[WIP]: Construct Runtime v2

[gupnik]

Fixes paritytech/polkadot-sdk#232

This PR introduces outer-macro approach for construct_runtime as discussed in the linked issue. It looks like the following:

#[frame_support::construct_runtime_v2]
mod runtime {
	#[frame::runtime]
	pub struct Runtime;

	#[frame::pallets]
	#[frame::derive(
		RuntimeCall,
		RuntimeEvent,
		RuntimeError,
		RuntimeOrigin,
		RuntimeFreezeReason,
		RuntimeHoldReason,
		RuntimeSlashReason,
		RuntimeLockId
	)]
	pub struct Pallets {
		System: frame_system,
		Timestamp: pallet_timestamp,
		Aura: pallet_aura,
		Grandpa: pallet_grandpa,
		Balances: pallet_balances,
		TransactionPayment: pallet_transaction_payment,
		Sudo: pallet_sudo,
		// Include the custom logic from the pallet-template in the runtime.
		#[frame::pallet_index(8)]
		#[frame::disable_call]
		TemplateModule: pallet_template,
	}
}

Features

• #[frame::runtime] attached to a struct defines the main runtime
• #[frame::pallets] attached to a struct defines the pallets in the runtime
• #[frame::derive] attached to this struct defines the types generated by construct_runtime
• #[frame::pallet_index] can be optionally attached to a pallet to override its index
• #[frame::disable_call] can be optionally attached to a pallet to disable its calls
• A pallet instance can be defined as TemplateModule: pallet_template<Instance>

Todo

• #[frame::disable_unsigned] to disable unsigned calls
• Errors and Edge-cases
• UI tests
• Docs

Extension

• Abstract away the Executive similar to Abstract away the executive #14742
• Optionally avoid the need to specify all runtime types (TBD)

[paritytech-cicd-pr]

The CI pipeline was cancelled due to failure one of the required jobs.
Job name: test-linux-stable-int
Logs: https://gitlab.parity.io/parity/mirrors/substrate/-/jobs/3413012

[bkchr]

• #[frame::pallet_index] can be optionally attached to a pallet to override its index

The index should be required and not be optional.

[gupnik]

• #[frame::pallet_index] can be optionally attached to a pallet to override its index

The index should be required and not be optional.

@bkchr By default, the index is derived from the order in which the pallets appear in the struct. If this attribute is specified, this default index is overridden. This is consistent with the current behaviour of construct_runtime. Do we want to get rid of this altogether?

[bkchr]

The indexes should be obligatory.