sp-api: Put frame-metadata behind some feature (#14398)

* sp-api: Put `frame-metadata` behind some feature

Closes: https://github.com/paritytech/substrate/issues/14296

* ".git/.scripts/commands/fmt/fmt.sh"

* Review feedback

---------

Co-authored-by: command-bot <>

substrate/primitives/api/proc-macro/src/decl_runtime_apis.rs

@@ -20,7 +20,6 @@ use crate::{
 		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,
@@ -188,13 +187,17 @@ 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 =
 			get_api_version(&found_attributes).map(|v| generate_runtime_api_version(v as u32))?;
 		let id = generate_runtime_api_id(&decl.ident.to_string());
 
+		#[cfg(feature = "frame-metadata")]
+		let metadata = crate::runtime_metadata::generate_decl_runtime_metadata(&decl);
+		#[cfg(not(feature = "frame-metadata"))]
+		let metadata = quote!();
+
 		let trait_api_version = get_api_version(&found_attributes)?;
 
 		let mut methods_by_version: BTreeMap<u64, Vec<TraitItemFn>> = BTreeMap::new();

substrate/primitives/api/proc-macro/src/impl_runtime_apis.rs

@@ -17,7 +17,6 @@
 
 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,
@@ -694,7 +693,11 @@ 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)?;
+
+	#[cfg(feature = "frame-metadata")]
+	let runtime_metadata = crate::runtime_metadata::generate_impl_runtime_metadata(api_impls)?;
+	#[cfg(not(feature = "frame-metadata"))]
+	let runtime_metadata = quote!();
 
 	let impl_ = quote!(
 		#base_runtime_api

substrate/primitives/api/proc-macro/src/lib.rs

@@ -25,6 +25,7 @@ mod common;
 mod decl_runtime_apis;
 mod impl_runtime_apis;
 mod mock_impl_runtime_apis;
+#[cfg(feature = "frame-metadata")]
 mod runtime_metadata;
 mod utils;
 

substrate/primitives/api/proc-macro/src/utils.rs

@@ -22,7 +22,7 @@ use syn::{
 	ImplItem, ItemImpl, Pat, Path, PathArguments, Result, ReturnType, Signature, Type, TypePath,
 };
 
-use quote::{format_ident, quote, ToTokens};
+use quote::{format_ident, quote};
 
 use proc_macro_crate::{crate_name, FoundCrate};
 
@@ -259,7 +259,10 @@ pub fn versioned_trait_name(trait_ident: &Ident, version: u64) -> Ident {
 }
 
 /// Extract the documentation from the provided attributes.
+#[cfg(feature = "frame-metadata")]
 pub fn get_doc_literals(attrs: &[syn::Attribute]) -> Vec<syn::Lit> {
+	use quote::ToTokens;
+
 	attrs
 		.iter()
 		.filter_map(|attr| {
@@ -275,6 +278,7 @@ pub fn get_doc_literals(attrs: &[syn::Attribute]) -> Vec<syn::Lit> {
 }
 
 /// Filters all attributes except the cfg ones.
+#[cfg(feature = "frame-metadata")]
 pub fn filter_cfg_attributes(attrs: &[syn::Attribute]) -> Vec<syn::Attribute> {
 	attrs.iter().filter(|a| a.path().is_ident("cfg")).cloned().collect()
 }