frame-executive: Reject invalid inherents in the executive (#12365)

* frame-executive: Reject invalid inherents in the executive

We already had support for making a block fail if an inherent returned, but it was part of the
signed extension `CheckWeight`. Rejecting blocks with invalid inherents should happen on the
`frame-executive` level without requiring any special signed extension. This is crucial to prevent
any kind of spamming of the network that could may happen with blocks that include failing inherents.

* FMT

* Update frame/executive/src/lib.rs

Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>

* Update primitives/runtime/src/transaction_validity.rs

Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>

Co-authored-by: parity-processbot <>
Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>

substrate/primitives/runtime/src/transaction_validity.rs

@@ -77,9 +77,9 @@ pub enum InvalidTransaction {
 	/// malicious validator or a buggy `provide_inherent`. In any case, it can result in
 	/// dangerously overweight blocks and therefore if found, invalidates the block.
 	BadMandatory,
-	/// A transaction with a mandatory dispatch. This is invalid; only inherent extrinsics are
-	/// allowed to have mandatory dispatches.
-	MandatoryDispatch,
+	/// An extrinsic with a mandatory dispatch tried to be validated.
+	/// This is invalid; only inherent extrinsics are allowed to have mandatory dispatches.
+	MandatoryValidation,
 	/// The sending address is disabled or known to be invalid.
 	BadSigner,
 }
@@ -109,8 +109,8 @@ impl From<InvalidTransaction> for &'static str {
 				"Inability to pay some fees (e.g. account balance too low)",
 			InvalidTransaction::BadMandatory =>
 				"A call was labelled as mandatory, but resulted in an Error.",
-			InvalidTransaction::MandatoryDispatch =>
-				"Transaction dispatch is mandatory; transactions may not have mandatory dispatches.",
+			InvalidTransaction::MandatoryValidation =>
+				"Transaction dispatch is mandatory; transactions must not be validated.",
 			InvalidTransaction::Custom(_) => "InvalidTransaction custom error",
 			InvalidTransaction::BadSigner => "Invalid signing address",
 		}