Split off TypeId so as not to pull in sr-io (#3740)

* Add type-id

* Builds with std now.

* Fix for cargo

* Remove unneeded stuff

* Move TypeId.

substrate/core/sr-primitives/src/lib.rs

@@ -56,7 +56,7 @@ pub mod weights;
 pub use generic::{DigestItem, Digest};
 
 /// Re-export this since it's part of the API of this crate.
-pub use primitives::crypto::{key_types, KeyTypeId, CryptoType};
+pub use primitives::{TypeId, crypto::{key_types, KeyTypeId, CryptoType}};
 pub use app_crypto::RuntimeAppPublic;
 
 /// Re-export arithmetic stuff.
@@ -82,7 +82,7 @@ use traits::{Verify, Lazy};
 #[derive(Clone, Copy, Eq, PartialEq, Encode, Decode)]
 pub struct ModuleId(pub [u8; 8]);
 
-impl traits::TypeId for ModuleId {
+impl TypeId for ModuleId {
 	const TYPE_ID: [u8; 4] = *b"modl";
 }
 

substrate/core/sr-primitives/src/traits.rs

@@ -23,7 +23,7 @@ use runtime_io;
 use std::fmt::{Debug, Display};
 #[cfg(feature = "std")]
 use serde::{Serialize, Deserialize, de::DeserializeOwned};
-use primitives::{self, Hasher, Blake2Hasher};
+use primitives::{self, Hasher, Blake2Hasher, TypeId};
 use crate::codec::{Codec, Encode, Decode, HasCompact};
 use crate::transaction_validity::{
 	ValidTransaction, TransactionValidity, TransactionValidityError, UnknownTransaction,
@@ -1123,12 +1123,6 @@ pub trait AccountIdConversion<AccountId>: Sized {
 	fn try_from_sub_account<S: Decode>(x: &AccountId) -> Option<(Self, S)>;
 }
 
-/// Provide a simple 4 byte identifier for a type.
-pub trait TypeId {
-	/// Simple 4 byte identifier.
-	const TYPE_ID: [u8; 4];
-}
-
 /// Format is TYPE_ID ++ encode(parachain ID) ++ 00.... where 00... is indefinite trailing zeroes to
 /// fill AccountId.
 impl<T: Encode + Decode + Default, Id: Encode + Decode + TypeId> AccountIdConversion<T> for Id {