Make hooks and call attributes optional in pallet macro (#8853)

* Make #[pallet::hooks] optional

* Make #[pallet::call] optional

* Remove unused imports

* Update UI test expectations

* Update UI test expectations

* Remove unnecessary HooksDef::empty method

* Remove unnecessary CallDef::empty method

* Clarify what would happen when no call or hooks are specified in a pallet

substrate/frame/support/test/tests/pallet.rs

@@ -406,20 +406,11 @@ pub mod pallet2 {
 /// Test that the supertrait check works when we pass some parameter to the `frame_system::Config`.
 #[frame_support::pallet]
 pub mod pallet3 {
-	use frame_support::pallet_prelude::*;
-	use frame_system::pallet_prelude::*;
-
 	#[pallet::config]
 	pub trait Config: frame_system::Config<Origin = ()> {}
 
 	#[pallet::pallet]
 	pub struct Pallet<T>(_);
-
-	#[pallet::hooks]
-	impl<T: Config> Hooks<BlockNumberFor<T>> for Pallet<T> {}
-
-	#[pallet::call]
-	impl<T: Config> Pallet<T> {}
 }
 
 frame_support::parameter_types!(

substrate/frame/support/test/tests/pallet_instance.rs

@@ -209,7 +209,6 @@ pub mod pallet {
 #[frame_support::pallet]
 pub mod pallet2 {
 	use frame_support::pallet_prelude::*;
-	use frame_system::pallet_prelude::*;
 
 	#[pallet::config]
 	pub trait Config<I: 'static = ()>: frame_system::Config {
@@ -220,12 +219,6 @@ pub mod pallet2 {
 	#[pallet::generate_store(pub(crate) trait Store)]
 	pub struct Pallet<T, I = ()>(PhantomData<(T, I)>);
 
-	#[pallet::hooks]
-	impl<T: Config<I>, I: 'static> Hooks<BlockNumberFor<T>> for Pallet<T, I> {}
-
-	#[pallet::call]
-	impl<T: Config<I>, I: 'static> Pallet<T, I> {}
-
 	#[pallet::event]
 	pub enum Event<T: Config<I>, I: 'static = ()> {
 		/// Something

substrate/frame/support/test/tests/pallet_ui/inconsistent_instance_1.stderr

@@ -1,3 +1,9 @@
+error: Invalid generic declaration, trait is defined with instance but generic use none
+  --> $DIR/inconsistent_instance_1.rs:10:20
+   |
+10 |     pub struct Pallet<T>(core::marker::PhantomData<T>);
+   |                       ^
+
 error: Invalid generic declaration, trait is defined with instance but generic use none
   --> $DIR/inconsistent_instance_1.rs:16:7
    |
@@ -10,12 +16,6 @@ error: Invalid generic declaration, trait is defined with instance but generic u
 16 |     impl<T: Config> Pallet<T> {}
    |                     ^^^^^^
 
-error: Invalid generic declaration, trait is defined with instance but generic use none
-  --> $DIR/inconsistent_instance_1.rs:10:20
-   |
-10 |     pub struct Pallet<T>(core::marker::PhantomData<T>);
-   |                       ^
-
 error: Invalid generic declaration, trait is defined with instance but generic use none
   --> $DIR/inconsistent_instance_1.rs:13:47
    |

substrate/frame/support/test/tests/pallet_ui/inconsistent_instance_2.stderr

@@ -1,3 +1,9 @@
+error: Invalid generic declaration, trait is defined without instance but generic use some
+  --> $DIR/inconsistent_instance_2.rs:10:20
+   |
+10 |     pub struct Pallet<T, I = ()>(core::marker::PhantomData<(T, I)>);
+   |                       ^
+
 error: Invalid generic declaration, trait is defined without instance but generic use some
   --> $DIR/inconsistent_instance_2.rs:16:7
    |
@@ -10,12 +16,6 @@ error: Invalid generic declaration, trait is defined without instance but generi
 16 |     impl<T: Config<I>, I: 'static> Pallet<T, I> {}
    |                                    ^^^^^^
 
-error: Invalid generic declaration, trait is defined without instance but generic use some
-  --> $DIR/inconsistent_instance_2.rs:10:20
-   |
-10 |     pub struct Pallet<T, I = ()>(core::marker::PhantomData<(T, I)>);
-   |                       ^
-
 error: Invalid generic declaration, trait is defined without instance but generic use some
   --> $DIR/inconsistent_instance_2.rs:13:62
    |