Switch to new proc-macro crate for implementing traits for tuples (#3598)

* Switch to new proc-macro crate for implementing traits for tuples

* Switch back to stable `Cargo.lock` format

* Reduce tuple number to match rusts default implementation

substrate/srml/system/Cargo.toml

@@ -14,6 +14,7 @@ runtime-io ={ package = "sr-io", path = "../../core/sr-io", default-features = f
 sr-primitives = { path = "../../core/sr-primitives", default-features = false }
 sr-version = { path = "../../core/sr-version", default-features = false }
 support = { package = "srml-support", path = "../support", default-features = false }
+impl-trait-for-tuples = "0.1"
 
 [dev-dependencies]
 criterion = "0.2"

substrate/srml/system/src/lib.rs

@@ -112,7 +112,7 @@ use sr_primitives::{
 use primitives::storage::well_known_keys;
 use support::{
 	storage, decl_module, decl_event, decl_storage, StorageDoubleMap, StorageValue, StorageMap,
-	Parameter, for_each_tuple, traits::{Contains, Get}, decl_error,
+	Parameter, traits::{Contains, Get}, decl_error,
 };
 use safe_mix::TripletMix;
 use codec::{Encode, Decode};
@@ -126,29 +126,12 @@ use primitives::ChangesTrieConfiguration;
 pub mod offchain;
 
 /// Handler for when a new account has been created.
+#[impl_trait_for_tuples::impl_for_tuples(30)]
 pub trait OnNewAccount<AccountId> {
 	/// A new account `who` has been registered.
 	fn on_new_account(who: &AccountId);
 }
 
-macro_rules! impl_on_new_account {
-	() => (
-		impl<AccountId> OnNewAccount<AccountId> for () {
-			fn on_new_account(_: &AccountId) {}
-		}
-	);
-
-	( $($t:ident)* ) => {
-		impl<AccountId, $($t: OnNewAccount<AccountId>),*> OnNewAccount<AccountId> for ($($t,)*) {
-			fn on_new_account(who: &AccountId) {
-				$($t::on_new_account(who);)*
-			}
-		}
-	}
-}
-
-for_each_tuple!(impl_on_new_account);
-
 /// Determiner to say whether a given account is unused.
 pub trait IsDeadAccount<AccountId> {
 	/// Is the given account dead?