feat!: Internal as a macro (#4898)

Implement internal functions as a macro. Internal functions are now
written with an `aztec(internal)` decorator as opposed to the `internal`
keyword.

---------

Co-authored-by: Tom French <tom@tomfren.ch>
Co-authored-by: Tom French <15848336+TomAFrench@users.noreply.github.com>

docs/docs/misc/migration_notes.md

@@ -42,6 +42,27 @@ The prelude consists of
 
 #include_code prelude /noir-projects/aztec-nr/aztec/src/prelude.nr rust
 
+### `internal` is now a macro
+
+The `internal` keyword is now removed from Noir, and is replaced by an `aztec(internal)` attribute in the function. The resulting behavior is exactly the same: these functions will only be callable from within the same contract.
+
+Before:
+```rust
+#[aztec(private)]
+internal fn double(input: Field) -> Field {
+    input * 2
+}
+```
+
+After:
+```rust
+#[aztec(private)]
+#[aztec(internal)]
+fn double(input: Field) -> Field {
+    input * 2
+}
+```
+
 ### [Aztec.nr] No SafeU120 anymore!
 Noir now have overflow checks by default. So we don't need SafeU120 like libraries anymore.
 

noir-projects/noir-contracts/contracts/app_subscription_contract/src/main.nr

@@ -86,7 +86,8 @@ contract AppSubscription {
     }
 
     #[aztec(public)]
-    internal fn init(
+    #[aztec(internal)]
+    fn init(
         target_address: AztecAddress,
         subscription_token_address: AztecAddress,
         subscription_recipient_address: AztecAddress,
@@ -101,12 +102,14 @@ contract AppSubscription {
     }
 
     #[aztec(public)]
-    internal fn assert_not_expired(expiry_block_number: Field) {
+    #[aztec(internal)]
+    fn assert_not_expired(expiry_block_number: Field) {
         assert((context.block_number()) as u64 < expiry_block_number as u64);
     }
 
     #[aztec(public)]
-    internal fn assert_block_number(expiry_block_number: Field) {
+    #[aztec(internal)]
+    fn assert_block_number(expiry_block_number: Field) {
         assert(
             (context.block_number() + SUBSCRIPTION_DURATION_IN_BLOCKS) as u64
             >= expiry_block_number as u64

noir-projects/noir-contracts/contracts/card_game_contract/src/main.nr

@@ -51,7 +51,8 @@ contract CardGame {
     }
 
     #[aztec(public)]
-    internal fn on_game_joined(game: u32, player: AztecAddress, deck_strength: u32) {
+    #[aztec(internal)]
+    fn on_game_joined(game: u32, player: AztecAddress, deck_strength: u32) {
         let game_storage = storage.games.at(game as Field);
 
         let mut game_data = game_storage.read();
@@ -87,7 +88,8 @@ contract CardGame {
     }
 
     #[aztec(public)]
-    internal fn on_card_played(game: u32, player: AztecAddress, card_as_field: Field) {
+    #[aztec(internal)]
+    fn on_card_played(game: u32, player: AztecAddress, card_as_field: Field) {
         let game_storage = storage.games.at(game as Field);
 
         let mut game_data = game_storage.read();
@@ -117,7 +119,8 @@ contract CardGame {
     }
 
     #[aztec(public)]
-    internal fn on_cards_claimed(game: u32, player: AztecAddress, cards_hash: Field) {
+    #[aztec(internal)]
+    fn on_cards_claimed(game: u32, player: AztecAddress, cards_hash: Field) {
         let game_storage = storage.games.at(game as Field);
         let mut game_data = game_storage.read();
 

noir-projects/noir-contracts/contracts/child_contract/src/main.nr

@@ -21,18 +21,11 @@ contract Child {
     fn value(input: Field) -> Field {
         input + context.chain_id() + context.version()
     }
-
-    fn check_sender(call_context: CallContext) {
-        assert(
-            call_context.msg_sender.eq(call_context.storage_contract_address), "Sender must be this contract"
-        );
-    }
-
     // 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)]
+    #[aztec(internal)]
     fn valueInternal(input: Field) -> Field {
-        check_sender(inputs.call_context);
         input + context.chain_id() + context.version()
     }
 
@@ -83,8 +76,8 @@ contract Child {
 
     // Increments `current_value` by `new_value`. Can only be called from this contract.
     #[aztec(public)] 
+    #[aztec(internal)]
     fn pubIncValueInternal(new_value: Field) -> Field {
-        check_sender(inputs.call_context);
         let old_value = storage.current_value.read();
         storage.current_value.write(old_value + new_value);
         emit_unencrypted_log(&mut context, new_value);

noir-projects/noir-contracts/contracts/docs_example_contract/src/main.nr

@@ -214,7 +214,8 @@ contract DocsExample {
     }
 
     #[aztec(public)]
-    internal fn update_leader(account: AztecAddress, points: u8) {
+    #[aztec(internal)]
+    fn update_leader(account: AztecAddress, points: u8) {
         let new_leader = Leader { account, points };
         storage.leader.write(new_leader);
     }

noir-projects/noir-contracts/contracts/easy_private_voting_contract/src/main.nr

@@ -28,7 +28,8 @@ contract EasyPrivateVoting {
     // docs:end:constructor
     // docs:start:initialize
     #[aztec(public)] // annotation to mark function as public and expose public context
-    internal fn _initialize(admin: AztecAddress) { // internal - can only be called by contract
+    #[aztec(internal)]
+    fn _initialize(admin: AztecAddress) { // internal - can only be called by contract
         storage.admin.write(admin);
         storage.voteEnded.write(false);
     }
@@ -49,7 +50,8 @@ contract EasyPrivateVoting {
 
     // docs:start:add_to_tally_public
     #[aztec(public)]
-    internal fn add_to_tally_public(candidate: Field) {
+    #[aztec(internal)]
+    fn add_to_tally_public(candidate: Field) {
         assert(storage.voteEnded.read() == false, "Vote has ended"); // assert that vote has not ended
         let new_tally = storage.tally.at(candidate).read() + 1;
         storage.tally.at(candidate).write(new_tally);

noir-projects/noir-contracts/contracts/ecdsa_account_contract/src/main.nr

@@ -51,12 +51,14 @@ contract EcdsaAccount {
     }
 
     #[aztec(private)]
-    internal fn cancel_authwit(outer_hash: Field) {
+    #[aztec(internal)]
+    fn cancel_authwit(outer_hash: Field) {
         context.push_new_nullifier(outer_hash, 0);
     }
 
     #[aztec(public)]
-    internal fn approve_public_authwit(outer_hash: Field) {
+    #[aztec(internal)]
+    fn approve_public_authwit(outer_hash: Field) {
         let actions = AccountActions::public(&mut context, ACCOUNT_ACTIONS_STORAGE_SLOT, is_valid_impl);
         actions.approve_public_authwit(outer_hash)
     }

noir-projects/noir-contracts/contracts/fpc_contract/src/main.nr

@@ -23,7 +23,8 @@ contract FPC {
     }
 
     #[aztec(public)]
-    internal fn _initialize(other_asset: AztecAddress, fee_asset: AztecAddress) {
+    #[aztec(internal)]
+    fn _initialize(other_asset: AztecAddress, fee_asset: AztecAddress) {
         storage.other_asset.initialize(other_asset);
         storage.fee_asset.initialize(fee_asset);
     }
@@ -63,12 +64,14 @@ contract FPC {
     }
 
     #[aztec(public)]
-    internal fn prepare_fee(from: AztecAddress, amount: Field, asset: AztecAddress, nonce: Field) {
+    #[aztec(internal)]
+    fn prepare_fee(from: AztecAddress, amount: Field, asset: AztecAddress, nonce: Field) {
         let _res = Token::at(asset).transfer_public(context, from, context.this_address(), amount, nonce);
     }
 
     #[aztec(public)]
-    internal fn pay_fee(refund_address: AztecAddress, amount: Field, asset: AztecAddress) {
+    #[aztec(internal)]
+    fn pay_fee(refund_address: AztecAddress, amount: Field, asset: AztecAddress) {
         let refund = context.call_public_function(
             storage.fee_asset.read_public(),
             FunctionSelector::from_signature("pay_fee(Field)"),

noir-projects/noir-contracts/contracts/inclusion_proofs_contract/src/main.nr

@@ -37,7 +37,8 @@ contract InclusionProofs {
     }
 
     #[aztec(public)]
-    internal fn _initialize(value: Field) {
+    #[aztec(internal)]
+    fn _initialize(value: Field) {
         storage.public_value.write(value);
     }
 

noir-projects/noir-contracts/contracts/lending_contract/src/main.nr

@@ -130,7 +130,8 @@ contract Lending {
     }
 
     #[aztec(public)]
-    internal fn _deposit(owner: AztecAddress, amount: Field, collateral_asset: AztecAddress) {
+    #[aztec(internal)]
+    fn _deposit(owner: AztecAddress, amount: Field, collateral_asset: AztecAddress) {
         let _asset = Lending::at(context.this_address()).update_accumulator(context);
 
         let coll_asset = storage.collateral_asset.read();
@@ -163,7 +164,8 @@ contract Lending {
     }
 
     #[aztec(public)]
-    internal fn _withdraw(owner: AztecAddress, recipient: AztecAddress, amount: Field) {
+    #[aztec(internal)]
+    fn _withdraw(owner: AztecAddress, recipient: AztecAddress, amount: Field) {
         let asset = Lending::at(context.this_address()).update_accumulator(context);
         let price = PriceFeed::at(asset.oracle).get_price(context);
 
@@ -220,7 +222,8 @@ contract Lending {
     }
 
     #[aztec(public)]
-    internal fn _borrow(owner: AztecAddress, to: AztecAddress, amount: Field) {
+    #[aztec(internal)]
+    fn _borrow(owner: AztecAddress, to: AztecAddress, amount: Field) {
         let asset = Lending::at(context.this_address()).update_accumulator(context);
         let price = PriceFeed::at(asset.oracle).get_price(context);
 
@@ -282,7 +285,8 @@ contract Lending {
     }
 
     #[aztec(public)]
-    internal fn _repay(owner: AztecAddress, amount: Field, stable_coin: AztecAddress) {
+    #[aztec(internal)]
+    fn _repay(owner: AztecAddress, amount: Field, stable_coin: AztecAddress) {
         let asset = Lending::at(context.this_address()).update_accumulator(context);
 
         // To ensure that private is using the correct token.

noir-projects/noir-contracts/contracts/schnorr_account_contract/src/main.nr

@@ -54,12 +54,14 @@ contract SchnorrAccount {
     }
 
     #[aztec(private)]
-    internal fn cancel_authwit(outer_hash: Field) {
+    #[aztec(internal)]
+    fn cancel_authwit(outer_hash: Field) {
         context.push_new_nullifier(outer_hash, 0);
     }
 
     #[aztec(public)]
-    internal fn approve_public_authwit(outer_hash: Field) {
+    #[aztec(internal)]
+    fn approve_public_authwit(outer_hash: Field) {
         let actions = AccountActions::public(&mut context, ACCOUNT_ACTIONS_STORAGE_SLOT, is_valid_impl);
         actions.approve_public_authwit(outer_hash)
     }

noir-projects/noir-contracts/contracts/schnorr_hardcoded_account_contract/src/main.nr

@@ -37,12 +37,14 @@ contract SchnorrHardcodedAccount {
     }
 
     #[aztec(private)]
-    internal fn cancel_authwit(outer_hash: Field) {
+    #[aztec(internal)]
+    fn cancel_authwit(outer_hash: Field) {
         context.push_new_nullifier(outer_hash, 0);
     }
 
     #[aztec(public)]
-    internal fn approve_public_authwit(outer_hash: Field) {
+    #[aztec(internal)]
+    fn approve_public_authwit(outer_hash: Field) {
         let actions = AccountActions::public(&mut context, ACCOUNT_ACTIONS_STORAGE_SLOT, is_valid_impl);
         actions.approve_public_authwit(outer_hash)
     }

noir-projects/noir-contracts/contracts/schnorr_single_key_account_contract/src/main.nr

@@ -34,12 +34,14 @@ contract SchnorrSingleKeyAccount {
     }
 
     #[aztec(private)]
-    internal fn cancel_authwit(outer_hash: Field) {
+    #[aztec(internal)]
+    fn cancel_authwit(outer_hash: Field) {
         context.push_new_nullifier(outer_hash, 0);
     }
 
     #[aztec(public)]
-    internal fn approve_public_authwit(outer_hash: Field) {
+    #[aztec(internal)]
+    fn approve_public_authwit(outer_hash: Field) {
         let actions = AccountActions::public(&mut context, ACCOUNT_ACTIONS_STORAGE_SLOT, is_valid_impl);
         actions.approve_public_authwit(outer_hash)
     }

noir-projects/noir-contracts/contracts/slow_tree_contract/src/main.nr

@@ -73,7 +73,8 @@ contract SlowTree {
     // docs:end:read_at_private
     // docs:start:assert_current_root
     #[aztec(public)]
-    internal fn _assert_current_root(caller: Field, expected: Field) {
+    #[aztec(internal)]
+    fn _assert_current_root(caller: Field, expected: Field) {
         let root = storage.trees.at(caller).current_root();
         assert(root == expected, "Root does not match expected");
     }
@@ -115,7 +116,8 @@ contract SlowTree {
     // docs:end:update_at_private
     // docs:start:_update
     #[aztec(public)]
-    internal fn _update(
+    #[aztec(internal)]
+    fn _update(
         caller: Field,
         index: Field,
         new_value: Field,

noir-projects/noir-contracts/contracts/token_blacklist_contract/src/main.nr

@@ -70,13 +70,15 @@ contract TokenBlacklist {
     }
 
     #[aztec(public)]
-    internal fn _init_slow_tree(caller: AztecAddress) {
+    #[aztec(internal)]
+    fn _init_slow_tree(caller: AztecAddress) {
         assert(storage.admin.read().eq(caller), "caller is not admin");
     }
 
     ///////
     #[aztec(public)]
-    internal fn _initialize(new_admin: AztecAddress, slow_updates_contract: AztecAddress) {
+    #[aztec(internal)]
+    fn _initialize(new_admin: AztecAddress, slow_updates_contract: AztecAddress) {
         assert(!new_admin.is_zero(), "invalid admin");
         storage.admin.write(new_admin);
         // docs:start:write_slow_update_public
@@ -282,13 +284,15 @@ contract TokenBlacklist {
     /// Internal ///
 
     #[aztec(public)]
-    internal fn _increase_public_balance(to: AztecAddress, amount: Field) {
+    #[aztec(internal)]
+    fn _increase_public_balance(to: AztecAddress, amount: Field) {
         let new_balance = storage.public_balances.at(to).read().add(U128::from_integer(amount));
         storage.public_balances.at(to).write(new_balance);
     }
 
     #[aztec(public)]
-    internal fn _reduce_total_supply(amount: Field) {
+    #[aztec(internal)]
+    fn _reduce_total_supply(amount: Field) {
         // Only to be called from burn.
         let new_supply = storage.total_supply.read().sub(U128::from_integer(amount));
         storage.total_supply.write(new_supply);

noir-projects/noir-contracts/contracts/token_bridge_contract/src/main.nr

@@ -138,7 +138,8 @@ contract TokenBridge {
     // docs:end:read_token
 
     #[aztec(public)]
-    internal fn _initialize(token: AztecAddress) {
+    #[aztec(internal)]
+    fn _initialize(token: AztecAddress) {
         storage.token.write(token);
     }
 
@@ -147,14 +148,16 @@ contract TokenBridge {
     // Also, note that user hashes their secret in private and only sends the hash in public
     // meaning only user can `redeem_shield` at a later time with their secret.
     #[aztec(public)]
-    internal fn _call_mint_on_token(amount: Field, secret_hash: Field) {
+    #[aztec(internal)]
+    fn _call_mint_on_token(amount: Field, secret_hash: Field) {
         Token::at(storage.token.read()).mint_private(context, amount, secret_hash);
     }
     // docs:end:call_mint_on_token
 
     // docs:start:assert_token_is_same
     #[aztec(public)]
-    internal fn _assert_token_is_same(token: AztecAddress) {
+    #[aztec(internal)]
+    fn _assert_token_is_same(token: AztecAddress) {
         assert(storage.token.read().eq(token), "Token address is not the same as seen in storage");
     }
     // docs:end:assert_token_is_same