Rollup merge of rust-lang#139776 - mejrs:diagn2, r=compiler-errors

Switch attrs to `diagnostic::on_unimplemented`

I missed these the last time 😅

Author: jhpratt

Diff for: compiler/rustc_data_structures/src/marker.rs

@@ -1,13 +1,13 @@
 use std::alloc::Allocator;
 
-#[rustc_on_unimplemented(message = "`{Self}` doesn't implement `DynSend`. \
+#[diagnostic::on_unimplemented(message = "`{Self}` doesn't implement `DynSend`. \
             Add it to `rustc_data_structures::marker` or use `IntoDynSyncSend` if it's already `Send`")]
 // This is an auto trait for types which can be sent across threads if `sync::is_dyn_thread_safe()`
 // is true. These types can be wrapped in a `FromDyn` to get a `Send` type. Wrapping a
 // `Send` type in `IntoDynSyncSend` will create a `DynSend` type.
 pub unsafe auto trait DynSend {}
 
-#[rustc_on_unimplemented(message = "`{Self}` doesn't implement `DynSync`. \
+#[diagnostic::on_unimplemented(message = "`{Self}` doesn't implement `DynSync`. \
             Add it to `rustc_data_structures::marker` or use `IntoDynSyncSend` if it's already `Sync`")]
 // This is an auto trait for types which can be shared across threads if `sync::is_dyn_thread_safe()`
 // is true. These types can be wrapped in a `FromDyn` to get a `Sync` type. Wrapping a