Add pallet attribute macro to declare pallets (paritytech#6877)

* rename system Config to system Trait.

command used:
```
find frame/ bin/ test-utils/ utils/ -name *.rs -exec sed -i 's/system::Trait>::/system::Config>::/g' {} \;
find frame/ bin/ test-utils/ utils/ -name *.rs -exec sed -i 's/impl frame_system::Trait for /impl frame_system::Config for /g' {} \;
find frame/ bin/ test-utils/ utils/ -name *.rs -exec sed -i 's/impl system::Trait for /impl system::Config for /g' {} \;
```
plus some manual ones especially for frame-support tests and frame-system

* make construct_runtime handle Pallet and Module

pallets can now be implemented on struct named Pallet or Module, both
definition are valid.
This is because next macro will generate only Pallet placeholder.

* introduce pallet attribute macro

currently just with tests, frame_system and other example hasn't been
upgraded

* allow to print some upgrade helper from decl_storage

* Improved error msg, typo.

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

* Improved error msg, typo.

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

* Improved error message on unexpected attributes + ui test

* add test for transactional

* various typo

* some tips when spans are lost

* allow pallet to depend on other pallet instances

* make event type metadata consistent with call and constant

* error messages

* ignore doc example

* fix pallet upgrade template

* fixup

* fix doc

* fix indentation

* Apply suggestions code formatting

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* some renames + fix compilation

* remove unsupported genesis config type alias

* merge fixup

* fix ui tests

* additional doc

* implement StorageInstance with new syntax

* fix line width

* fix doc: because pallet doc goes below reexport doc

* Update frame/support/procedural/src/pallet/parse/event.rs

Co-authored-by: Andrew Jones <ascjones@gmail.com>

* Update frame/system/src/lib.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update frame/support/test/tests/pallet_ui.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* improve doc as suggested

* revert construct_runtime Pallet part.

This revert the changes on construct_runtime. Now construct_runtime is
unchanged and instead pallet macro create a type alias
`type Module<..> = Pallet<..>` to be used by construct_runtime

* refactor with less intricated code

* fix ui test with new image

* fix ui tests

* add minor tests

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>
Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>
Co-authored-by: Andrew Jones <ascjones@gmail.com>
Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

frame/support/procedural/src/lib.rs

@@ -21,12 +21,14 @@
 
 mod storage;
 mod construct_runtime;
+mod pallet;
 mod pallet_version;
 mod transactional;
 mod debug_no_bound;
 mod clone_no_bound;
 mod partial_eq_no_bound;
 
+pub(crate) use storage::INHERENT_INSTANCE_NAME;
 use proc_macro::TokenStream;
 
 /// Declares strongly-typed wrappers around codec-compatible types in storage.
@@ -305,6 +307,12 @@ pub fn construct_runtime(input: TokenStream) -> TokenStream {
 	construct_runtime::construct_runtime(input)
 }
 
+/// Macro to define a pallet. Docs are at `frame_support::pallet`.
+#[proc_macro_attribute]
+pub fn pallet(attr: TokenStream, item: TokenStream) -> TokenStream {
+	pallet::pallet(attr, item)
+}
+
 /// Execute the annotated function in a new storage transaction.
 ///
 /// The return type of the annotated function must be `Result`. All changes to storage performed

frame/support/procedural/src/pallet/expand/call.rs

@@ -0,0 +1,201 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2020 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use crate::pallet::Def;
+use frame_support_procedural_tools::clean_type_string;
+use syn::spanned::Spanned;
+
+/// * Generate enum call and implement various trait on it.
+/// * Implement Callable and call_function on `Pallet`
+pub fn expand_call(def: &mut Def) -> proc_macro2::TokenStream {
+	let frame_support = &def.frame_support;
+	let frame_system = &def.frame_system;
+	let type_impl_gen = &def.type_impl_generics();
+	let type_decl_bounded_gen = &def.type_decl_bounded_generics();
+	let type_use_gen = &def.type_use_generics();
+	let call_ident = syn::Ident::new("Call", def.call.attr_span.clone());
+	let pallet_ident = &def.pallet_struct.pallet;
+	let where_clause = &def.call.where_clause;
+
+	let fn_name = def.call.methods.iter().map(|method| &method.name).collect::<Vec<_>>();
+
+	let fn_weight = def.call.methods.iter().map(|method| &method.weight);
+
+	let fn_doc = def.call.methods.iter().map(|method| &method.docs).collect::<Vec<_>>();
+
+	let args_name = def.call.methods.iter()
+		.map(|method| method.args.iter().map(|(_, name, _)| name.clone()).collect::<Vec<_>>())
+		.collect::<Vec<_>>();
+
+	let args_type = def.call.methods.iter()
+		.map(|method| method.args.iter().map(|(_, _, type_)| type_.clone()).collect::<Vec<_>>())
+		.collect::<Vec<_>>();
+
+	let args_compact_attr = def.call.methods.iter().map(|method| {
+		method.args.iter()
+			.map(|(is_compact, _, type_)| {
+				if *is_compact {
+					quote::quote_spanned!(type_.span() => #[codec(compact)] )
+				} else {
+					quote::quote!()
+				}
+			})
+			.collect::<Vec<_>>()
+	});
+
+	let args_metadata_type = def.call.methods.iter().map(|method| {
+		method.args.iter()
+			.map(|(is_compact, _, type_)| {
+				let final_type = if *is_compact {
+					quote::quote!(Compact<#type_>)
+				} else {
+					quote::quote!(#type_)
+				};
+				clean_type_string(&final_type.to_string())
+			})
+			.collect::<Vec<_>>()
+	});
+
+	quote::quote_spanned!(def.call.attr_span =>
+		#[derive(
+			#frame_support::RuntimeDebugNoBound,
+			#frame_support::CloneNoBound,
+			#frame_support::EqNoBound,
+			#frame_support::PartialEqNoBound,
+			#frame_support::codec::Encode,
+			#frame_support::codec::Decode,
+		)]
+		#[allow(non_camel_case_types)]
+		pub enum #call_ident<#type_decl_bounded_gen> #where_clause {
+			#[doc(hidden)]
+			#[codec(skip)]
+			__Ignore(
+				#frame_support::sp_std::marker::PhantomData<(#type_use_gen,)>,
+				#frame_support::Never,
+			),
+			#( #fn_name( #( #args_compact_attr #args_type ),* ), )*
+		}
+
+		impl<#type_impl_gen> #frame_support::dispatch::GetDispatchInfo
+			for #call_ident<#type_use_gen>
+			#where_clause
+		{
+			fn get_dispatch_info(&self) -> #frame_support::dispatch::DispatchInfo {
+				match *self {
+					#(
+						Self::#fn_name ( #( ref #args_name, )* ) => {
+							let base_weight = #fn_weight;
+
+							let weight = <
+								dyn #frame_support::dispatch::WeighData<( #( & #args_type, )* )>
+							>::weigh_data(&base_weight, ( #( #args_name, )* ));
+
+							let class = <
+								dyn #frame_support::dispatch::ClassifyDispatch<
+									( #( & #args_type, )* )
+								>
+							>::classify_dispatch(&base_weight, ( #( #args_name, )* ));
+
+							let pays_fee = <
+								dyn #frame_support::dispatch::PaysFee<( #( & #args_type, )* )>
+							>::pays_fee(&base_weight, ( #( #args_name, )* ));
+
+							#frame_support::dispatch::DispatchInfo {
+								weight,
+								class,
+								pays_fee,
+							}
+						},
+					)*
+					Self::__Ignore(_, _) => unreachable!("__Ignore cannot be used"),
+				}
+			}
+		}
+
+		impl<#type_impl_gen> #frame_support::dispatch::GetCallName for #call_ident<#type_use_gen>
+			#where_clause
+		{
+			fn get_call_name(&self) -> &'static str {
+				match *self {
+					#( Self::#fn_name(..) => stringify!(#fn_name), )*
+					Self::__Ignore(_, _) => unreachable!("__PhantomItem cannot be used."),
+				}
+			}
+
+			fn get_call_names() -> &'static [&'static str] {
+				&[ #( stringify!(#fn_name), )* ]
+			}
+		}
+
+		impl<#type_impl_gen> #frame_support::traits::UnfilteredDispatchable
+			for #call_ident<#type_use_gen>
+			#where_clause
+		{
+			type Origin = #frame_system::pallet_prelude::OriginFor<T>;
+			fn dispatch_bypass_filter(
+				self,
+				origin: Self::Origin
+			) -> #frame_support::dispatch::DispatchResultWithPostInfo {
+				match self {
+					#(
+						Self::#fn_name( #( #args_name, )* ) =>
+							<#pallet_ident<#type_use_gen>>::#fn_name(origin, #( #args_name, )* )
+								.map(Into::into).map_err(Into::into),
+					)*
+					Self::__Ignore(_, _) => {
+						let _ = origin; // Use origin for empty Call enum
+						unreachable!("__PhantomItem cannot be used.");
+					},
+				}
+			}
+		}
+
+		impl<#type_impl_gen> #frame_support::dispatch::Callable<T> for #pallet_ident<#type_use_gen>
+			#where_clause
+		{
+			type Call = #call_ident<#type_use_gen>;
+		}
+
+		impl<#type_impl_gen> #pallet_ident<#type_use_gen> #where_clause {
+			#[doc(hidden)]
+			pub fn call_functions() -> &'static [#frame_support::dispatch::FunctionMetadata] {
+				&[ #(
+					#frame_support::dispatch::FunctionMetadata {
+						name: #frame_support::dispatch::DecodeDifferent::Encode(
+							stringify!(#fn_name)
+						),
+						arguments: #frame_support::dispatch::DecodeDifferent::Encode(
+							&[ #(
+								#frame_support::dispatch::FunctionArgumentMetadata {
+									name: #frame_support::dispatch::DecodeDifferent::Encode(
+										stringify!(#args_name)
+									),
+									ty: #frame_support::dispatch::DecodeDifferent::Encode(
+										#args_metadata_type
+									),
+								},
+							)* ]
+						),
+						documentation: #frame_support::dispatch::DecodeDifferent::Encode(
+							&[ #( #fn_doc ),* ]
+						),
+					},
+				)* ]
+			}
+		}
+	)
+}

frame/support/procedural/src/pallet/expand/constants.rs

@@ -0,0 +1,138 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2020 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use crate::pallet::Def;
+use frame_support_procedural_tools::clean_type_string;
+use quote::ToTokens;
+
+struct ConstDef {
+	/// Name of the associated type.
+	pub ident: syn::Ident,
+	/// The type in Get, e.g. `u32` in `type Foo: Get<u32>;`, but `Self` is replaced by `T`
+	pub type_: syn::Type,
+	/// The doc associated
+	pub doc: Vec<syn::Lit>,
+	/// default_byte implementation
+	pub default_byte_impl: proc_macro2::TokenStream,
+}
+
+/// * Impl fn module_constant_metadata for pallet.
+pub fn expand_constants(def: &mut Def) -> proc_macro2::TokenStream {
+	let frame_support = &def.frame_support;
+	let type_impl_gen = &def.type_impl_generics();
+	let type_decl_gen = &def.type_decl_generics();
+	let type_use_gen = &def.type_use_generics();
+	let pallet_ident = &def.pallet_struct.pallet;
+
+	let mut where_clauses = vec![&def.config.where_clause];
+	where_clauses.extend(def.extra_constants.iter().map(|d| &d.where_clause));
+	let completed_where_clause = super::merge_where_clauses(&where_clauses);
+
+	let config_consts = def.config.consts_metadata.iter().map(|const_| {
+		let ident = &const_.ident;
+		let const_type = &const_.type_;
+
+		ConstDef {
+			ident: const_.ident.clone(),
+			type_: const_.type_.clone(),
+			doc: const_.doc.clone(),
+			default_byte_impl: quote::quote!(
+				let value = <T::#ident as #frame_support::traits::Get<#const_type>>::get();
+				#frame_support::codec::Encode::encode(&value)
+			),
+		}
+	});
+
+	let extra_consts = def.extra_constants.iter().flat_map(|d| &d.extra_constants).map(|const_| {
+		let ident = &const_.ident;
+
+		ConstDef {
+			ident: const_.ident.clone(),
+			type_: const_.type_.clone(),
+			doc: const_.doc.clone(),
+			default_byte_impl: quote::quote!(
+				let value = <Pallet<#type_use_gen>>::#ident();
+				#frame_support::codec::Encode::encode(&value)
+			),
+		}
+	});
+
+	let consts = config_consts.chain(extra_consts)
+		.map(|const_| {
+			let const_type = &const_.type_;
+			let const_type_str = clean_type_string(&const_type.to_token_stream().to_string());
+			let ident = &const_.ident;
+			let ident_str = format!("{}", ident);
+			let doc = const_.doc.clone().into_iter();
+			let default_byte_impl = &const_.default_byte_impl;
+			let default_byte_getter = syn::Ident::new(
+				&format!("{}DefaultByteGetter", ident),
+				ident.span()
+			);
+
+			quote::quote!({
+				#[allow(non_upper_case_types)]
+				#[allow(non_camel_case_types)]
+				struct #default_byte_getter<#type_decl_gen>(
+					#frame_support::sp_std::marker::PhantomData<(#type_use_gen)>
+				);
+
+				impl<#type_impl_gen> #frame_support::dispatch::DefaultByte for
+					#default_byte_getter<#type_use_gen>
+					#completed_where_clause
+				{
+					fn default_byte(&self) -> #frame_support::sp_std::vec::Vec<u8> {
+						#default_byte_impl
+					}
+				}
+
+				unsafe impl<#type_impl_gen> Send for #default_byte_getter<#type_use_gen>
+					#completed_where_clause
+				{}
+				unsafe impl<#type_impl_gen> Sync for #default_byte_getter<#type_use_gen>
+					#completed_where_clause
+				{}
+
+				#frame_support::dispatch::ModuleConstantMetadata {
+					name: #frame_support::dispatch::DecodeDifferent::Encode(#ident_str),
+					ty: #frame_support::dispatch::DecodeDifferent::Encode(#const_type_str),
+					value: #frame_support::dispatch::DecodeDifferent::Encode(
+						#frame_support::dispatch::DefaultByteGetter(
+							&#default_byte_getter::<#type_use_gen>(
+								#frame_support::sp_std::marker::PhantomData
+							)
+						)
+					),
+					documentation: #frame_support::dispatch::DecodeDifferent::Encode(
+						&[ #( #doc ),* ]
+					),
+				}
+			})
+		});
+
+	quote::quote!(
+		impl<#type_impl_gen> #pallet_ident<#type_use_gen> #completed_where_clause{
+
+			#[doc(hidden)]
+			pub fn module_constants_metadata()
+				-> &'static [#frame_support::dispatch::ModuleConstantMetadata]
+			{
+				&[ #( #consts ),* ]
+			}
+		}
+	)
+}