Metadata V15: Add Runtime API metadata (#13302)

* impl_runtime_apis: Generate getters for `metadata_at` functions Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * runtime: Implement new `Metadata` runtime trait Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * runtime: Move `metadata_at` functions to construct_runtime macro Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * contruct_runtime: Use `OpaqueMetadata` from hidden imports Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * Adjust testing Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * frame/tests: Add tests for the new API Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/proc-macro: Helper to extract documentation literals Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/proc-macro: Helper to filter all `cfg` attributes Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/proc-macro: Generate documentation getters for metadata Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/proc-macro: Avoid trait collision with snake case methods Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * proc-macro/tests: Check doc getters Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/proc-macro: Generate metadata for runtime methods Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/api: Export scale-info and frame-metadata Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/proc-macro: Generate metadata for runtime traits Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * frame/runtime: Expose metadata v15 internally Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * test: Use metadata v15 from `lexnv/md_v15_test` branch Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/proc-macro: Generate crate access one module up Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * frame: Implement `runtime_metadata` for mocks and tests Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/proc-macro: Fix warnings Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/proc-macro: Add no-docs flag Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * frame: Adjust more tests Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * frame/tests: Check runtime metadata correctness Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * frame/benchmarking: Adjust benchmarks Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * frame/benchmarks: Adjust more benchmarks Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/api: Fix clippy Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/proc-macro: Generate runtime metadata on the `decl_runtime_apis` Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * frame: Abuse Deref to resolve `runtime_metadata` Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * Revert "frame: Implement `runtime_metadata` for mocks and tests" This reverts commit b7f41aa189218589392a6e713ea9488e93c4db45. Revert "frame: Adjust more tests" This reverts commit 3cba5982c7f45552e76335e96c430aecbc42d8c6. Revert "frame/benchmarking: Adjust benchmarks" This reverts commit 60b382ada486c791ffceeb65da587e949b90ec5d. Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> Revert "frame/benchmarks: Adjust more benchmarks" This reverts commit eb75c477179b1a27347a5554c5732ef26a00d7e8. * primitives/proc-macro: Remove unused imports and function Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * frame/support: Adjust runtime metadata test Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/tests: Remove doc getter test Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * frame/support: Enable `no-metadata-docs` feature from `sp-api` Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/tests: Add `TypeInfo` for test::extrinsic Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/api: Expose scale-info and frame-metadata Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * Update frame-metadata to include v15 Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * Fix merge conflicts Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * frame/metadata_ir: Add IR for runtime API metadata Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * frame/metadata_ir: Convert IR to V15 Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/api: Collect IR metadata for runtime API Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/api: Move `metadata_ir` from frame/support Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * frame/tests: Adjust testing Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * frame/tests: Adjust `metadata_versions` test Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/runtime_metadata: Exclude default type parameters from methods Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * Update primitives/api/proc-macro/src/runtime_metadata.rs Co-authored-by: Bastian Köcher <git@kchr.de> * Update primitives/api/src/metadata_ir/types.rs Co-authored-by: Bastian Köcher <git@kchr.de> * Update primitives/api/src/metadata_ir/mod.rs Co-authored-by: Bastian Köcher <git@kchr.de> * Update primitives/api/proc-macro/src/utils.rs Co-authored-by: Bastian Köcher <git@kchr.de> * Update primitives/api/proc-macro/src/runtime_metadata.rs Co-authored-by: Bastian Köcher <git@kchr.de> * Update primitives/api/proc-macro/src/runtime_metadata.rs Co-authored-by: Bastian Köcher <git@kchr.de> * Update primitives/api/proc-macro/src/runtime_metadata.rs Co-authored-by: Bastian Köcher <git@kchr.de> * Update primitives/api/proc-macro/src/runtime_metadata.rs Co-authored-by: Bastian Köcher <git@kchr.de> * Update primitives/api/proc-macro/src/runtime_metadata.rs Co-authored-by: Bastian Köcher <git@kchr.de> * Update primitives/api/proc-macro/src/runtime_metadata.rs Co-authored-by: Bastian Köcher <git@kchr.de> * primitives: Fix build Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives/metadata-ir: Move IR to dedicated crate Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives: Reexport metadata-ir and frame-metadata Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * frame: Use apis field instead of runtime Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * Better documentation for the `Deref` abstraction Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * ui-tests: Check empty `impl_runtime_apis` Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives: Remove unneeded bounds on generic params Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives: Rename `collect_where_bounds` to `get_argument_type_param` Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives: Generate crate access per fn call Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * Revert "primitives: Remove unneeded bounds on generic params" This reverts commit 5178e38cf21cfb481156eefd628d62989201d59a. * metadata-ir: Add no-std Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * primitives: Adjust where bounds Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * Change `frame-metadata` branch to "origin/main" Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * Update to `main` from origin Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * Update frame-metadata to crates.io v15.1 Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * Revert "ui-tests: Check empty `impl_runtime_apis`" This reverts commit cf78a7190ad9cba3c3bb2e78dc3d0dc382b2fea9. * Move ui test to primitives/ui Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * Update frame/support/test/tests/runtime_metadata.rs Co-authored-by: Bastian Köcher <git@kchr.de> * Update primitives/api/proc-macro/src/runtime_metadata.rs Co-authored-by: Bastian Köcher <git@kchr.de> * Test already covered by `empty_impl_runtime_apis_call.stderr` This reverts commit 3bafb294cbe9745569bf5e5a1a2e6b4a4c1aadc5. * Retriger CI Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * Import `TokenStream` as `TokenStream2` Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> --------- Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> Co-authored-by: parity-processbot <> Co-authored-by: Bastian Köcher <git@kchr.de>
2026-04-26 09:57:56 +00:00 · 2023-04-11 14:07:52 +03:00
parent 17765733f0
commit 29ea9e0ad9
25 changed files with 993 additions and 31 deletions
@@ -15,16 +15,18 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.

-use crate::utils::{
-	extract_parameter_names_types_and_borrows, fold_fn_decl_for_client_side, generate_crate_access,
-	generate_runtime_mod_name_for_trait, parse_runtime_api_version, prefix_function_with_trait,
-	replace_wild_card_parameter_names, return_type_extract_type, versioned_trait_name,
-	AllowSelfRefInParameters,
-};
-
-use crate::common::{
-	API_VERSION_ATTRIBUTE, BLOCK_GENERIC_IDENT, CHANGED_IN_ATTRIBUTE, CORE_TRAIT_ATTRIBUTE,
-	RENAMED_ATTRIBUTE, SUPPORTED_ATTRIBUTE_NAMES,
+use crate::{
+	common::{
+		API_VERSION_ATTRIBUTE, BLOCK_GENERIC_IDENT, CHANGED_IN_ATTRIBUTE, CORE_TRAIT_ATTRIBUTE,
+		RENAMED_ATTRIBUTE, SUPPORTED_ATTRIBUTE_NAMES,
+	},
+	runtime_metadata::generate_decl_runtime_metadata,
+	utils::{
+		extract_parameter_names_types_and_borrows, fold_fn_decl_for_client_side,
+		generate_crate_access, generate_runtime_mod_name_for_trait, parse_runtime_api_version,
+		prefix_function_with_trait, replace_wild_card_parameter_names, return_type_extract_type,
+		versioned_trait_name, AllowSelfRefInParameters,
+	},
 };

 use proc_macro2::{Span, TokenStream};
@@ -219,6 +221,7 @@ fn generate_runtime_decls(decls: &[ItemTrait]) -> Result<TokenStream> {
 		let mut decl = decl.clone();
 		let decl_span = decl.span();
 		extend_generics_with_block(&mut decl.generics);
+		let metadata = generate_decl_runtime_metadata(&decl);
 		let mod_name = generate_runtime_mod_name_for_trait(&decl.ident);
 		let found_attributes = remove_supported_attributes(&mut decl.attrs);
 		let api_version =
@@ -304,6 +307,8 @@ fn generate_runtime_decls(decls: &[ItemTrait]) -> Result<TokenStream> {

 				pub use #versioned_ident as #main_api_ident;

+				#metadata
+
 				pub #api_version

 				pub #id
@@ -15,15 +15,17 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.

-use crate::utils::{
-	extract_all_signature_types, extract_block_type_from_trait_path, extract_impl_trait,
-	extract_parameter_names_types_and_borrows, generate_crate_access,
-	generate_runtime_mod_name_for_trait, parse_runtime_api_version, prefix_function_with_trait,
-	versioned_trait_name, AllowSelfRefInParameters, RequireQualifiedTraitPath,
+use crate::{
+	common::API_VERSION_ATTRIBUTE,
+	runtime_metadata::generate_impl_runtime_metadata,
+	utils::{
+		extract_all_signature_types, extract_block_type_from_trait_path, extract_impl_trait,
+		extract_parameter_names_types_and_borrows, generate_crate_access,
+		generate_runtime_mod_name_for_trait, parse_runtime_api_version, prefix_function_with_trait,
+		versioned_trait_name, AllowSelfRefInParameters, RequireQualifiedTraitPath,
+	},
 };

-use crate::common::API_VERSION_ATTRIBUTE;
-
 use proc_macro2::{Span, TokenStream};

 use quote::quote;
@@ -685,6 +687,7 @@ fn impl_runtime_apis_impl_inner(api_impls: &[ItemImpl]) -> Result<TokenStream> {
 	let runtime_api_versions = generate_runtime_api_versions(api_impls)?;
 	let wasm_interface = generate_wasm_interface(api_impls)?;
 	let api_impls_for_runtime_api = generate_api_impl_for_runtime_api(api_impls)?;
+	let runtime_metadata = generate_impl_runtime_metadata(api_impls)?;

 	let impl_ = quote!(
 		#base_runtime_api
@@ -695,6 +698,8 @@ fn impl_runtime_apis_impl_inner(api_impls: &[ItemImpl]) -> Result<TokenStream> {

 		#runtime_api_versions

+		#runtime_metadata
+
 		pub mod api {
 			use super::*;

@@ -25,6 +25,7 @@ mod common;
 mod decl_runtime_apis;
 mod impl_runtime_apis;
 mod mock_impl_runtime_apis;
+mod runtime_metadata;
 mod utils;

 #[proc_macro]
@@ -0,0 +1,271 @@
+// This file is part of Substrate.
+
+// Copyright (C) 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 proc_macro2::TokenStream as TokenStream2;
+use quote::quote;
+use syn::{parse_quote, ItemImpl, ItemTrait, Result};
+
+use crate::{
+	common::CHANGED_IN_ATTRIBUTE,
+	utils::{
+		extract_impl_trait, filter_cfg_attributes, generate_crate_access,
+		generate_runtime_mod_name_for_trait, get_doc_literals, RequireQualifiedTraitPath,
+	},
+};
+
+/// Get the type parameter argument without lifetime or mutability
+/// of a runtime metadata function.
+///
+/// In the following example, both the `AccountId` and `Index` generic
+/// type parameters must implement `scale_info::TypeInfo` because they
+/// are added into the metadata using `scale_info::meta_type`.
+///
+/// ```ignore
+/// trait ExampleAccountNonceApi<AccountId, Index> {
+///   fn account_nonce<'a>(account: &'a AccountId) -> Index;
+/// }
+/// ```
+///
+/// Instead of returning `&'a AccountId` for the first parameter, this function
+/// returns `AccountId` to place bounds around it.
+fn get_type_param(ty: &syn::Type) -> syn::Type {
+	// Remove the lifetime and mutability of the type T to
+	// place bounds around it.
+	let ty_elem = match &ty {
+		syn::Type::Reference(reference) => &reference.elem,
+		syn::Type::Ptr(ptr) => &ptr.elem,
+		syn::Type::Slice(slice) => &slice.elem,
+		syn::Type::Array(arr) => &arr.elem,
+		_ => ty,
+	};
+
+	ty_elem.clone()
+}
+
+/// Extract the documentation from the provided attributes.
+///
+/// It takes into account the `no-metadata-docs` feature.
+fn collect_docs(attrs: &[syn::Attribute], crate_: &TokenStream2) -> TokenStream2 {
+	if cfg!(feature = "no-metadata-docs") {
+		quote!(#crate_::vec![])
+	} else {
+		let docs = get_doc_literals(&attrs);
+		quote!(#crate_::vec![ #( #docs, )* ])
+	}
+}
+
+/// Generate the runtime metadata of the provided trait.
+///
+/// The metadata is exposed as a generic function on the hidden module
+/// of the trait generated by the `decl_runtime_apis`.
+pub fn generate_decl_runtime_metadata(decl: &ItemTrait) -> TokenStream2 {
+	let crate_ = generate_crate_access();
+	let mut methods = Vec::new();
+
+	// Ensure that any function parameter that relies on the `BlockT` bounds
+	// also has `TypeInfo + 'static` bounds (required by `scale_info::meta_type`).
+	//
+	// For example, if a runtime API defines a method that has an input:
+	// `fn func(input: <Block as BlockT>::Header)`
+	// then the runtime metadata will imply `<Block as BlockT>::Header: TypeInfo + 'static`.
+	//
+	// This restricts the bounds at the metadata level, without needing to modify the `BlockT`
+	// itself, since the concrete implementations are already satisfying `TypeInfo`.
+	let mut where_clause = Vec::new();
+	for item in &decl.items {
+		// Collect metadata for methods only.
+		let syn::TraitItem::Method(method) = item else {
+			continue
+		};
+
+		// Collect metadata only for the latest methods.
+		let is_changed_in =
+			method.attrs.iter().any(|attr| attr.path.is_ident(CHANGED_IN_ATTRIBUTE));
+		if is_changed_in {
+			continue
+		}
+
+		let mut inputs = Vec::new();
+		let signature = &method.sig;
+		for input in &signature.inputs {
+			// Exclude `self` from metadata collection.
+			let syn::FnArg::Typed(typed) = input else {
+				continue
+			};
+
+			let pat = &typed.pat;
+			let name = quote!(#pat).to_string();
+			let ty = &typed.ty;
+
+			where_clause.push(get_type_param(ty));
+
+			inputs.push(quote!(
+				#crate_::metadata_ir::RuntimeApiMethodParamMetadataIR {
+					name: #name,
+					ty: #crate_::scale_info::meta_type::<#ty>(),
+				}
+			));
+		}
+
+		let output = match &signature.output {
+			syn::ReturnType::Default => quote!(#crate_::scale_info::meta_type::<()>()),
+			syn::ReturnType::Type(_, ty) => {
+				where_clause.push(get_type_param(ty));
+				quote!(#crate_::scale_info::meta_type::<#ty>())
+			},
+		};
+
+		// String method name including quotes for constructing `v15::RuntimeApiMethodMetadata`.
+		let method_name = signature.ident.to_string();
+		let docs = collect_docs(&method.attrs, &crate_);
+
+		// Include the method metadata only if its `cfg` features are enabled.
+		let attrs = filter_cfg_attributes(&method.attrs);
+		methods.push(quote!(
+			#( #attrs )*
+			#crate_::metadata_ir::RuntimeApiMethodMetadataIR {
+				name: #method_name,
+				inputs: #crate_::vec![ #( #inputs, )* ],
+				output: #output,
+				docs: #docs,
+			}
+		));
+	}
+
+	let trait_name_ident = &decl.ident;
+	let trait_name = trait_name_ident.to_string();
+	let docs = collect_docs(&decl.attrs, &crate_);
+	let attrs = filter_cfg_attributes(&decl.attrs);
+	// The trait generics where already extended with `Block: BlockT`.
+	let mut generics = decl.generics.clone();
+	for generic_param in generics.params.iter_mut() {
+		let syn::GenericParam::Type(ty) = generic_param else {
+			continue
+		};
+
+		// Default type parameters are not allowed in functions.
+		ty.eq_token = None;
+		ty.default = None;
+	}
+
+	let where_clause = where_clause
+		.iter()
+		.map(|ty| quote!(#ty: #crate_::scale_info::TypeInfo + 'static));
+
+	quote!(
+		#( #attrs )*
+		#[inline(always)]
+		pub fn runtime_metadata #generics () -> #crate_::metadata_ir::RuntimeApiMetadataIR
+		where #( #where_clause, )*
+		{
+			#crate_::metadata_ir::RuntimeApiMetadataIR {
+				name: #trait_name,
+				methods: #crate_::vec![ #( #methods, )* ],
+				docs: #docs,
+			}
+		}
+	)
+}
+
+/// Implement the `runtime_metadata` function on the runtime that
+/// generates the metadata for the given traits.
+///
+/// The metadata of each trait is extracted from the generic function
+/// exposed by `generate_decl_runtime_metadata`.
+pub fn generate_impl_runtime_metadata(impls: &[ItemImpl]) -> Result<TokenStream2> {
+	if impls.is_empty() {
+		return Ok(quote!())
+	}
+
+	let crate_ = generate_crate_access();
+
+	// Get the name of the runtime for which the traits are implemented.
+	let runtime_name = &impls
+		.get(0)
+		.expect("Traits should contain at least one implementation; qed")
+		.self_ty;
+
+	let mut metadata = Vec::new();
+
+	for impl_ in impls {
+		let mut trait_ = extract_impl_trait(&impl_, RequireQualifiedTraitPath::Yes)?.clone();
+
+		// Implementation traits are always references with a path `impl client::Core<generics> ...`
+		// The trait name is the last segment of this path.
+		let trait_name_ident = &trait_
+			.segments
+			.last()
+			.as_ref()
+			.expect("Trait path should always contain at least one item; qed")
+			.ident;
+
+		// Extract the generics from the trait to pass to the `runtime_metadata`
+		// function on the hidden module.
+		let generics = trait_
+			.segments
+			.iter()
+			.find_map(|segment| {
+				if let syn::PathArguments::AngleBracketed(generics) = &segment.arguments {
+					Some(generics.clone())
+				} else {
+					None
+				}
+			})
+			.expect("Trait path should always contain at least one generic parameter; qed");
+
+		let mod_name = generate_runtime_mod_name_for_trait(&trait_name_ident);
+		// Get absolute path to the `runtime_decl_for_` module by replacing the last segment.
+		if let Some(segment) = trait_.segments.last_mut() {
+			*segment = parse_quote!(#mod_name);
+		}
+
+		let attrs = filter_cfg_attributes(&impl_.attrs);
+		metadata.push(quote!(
+			#( #attrs )*
+			#trait_::runtime_metadata::#generics()
+		));
+	}
+
+	// Each runtime must expose the `runtime_metadata()` to fetch the runtime API metadata.
+	// The function is implemented by calling `impl_runtime_apis!`.
+	//
+	// However, the `construct_runtime!` may be called without calling `impl_runtime_apis!`.
+	// Rely on the `Deref` trait to differentiate between a runtime that implements
+	// APIs (by macro impl_runtime_apis!) and a runtime that is simply created (by macro
+	// construct_runtime!).
+	//
+	// Both `InternalConstructRuntime` and `InternalImplRuntimeApis` expose a `runtime_metadata()`
+	// function. `InternalConstructRuntime` is implemented by the `construct_runtime!` for Runtime
+	// references (`& Runtime`), while `InternalImplRuntimeApis` is implemented by the
+	// `impl_runtime_apis!` for Runtime (`Runtime`).
+	//
+	// Therefore, the `Deref` trait will resolve the `runtime_metadata` from `impl_runtime_apis!`
+	// when both macros are called; and will resolve an empty `runtime_metadata` when only the
+	// `construct_runtime!` is called.
+
+	Ok(quote!(
+		#[doc(hidden)]
+		trait InternalImplRuntimeApis {
+			#[inline(always)]
+			fn runtime_metadata(&self) -> #crate_::vec::Vec<#crate_::metadata_ir::RuntimeApiMetadataIR> {
+				#crate_::vec![ #( #metadata, )* ]
+			}
+		}
+		#[doc(hidden)]
+		impl InternalImplRuntimeApis for #runtime_name {}
+	))
+}
@@ -253,7 +253,74 @@ pub fn parse_runtime_api_version(version: &Attribute) -> Result<u64> {
 	version.base10_parse()
 }

-// Each versioned trait is named 'ApiNameVN' where N is the specific version. E.g. ParachainHostV2
+/// Each versioned trait is named 'ApiNameVN' where N is the specific version. E.g. ParachainHostV2
 pub fn versioned_trait_name(trait_ident: &Ident, version: u64) -> Ident {
 	format_ident!("{}V{}", trait_ident, version)
 }
+
+/// Extract the documentation from the provided attributes.
+pub fn get_doc_literals(attrs: &[syn::Attribute]) -> Vec<syn::Lit> {
+	attrs
+		.iter()
+		.filter_map(|attr| {
+			let Ok(syn::Meta::NameValue(meta)) = attr.parse_meta() else {
+				return None
+			};
+
+			meta.path.get_ident().filter(|ident| *ident == "doc").map(|_| meta.lit)
+		})
+		.collect()
+}
+
+/// Filters all attributes except the cfg ones.
+pub fn filter_cfg_attributes(attrs: &[syn::Attribute]) -> Vec<syn::Attribute> {
+	attrs.iter().filter(|a| a.path.is_ident("cfg")).cloned().collect()
+}
+
+#[cfg(test)]
+mod tests {
+	use assert_matches::assert_matches;
+
+	use super::*;
+
+	#[test]
+	fn check_get_doc_literals() {
+		const FIRST: &'static str = "hello";
+		const SECOND: &'static str = "WORLD";
+
+		let doc: Attribute = parse_quote!(#[doc = #FIRST]);
+		let doc_world: Attribute = parse_quote!(#[doc = #SECOND]);
+
+		let attrs = vec![
+			doc.clone(),
+			parse_quote!(#[derive(Debug)]),
+			parse_quote!(#[test]),
+			parse_quote!(#[allow(non_camel_case_types)]),
+			doc_world.clone(),
+		];
+
+		let docs = get_doc_literals(&attrs);
+		assert_eq!(docs.len(), 2);
+		assert_matches!(&docs[0], syn::Lit::Str(val) if val.value() == FIRST);
+		assert_matches!(&docs[1], syn::Lit::Str(val) if val.value() == SECOND);
+	}
+
+	#[test]
+	fn check_filter_cfg_attributes() {
+		let cfg_std: Attribute = parse_quote!(#[cfg(feature = "std")]);
+		let cfg_benchmarks: Attribute = parse_quote!(#[cfg(feature = "runtime-benchmarks")]);
+
+		let attrs = vec![
+			cfg_std.clone(),
+			parse_quote!(#[derive(Debug)]),
+			parse_quote!(#[test]),
+			cfg_benchmarks.clone(),
+			parse_quote!(#[allow(non_camel_case_types)]),
+		];
+
+		let filtered = filter_cfg_attributes(&attrs);
+		assert_eq!(filtered.len(), 2);
+		assert_eq!(cfg_std, filtered[0]);
+		assert_eq!(cfg_benchmarks, filtered[1]);
+	}
+}