Make API backwards compatible with CC (#1697)

* Rework how a runtime api calls into the runtime

Now we generate a default implementation for each api call that calls
a generated method `method_runtime_api_impl`. This newly generated
method is the one that will be implemented by the `impl_runtime_apis`
macro in the runtime for the client side.

* Support `changed_in` to change runtime api function signatures

* Update documentation

* Fixes tests

* Implement checking the api version with a predicate

* Make the implementation backwards compatible with CC

* Update wasm files after merge

* Check for wasm runtime differences by building master and current branch

* Update spec_version and wasm files

* Fixes

* Revert my changes

* Remove `patch.crates-io` from test-runtime

substrate/core/sr-api-macros/tests/decl_and_impl.rs

@@ -28,6 +28,8 @@ decl_runtime_apis! {
 	#[api_version(2)]
 	pub trait ApiWithCustomVersion {
 		fn same_name();
+		#[changed_in(2)]
+		fn same_name() -> String;
 	}
 }
 
@@ -77,6 +79,11 @@ fn test_client_side_function_signature() {
 	let _something_with_block:
 		fn(&RuntimeApiImpl<TestClient>, &BlockId<Block>, Block) -> Result<Block> =
 			RuntimeApiImpl::<TestClient>::something_with_block;
+
+	#[allow(deprecated)]
+	let _same_name_before_version_2:
+		fn(&RuntimeApiImpl<TestClient>, &BlockId<Block>) -> Result<String> =
+			RuntimeApiImpl::<TestClient>::same_name_before_version_2;
 }
 
 #[test]

substrate/core/sr-api-macros/tests/runtime_calls.rs

@@ -58,3 +58,23 @@ fn calling_native_runtime_function_with_non_decodable_return_value() {
 	let block_id = BlockId::Number(client.info().unwrap().chain.best_number);
 	runtime_api.fail_convert_return_value(&block_id).unwrap();
 }
+
+#[test]
+fn calling_native_runtime_signature_changed_function() {
+	let client = test_client::new_with_api_execution_strat(ExecutionStrategy::NativeWhenPossible);
+	let runtime_api = client.runtime_api();
+	let block_id = BlockId::Number(client.info().unwrap().chain.best_number);
+
+	assert_eq!(runtime_api.function_signature_changed(&block_id).unwrap(), 1);
+}
+
+#[test]
+fn calling_wasm_runtime_signature_changed_old_function() {
+	let client = test_client::new_with_api_execution_strat(ExecutionStrategy::AlwaysWasm);
+	let runtime_api = client.runtime_api();
+	let block_id = BlockId::Number(client.info().unwrap().chain.best_number);
+
+	#[allow(deprecated)]
+	let res = runtime_api.function_signature_changed_before_version_2(&block_id).unwrap();
+	assert_eq!(&res, &[1, 2]);
+}