Make priviledged functions explicity use origin (#3045)

* Make priviledged functions explicity use `origin`

* Fix typo in docs

* Fix more tests

* Remove `root` pathway, add semicolons

substrate/srml/example/src/lib.rs

@@ -254,7 +254,7 @@
 #![cfg_attr(not(feature = "std"), no_std)]
 
 use srml_support::{StorageValue, dispatch::Result, decl_module, decl_storage, decl_event};
-use system::ensure_signed;
+use system::{ensure_signed, ensure_root};
 use sr_primitives::weights::TransactionWeight;
 
 /// Our module's configuration trait. All our types and consts go in here. If the
@@ -440,7 +440,7 @@ decl_module! {
 		}
 
 		/// A privileged call; in this case it resets our dummy value to something new.
-		// Implementation of a privileged call. This doesn't have an `origin` parameter because
+		// Implementation of a privileged call. The `origin` parameter is ROOT because
 		// it's not (directly) from an extrinsic, but rather the system as a whole has decided
 		// to execute it. Different runtimes have different reasons for allow privileged
 		// calls to be executed - we don't need to care why. Because it's privileged, we can
@@ -448,7 +448,8 @@ decl_module! {
 		// without worrying about gameability or attack scenarios.
 		// If you not specify `Result` explicitly as return value, it will be added automatically
 		// for you and `Ok(())` will be returned.
-		fn set_dummy(#[compact] new_value: T::Balance) {
+		fn set_dummy(origin, #[compact] new_value: T::Balance) {
+			ensure_root(origin)?;
 			// Put the new value into storage.
 			<Dummy<T>>::put(new_value);
 		}