Add a new host function for reporting fatal errors; make WASM backtraces readable when printing out errors (#10741)

* Add a new host function for reporting fatal errors

* Fix one of the wasmtime executor tests

* Have `#[runtime_interface(wasm_only)]` actually mean WASM-only, and not no_std-only

* Print out errors through `Display` instead of `Debug`

* Switch one more trait to require `Error` for its error instead of only `Debug`

* Align to review comments

substrate/client/finality-grandpa/src/aux_schema.rs

@@ -100,7 +100,7 @@ where
 				// previously we only supported at most one pending change per fork
 				&|_, _| Ok(false),
 			) {
-				warn!(target: "afg", "Error migrating pending authority set change: {:?}.", err);
+				warn!(target: "afg", "Error migrating pending authority set change: {}", err);
 				warn!(target: "afg", "Node is in a potentially inconsistent state.");
 			}
 		}

substrate/client/finality-grandpa/src/environment.rs

@@ -609,7 +609,7 @@ where
 	let tree_route = match tree_route_res {
 		Ok(tree_route) => tree_route,
 		Err(e) => {
-			debug!(target: "afg", "Encountered error computing ancestry between block {:?} and base {:?}: {:?}",
+			debug!(target: "afg", "Encountered error computing ancestry between block {:?} and base {:?}: {}",
 				   block, base, e);
 
 			return Err(GrandpaError::NotDescendent)
@@ -1098,7 +1098,7 @@ where
 	) {
 		warn!(target: "afg", "Detected prevote equivocation in the finality worker: {:?}", equivocation);
 		if let Err(err) = self.report_equivocation(equivocation.into()) {
-			warn!(target: "afg", "Error reporting prevote equivocation: {:?}", err);
+			warn!(target: "afg", "Error reporting prevote equivocation: {}", err);
 		}
 	}
 
@@ -1109,7 +1109,7 @@ where
 	) {
 		warn!(target: "afg", "Detected precommit equivocation in the finality worker: {:?}", equivocation);
 		if let Err(err) = self.report_equivocation(equivocation.into()) {
-			warn!(target: "afg", "Error reporting precommit equivocation: {:?}", err);
+			warn!(target: "afg", "Error reporting precommit equivocation: {}", err);
 		}
 	}
 }
@@ -1224,7 +1224,7 @@ where
 				.or_else(|| Some((target_header.hash(), *target_header.number())))
 		},
 		Err(e) => {
-			warn!(target: "afg", "Encountered error finding best chain containing {:?}: {:?}", block, e);
+			warn!(target: "afg", "Encountered error finding best chain containing {:?}: {}", block, e);
 			None
 		},
 	};
@@ -1293,7 +1293,7 @@ where
 		) {
 			if let Some(sender) = justification_sender {
 				if let Err(err) = sender.notify(justification) {
-					warn!(target: "afg", "Error creating justification for subscriber: {:?}", err);
+					warn!(target: "afg", "Error creating justification for subscriber: {}", err);
 				}
 			}
 		}
@@ -1344,7 +1344,7 @@ where
 		client
 			.apply_finality(import_op, BlockId::Hash(hash), persisted_justification, true)
 			.map_err(|e| {
-				warn!(target: "afg", "Error applying finality to block {:?}: {:?}", (hash, number), e);
+				warn!(target: "afg", "Error applying finality to block {:?}: {}", (hash, number), e);
 				e
 			})?;
 

substrate/client/finality-grandpa/src/import.rs

@@ -598,7 +598,7 @@ where
 				Err(e) => {
 					debug!(
 						target: "afg",
-						"Restoring old authority set after block import error: {:?}",
+						"Restoring old authority set after block import error: {}",
 						e,
 					);
 					pending_changes.revert();
@@ -663,8 +663,12 @@ where
 
 				import_res.unwrap_or_else(|err| {
 					if needs_justification {
-						debug!(target: "afg", "Imported block #{} that enacts authority set change with \
-							invalid justification: {:?}, requesting justification from peers.", number, err);
+						debug!(
+							target: "afg",
+							"Requesting justification from peers due to imported block #{} that enacts authority set change with invalid justification: {}",
+							number,
+							err
+						);
 						imported_aux.bad_justification = true;
 						imported_aux.needs_justification = true;
 					}

substrate/client/finality-grandpa/src/lib.rs

@@ -275,23 +275,38 @@ impl Config {
 }
 
 /// Errors that can occur while voting in GRANDPA.
-#[derive(Debug)]
+#[derive(Debug, thiserror::Error)]
 pub enum Error {
 	/// An error within grandpa.
+	#[error("grandpa error: {0}")]
 	Grandpa(GrandpaError),
+
 	/// A network error.
+	#[error("network error: {0}")]
 	Network(String),
+
 	/// A blockchain error.
+	#[error("blockchain error: {0}")]
 	Blockchain(String),
+
 	/// Could not complete a round on disk.
+	#[error("could not complete a round on disk: {0}")]
 	Client(ClientError),
+
 	/// Could not sign outgoing message
+	#[error("could not sign outgoing message: {0}")]
 	Signing(String),
+
 	/// An invariant has been violated (e.g. not finalizing pending change blocks in-order)
+	#[error("safety invariant has been violated: {0}")]
 	Safety(String),
+
 	/// A timer failed to fire.
+	#[error("a timer failed to fire: {0}")]
 	Timer(io::Error),
+
 	/// A runtime api request failed.
+	#[error("runtime API request failed: {0}")]
 	RuntimeApi(sp_api::ApiError),
 }
 
@@ -322,7 +337,7 @@ where
 {
 	fn block_number(&self, hash: Block::Hash) -> Result<Option<NumberFor<Block>>, Error> {
 		self.block_number_from_id(&BlockId::Hash(hash))
-			.map_err(|e| Error::Blockchain(format!("{:?}", e)))
+			.map_err(|e| Error::Blockchain(e.to_string()))
 	}
 }
 
@@ -459,7 +474,7 @@ impl<H: fmt::Debug, N: fmt::Debug> ::std::error::Error for CommandOrError<H, N>
 impl<H, N> fmt::Display for CommandOrError<H, N> {
 	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 		match *self {
-			CommandOrError::Error(ref e) => write!(f, "{:?}", e),
+			CommandOrError::Error(ref e) => write!(f, "{}", e),
 			CommandOrError::VoterCommand(ref cmd) => write!(f, "{}", cmd),
 		}
 	}
@@ -838,7 +853,7 @@ where
 		Ok(()) => error!(target: "afg",
 			"GRANDPA voter future has concluded naturally, this should be unreachable."
 		),
-		Err(e) => error!(target: "afg", "GRANDPA voter error: {:?}", e),
+		Err(e) => error!(target: "afg", "GRANDPA voter error: {}", e),
 	});
 
 	// Make sure that `telemetry_task` doesn't accidentally finish and kill grandpa.

substrate/client/finality-grandpa/src/observer.rs

@@ -203,7 +203,7 @@ where
 	);
 
 	let observer_work = observer_work.map_ok(|_| ()).map_err(|e| {
-		warn!("GRANDPA Observer failed: {:?}", e);
+		warn!("GRANDPA Observer failed: {}", e);
 	});
 
 	Ok(observer_work.map(drop))