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/primitives/src/lib.rs

@@ -42,6 +42,8 @@ pub use serde;// << for macro
 #[doc(hidden)]
 pub use codec::{Encode, Decode};// << for macro
 
+pub use substrate_debug_derive::RuntimeDebug;
+
 #[cfg(feature = "std")]
 pub use impl_serde::serialize as bytes;
 
@@ -116,8 +118,8 @@ impl ExecutionContext {
 }
 
 /// Hex-serialized shim for `Vec<u8>`.
-#[derive(PartialEq, Eq, Clone)]
-#[cfg_attr(feature = "std", derive(Serialize, Deserialize, Debug, Hash, PartialOrd, Ord))]
+#[derive(PartialEq, Eq, Clone, RuntimeDebug)]
+#[cfg_attr(feature = "std", derive(Serialize, Deserialize, Hash, PartialOrd, Ord))]
 pub struct Bytes(#[cfg_attr(feature = "std", serde(with="bytes"))] pub Vec<u8>);
 
 impl From<Vec<u8>> for Bytes {
@@ -162,8 +164,8 @@ pub enum NativeOrEncoded<R> {
 }
 
 #[cfg(feature = "std")]
-impl<R: codec::Encode> ::std::fmt::Debug for NativeOrEncoded<R> {
-	fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+impl<R: codec::Encode> rstd::fmt::Debug for NativeOrEncoded<R> {
+	fn fmt(&self, f: &mut rstd::fmt::Formatter) -> rstd::fmt::Result {
 		hexdisplay::HexDisplay::from(&self.as_encoded().as_ref()).fmt(f)
 	}
 }
@@ -229,3 +231,58 @@ pub trait TypeId {
 	/// Simple 4 byte identifier.
 	const TYPE_ID: [u8; 4];
 }
+
+/// A log level matching the one from `log` crate.
+///
+/// Used internally by `runtime_io::log` method.
+#[repr(u32)]
+pub enum LogLevel {
+	/// `Error` log level.
+	Error = 1,
+	/// `Warn` log level.
+	Warn = 2,
+	/// `Info` log level.
+	Info = 3,
+	/// `Debug` log level.
+	Debug = 4,
+	/// `Trace` log level.
+	Trace = 5,
+}
+
+impl From<u32> for LogLevel {
+	fn from(val: u32) -> Self {
+		match val {
+			x if x == LogLevel::Warn as u32 => LogLevel::Warn,
+			x if x == LogLevel::Info as u32 => LogLevel::Info,
+			x if x == LogLevel::Debug as u32 => LogLevel::Debug,
+			x if x == LogLevel::Trace as u32 => LogLevel::Trace,
+			_ => LogLevel::Error,
+		}
+	}
+}
+
+impl From<log::Level> for LogLevel {
+	fn from(l: log::Level) -> Self {
+		use log::Level::*;
+		match l {
+			Error => Self::Error,
+			Warn => Self::Warn,
+			Info => Self::Info,
+			Debug => Self::Debug,
+			Trace => Self::Trace,
+		}
+	}
+}
+
+impl From<LogLevel> for log::Level {
+	fn from(l: LogLevel) -> Self {
+		use self::LogLevel::*;
+		match l {
+			Error => Self::Error,
+			Warn => Self::Warn,
+			Info => Self::Info,
+			Debug => Self::Debug,
+			Trace => Self::Trace,
+		}
+	}
+}