feat(Aztec.nr): Kernel return types abstraction (#1924)

yarn-project/noir-contracts/src/contracts/child_contract/src/main.nr

@@ -12,56 +12,59 @@ contract Child {
     #[aztec(private)]
     fn value(
         input: Field,
-    ) {
-        context.return_values.push(input + context.chain_id() + context.version());
+    ) -> Field {
+        input + context.chain_id() + context.version()
     }
 
     // Returns a sum of the input and the chain id and version of the contract in private circuit public input's return_values. 
     // Can only be called from this contract.
     #[aztec(private)]
     fn valueInternal(
         input: Field,
-    ) {
+    ) -> Field {
         assert(inputs.call_context.msg_sender == inputs.call_context.storage_contract_address);
-        context.return_values.push(input + context.chain_id() + context.version());
+        input + context.chain_id() + context.version()
     }
 
     // Returns base_value + 42.
     #[aztec(public)]
-    fn pubGetValue(base_value: Field) {
+    fn pubGetValue(base_value: Field) -> Field {
         let returnValue = base_value + context.chain_id() + context.version() + context.block_number() + context.timestamp();
 
-        context.return_values.push(returnValue);
+        returnValue
     }
 
     // Sets `current_value` to `new_value`
     #[aztec(public)]
-    fn pubSetValue(new_value: Field) {
+    fn pubSetValue(new_value: Field) -> Field {
         let storage = Storage::init();
         storage.current_value.write(new_value);
         let _hash = emit_unencrypted_log(new_value);
-        context.return_values.push(new_value);
+
+        new_value
     }
 
     // Increments `current_value` by `new_value`
     #[aztec(public)]
-    fn pubIncValue(new_value: Field) {
+    fn pubIncValue(new_value: Field) -> Field {
         let storage = Storage::init();
         let old_value = storage.current_value.read();
         storage.current_value.write(old_value + new_value);
         let _hash = emit_unencrypted_log(new_value);
-        context.return_values.push(new_value);
+
+        new_value
     }
 
     // Increments `current_value` by `new_value`. Can only be called from this contract.
-    #[aztec(public)]
-    fn pubIncValueInternal(new_value: Field) {
+    #[aztec(public)] 
+    fn pubIncValueInternal(new_value: Field) -> Field {
         let storage = Storage::init();
         assert(inputs.call_context.msg_sender == inputs.call_context.storage_contract_address);
         let old_value = storage.current_value.read();
         storage.current_value.write(old_value + new_value);
         let _hash = emit_unencrypted_log(new_value);
-        context.return_values.push(new_value);
+
+        new_value
     }
 
     #[aztec(public)]

yarn-project/noir-contracts/src/contracts/ecdsa_account_contract/src/main.nr

@@ -52,6 +52,7 @@ contract EcdsaAccount {
         payload.execute_calls(&mut context);
     }
 
+
     // Creates a new account out of an ECDSA public key to use for signature verification
     #[aztec(private)]
     fn constructor(

yarn-project/noir-contracts/src/contracts/example_public_state_increment_BROKE/src/main.nr

@@ -28,7 +28,7 @@ contract ExamplePublicStateIncrement {
 
     // a = 100;
     #[aztec(public)]
-    open internal fn initialise_a() {
+    internal fn initialise_a() {
         let storage = Storage::init();
         storage.a.write(100);
     }

yarn-project/noir-contracts/src/contracts/import_test_contract/src/main.nr

@@ -24,7 +24,7 @@ contract ImportTest {
     #[aztec(private)]
     fn main(
         target: Field
-    ) {
+    ) -> Field {
         let test_contract_instance = TestPrivateContextInterface::at(target);
         let return_values = test_contract_instance.testCodeGen(
             &mut context,
@@ -45,7 +45,7 @@ contract ImportTest {
             }
         );
 
-        context.return_values.push(return_values[0]);
+        return_values[0]
     }
 
     // Calls the getThisAddress on the Test contract at the target address
@@ -54,10 +54,11 @@ contract ImportTest {
     #[aztec(private)]
     fn callNoArgs(
         target: Field
-    ) {
+    ) -> Field {
         let test_contract_instance = TestPrivateContextInterface::at(target);
         let return_values = test_contract_instance.getThisAddress(&mut context);
-        context.return_values.push(return_values[0]);
+
+        return_values[0]
     }
 
     // Calls the createNullifierPublic on the Test contract at the target address
@@ -77,10 +78,11 @@ contract ImportTest {
     #[aztec(public)]
     fn pubCallOpenFn(
         target: Field,
-    ) {
+    ) -> Field {
         let test_contract_instance = TestPublicContextInterface::at(target);
         let ret = test_contract_instance.createNullifierPublic(context, 1, 2);
-        context.return_values.push(ret[0]);
+
+        ret[0]
     }
 }
 

yarn-project/noir-contracts/src/contracts/lending_contract/src/main.nr

@@ -35,7 +35,7 @@ contract Lending {
         loan_to_value: Field,
         collateral_asset: Field,
         stable_coin: Field,
-    ) {
+    ) -> Field {
         let storage = Storage::init();
         let asset_loc = storage.assets.at(0);
         let asset = asset_loc.read();
@@ -54,13 +54,13 @@ contract Lending {
         storage.collateral_asset.write(collateral_asset);
         storage.stable_coin.write(stable_coin);
 
-        context.return_values.push(1);
+        1
     }
 
     // Create a position.
     // keccak256("update_accumulator()") >> 224 -> 0x1873b536
     #[aztec(public)]
-    fn update_accumulator() {
+    fn update_accumulator() -> Asset {
         let storage = Storage::init();
 
         let asset_loc = storage.assets.at(0);
@@ -82,7 +82,7 @@ contract Lending {
             asset_loc.write(asset);
         }
 
-        context.return_values.push_array(asset.serialise());
+        asset
     }
 
     // This don't need to be on behalf of self. We should be able to repay on behalf of someone else.
@@ -105,19 +105,20 @@ contract Lending {
         owner: Field,
         amount: Field,
         collateral_asset: Field,
-    ) {
+    ) -> Field {
         Token::at(collateral_asset).transfer_from_pub(context, context.msg_sender(), context.this_address(), amount);
         let return_values = context.call_public_function(context.this_address(), 0x08506e50, [owner, amount, collateral_asset]);
-        context.return_values.push(return_values[0]);
+
+        return_values[0]
     }
 
     #[aztec(public)]
     // keccak256("_deposit(field,field,field)") >> 224 -> 0x08506e50
-    open internal fn _deposit(
+    internal fn _deposit(
         owner: Field,
         amount: Field,
         collateral_asset: Field,
-    ) {
+    ) -> Field {
         let _asset = Lending::at(context.this_address()).update_accumulator(context);
         let storage = Storage::init();
 
@@ -128,7 +129,7 @@ contract Lending {
         let collateral = coll_loc.read();
         coll_loc.write(collateral + amount);
 
-        context.return_values.push(1);
+        1
     }
 
     #[aztec(private)]
@@ -145,19 +146,20 @@ contract Lending {
     fn withdraw_public(
         to: Field,
         amount: Field,
-    ) {
+    ) -> Field {
         // _withdraw(msg.sender, to, amount);
         let return_values = context.call_public_function(context.this_address(), 0x5af6f634, [context.msg_sender(), to, amount]);
-        context.return_values.push(return_values[0]);
+
+        return_values[0]
     }
 
     // keccak256("_withdraw(field,field,field)") >> 224 -> 0x5af6f634
     #[aztec(public)]
-    open internal fn _withdraw(
+    internal fn _withdraw(
         owner: Field,
         recipient: Field,
         amount: Field
-    ) {
+    ) -> Field {
         let asset = Lending::at(context.this_address()).update_accumulator(context);
         let price = PriceFeed::at(asset.oracle_address).get_price(context);
 
@@ -182,7 +184,7 @@ contract Lending {
         let collateral_asset = storage.collateral_asset.read();
         Token::at(collateral_asset).transfer_pub(context, recipient, amount);
 
-        context.return_values.push(1);
+        1
     }
 
     #[aztec(private)]
@@ -200,19 +202,20 @@ contract Lending {
     fn borrow_public(
         to: Field,
         amount: Field
-    ) {
+    ) -> Field {
         // _borrow(msg.sender, to, amount)
         let return_values = context.call_public_function(context.this_address(), 0xceffa31a, [context.msg_sender(), to, amount]);
-        context.return_values.push(return_values[0]);
+
+        return_values[0]
     }
 
     // keccak256("_borrow(field,field,field)") >> 224 -> 0xceffa31a
     #[aztec(public)]
-    open internal fn _borrow(
+    internal fn _borrow(
         owner: Field,
         to: Field,
         amount: Field
-    ) {
+    ) -> Field {
         let asset = Lending::at(context.this_address()).update_accumulator(context);
         let price = PriceFeed::at(asset.oracle_address).get_price(context);
 
@@ -233,7 +236,7 @@ contract Lending {
         let stable_coin = storage.stable_coin.read();
         Token::at(stable_coin).owner_mint_pub(context, to, amount);
 
-        context.return_values.push(1);
+        1
     }
 
     #[aztec(private)]
@@ -254,16 +257,17 @@ contract Lending {
         owner: Field,
         amount: Field,
         stable_coin: Field,
-    ) {
+    ) -> Field {
         // Should probably just burn the tokens actually :thinking:
         Token::at(stable_coin).transfer_from_pub(context, context.msg_sender(), context.this_address(), amount);
         let return_values = context.call_public_function(context.this_address(), 0xfa94ab54, [owner, amount, stable_coin]);
-        context.return_values.push(return_values[0]);
+
+        return_values[0]
     }
 
     // keccak256("_repay(field,field,field)") >> 224 -> 0xfa94ab54
     #[aztec(public)]
-    open internal fn _repay(
+    internal fn _repay(
         owner: Field,
         amount: Field,
         stable_coin: Field,
@@ -279,7 +283,7 @@ contract Lending {
 
         storage.static_debt.at(owner).write(debt_returns.static_debt as Field);
 
-        context.return_values.push(1);
+        1
     }
 
     unconstrained fn get_asset(

yarn-project/noir-contracts/src/contracts/lending_contract/src/storage.nr

@@ -34,7 +34,8 @@ fn serialiseAsset(asset: Asset) -> [Field; ASSET_SERIALISED_LEN] {
 }
 
 impl Asset {
-    fn serialise (self: Self) -> [Field; ASSET_SERIALISED_LEN] {
+    // TODO(Maddiaa): Rename all serialise -> serialize
+    fn serialize (self: Self) -> [Field; ASSET_SERIALISED_LEN] {
         serialiseAsset(self)
     }
 }

yarn-project/noir-contracts/src/contracts/multi_transfer_contract/src/main.nr

@@ -30,7 +30,7 @@ contract MultiTransfer {
         owner: Field, // Owner of the asset
         batch_transfer_selector: Field, // Function selector for transfer
         note_offsets: [Field; 4], // Offsets from which 4 notes of the owner would be read.
-    ) {
+    ) -> [Field; 4] {
         // First batch transfer call
         let return_values_1 = context.call_private_function(asset, batch_transfer_selector, [
             owner, 
@@ -43,7 +43,6 @@ contract MultiTransfer {
             note_offsets[0],
         ]);
         let result1 = return_values_1[0];
-        context.return_values.push(result1);
 
         // Second batch transfer call
         let return_values_2 = context.call_private_function(asset, batch_transfer_selector, [
@@ -57,7 +56,6 @@ contract MultiTransfer {
             note_offsets[1],
         ]);
         let result2 = return_values_2[0];
-        context.return_values.push(result2);
 
         // Third batch transfer call
         let return_values_3 = context.call_private_function(asset, batch_transfer_selector, [
@@ -71,7 +69,6 @@ contract MultiTransfer {
             note_offsets[2],
         ]);
         let result3 = return_values_3[0];
-        context.return_values.push(result3);
 
         // Fourth batch transfer call
         let return_values_4 = context.call_private_function(asset, batch_transfer_selector, [
@@ -85,6 +82,7 @@ contract MultiTransfer {
             note_offsets[3],
         ]);
         let result4 = return_values_4[0];
-        context.return_values.push(result4);
+
+        [result1, result2, result3, result4]
     }
 }