wip/PoC: Enrich metadata custom types with essential types for chain communications

substrate/frame/support/procedural/src/construct_runtime/expand/metadata.rs

@@ -27,6 +27,8 @@ pub fn expand_runtime_metadata(
 	scrate: &TokenStream,
 	extrinsic: &TokenStream,
 	system_path: &PalletPath,
+	assets_pallet: Option<&Pallet>,
+	header: &TokenStream,
 ) -> TokenStream {
 	let pallets = pallet_declarations
 		.iter()
@@ -75,6 +77,23 @@ pub fn expand_runtime_metadata(
 		})
 		.collect::<Vec<_>>();
 
+	let maybe_asset_id = assets_pallet
+		.map(|pallet| {
+			let path = &pallet.path;
+			let instance = &pallet.instance;
+			let maybe_instance = instance.as_ref().map(|inst| quote! { <#inst> });
+
+			quote! {
+				(
+					"AssetId".into(),
+					#scrate::__private::scale_info::meta_type::<
+							<#runtime as #path::Config #maybe_instance>::AssetId
+						>(),
+				),
+			}
+		})
+		.unwrap_or_default();
+
 	quote! {
 		impl #runtime {
 			fn metadata_ir() -> #scrate::__private::metadata_ir::MetadataIR {
@@ -140,6 +159,43 @@ pub fn expand_runtime_metadata(
 							>(),
 						event_enum_ty: #scrate::__private::scale_info::meta_type::<RuntimeEvent>(),
 						error_enum_ty: #scrate::__private::scale_info::meta_type::<RuntimeError>(),
+					},
+					custom_types: #scrate::__private::metadata_ir::CustomMetadataIR {
+						map: [
+							(
+								"AccountId".into(),
+								#scrate::__private::scale_info::meta_type::<
+										<#runtime as #system_path::Config>::AccountId
+									>(),
+							),
+							(
+								"Address".into(),
+								address_ty,
+							),
+							(
+								"Signature".into(),
+								signature_ty,
+							),
+							(
+								"Hash".into(),
+								#scrate::__private::scale_info::meta_type::<
+										<#runtime as #system_path::Config>::Hash
+									>(),
+							),
+							(
+								"Hashing".into(),
+								#scrate::__private::scale_info::meta_type::<
+										<#runtime as #system_path::Config>::Hashing
+									>(),
+							),
+							(
+								"Header".into(),
+								#scrate::__private::scale_info::meta_type::<#header>(),
+							),
+							#maybe_asset_id
+						]
+						.into_iter()
+						.collect(),
 					}
 				}
 			}

substrate/frame/support/procedural/src/construct_runtime/mod.rs

@@ -226,6 +226,10 @@ use syn::{spanned::Spanned, Ident, Result};
 
 /// The fixed name of the system pallet.
 const SYSTEM_PALLET_NAME: &str = "System";
+/// The fixed name of the ForeignAssets pallet.
+const FOREIGN_ASSETS_PALLET_NAME: &str = "ForeignAssets";
+/// The fixed name of the Assets pallet.
+const ASSETS_PALLET_NAME: &str = "Assets";
 
 /// Implementation of `construct_runtime` macro. Either expand to some code which will call
 /// `construct_runtime` again, or expand to the final runtime definition.
@@ -365,6 +369,12 @@ fn construct_runtime_final_expansion(
 		))
 	}
 
+	// Find either the foreign assets pallet or the local assets pallet in this order.
+	let assets_pallet = pallets
+		.iter()
+		.find(|decl| decl.name == FOREIGN_ASSETS_PALLET_NAME)
+		.or_else(|| pallets.iter().find(|decl| decl.name == ASSETS_PALLET_NAME));
+
 	let features = pallets
 		.iter()
 		.filter_map(|decl| {
@@ -388,6 +398,7 @@ fn construct_runtime_final_expansion(
 	let frame_system = generate_access_from_frame_or_crate("frame-system")?;
 	let block = quote!(<#name as #frame_system::Config>::Block);
 	let unchecked_extrinsic = quote!(<#block as #scrate::sp_runtime::traits::Block>::Extrinsic);
+	let header = quote!(<#block as #scrate::sp_runtime::traits::Block>::Header);
 
 	let outer_event =
 		expand::expand_outer_enum(&name, &pallets, &scrate, expand::OuterEnumType::Event)?;
@@ -406,6 +417,8 @@ fn construct_runtime_final_expansion(
 		&scrate,
 		&unchecked_extrinsic,
 		&system_pallet.path,
+		assets_pallet,
+		&header,
 	);
 	let outer_config = expand::expand_outer_config(&name, &pallets, &scrate);
 	let inherent =

substrate/frame/support/procedural/src/runtime/expand/mod.rs

@@ -39,6 +39,10 @@ use syn::{Ident, Result};
 
 /// The fixed name of the system pallet.
 const SYSTEM_PALLET_NAME: &str = "System";
+/// The fixed name of the ForeignAssets pallet.
+const FOREIGN_ASSETS_PALLET_NAME: &str = "ForeignAssets";
+/// The fixed name of the Assets pallet.
+const ASSETS_PALLET_NAME: &str = "Assets";
 
 pub fn expand(def: Def, legacy_ordering: bool) -> TokenStream2 {
 	let input = def.input;
@@ -143,6 +147,12 @@ fn construct_runtime_final_expansion(
 		))
 	}
 
+	// Find either the foreign assets pallet or the local assets pallet in this order.
+	let assets_pallet = pallets
+		.iter()
+		.find(|decl| decl.name == FOREIGN_ASSETS_PALLET_NAME)
+		.or_else(|| pallets.iter().find(|decl| decl.name == ASSETS_PALLET_NAME));
+
 	let features = pallets
 		.iter()
 		.filter_map(|decl| {
@@ -166,6 +176,7 @@ fn construct_runtime_final_expansion(
 	let frame_system = generate_access_from_frame_or_crate("frame-system")?;
 	let block = quote!(<#name as #frame_system::Config>::Block);
 	let unchecked_extrinsic = quote!(<#block as #scrate::sp_runtime::traits::Block>::Extrinsic);
+	let header = quote!(<#block as #scrate::sp_runtime::traits::Block>::Header);
 
 	let mut dispatch = None;
 	let mut outer_event = None;
@@ -230,6 +241,8 @@ fn construct_runtime_final_expansion(
 		&scrate,
 		&unchecked_extrinsic,
 		&system_pallet.path,
+		assets_pallet,
+		&header,
 	);
 	let outer_config = expand::expand_outer_config(&name, &pallets, &scrate);
 	let inherent =

substrate/primitives/metadata-ir/src/types.rs

@@ -18,7 +18,7 @@
 use codec::Encode;
 use scale_info::{
 	form::{Form, MetaForm, PortableForm},
-	prelude::vec::Vec,
+	prelude::{collections::BTreeMap, vec::Vec},
 	IntoPortable, MetaType, Registry,
 };
 
@@ -41,6 +41,8 @@ pub struct MetadataIR<T: Form = MetaForm> {
 	pub apis: Vec<RuntimeApiMetadataIR<T>>,
 	/// The outer enums types as found in the runtime.
 	pub outer_enums: OuterEnumsIR<T>,
+	/// The custom types collected by the runtime.
+	pub custom_types: CustomMetadataIR<T>,
 }
 
 /// Metadata of a runtime trait.
@@ -368,6 +370,27 @@ impl From<MetaType> for PalletEventMetadataIR {
 	}
 }
 
+/// Metadata for custom types.
+#[derive(Clone, PartialEq, Eq, Encode, Debug)]
+pub struct CustomMetadataIR<T: Form = MetaForm> {
+	/// The custom map.
+	pub map: BTreeMap<T::String, T::Type>,
+}
+
+impl IntoPortable for CustomMetadataIR {
+	type Output = CustomMetadataIR<PortableForm>;
+
+	fn into_portable(self, registry: &mut Registry) -> Self::Output {
+		let map = self
+			.map
+			.into_iter()
+			.map(|(key, value)| (key.into_portable(registry), registry.register_type(&value)))
+			.collect();
+
+		CustomMetadataIR { map }
+	}
+}
+
 /// Metadata about one pallet constant.
 #[derive(Clone, PartialEq, Eq, Encode, Debug)]
 pub struct PalletConstantMetadataIR<T: Form = MetaForm> {

substrate/primitives/metadata-ir/src/v15.rs

@@ -17,17 +17,16 @@
 
 //! Convert the IR to V15 metadata.
 
-use crate::OuterEnumsIR;
-
 use super::types::{
-	ExtrinsicMetadataIR, MetadataIR, PalletMetadataIR, RuntimeApiMetadataIR,
-	RuntimeApiMethodMetadataIR, RuntimeApiMethodParamMetadataIR, SignedExtensionMetadataIR,
+	CustomMetadataIR, ExtrinsicMetadataIR, MetadataIR, OuterEnumsIR, PalletMetadataIR,
+	RuntimeApiMetadataIR, RuntimeApiMethodMetadataIR, RuntimeApiMethodParamMetadataIR,
+	SignedExtensionMetadataIR,
 };
 
 use frame_metadata::v15::{
-	CustomMetadata, ExtrinsicMetadata, OuterEnums, PalletMetadata, RuntimeApiMetadata,
-	RuntimeApiMethodMetadata, RuntimeApiMethodParamMetadata, RuntimeMetadataV15,
-	SignedExtensionMetadata,
+	CustomMetadata, CustomValueMetadata, ExtrinsicMetadata, OuterEnums, PalletMetadata,
+	RuntimeApiMetadata, RuntimeApiMethodMetadata, RuntimeApiMethodParamMetadata,
+	RuntimeMetadataV15, SignedExtensionMetadata,
 };
 
 impl From<MetadataIR> for RuntimeMetadataV15 {
@@ -38,9 +37,8 @@ impl From<MetadataIR> for RuntimeMetadataV15 {
 			ir.ty,
 			ir.apis.into_iter().map(Into::into).collect(),
 			ir.outer_enums.into(),
-			// Substrate does not collect yet the custom metadata fields.
 			// This allows us to extend the V15 easily.
-			CustomMetadata { map: Default::default() },
+			ir.custom_types.into(),
 		)
 	}
 }
@@ -119,3 +117,15 @@ impl From<OuterEnumsIR> for OuterEnums {
 		}
 	}
 }
+
+impl From<CustomMetadataIR> for CustomMetadata {
+	fn from(ir: CustomMetadataIR) -> Self {
+		CustomMetadata {
+			map: ir
+				.map
+				.into_iter()
+				.map(|(name, ty)| (name, CustomValueMetadata { ty, value: Default::default() }))
+				.collect(),
+		}
+	}
+}