v16: Expose the unstable metadata v16

Cargo.toml

@@ -760,7 +760,7 @@ frame-benchmarking-pallet-pov = { default-features = false, path = "substrate/fr
 frame-election-provider-solution-type = { path = "substrate/frame/election-provider-support/solution-type", default-features = false }
 frame-election-provider-support = { path = "substrate/frame/election-provider-support", default-features = false }
 frame-executive = { path = "substrate/frame/executive", default-features = false }
-frame-metadata = { version = "16.0.0", default-features = false }
+frame-metadata = { git = "https://github.com/paritytech/frame-metadata.git", branch = "lexnv/metadata-v16-associated-types", default-features = false }
 frame-metadata-hash-extension = { path = "substrate/frame/metadata-hash-extension", default-features = false }
 frame-support = { path = "substrate/frame/support", default-features = false }
 frame-support-procedural = { path = "substrate/frame/support/procedural", default-features = false }

prdoc/pr_5274.prdoc

@@ -0,0 +1,24 @@
+title: Enrich metadata IR with associated types of config traits
+
+doc:
+  - audience: Runtime Dev
+    description: |
+      This feature is part of the upcoming metadata V16. The associated types of the `Config` trait that require the `TypeInfo`
+      or `Parameter` bounds are included in the metadata of the pallet. The metadata is not yet exposed to the end-user, however
+      the metadata intermediate representation (IR) contains these types.
+
+      Developers can opt out of metadata collection of the associated types by specifying `without_metadata` optional attribute
+      to the `#[pallet::config]`.
+
+      Furthermore, the `without_metadata` argument can be used in combination with the newly added `#[pallet::include_metadata]`
+      attribute to selectively include only certain associated types in the metadata collection.
+
+crates:
+  - name: frame-support
+    bump: patch
+  - name: frame-support-procedural
+    bump: patch
+  - name: frame-support-procedural-tools
+    bump: patch
+  - name: sp-metadata-ir
+    bump: major

substrate/frame/metadata-hash-extension/Cargo.toml

@@ -24,7 +24,7 @@ substrate-test-runtime-client = { workspace = true }
 sp-api = { workspace = true, default-features = true }
 sp-transaction-pool = { workspace = true, default-features = true }
 merkleized-metadata = { workspace = true }
-frame-metadata = { features = ["current"], workspace = true, default-features = true }
+frame-metadata = { features = ["current","unstable"], workspace = true, default-features = true }
 sp-tracing = { workspace = true, default-features = true }
 
 [features]

substrate/frame/support/Cargo.toml

@@ -28,6 +28,7 @@ scale-info = { features = [
 ], workspace = true }
 frame-metadata = { features = [
 	"current",
+	"unstable",
 ], workspace = true }
 sp-api = { features = [
 	"frame-metadata",

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

@@ -49,6 +49,7 @@ pub fn expand_runtime_metadata(
 			let event = expand_pallet_metadata_events(&filtered_names, runtime, decl);
 			let constants = expand_pallet_metadata_constants(runtime, decl);
 			let errors = expand_pallet_metadata_errors(runtime, decl);
+			let associated_types = expand_pallet_metadata_associated_types(runtime, decl);
 			let docs = expand_pallet_metadata_docs(runtime, decl);
 			let attr = decl.cfg_pattern.iter().fold(TokenStream::new(), |acc, pattern| {
 				let attr = TokenStream::from_str(&format!("#[cfg({})]", pattern.original()))
@@ -70,6 +71,7 @@ pub fn expand_runtime_metadata(
 					constants: #constants,
 					error: #errors,
 					docs: #docs,
+					associated_types: #associated_types,
 					deprecation_info: #deprecation_info,
 				}
 			}
@@ -261,3 +263,12 @@ fn expand_pallet_metadata_docs(runtime: &Ident, decl: &Pallet) -> TokenStream {
 		#path::Pallet::<#runtime #(, #path::#instance)*>::pallet_documentation_metadata()
 	}
 }
+
+fn expand_pallet_metadata_associated_types(runtime: &Ident, decl: &Pallet) -> TokenStream {
+	let path = &decl.path;
+	let instance = decl.instance.as_ref().into_iter();
+
+	quote! {
+		#path::Pallet::<#runtime #(, #path::#instance)*>::pallet_associated_types_metadata()
+	}
+}

substrate/frame/support/procedural/src/lib.rs

@@ -956,6 +956,15 @@ pub fn event(_: TokenStream, _: TokenStream) -> TokenStream {
 	pallet_macro_stub()
 }
 
+///
+/// ---
+///
+/// Documentation for this macro can be found at `frame_support::pallet_macros::include_metadata`.
+#[proc_macro_attribute]
+pub fn include_metadata(_: TokenStream, _: TokenStream) -> TokenStream {
+	pallet_macro_stub()
+}
+
 ///
 /// ---
 ///

substrate/frame/support/procedural/src/pallet/expand/config.rs

@@ -95,3 +95,50 @@ Consequently, a runtime that wants to include this pallet must implement this tr
 		_ => Default::default(),
 	}
 }
+
+/// Generate the metadata for the associated types of the config trait.
+///
+/// Implements the `pallet_associated_types_metadata` function for the pallet.
+pub fn expand_config_metadata(def: &Def) -> proc_macro2::TokenStream {
+	let frame_support = &def.frame_support;
+	let type_impl_gen = &def.type_impl_generics(proc_macro2::Span::call_site());
+	let type_use_gen = &def.type_use_generics(proc_macro2::Span::call_site());
+	let pallet_ident = &def.pallet_struct.pallet;
+	let trait_use_gen = &def.trait_use_generics(proc_macro2::Span::call_site());
+
+	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 types = def.config.associated_types_metadata.iter().map(|metadata| {
+		let ident = &metadata.ident;
+		let ident_str = format!("{}", ident);
+		let cfgs = &metadata.cfg;
+
+		let no_docs = vec![];
+		let doc = if cfg!(feature = "no-metadata-docs") { &no_docs } else { &metadata.doc };
+
+		quote::quote!({
+			#( #cfgs ) *
+			#frame_support::__private::metadata_ir::PalletAssociatedTypeMetadataIR {
+				name: #ident_str,
+				ty: #frame_support::__private::scale_info::meta_type::<
+						<T as Config #trait_use_gen>::#ident
+					>(),
+				docs: #frame_support::__private::sp_std::vec![ #( #doc ),* ],
+			}
+		})
+	});
+
+	quote::quote!(
+		impl<#type_impl_gen> #pallet_ident<#type_use_gen> #completed_where_clause {
+
+			#[doc(hidden)]
+			pub fn pallet_associated_types_metadata()
+				-> #frame_support::__private::sp_std::vec::Vec<#frame_support::__private::metadata_ir::PalletAssociatedTypeMetadataIR>
+			{
+				#frame_support::__private::sp_std::vec![ #( #types ),* ]
+			}
+		}
+	)
+}

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

@@ -60,6 +60,7 @@ pub fn expand(mut def: Def) -> proc_macro2::TokenStream {
 	let constants = constants::expand_constants(&mut def);
 	let pallet_struct = pallet_struct::expand_pallet_struct(&mut def);
 	let config = config::expand_config(&mut def);
+	let associated_types = config::expand_config_metadata(&def);
 	let call = call::expand_call(&mut def);
 	let tasks = tasks::expand_tasks(&mut def);
 	let error = error::expand_error(&mut def);
@@ -101,6 +102,7 @@ storage item. Otherwise, all storage items are listed among [*Type Definitions*]
 		#constants
 		#pallet_struct
 		#config
+		#associated_types
 		#call
 		#tasks
 		#error