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/support/src/lib.rs

@@ -266,21 +266,6 @@ pub enum Void {}
 #[doc(hidden)]
 pub use serde::{Serialize, Deserialize};
 
-/// Programatically create derivations for tuples of up to 19 elements. You provide a second macro
-/// which is called once per tuple size, along with a number of identifiers, one for each element
-/// of the tuple.
-#[macro_export]
-macro_rules! for_each_tuple {
-	($m:ident) => {
-		for_each_tuple! { @IMPL $m !! A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, }
-	};
-	(@IMPL $m:ident !!) => { $m! { } };
-	(@IMPL $m:ident !! $h:ident, $($t:ident,)*) => {
-		$m! { $h $($t)* }
-		for_each_tuple! { @IMPL $m !! $($t,)* }
-	}
-}
-
 #[cfg(test)]
 mod tests {
 	use super::*;

substrate/srml/support/src/traits.rs

@@ -24,8 +24,6 @@ use primitives::u32_trait::Value as U32;
 use crate::sr_primitives::traits::{MaybeSerializeDebug, SimpleArithmetic, Saturating};
 use crate::sr_primitives::ConsensusEngineId;
 
-use super::for_each_tuple;
-
 /// Anything that can have a `::len()` method.
 pub trait Len {
 	/// Return the length of data type.
@@ -63,29 +61,12 @@ impl<V: PartialEq, T: Get<V>> Contains<V> for T {
 }
 
 /// The account with the given id was killed.
+#[impl_trait_for_tuples::impl_for_tuples(30)]
 pub trait OnFreeBalanceZero<AccountId> {
 	/// The account was the given id was killed.
 	fn on_free_balance_zero(who: &AccountId);
 }
 
-macro_rules! impl_on_free_balance_zero {
-	() => (
-		impl<AccountId> OnFreeBalanceZero<AccountId> for () {
-			fn on_free_balance_zero(_: &AccountId) {}
-		}
-	);
-
-	( $($t:ident)* ) => {
-		impl<AccountId, $($t: OnFreeBalanceZero<AccountId>),*> OnFreeBalanceZero<AccountId> for ($($t,)*) {
-			fn on_free_balance_zero(who: &AccountId) {
-				$($t::on_free_balance_zero(who);)*
-			}
-		}
-	}
-}
-
-for_each_tuple!(impl_on_free_balance_zero);
-
 /// Trait for a hook to get called when some balance has been minted, causing dilution.
 pub trait OnDilution<Balance> {
 	/// Some `portion` of the total balance just "grew" by `minted`. `portion` is the pre-growth