Backing/GetBacking: Abstraction over pluralistic origins for XCM. (#8579)

* Backing/GetBacking: Abstraction over pluralistic origins for XCM.

* Update frame/support/src/traits/misc.rs

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Update frame/support/src/traits/misc.rs

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

substrate/frame/collective/src/lib.rs

@@ -55,7 +55,7 @@ use frame_support::{
 		PostDispatchInfo,
 	},
 	ensure,
-	traits::{ChangeMembers, EnsureOrigin, Get, InitializeMembers},
+	traits::{ChangeMembers, EnsureOrigin, Get, InitializeMembers, GetBacking, Backing},
 	weights::{DispatchClass, GetDispatchInfo, Weight, Pays},
 };
 use frame_system::{self as system, ensure_signed, ensure_root};
@@ -165,6 +165,15 @@ pub enum RawOrigin<AccountId, I> {
 	_Phantom(sp_std::marker::PhantomData<I>),
 }
 
+impl<AccountId, I> GetBacking for RawOrigin<AccountId, I> {
+	fn get_backing(&self) -> Option<Backing> {
+		match self {
+			RawOrigin::Members(n, d) => Some(Backing { approvals: *n, eligible: *d }),
+			_ => None,
+		}
+	}
+}
+
 /// Origin for the collective module.
 pub type Origin<T, I=DefaultInstance> = RawOrigin<<T as frame_system::Config>::AccountId, I>;
 

substrate/frame/support/src/traits.rs

@@ -46,7 +46,7 @@ pub use filter::{
 mod misc;
 pub use misc::{
 	Len, Get, GetDefault, HandleLifetime, TryDrop, Time, UnixTime, IsType, IsSubType, ExecuteBlock,
-	SameOrOther, OnNewAccount, OnKilledAccount, OffchainWorker,
+	SameOrOther, OnNewAccount, OnKilledAccount, OffchainWorker, GetBacking, Backing,
 };
 
 mod stored_map;

substrate/frame/support/src/traits/misc.rs

@@ -269,3 +269,18 @@ pub trait OffchainWorker<BlockNumber> {
 	fn offchain_worker(_n: BlockNumber) {}
 }
 
+/// Some amount of backing from a group. The precise defintion of what it means to "back" something
+/// is left flexible.
+pub struct Backing {
+	/// The number of members of the group that back some motion.
+	pub approvals: u32,
+	/// The total count of group members.
+	pub eligible: u32,
+}
+
+/// Retrieve the backing from an object's ref.
+pub trait GetBacking {
+	/// Returns `Some` `Backing` if `self` represents a fractional/groupwise backing of some
+	/// implicit motion. `None` if it does not.
+	fn get_backing(&self) -> Option<Backing>;
+}