chore!: replace dummy ABIs with FunctionSignature type alias (#930)

* chore:replace dummy ABIs with `FunctionSignature` type

* chore: rename `build_empty_map` to `build_placeholder_input_map`

crates/nargo/src/cli/check_cmd.rs

@@ -2,7 +2,7 @@ use crate::{errors::CliError, resolver::Resolver};
 use acvm::ProofSystemCompiler;
 use clap::Args;
 use iter_extended::btree_map;
-use noirc_abi::{Abi, AbiParameter, AbiType};
+use noirc_abi::{AbiParameter, AbiType, MAIN_RETURN_NAME};
 use std::{
     collections::BTreeMap,
     path::{Path, PathBuf},
@@ -37,7 +37,7 @@ fn check_from_path<P: AsRef<Path>>(p: P, allow_warnings: bool) -> Result<(), Cli
     }
 
     // XXX: We can have a --overwrite flag to determine if you want to overwrite the Prover/Verifier.toml files
-    if let Some(abi) = driver.compute_abi() {
+    if let Some((parameters, return_type)) = driver.compute_function_signature() {
         // XXX: The root config should return an enum to determine if we are looking for .json or .toml
         // For now it is hard-coded to be toml.
         //
@@ -49,12 +49,15 @@ fn check_from_path<P: AsRef<Path>>(p: P, allow_warnings: bool) -> Result<(), Cli
         // If they are not available, then create them and
         // populate them based on the ABI
         if !path_to_prover_input.exists() {
-            let toml = toml::to_string(&build_empty_map(abi.clone())).unwrap();
+            let toml =
+                toml::to_string(&build_placeholder_input_map(parameters.clone(), None)).unwrap();
             write_to_file(toml.as_bytes(), &path_to_prover_input);
         }
         if !path_to_verifier_input.exists() {
-            let public_abi = abi.public_abi();
-            let toml = toml::to_string(&build_empty_map(public_abi)).unwrap();
+            let public_inputs = parameters.into_iter().filter(|param| param.is_public()).collect();
+
+            let toml =
+                toml::to_string(&build_placeholder_input_map(public_inputs, return_type)).unwrap();
             write_to_file(toml.as_bytes(), &path_to_verifier_input);
         }
     } else {
@@ -63,11 +66,26 @@ fn check_from_path<P: AsRef<Path>>(p: P, allow_warnings: bool) -> Result<(), Cli
     Ok(())
 }
 
-fn build_empty_map(abi: Abi) -> BTreeMap<String, &'static str> {
-    btree_map(abi.parameters, |AbiParameter { name, typ, .. }| {
-        let default_value = if matches!(typ, AbiType::Array { .. }) { "[]" } else { "" };
-        (name, default_value)
-    })
+fn build_placeholder_input_map(
+    parameters: Vec<AbiParameter>,
+    return_type: Option<AbiType>,
+) -> BTreeMap<String, &'static str> {
+    let default_value = |typ: AbiType| {
+        if matches!(typ, AbiType::Array { .. }) {
+            "[]"
+        } else {
+            ""
+        }
+    };
+
+    let mut map =
+        btree_map(parameters, |AbiParameter { name, typ, .. }| (name, default_value(typ)));
+
+    if let Some(typ) = return_type {
+        map.insert(MAIN_RETURN_NAME.to_owned(), default_value(typ));
+    }
+
+    map
 }
 
 #[cfg(test)]

crates/noirc_abi/src/lib.rs

@@ -24,6 +24,9 @@ pub type InputMap = BTreeMap<String, InputValue>;
 /// A map from the witnesses in a constraint system to the field element values
 pub type WitnessMap = BTreeMap<Witness, FieldElement>;
 
+/// A tuple of the arguments to a function along with its return value.
+pub type FunctionSignature = (Vec<AbiParameter>, Option<AbiType>);
+
 pub const MAIN_RETURN_NAME: &str = "return";
 
 #[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]

crates/noirc_driver/src/lib.rs

@@ -4,7 +4,7 @@
 
 use acvm::Language;
 use fm::FileType;
-use noirc_abi::Abi;
+use noirc_abi::FunctionSignature;
 use noirc_errors::{reporter, ReportedError};
 use noirc_evaluator::create_circuit;
 use noirc_frontend::graph::{CrateId, CrateName, CrateType, LOCAL_CRATE};
@@ -129,15 +129,14 @@ impl Driver {
         reporter::finish_report(error_count)
     }
 
-    pub fn compute_abi(&self) -> Option<Abi> {
+    pub fn compute_function_signature(&self) -> Option<FunctionSignature> {
         let local_crate = self.context.def_map(LOCAL_CRATE).unwrap();
 
         let main_function = local_crate.main_function()?;
 
         let func_meta = self.context.def_interner.function_meta(&main_function);
 
-        let abi = func_meta.into_abi(&self.context.def_interner);
-        Some(abi)
+        Some(func_meta.into_function_signature(&self.context.def_interner))
     }
 
     pub fn into_compiled_program(

crates/noirc_evaluator/src/lib.rs

@@ -63,14 +63,14 @@ pub fn create_circuit(
 
     let witness_index = evaluator.current_witness_index();
 
-    let mut abi = program.abi;
+    let (parameters, return_type) = program.main_function_signature;
 
     // TODO: remove return value from `param_witnesses` once we track public outputs
     // see https://github.com/noir-lang/acvm/pull/56
     let mut param_witnesses = evaluator.param_witnesses;
     let return_witnesses = param_witnesses.remove(MAIN_RETURN_NAME).unwrap_or_default();
-    abi.param_witnesses = param_witnesses;
-    abi.return_witnesses = return_witnesses;
+
+    let abi = Abi { parameters, param_witnesses, return_type, return_witnesses };
 
     let optimized_circuit = acvm::compiler::compile(
         Circuit {
@@ -287,7 +287,7 @@ impl Evaluator {
         // The new grammar has been conceived, and will be implemented.
         let main = ir_gen.program.main();
         let main_params = std::mem::take(&mut main.parameters);
-        let abi_params = std::mem::take(&mut ir_gen.program.abi.parameters);
+        let abi_params = std::mem::take(&mut ir_gen.program.main_function_signature.0);
 
         assert_eq!(main_params.len(), abi_params.len());
 

crates/noirc_frontend/src/hir_def/function.rs

@@ -1,7 +1,5 @@
-use std::collections::BTreeMap;
-
 use iter_extended::vecmap;
-use noirc_abi::{Abi, AbiParameter, AbiVisibility};
+use noirc_abi::{AbiParameter, AbiType, AbiVisibility};
 use noirc_errors::{Location, Span};
 
 use super::expr::{HirBlockExpression, HirExpression, HirIdent};
@@ -55,20 +53,14 @@ fn get_param_name<'a>(pattern: &HirPattern, interner: &'a NodeInterner) -> Optio
 pub struct Parameters(pub Vec<Param>);
 
 impl Parameters {
-    fn into_abi(self, interner: &NodeInterner) -> Abi {
-        let parameters = vecmap(self.0, |param| {
+    fn into_abi_params(self, interner: &NodeInterner) -> Vec<AbiParameter> {
+        vecmap(self.0, |param| {
             let param_name = get_param_name(&param.0, interner)
                 .expect("Abi for tuple and struct parameters is unimplemented")
                 .to_owned();
             let as_abi = param.1.as_abi_type();
             AbiParameter { name: param_name, typ: as_abi, visibility: param.2 }
-        });
-        noirc_abi::Abi {
-            parameters,
-            param_witnesses: BTreeMap::new(),
-            return_type: None,
-            return_witnesses: Vec::new(),
-        }
+        })
     }
 
     pub fn span(&self) -> Span {
@@ -155,15 +147,18 @@ impl FuncMeta {
         }
     }
 
-    pub fn into_abi(self, interner: &NodeInterner) -> Abi {
-        let return_type = self.return_type().clone();
-        let mut abi = self.parameters.into_abi(interner);
-        abi.return_type = match return_type {
+    pub fn into_function_signature(
+        self,
+        interner: &NodeInterner,
+    ) -> (Vec<AbiParameter>, Option<AbiType>) {
+        let return_type = match self.return_type() {
             Type::Unit => None,
-            _ => Some(return_type.as_abi_type()),
+            typ => Some(typ.as_abi_type()),
         };
 
-        abi
+        let params = self.parameters.into_abi_params(interner);
+
+        (params, return_type)
     }
 
     /// Gives the (uninstantiated) return type of this function.

crates/noirc_frontend/src/monomorphization/ast.rs

@@ -1,6 +1,6 @@
 use acvm::FieldElement;
 use iter_extended::vecmap;
-use noirc_abi::Abi;
+use noirc_abi::FunctionSignature;
 use noirc_errors::Location;
 
 use crate::{BinaryOpKind, Signedness};
@@ -185,12 +185,12 @@ impl Type {
 #[derive(Debug, Clone)]
 pub struct Program {
     pub functions: Vec<Function>,
-    pub abi: Abi,
+    pub main_function_signature: FunctionSignature,
 }
 
 impl Program {
-    pub fn new(functions: Vec<Function>, abi: Abi) -> Program {
-        Program { functions, abi }
+    pub fn new(functions: Vec<Function>, main_function_signature: FunctionSignature) -> Program {
+        Program { functions, main_function_signature }
     }
 
     pub fn main(&mut self) -> &mut Function {

crates/noirc_frontend/src/monomorphization/mod.rs

@@ -1,6 +1,6 @@
 use acvm::FieldElement;
 use iter_extended::{btree_map, vecmap};
-use noirc_abi::Abi;
+use noirc_abi::FunctionSignature;
 use std::collections::{BTreeMap, HashMap, VecDeque};
 
 use crate::{
@@ -40,7 +40,7 @@ type HirType = crate::Type;
 
 pub fn monomorphize(main: node_interner::FuncId, interner: &NodeInterner) -> Program {
     let mut monomorphizer = Monomorphizer::new(interner);
-    let abi = monomorphizer.compile_main(main);
+    let function_sig = monomorphizer.compile_main(main);
 
     while !monomorphizer.queue.is_empty() {
         let (next_fn_id, new_id, bindings) = monomorphizer.queue.pop_front().unwrap();
@@ -52,7 +52,7 @@ pub fn monomorphize(main: node_interner::FuncId, interner: &NodeInterner) -> Pro
     }
 
     let functions = vecmap(monomorphizer.finished_functions, |(_, f)| f);
-    Program::new(functions, abi)
+    Program::new(functions, function_sig)
 }
 
 impl<'interner> Monomorphizer<'interner> {
@@ -129,13 +129,13 @@ impl<'interner> Monomorphizer<'interner> {
         self.globals.entry(id).or_default().insert(typ, new_id);
     }
 
-    fn compile_main(&mut self, main_id: node_interner::FuncId) -> Abi {
+    fn compile_main(&mut self, main_id: node_interner::FuncId) -> FunctionSignature {
         let new_main_id = self.next_function_id();
         assert_eq!(new_main_id, Program::main_id());
         self.function(main_id, new_main_id);
 
         let main_meta = self.interner.function_meta(&main_id);
-        main_meta.into_abi(self.interner)
+        main_meta.into_function_signature(self.interner)
     }
 
     fn function(&mut self, f: node_interner::FuncId, id: FuncId) {