feat(noir): autogenerate contract interface for calling from external…

… contracts (#1487)

Builds on @iAmMichaelConnor work to generate a contract interface for
simplifying calling function in other contracts. Uses only information
present in the ABI. For each function in the target contract, creates a
wrapper function that receives the same arguments, serialises them based
on the standard ABI encoding format (see
[here](https://github.com/AztecProtocol/aztec-packages/blob/49d272159f1b27521ad34081c7f1622ccac19dff/yarn-project/foundation/src/abi/encoder.ts)),
and uses the `call_private_function` from the `context` to call into
them.

To handle custom structs, we're re-defining them in the contract
interface. Until we get struct type names in the ABI (see
noir-lang/noir#2238), we are autogenerating
the name as well, based on the function name and param name where they
are used. Serialisation is done manually in the code, but we may want to
replace it with a Noir intrinsic when available (see
noir-lang/noir#2240).

See [this
file](https://github.com/AztecProtocol/aztec-packages/blob/49d272159f1b27521ad34081c7f1622ccac19dff/yarn-project/noir-contracts/src/contracts/test_contract/src/test_contract_interface.nr)
for example output.

Fixes #1237

---------

Co-authored-by: iAmMichaelConnor <[email protected]>

yarn-project/noir-libs/noir-aztec/src/abi.nr

@@ -358,21 +358,25 @@ global ARGS_HASH_CHUNK_LENGTH: u32 = 32;
 global ARGS_HASH_CHUNK_COUNT: u32 = 16;
 
 fn hash_args<N>(args: [Field; N]) -> Field {
-    let mut chunks_hashes = [0; ARGS_HASH_CHUNK_COUNT];
-    for i in 0..ARGS_HASH_CHUNK_COUNT {
-        let mut chunk_hash = 0;
-        let start_chunk_index = i * ARGS_HASH_CHUNK_LENGTH;
-        if start_chunk_index < (args.len() as u32) {
-            let mut chunk_args = [0; ARGS_HASH_CHUNK_LENGTH];
-            for j in 0..ARGS_HASH_CHUNK_LENGTH {
-                let item_index = i * ARGS_HASH_CHUNK_LENGTH + j;
-                if item_index < (args.len() as u32) {
-                    chunk_args[j] = args[item_index];
+    if args.len() == 0 {
+        0
+    } else {
+        let mut chunks_hashes = [0; ARGS_HASH_CHUNK_COUNT];
+        for i in 0..ARGS_HASH_CHUNK_COUNT {
+            let mut chunk_hash = 0;
+            let start_chunk_index = i * ARGS_HASH_CHUNK_LENGTH;
+            if start_chunk_index < (args.len() as u32) {
+                let mut chunk_args = [0; ARGS_HASH_CHUNK_LENGTH];
+                for j in 0..ARGS_HASH_CHUNK_LENGTH {
+                    let item_index = i * ARGS_HASH_CHUNK_LENGTH + j;
+                    if item_index < (args.len() as u32) {
+                        chunk_args[j] = args[item_index];
+                    }
                 }
+                chunk_hash = dep::std::hash::pedersen_with_separator(chunk_args, GENERATOR_INDEX__FUNCTION_ARGS)[0];
             }
-            chunk_hash = dep::std::hash::pedersen_with_separator(chunk_args, GENERATOR_INDEX__FUNCTION_ARGS)[0];
+            chunks_hashes[i] = chunk_hash;
         }
-        chunks_hashes[i] = chunk_hash;
+        dep::std::hash::pedersen_with_separator(chunks_hashes, GENERATOR_INDEX__FUNCTION_ARGS)[0]
     }
-    dep::std::hash::pedersen_with_separator(chunks_hashes, GENERATOR_INDEX__FUNCTION_ARGS)[0]
 }

yarn-project/noir-libs/noir-aztec/src/context.nr

@@ -296,7 +296,7 @@ impl Context {
         contract_address: Field, 
         function_selector: Field, 
         args: [Field; ARGS_COUNT]
-    ) -> [Field; RETURN_VALUES_LENGTH] {
+    ) {
         let args_hash = hash_args(args);
         assert(args_hash == arguments::pack_arguments(args));
         self.call_public_function_with_packed_args(contract_address, function_selector, args_hash)
@@ -306,7 +306,7 @@ impl Context {
         &mut self,
         contract_address: Field, 
         function_selector: Field,
-    ) -> [Field; RETURN_VALUES_LENGTH] {
+    ) {
         self.call_public_function_with_packed_args(contract_address, function_selector, 0)
     }
 
@@ -315,7 +315,7 @@ impl Context {
         contract_address: Field,
         function_selector: Field,
         args_hash: Field
-    ) -> [Field; RETURN_VALUES_LENGTH] {
+    ) {
         let fields = enqueue_public_function_call_internal(
             contract_address, 
             function_selector, 
@@ -372,7 +372,5 @@ impl Context {
         assert(item.public_inputs.call_context.storage_contract_address == contract_address);
 
         self.public_call_stack.push(item.hash());
-
-        item.public_inputs.return_values
     }
 }

yarn-project/noir-libs/noir-aztec/src/state_vars.nr

@@ -1,6 +1,5 @@
 mod immutable_singleton;
 mod map;
 mod public_state;
-mod type_serialisation;
 mod set;
 mod singleton;

yarn-project/noir-libs/noir-aztec/src/state_vars/public_state.nr

@@ -1,6 +1,6 @@
 use crate::oracle::storage::storage_read;
 use crate::oracle::storage::storage_write;
-use crate::state_vars::type_serialisation::TypeSerialisationInterface;
+use crate::types::type_serialisation::TypeSerialisationInterface;
 
 struct PublicState<T, T_SERIALISED_LEN> {
     storage_slot: Field,

yarn-project/noir-libs/noir-aztec/src/types.nr

@@ -1,3 +1,4 @@
+mod option; // This can/should be moved out into an official noir library
 mod point;
 mod vec; // This can/should be moved out into an official noir library
-mod option; // This can/should be moved out into an official noir library
+mod type_serialisation;

yarn-project/noir-libs/noir-aztec/src/types/point.nr

@@ -1,3 +1,5 @@
+use crate::types::type_serialisation::TypeSerialisationInterface;
+
 struct Point {
     x: Field,
     y: Field,
@@ -7,4 +9,22 @@ impl Point {
     fn new(x: Field, y: Field) -> Self {
         Point { x, y }
     } 
-}
+}
+
+global POINT_SERIALISED_LEN: Field = 2;
+
+fn deserialisePoint(fields: [Field; POINT_SERIALISED_LEN]) -> Point {
+    Point {
+        x: fields[0],
+        y: fields[1],
+    }
+}
+
+fn serialisePoint(point: Point) -> [Field; POINT_SERIALISED_LEN] {
+    [point.x, point.y]
+}
+
+global PointSerialisationMethods = TypeSerialisationInterface {
+    deserialise: deserialisePoint,
+    serialise: serialisePoint,
+};

yarn-project/noir-libs/noir-aztec/src/state_vars/type_serialisation.nr → yarn-project/noir-libs/noir-aztec/src/types/type_serialisation.nr

@@ -1,3 +1,4 @@
+mod bool_serialisation;
 mod field_serialisation;
 mod u32_serialisation;
 

yarn-project/noir-libs/noir-aztec/src/types/type_serialisation/bool_serialisation.nr

@@ -0,0 +1,16 @@
+use crate::types::type_serialisation::TypeSerialisationInterface;
+
+global BOOL_SERIALISED_LEN: Field = 1;
+
+fn deserialiseBool(fields: [Field; BOOL_SERIALISED_LEN]) -> bool {
+    fields[0] as bool
+}
+
+fn serialiseBool(value: bool) -> [Field; BOOL_SERIALISED_LEN] {
+    [value as Field]
+}
+
+global BoolSerialisationMethods = TypeSerialisationInterface {
+    deserialise: deserialiseBool,
+    serialise: serialiseBool,
+};

yarn-project/noir-libs/noir-aztec/src/state_vars/type_serialisation/field_serialisation.nr → yarn-project/noir-libs/noir-aztec/src/types/type_serialisation/field_serialisation.nr

@@ -1,4 +1,4 @@
-use crate::state_vars::type_serialisation::TypeSerialisationInterface;
+use crate::types::type_serialisation::TypeSerialisationInterface;
 
 global FIELD_SERIALISED_LEN: Field = 1;
 

yarn-project/noir-libs/noir-aztec/src/state_vars/type_serialisation/u32_serialisation.nr → yarn-project/noir-libs/noir-aztec/src/types/type_serialisation/u32_serialisation.nr

@@ -1,4 +1,4 @@
-use crate::state_vars::type_serialisation::TypeSerialisationInterface;
+use crate::types::type_serialisation::TypeSerialisationInterface;
 
 global U32_SERIALISED_LEN: Field = 1;