[Feature] Introduce storage_alias for CountedStorageMap (#13366)

* [Feature] Introduce storagage_alias for CountedStorageMap

* bit more dry

* bit more dry

* address review comments

* some tests and fixes

* fix ui tests

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <git@kchr.de>

* compare metadata

---------

Co-authored-by: parity-processbot <>
Co-authored-by: Bastian Köcher <git@kchr.de>

substrate/frame/support/procedural/src/pallet/expand/storage.rs

@@ -15,9 +15,12 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use crate::pallet::{
-	parse::storage::{Metadata, QueryKind, StorageDef, StorageGenerics},
-	Def,
+use crate::{
+	counter_prefix,
+	pallet::{
+		parse::storage::{Metadata, QueryKind, StorageDef, StorageGenerics},
+		Def,
+	},
 };
 use quote::ToTokens;
 use std::{collections::HashMap, ops::IndexMut};
@@ -39,12 +42,6 @@ fn counter_prefix_ident(storage_ident: &syn::Ident) -> syn::Ident {
 	)
 }
 
-/// Generate the counter_prefix related to the storage.
-/// counter_prefix is used by counted storage map.
-fn counter_prefix(prefix: &str) -> String {
-	format!("CounterFor{}", prefix)
-}
-
 /// Check for duplicated storage prefixes. This step is necessary since users can specify an
 /// alternative storage prefix using the #[pallet::storage_prefix] syntax, and we need to ensure
 /// that the prefix specified by the user is not a duplicate of an existing one.