent_impl]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[deprecated(since = "1.3.0", note = "renamed to join")]
+    #[deprecated(since = "1.3.0", note = "renamed to join", suggestion = "join")]
     pub fn connect<Separator>(&self, sep: Separator) -> <Self as Join<Separator>>::Output
     where
         Self: Join<Separator>,