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/core/sr-arithmetic/src/biguint.rs

@@ -427,8 +427,8 @@ impl BigUint {
 	}
 }
 
-#[cfg(feature = "std")]
 impl rstd::fmt::Debug for BigUint {
+	#[cfg(feature = "std")]
 	fn fmt(&self, f: &mut rstd::fmt::Formatter<'_>) -> rstd::fmt::Result {
 		write!(
 			f,
@@ -437,6 +437,12 @@ impl rstd::fmt::Debug for BigUint {
 			u128::try_from(self.clone()).unwrap_or(0),
 		)
 	}
+
+	#[cfg(not(feature = "std"))]
+	fn fmt(&self, _: &mut rstd::fmt::Formatter<'_>) -> rstd::fmt::Result {
+		Ok(())
+	}
+
 }
 
 impl PartialEq for BigUint {

substrate/core/sr-arithmetic/src/fixed64.rs

@@ -144,11 +144,16 @@ impl CheckedAdd for Fixed64 {
 	}
 }
 
-#[cfg(feature = "std")]
 impl rstd::fmt::Debug for Fixed64 {
-	fn fmt(&self, f: &mut rstd::fmt::Formatter<'_>) -> rstd::fmt::Result {
+	#[cfg(feature = "std")]
+	fn fmt(&self, f: &mut rstd::fmt::Formatter) -> rstd::fmt::Result {
 		write!(f, "Fixed64({},{})", self.0 / DIV, (self.0 % DIV) / 1000)
 	}
+
+	#[cfg(not(feature = "std"))]
+	fn fmt(&self, _: &mut rstd::fmt::Formatter) -> rstd::fmt::Result {
+		Ok(())
+	}
 }
 
 #[cfg(test)]

substrate/core/sr-arithmetic/src/per_things.rs

@@ -20,14 +20,15 @@ use serde::{Serialize, Deserialize};
 use rstd::{ops, prelude::*, convert::TryInto};
 use codec::{Encode, Decode, CompactAs};
 use crate::traits::{SaturatedConversion, UniqueSaturatedInto, Saturating};
+use substrate_debug_derive::RuntimeDebug;
 
 macro_rules! implement_per_thing {
 	($name:ident, $test_mod:ident, [$($test_units:tt),+], $max:tt, $type:ty, $upper_type:ty, $title:expr $(,)?) => {
 		/// A fixed point representation of a number between in the range [0, 1].
 		///
 		#[doc = $title]
-		#[cfg_attr(feature = "std", derive(Serialize, Deserialize, Debug, Ord, PartialOrd))]
-		#[derive(Encode, Decode, Default, Copy, Clone, PartialEq, Eq, CompactAs)]
+		#[cfg_attr(feature = "std", derive(Serialize, Deserialize, Ord, PartialOrd))]
+		#[derive(Encode, Decode, Default, Copy, Clone, PartialEq, Eq, RuntimeDebug, CompactAs)]
 		pub struct $name($type);
 
 		impl $name {
@@ -189,7 +190,7 @@ macro_rules! implement_per_thing {
 		#[cfg(test)]
 		mod $test_mod {
 			use codec::{Encode, Decode};
-			use super::{$name, Saturating};
+			use super::{$name, Saturating, RuntimeDebug};
 			use crate::traits::Zero;
 
 
@@ -208,7 +209,7 @@ macro_rules! implement_per_thing {
 				assert!(<$upper_type>::from($max).checked_mul($max.into()).is_some());
 			}
 
-			#[derive(Encode, Decode, PartialEq, Eq, Debug)]
+			#[derive(Encode, Decode, PartialEq, Eq, RuntimeDebug)]
 			struct WithCompact<T: codec::HasCompact> {
 				data: T,
 			}

substrate/core/sr-arithmetic/src/rational128.rs

@@ -17,10 +17,10 @@
 use rstd::{cmp::Ordering, prelude::*};
 use crate::helpers_128bit;
 use num_traits::Zero;
+use substrate_debug_derive::RuntimeDebug;
 
 /// A wrapper for any rational number with a 128 bit numerator and denominator.
-#[derive(Clone, Copy, Default, Eq)]
-#[cfg_attr(feature = "std", derive(Debug))]
+#[derive(Clone, Copy, Default, Eq, RuntimeDebug)]
 pub struct Rational128(u128, u128);
 
 impl Rational128 {