Metadata V15: Add Runtime API metadata

Cargo.toml

@@ -202,6 +202,7 @@ members = [
 	"primitives/keystore",
 	"primitives/maybe-compressed-blob",
 	"primitives/merkle-mountain-range",
+	"primitives/metadata-ir",
 	"primitives/npos-elections",
 	"primitives/npos-elections/fuzzer",
 	"primitives/offchain",

frame/support/Cargo.toml

@@ -16,7 +16,7 @@ targets = ["x86_64-unknown-linux-gnu"]
 serde = { version = "1.0.136", optional = true, features = ["derive"] }
 codec = { package = "parity-scale-codec", version = "3.2.2", default-features = false, features = ["derive", "max-encoded-len"] }
 scale-info = { version = "2.1.1", default-features = false, features = ["derive"] }
-frame-metadata = { version = "15.0.0", default-features = false, features = ["v14"] }
+frame-metadata = { version = "15.1.0", default-features = false, features = ["v14", "v15-unstable"] }
 sp-api = { version = "4.0.0-dev", default-features = false, path = "../../primitives/api" }
 sp-std = { version = "5.0.0", default-features = false, path = "../../primitives/std" }
 sp-io = { version = "7.0.0", default-features = false, path = "../../primitives/io" }
@@ -74,7 +74,7 @@ runtime-benchmarks = []
 try-runtime = []
 # By default some types have documentation, `no-metadata-docs` allows to reduce the documentation
 # in the metadata.
-no-metadata-docs = ["frame-support-procedural/no-metadata-docs"]
+no-metadata-docs = ["frame-support-procedural/no-metadata-docs", "sp-api/no-metadata-docs"]
 # By default some types have documentation, `full-metadata-docs` allows to add documentation to
 # more types in the metadata.
 full-metadata-docs = ["scale-info/docs"]

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

@@ -77,6 +77,24 @@ pub fn expand_runtime_metadata(
 	quote! {
 		impl #runtime {
 			fn metadata_ir() -> #scrate::metadata_ir::MetadataIR {
+				// 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.
+				//
+				// `Deref` needs a reference for resolving the function call.
+				let rt = #runtime;
+
 				#scrate::metadata_ir::MetadataIR {
 					pallets: #scrate::sp_std::vec![ #(#pallets),* ],
 					extrinsic: #scrate::metadata_ir::ExtrinsicMetadataIR {
@@ -95,7 +113,8 @@ pub fn expand_runtime_metadata(
 								})
 								.collect(),
 					},
-					ty: #scrate::scale_info::meta_type::<#runtime>()
+					ty: #scrate::scale_info::meta_type::<#runtime>(),
+					apis: (&rt).runtime_metadata(),
 				}
 			}
 

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

@@ -296,6 +296,31 @@ fn construct_runtime_final_expansion(
 			type RuntimeBlock = #block;
 		}
 
+		// 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.
+
+		#[doc(hidden)]
+		trait InternalConstructRuntime {
+			#[inline(always)]
+			fn runtime_metadata(&self) -> #scrate::sp_std::vec::Vec<#scrate::metadata_ir::RuntimeApiMetadataIR> {
+				Default::default()
+			}
+		}
+		#[doc(hidden)]
+		impl InternalConstructRuntime for &#name {}
+
 		#outer_event
 
 		#outer_origin

frame/support/src/lib.rs

@@ -50,6 +50,7 @@ pub use paste;
 pub use scale_info;
 #[cfg(feature = "std")]
 pub use serde;
+pub use sp_api::metadata_ir;
 pub use sp_core::{OpaqueMetadata, Void};
 #[doc(hidden)]
 pub use sp_core_hashing_proc_macro;
@@ -80,7 +81,6 @@ pub mod error;
 pub mod crypto;
 pub mod dispatch_context;
 pub mod instances;
-pub mod metadata_ir;
 pub mod migrations;
 pub mod traits;
 pub mod weights;

frame/support/test/Cargo.toml

@@ -15,6 +15,7 @@ targets = ["x86_64-unknown-linux-gnu"]
 serde = { version = "1.0.136", default-features = false, features = ["derive"] }
 codec = { package = "parity-scale-codec", version = "3.2.2", default-features = false, features = ["derive"] }
 scale-info = { version = "2.1.1", default-features = false, features = ["derive"] }
+sp-api = { version = "4.0.0-dev", default-features = false, path = "../../../primitives/api" }
 sp-arithmetic = { version = "6.0.0", default-features = false, path = "../../../primitives/arithmetic" }
 sp-io = { version = "7.0.0", path = "../../../primitives/io", default-features = false }
 sp-state-machine = { version = "0.13.0", optional = true, path = "../../../primitives/state-machine" }
@@ -47,6 +48,7 @@ std = [
 	"sp-state-machine",
 	"sp-arithmetic/std",
 	"sp-version/std",
+	"sp-api/std",
 ]
 try-runtime = ["frame-support/try-runtime"]
 # WARNING:

frame/support/test/tests/pallet.rs

@@ -1671,7 +1671,7 @@ fn metadata_at_version() {
 
 #[test]
 fn metadata_versions() {
-	assert_eq!(vec![LATEST_METADATA_VERSION], Runtime::metadata_versions());
+	assert_eq!(vec![LATEST_METADATA_VERSION, u32::MAX], Runtime::metadata_versions());
 }
 
 #[test]