Reference key storage api (#447)

* codegen: Update polkadot.rs

polkadot commit-hash: d96d3bea85
polkadot tag: v0.9.16-rc2

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Reference key storage api

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Regenerate polkadot.rs with reference api

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* tests: Update tests with reference interface

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* cli: Fix polkadot.rs license check

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Update polkadot.rs with copyright

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Revert "codegen: Update polkadot.rs with copyright"

This reverts commit 2970d0573dc0b11d01072b270a525ad497992ddf.

Revert "cli: Fix polkadot.rs license check"

This reverts commit 6fe8818582ae39669c059c1ed0424b6606620295.

* codegen: Implement AccountData trait in the expected order

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Store implementation of StorageEntry

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Generate AccountDefaultData wrapper struct

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Allow `Account` references

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Update polkadot.rs

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Utilize AccountDefaultData instead of Account

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Update polkadot.rs

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* tests: Update tests to utilize `Account` reference

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Rename AccountDefaultData to AccountOwned

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Add comments for wrapper account

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Obtain vector type parameter for TypePath::Type

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Use slices instead of `& std::vec` in storage API

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Update polkadot.rs

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Fix documentation

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* tests: Remove extra reference

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* examples: Add staking example to exercise storage API

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Update polkadot.rs

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* tests: Update storage tests

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Fix cargo clippy

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Simplify vec_type_param

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* examples: Rename staking_details.rs to fetch_staking_details.rs

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* tests: Remove dummy variable

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* examples: Update polkadot version

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Apply rust-fmt

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Regenerate polkadot.rs

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* examples: Remove comment

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

codegen/src/api/mod.rs

@@ -443,7 +443,8 @@ fn generate_default_account_data_impl(
         };
 
     // this path to the storage entry depends on storage codegen.
-    let storage_entry_path = quote!(self::system::storage::Account);
+    // AccountOwned contains the same data as Account does, but without references.
+    let storage_entry_path = quote!(self::system::storage::AccountOwned);
 
     Some(quote! {
         /// The default storage entry from which to fetch an account nonce, required for
@@ -455,12 +456,12 @@ fn generate_default_account_data_impl(
             type AccountId = #account_id_ty;
             type Index = #account_nonce_ty;
 
-            fn nonce(result: &<Self::StorageEntry as ::subxt::StorageEntry>::Value) -> Self::Index {
-                result.nonce
-            }
             fn storage_entry(account_id: Self::AccountId) -> Self::StorageEntry {
                 #storage_entry_path(account_id)
             }
+            fn nonce(result: &<Self::StorageEntry as ::subxt::StorageEntry>::Value) -> Self::Index {
+                result.nonce
+            }
         }
     })
 }