Implementation of ah-client and rc-client staking pallets (paritytech…

…#7582)

Recreation of paritytech#7357 on
top of master. The old PR messes up the git history too much so I am
recreating it from scratch.

This PR is work in progress. It's purpose is to commit initial structure
of `pallet-staking-ah-client` and `pallet-staking-rc-client` to master.
The changes will be polished by a follow up PRs which will be
backported.

Related issues: paritytech#6167
and paritytech#6166

This PR introduces the initial structure for `pallet-ah-client` and
`pallet-rc-client`. These pallets will reside on the relay chain and
AssetHub, respectively, and will manage the interaction between
`pallet-session` on the relay chain and `pallet-staking` on AssetHub.

Both pallets are experimental and not intended for production use.

TODOs:
- [ ] Probably handle
paritytech#6344 here.

---------

Co-authored-by: cmd[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Ankan <[email protected]>

Cargo.toml

@@ -420,6 +420,8 @@ members = [
 	"substrate/frame/session/benchmarking",
 	"substrate/frame/society",
 	"substrate/frame/staking",
+	"substrate/frame/staking/ah-client",
+	"substrate/frame/staking/rc-client",
 	"substrate/frame/staking/reward-curve",
 	"substrate/frame/staking/reward-fn",
 	"substrate/frame/staking/runtime-api",
@@ -998,6 +1000,8 @@ pallet-session-benchmarking = { path = "substrate/frame/session/benchmarking", d
 pallet-skip-feeless-payment = { path = "substrate/frame/transaction-payment/skip-feeless-payment", default-features = false }
 pallet-society = { path = "substrate/frame/society", default-features = false }
 pallet-staking = { path = "substrate/frame/staking", default-features = false }
+pallet-staking-ah-client = { path = "substrate/frame/staking/ah-client", default-features = false }
+pallet-staking-rc-client = { path = "substrate/frame/staking/rc-client", default-features = false }
 pallet-staking-reward-curve = { path = "substrate/frame/staking/reward-curve", default-features = false }
 pallet-staking-reward-fn = { path = "substrate/frame/staking/reward-fn", default-features = false }
 pallet-staking-runtime-api = { path = "substrate/frame/staking/runtime-api", default-features = false }

prdoc/pr_7582.prdoc

@@ -0,0 +1,17 @@
+title: Implementation of `ah-client` and `rc-client` staking pallets
+doc:
+- audience: Runtime Dev
+  description: |-
+    This PR introduces the initial structure for `pallet-ah-client` and `pallet-rc-client`. These
+    pallets will reside on the relay chain and AssetHub, respectively, and will manage the interaction
+    between `pallet-session` on the relay chain and `pallet-staking` on AssetHub.
+    Both pallets are experimental and not intended for production use.
+crates:
+- name: pallet-staking-ah-client
+  bump: major
+- name: pallet-staking-rc-client
+  bump: major
+- name: pallet-election-provider-multi-block
+  bump: minor
+- name: pallet-staking
+  bump: major

substrate/frame/election-provider-multi-block/src/lib.rs

@@ -66,7 +66,7 @@
 //!
 //! ## Pagination
 //!
-//! Most of the external APIs of this pallet are paginated. All pagination follow a patter where if
+//! Most of the external APIs of this pallet are paginated. All pagination follow a pattern where if
 //! `N` pages exist, the first paginated call is `function(N-1)` and the last one is `function(0)`.
 //! For example, with 3 pages, the `elect` of [`ElectionProvider`] is expected to be called as
 //! `elect(2) -> elect(1) -> elect(0)`. In essence, calling a paginated function with index 0 is

substrate/frame/staking/ah-client/Cargo.toml

@@ -0,0 +1,66 @@
+[package]
+name = "pallet-staking-ah-client"
+description = "Pallet handling the communication with staking-rc-client. It's role is to glue the staking pallet (on AssetHub chain) and session pallet (on Relay Chain) in a transparent way."
+license = "Apache-2.0"
+version = "0.1.0"
+edition.workspace = true
+authors.workspace = true
+repository.workspace = true
+
+[dependencies]
+codec = { workspace = true, features = ["derive"] }
+frame-support = { workspace = true }
+frame-system = { workspace = true }
+log = { workspace = true }
+pallet-authorship = { workspace = true }
+pallet-session = { features = ["historical"], workspace = true }
+pallet-staking = { workspace = true }
+pallet-staking-rc-client = { workspace = true }
+polkadot-primitives = { workspace = true }
+polkadot-runtime-parachains = { workspace = true }
+scale-info = { workspace = true, features = ["derive"] }
+sp-core = { workspace = true }
+sp-runtime = { workspace = true }
+sp-staking = { workspace = true }
+xcm = { workspace = true }
+
+[features]
+default = ["std"]
+std = [
+	"codec/std",
+	"frame-support/std",
+	"frame-system/std",
+	"log/std",
+	"pallet-authorship/std",
+	"pallet-session/std",
+	"pallet-staking-rc-client/std",
+	"pallet-staking/std",
+	"polkadot-primitives/std",
+	"polkadot-runtime-parachains/std",
+	"scale-info/std",
+	"sp-core/std",
+	"sp-runtime/std",
+	"sp-staking/std",
+	"xcm/std",
+]
+runtime-benchmarks = [
+	"frame-support/runtime-benchmarks",
+	"frame-system/runtime-benchmarks",
+	"pallet-staking-rc-client/runtime-benchmarks",
+	"pallet-staking/runtime-benchmarks",
+	"polkadot-primitives/runtime-benchmarks",
+	"polkadot-runtime-parachains/runtime-benchmarks",
+	"sp-runtime/runtime-benchmarks",
+	"sp-staking/runtime-benchmarks",
+	"xcm/runtime-benchmarks",
+]
+try-runtime = [
+	"frame-support/try-runtime",
+	"frame-system/try-runtime",
+	"pallet-authorship/try-runtime",
+	"pallet-session/try-runtime",
+	"pallet-staking-rc-client/try-runtime",
+	"pallet-staking/try-runtime",
+	"polkadot-runtime-parachains/try-runtime",
+	"sp-runtime/try-runtime",
+]