Fix synthesis of circuits with Scalar outputs

.circleci/config.yml

@@ -1290,6 +1290,7 @@ workflows:
       or pipeline.git.branch == "testnet"
       or pipeline.git.branch == "mainnet"
       or pipeline.git.branch == "copilot/adjust-transaction-cache-key"
+      or pipeline.git.branch == "fix/scalar-outputs"
     jobs:
       - check-unused-dependencies # This can be cleaned up before releases
       - check-cargo-semver-checks # This can be cleaned up before releases

circuit/program/src/data/future/mod.rs

@@ -94,4 +94,10 @@ impl<A: Aleo> Future<A> {
     pub fn inputs(&self) -> &[Argument<A>] {
         &self.arguments
     }
+
+    /// Returns the arguments.
+    #[inline]
+    pub fn arguments(&self) -> &[Argument<A>] {
+        &self.arguments
+    }
 }

synthesizer/process/src/execute.rs

@@ -48,7 +48,9 @@ impl<N: Network> Process<N> {
         // Retrieve the stack.
         let stack = self.get_stack(request.program_id())?;
         // Execute the circuit.
-        let response = stack.execute_function::<A, R>(call_stack, caller, root_tvk, rng)?;
+        let Some(response) = stack.execute_function::<A, R>(call_stack, caller, root_tvk, rng)? else {
+            return Err(anyhow!("Response should be present in `Execute` mode.").into());
+        };
         lap!(timer, "Execute the function");
 
         // Extract the trace.

synthesizer/process/src/stack/call/dynamic.rs

@@ -337,8 +337,11 @@ impl<N: Network> CallTrait<N> for CallDynamic<N> {
                         authorization.push(callee_request.clone())?;
 
                         // Execute the callee's request.
-                        let callee_response =
-                            target.substack().execute_function::<A, R>(call_stack, console_caller, root_tvk, rng)?;
+                        let Some(callee_response) =
+                            target.substack().execute_function::<A, R>(call_stack, console_caller, root_tvk, rng)?
+                        else {
+                            return Err(anyhow!("Response should be present in `Authorize` mode.").into());
+                        };
 
                         // Convert the callee's outputs to the caller's context.
                         let caller_response_outputs = callee_response.to_dynamic_outputs()?;
@@ -467,8 +470,11 @@ impl<N: Network> CallTrait<N> for CallDynamic<N> {
                         call_stack.push(callee_request.clone())?;
 
                         // Evaluate the callee's request.
-                        let callee_response =
-                            target.substack().execute_function::<A, _>(call_stack, console_caller, root_tvk, rng)?;
+                        let Some(callee_response) =
+                            target.substack().execute_function::<A, _>(call_stack, console_caller, root_tvk, rng)?
+                        else {
+                            return Err(anyhow!("Response should be present in `PackageRun` mode.").into());
+                        };
 
                         // Convert the callee's outputs to the caller's context.
                         let caller_response_outputs = callee_response.to_dynamic_outputs()?;
@@ -511,12 +517,15 @@ impl<N: Network> CallTrait<N> for CallDynamic<N> {
                             rng,
                         )?;
                         // Execute the request.
-                        let callee_response = target.substack().execute_function::<A, R>(
+                        let Some(callee_response) = target.substack().execute_function::<A, R>(
                             registers.call_stack(),
                             console_caller,
                             root_tvk,
                             rng,
-                        )?;
+                        )?
+                        else {
+                            return Err(anyhow!("Response should be present in `Execute` mode.").into());
+                        };
 
                         // Ensure the values are equal.
                         if console_callee_response.outputs() != callee_response.outputs() {

synthesizer/process/src/stack/call/standard.rs

@@ -328,11 +328,18 @@ impl<N: Network> CallTrait<N> for Call<N> {
                         // Push the request onto the call stack.
                         call_stack.push(request.clone())?;
 
-                        // Execute the request.
+                        // Synthesize the circuit. Note the response will be empty.
                         let response = substack.execute_function::<A, R>(call_stack, console_caller, root_tvk, rng)?;
 
+                        if response.is_some() {
+                            return Err(anyhow!(
+                                "execute_function should return an empty Response in Synthesize mode."
+                            )
+                            .into());
+                        }
+
                         // Return the request and response.
-                        (request, response)
+                        (request, None)
                     }
                     // In Synthesize mode (with an existing proving key) or CheckDeployment mode, we generate dummy outputs to avoid building a full sub-circuit.
                     CallStack::Synthesize(_, private_key, ..) | CallStack::CheckDeployment(_, private_key, ..) => {
@@ -350,63 +357,8 @@ impl<N: Network> CallTrait<N> for Call<N> {
                             rng,
                         )?;
 
-                        // Compute the address.
-                        let address = Address::try_from(private_key)?;
-
-                        // For each output, if it's a record, compute the randomizer and nonce.
-                        let outputs = function
-                            .outputs()
-                            .iter()
-                            .map(|output| match output.value_type() {
-                                ValueType::Record(record_name) => {
-                                    let index = match output.operand() {
-                                        Operand::Register(Register::Locator(index)) => Field::from_u64(*index),
-                                        _ => {
-                                            return Err(anyhow!(
-                                                "Expected a `Register::Locator` operand for a record output."
-                                            ));
-                                        }
-                                    };
-                                    // Sample the record.
-                                    Ok(Value::Record(substack.sample_record_using_tvk(
-                                        &address,
-                                        record_name,
-                                        *request.tvk(),
-                                        index,
-                                        rng,
-                                    )?))
-                                }
-                                // For non-record outputs, call sample_value.
-                                _ => substack.sample_value(&address, &output.value_type().into(), rng),
-                            })
-                            .collect::<Result<Vec<_>>>()?;
-
-                        // Construct the dummy response from these outputs.
-                        let output_registers = function
-                            .outputs()
-                            .iter()
-                            .map(|output| match output.operand() {
-                                Operand::Register(register) => Some(register.clone()),
-                                _ => None,
-                            })
-                            .collect::<Vec<_>>();
-
-                        // Execute the request.
-                        let response = crate::Response::new(
-                            request.signer(),
-                            request.network_id(),
-                            substack.program().id(),
-                            function.name(),
-                            request.inputs().len(),
-                            request.tvk(),
-                            request.tcm(),
-                            outputs,
-                            &function.output_types(),
-                            &output_registers,
-                        )?;
-
                         // Return the request and response.
-                        (request, response)
+                        (request, None)
                     }
                     // In PackageRun mode, we sign and execute the request once.
                     CallStack::PackageRun(_, private_key, ..) => {
@@ -465,8 +417,12 @@ impl<N: Network> CallTrait<N> for Call<N> {
                             rng,
                         )?;
                         // Execute the request.
-                        let response =
-                            substack.execute_function::<A, R>(registers.call_stack(), console_caller, root_tvk, rng)?;
+                        let Some(response) =
+                            substack.execute_function::<A, R>(registers.call_stack(), console_caller, root_tvk, rng)?
+                        else {
+                            return Err(anyhow!("Response should be present in `Execute` mode.").into());
+                        };
+
                         // Ensure the values are equal.
                         if console_response.outputs() != response.outputs() {
                             dev_eprintln!("\n{:#?} != {:#?}\n", console_response.outputs(), response.outputs());
@@ -477,7 +433,7 @@ impl<N: Network> CallTrait<N> for Call<N> {
                             .into());
                         }
                         // Return the request and response.
-                        (request, response)
+                        (request, Some(response))
                     }
                 }
             };
@@ -547,6 +503,56 @@ impl<N: Network> CallTrait<N> for Call<N> {
                 })
                 .collect::<Vec<_>>();
 
+            let outputs = match registers.call_stack_ref() {
+                // In Synthesize and CheckDeployment modes, `response` is None at this point. Only its outputs
+                // are used in the remainder of this function, and only their types (and not specific values)
+                // are relevant, so we sample them instead.
+                CallStack::Synthesize(_, private_key, ..) | CallStack::CheckDeployment(_, private_key, ..) => {
+                    if response.is_some() {
+                        return Err(anyhow!("Response should be empty in Synthesize and CheckDeployment modes.").into());
+                    }
+
+                    let address = Address::try_from(private_key)?;
+
+                    function
+                        .outputs()
+                        .iter()
+                        .map(|output| match output.value_type() {
+                            ValueType::Record(record_name) => {
+                                let index = match output.operand() {
+                                    Operand::Register(Register::Locator(index)) => Field::from_u64(*index),
+                                    _ => {
+                                        return Err(anyhow!(
+                                            "Expected a `Register::Locator` operand for a record output."
+                                        ));
+                                    }
+                                };
+                                // Sample the record.
+                                Ok(Value::Record(substack.sample_record_using_tvk(
+                                    &address,
+                                    record_name,
+                                    *request.tvk(),
+                                    index,
+                                    rng,
+                                )?))
+                            }
+                            // For non-record outputs, call sample_value.
+                            _ => substack.sample_value(&address, &output.value_type().into(), rng),
+                        })
+                        .collect::<Result<Vec<_>>>()?
+                }
+                _ => {
+                    if let Some(response) = response {
+                        response.outputs().to_vec()
+                    } else {
+                        return Err(anyhow!(
+                            "Response should be populated in all modes except Synthesize and CheckDeployment."
+                        )
+                        .into());
+                    }
+                }
+            };
+
             // Inject the outputs as `Mode::Private` (with the 'tcm' and output IDs as `Mode::Public`).
             let outputs = circuit::Response::process_outputs_from_callback(
                 &network_id,
@@ -555,7 +561,7 @@ impl<N: Network> CallTrait<N> for Call<N> {
                 num_inputs,
                 &tvk,
                 &tcm,
-                response.outputs().to_vec(),
+                outputs,
                 &function.output_types(),
                 &output_registers,
                 None,

synthesizer/process/src/stack/execute.rs

@@ -184,7 +184,8 @@ impl<N: Network> Stack<N> {
         outputs
     }
 
-    /// Executes a program function on the given inputs.
+    /// Executes a program function on the given inputs. The output includes a `Response` object if
+    /// not in `CheckDeployment` or `Synthesize` mode.
     ///
     /// Note: To execute a transition, do **not** call this method. Instead, call `Process::execute`.
     ///
@@ -196,7 +197,7 @@ impl<N: Network> Stack<N> {
         console_caller: Option<ProgramID<N>>,
         console_root_tvk: Option<Field<N>>,
         rng: &mut R,
-    ) -> Result<Response<N>, StackExecError> {
+    ) -> Result<Option<Response<N>>, StackExecError> {
         let timer = timer!("Stack::execute_function");
 
         // Ensure the global constants for the Aleo environment are initialized.
@@ -541,17 +542,26 @@ impl<N: Network> Stack<N> {
         Self::log_circuit::<A>("Complete", &call_stack_type);
 
         // Eject the response.
-        let response = response.eject_value();
+        let console_response =
+            if matches!(registers.call_stack_ref(), CallStack::Synthesize(..) | CallStack::CheckDeployment(..)) {
+                // When synthesizing proving/verifying keys or checking the latter,
+                // the values in the Response object are not relevant, and neither is its console counterpart.
+                None
+            } else {
+                let console_response = response.eject_value();
+
+                if console_response.outputs().len() != output_types.len() {
+                    return Err(anyhow!("Number of outputs does not match number of output types").into());
+                }
 
-        if response.outputs().len() != output_types.len() {
-            return Err(anyhow!("Number of outputs does not match number of output types").into());
-        }
+                // Ensure the outputs matches the expected value types.
+                console_response.outputs().iter().zip_eq(&output_types).try_for_each(|(output, output_type)| {
+                    // Ensure the output matches its expected type.
+                    self.matches_value_type(output, output_type)
+                })?;
 
-        // Ensure the outputs matches the expected value types.
-        response.outputs().iter().zip_eq(&output_types).try_for_each(|(output, output_type)| {
-            // Ensure the output matches its expected type.
-            self.matches_value_type(output, output_type)
-        })?;
+                Some(console_response)
+            };
 
         // If the circuit is in `Execute` or `PackageRun` mode, then ensure the circuit is satisfied.
         if matches!(registers.call_stack_ref(), CallStack::Execute(..) | CallStack::PackageRun(..)) {
@@ -582,7 +592,12 @@ impl<N: Network> Stack<N> {
         // If the circuit is in `Authorize` mode, then save the transition.
         if let CallStack::Authorize(_, _, authorization) = registers.call_stack_ref() {
             // Construct the transition.
-            let transition = Transition::from(&console_request, &response, &output_types, &output_registers)?;
+            let transition = Transition::from(
+                &console_request,
+                console_response.as_ref().unwrap(),
+                &output_types,
+                &output_registers,
+            )?;
 
             // Add the transition to the authorization.
             authorization.insert_transition(transition)?;
@@ -608,7 +623,12 @@ impl<N: Network> Stack<N> {
             registers.ensure_console_and_circuit_registers_match()?;
 
             // Construct the transition.
-            let transition = Transition::from(&console_request, &response, &output_types, &output_registers)?;
+            let transition = Transition::from(
+                &console_request,
+                console_response.as_ref().unwrap(),
+                &output_types,
+                &output_registers,
+            )?;
 
             // Retrieve the proving key.
             let proving_key = self.get_proving_key(function.name())?;
@@ -655,7 +675,7 @@ impl<N: Network> Stack<N> {
         finish!(timer);
 
         // Return the response.
-        Ok(response)
+        Ok(console_response)
     }
 }
 

synthesizer/process/src/stack/registers/mod.rs

@@ -19,7 +19,7 @@ mod registers_trait;
 use crate::{CallStack, RegisterTypes};
 use console::{
     network::prelude::*,
-    program::{Entry, Literal, Plaintext, Register, Request, Value},
+    program::{Entry, Literal, Plaintext, PlaintextType, Register, RegisterType, Request, Value},
     types::{Address, Field},
 };
 use snarkvm_synthesizer_program::{Operand, RegistersCircuit, RegistersSigner, RegistersTrait, StackTrait};