Runtime logging. (#3821)

* Implement Printable for tuples.

* Add debugging function.

* Add debug 1.

* Implement  for everything.

* RuntimeDebug derive.

* Introduce RuntimeDebug.

* Add some dummy logging.

* Replace RuntimeDebug with Debug.

* Revert "Replace RuntimeDebug with Debug."

This reverts commit bc47070a8cb30241b2b590b2fa29fd195088162f.

* Working on Debug for all.

* Fix bounds.

* Add debug utils.

* Implement runtime logging.

* Add some docs and clean up.

* Clean up derives.

* Fix custom derive impl.

* Bump runtime.

* Fix long lines.

* Fix doc test.

* Use CARGO_CFG_STD.

* Revert "Use CARGO_CFG_STD."

This reverts commit ea429566de18ed0fa052571b359eb9826a64a9f4.

* Use parse_macro_input

* Update lockfile.

* Apply review suggestions.

* Remove stray re-export.

* Add no-std impl.

* Update lockfile.

substrate/srml/staking/src/lib.rs

@@ -263,6 +263,7 @@ use support::{
 use session::{historical::OnSessionEnding, SelectInitialValidators};
 use sr_primitives::{
 	Perbill,
+	RuntimeDebug,
 	curve::PiecewiseLinear,
 	weights::SimpleDispatchInfo,
 	traits::{
@@ -313,7 +314,8 @@ impl EraPoints {
 }
 
 /// Indicates the initial status of the staker.
-#[cfg_attr(feature = "std", derive(Debug, Serialize, Deserialize))]
+#[derive(RuntimeDebug)]
+#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
 pub enum StakerStatus<AccountId> {
 	/// Chilling.
 	Idle,
@@ -324,8 +326,7 @@ pub enum StakerStatus<AccountId> {
 }
 
 /// A destination account for payment.
-#[derive(PartialEq, Eq, Copy, Clone, Encode, Decode)]
-#[cfg_attr(feature = "std", derive(Debug))]
+#[derive(PartialEq, Eq, Copy, Clone, Encode, Decode, RuntimeDebug)]
 pub enum RewardDestination {
 	/// Pay into the stash account, increasing the amount at stake accordingly.
 	Staked,
@@ -342,8 +343,7 @@ impl Default for RewardDestination {
 }
 
 /// Preference of what happens on a slash event.
-#[derive(PartialEq, Eq, Clone, Encode, Decode)]
-#[cfg_attr(feature = "std", derive(Debug))]
+#[derive(PartialEq, Eq, Clone, Encode, Decode, RuntimeDebug)]
 pub struct ValidatorPrefs<Balance: HasCompact> {
 	/// Reward that validator takes up-front; only the rest is split between themselves and
 	/// nominators.
@@ -360,8 +360,7 @@ impl<B: Default + HasCompact + Copy> Default for ValidatorPrefs<B> {
 }
 
 /// Just a Balance/BlockNumber tuple to encode when a chunk of funds will be unlocked.
-#[derive(PartialEq, Eq, Clone, Encode, Decode)]
-#[cfg_attr(feature = "std", derive(Debug))]
+#[derive(PartialEq, Eq, Clone, Encode, Decode, RuntimeDebug)]
 pub struct UnlockChunk<Balance: HasCompact> {
 	/// Amount of funds to be unlocked.
 	#[codec(compact)]
@@ -372,8 +371,7 @@ pub struct UnlockChunk<Balance: HasCompact> {
 }
 
 /// The ledger of a (bonded) stash.
-#[derive(PartialEq, Eq, Clone, Encode, Decode)]
-#[cfg_attr(feature = "std", derive(Debug))]
+#[derive(PartialEq, Eq, Clone, Encode, Decode, RuntimeDebug)]
 pub struct StakingLedger<AccountId, Balance: HasCompact> {
 	/// The stash account whose balance is actually locked and at stake.
 	pub stash: AccountId,
@@ -411,8 +409,7 @@ impl<
 }
 
 /// The amount of exposure (to slashing) than an individual nominator has.
-#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Encode, Decode)]
-#[cfg_attr(feature = "std", derive(Debug))]
+#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Encode, Decode, RuntimeDebug)]
 pub struct IndividualExposure<AccountId, Balance: HasCompact> {
 	/// The stash account of the nominator in question.
 	who: AccountId,
@@ -422,8 +419,7 @@ pub struct IndividualExposure<AccountId, Balance: HasCompact> {
 }
 
 /// A snapshot of the stake backing a single validator in the system.
-#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Encode, Decode, Default)]
-#[cfg_attr(feature = "std", derive(Debug))]
+#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Encode, Decode, Default, RuntimeDebug)]
 pub struct Exposure<AccountId, Balance: HasCompact> {
 	/// The total balance backing this validator.
 	#[codec(compact)]
@@ -436,8 +432,7 @@ pub struct Exposure<AccountId, Balance: HasCompact> {
 }
 
 /// A slashing event occurred, slashing a validator for a given amount of balance.
-#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Encode, Decode, Default)]
-#[cfg_attr(feature = "std", derive(Debug))]
+#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Encode, Decode, Default, RuntimeDebug)]
 pub struct SlashJournalEntry<AccountId, Balance: HasCompact> {
 	who: AccountId,
 	amount: Balance,
@@ -532,8 +527,8 @@ pub trait Trait: system::Trait {
 }
 
 /// Mode of era-forcing.
-#[derive(Copy, Clone, PartialEq, Eq, Encode, Decode)]
-#[cfg_attr(feature = "std", derive(Debug, Serialize, Deserialize))]
+#[derive(Copy, Clone, PartialEq, Eq, Encode, Decode, RuntimeDebug)]
+#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
 pub enum Forcing {
 	/// Not forcing anything - just let whatever happen.
 	NotForcing,