promise transfer no data - syntactic sugar

Author: andrei-marinica

contracts/feature-tests/composability/promises-features/src/fwd_call_promises.rs

@@ -64,7 +64,6 @@ pub trait CallPromisesModule: common::CommonModule {
 
         self.tx()
             .to(&to)
-            .raw_call("")
             .gas(gas_limit)
             .payment(payment)
             .callback(self.callbacks().transfer_callback())

framework/base/src/types/interaction/tx_exec/tx_exec_async_promises.rs

@@ -188,26 +188,26 @@ where
     }
 }
 
-impl<Api, To, Payment, Callback> Tx<TxScEnv<Api>, (), To, Payment, (), FunctionCall<Api>, Callback>
+impl<Api, To, Payment, GasValue, Callback>
+    Tx<TxScEnv<Api>, (), To, Payment, ExplicitGas<GasValue>, (), Callback>
 where
     Api: CallTypeApi,
     To: TxToSpecified<TxScEnv<Api>>,
     Payment: TxPayment<TxScEnv<Api>>,
+    GasValue: TxGasValue<TxScEnv<Api>>,
     Callback: TxPromisesCallback<Api>,
 {
-    /// ## Incorrect call
-    ///
-    /// Must set **gas** in order to call `register_promise`.
+    /// Launches a transaction as an asynchronous promise (async v2 mechanism),
+    /// but without calling any function on the destination.
     ///
-    /// ## Safety
-    ///
-    /// This version of the method must never be called. It is only here to provide a more readable error.
-    pub unsafe fn register_promise(self) {
-        ErrorHelper::<Api>::signal_error_with_message("register_promise requires explicit gas");
+    /// Such calls are useful for appending callbacks to simple transfers,
+    /// mitigating edge cases such as non-payable SCs and frozen assets.
+    pub fn register_promise(self) {
+        self.raw_call("").register_promise();
     }
 }
 
-impl<Api, To, Payment, Callback> Tx<TxScEnv<Api>, (), To, Payment, (), (), Callback>
+impl<Api, To, Payment, Callback> Tx<TxScEnv<Api>, (), To, Payment, (), FunctionCall<Api>, Callback>
 where
     Api: CallTypeApi,
     To: TxToSpecified<TxScEnv<Api>>,
@@ -216,36 +216,34 @@ where
 {
     /// ## Incorrect call
     ///
-    /// Must set **gas** and **function call** in order to call `register_promise`.
+    /// Must set **gas** in order to call `register_promise`.
     ///
     /// ## Safety
     ///
     /// This version of the method must never be called. It is only here to provide a more readable error.
     pub unsafe fn register_promise(self) {
-        ErrorHelper::<Api>::signal_error_with_message(
-            "register_promise requires explicit gas and function call",
-        );
+        ErrorHelper::<Api>::signal_error_with_message("register_promise requires explicit gas");
     }
 }
 
-impl<Api, To, Payment, GasValue, Callback>
-    Tx<TxScEnv<Api>, (), To, Payment, ExplicitGas<GasValue>, (), Callback>
+impl<Api, To, Payment, Callback> Tx<TxScEnv<Api>, (), To, Payment, (), (), Callback>
 where
     Api: CallTypeApi,
     To: TxToSpecified<TxScEnv<Api>>,
     Payment: TxPayment<TxScEnv<Api>>,
-    GasValue: TxGasValue<TxScEnv<Api>>,
     Callback: TxPromisesCallback<Api>,
 {
     /// ## Incorrect call
     ///
-    /// Must set **function call** in order to call `register_promise`.
+    /// Must set **gas** in order to call `register_promise`, even when no SC endpoint is called.
     ///
     /// ## Safety
     ///
     /// This version of the method must never be called. It is only here to provide a more readable error.
     pub unsafe fn register_promise(self) {
-        ErrorHelper::<Api>::signal_error_with_message("register_promise requires function call");
+        ErrorHelper::<Api>::signal_error_with_message(
+            "register_promise requires explicit gas (even when no SC endpoint is called)",
+        );
     }
 }