fix not padding witness vars

examples/less_than.rs

@@ -36,8 +36,7 @@ fn num_to_bits_le_bounded<F: PrimeField>(
       // TODO: Why do I need namespaces here?
       // TODO: Namespace can't use string ids, only const ids
       // let namespaced_cs = Namespace::from(cs.clone());
-      // TODO: Is it a "new_input" or a different type of a variable?
-        AllocatedBool::<F>::new_input(cs.clone(), || b.ok_or(SynthesisError::AssignmentMissing))
+        AllocatedBool::<F>::new_witness(cs.clone(), || b.ok_or(SynthesisError::AssignmentMissing))
     })
     .collect::<Result<Vec<AllocatedBool<F>>, SynthesisError>>()?;
 
@@ -100,7 +99,7 @@ impl<F: PrimeField> ConstraintSynthesizer<F> for LessThanCircuitUnsafe<F> {
     assert!(F::MODULUS_BIT_SIZE > self.num_bits as u32 + 1);
 
     let input_ns = ns!(cs.clone(), "input");
-    let input = AllocatedFp::<F>::new_input(input_ns, || Ok(self.input))?;
+    let input = AllocatedFp::<F>::new_witness(input_ns, || Ok(self.input))?;
 
     let shifted_ns = ns!(cs.clone(), "shifted_diff");
     let shifted_diff = AllocatedFp::<F>::new_witness(shifted_ns, || {
@@ -158,7 +157,7 @@ impl<F: PrimeField> ConstraintSynthesizer<F> for LessThanCircuitSafe<F> {
   fn generate_constraints(self, cs: ConstraintSystemRef<F>) -> Result<(), SynthesisError> {
     // TODO: Do we need to use a namespace here?
     let input_ns = Namespace::from(cs.clone());
-    let input = AllocatedFp::<F>::new_input(input_ns, || Ok(self.input))?;
+    let input = AllocatedFp::<F>::new_witness(input_ns, || Ok(self.input))?;
 
     // Perform the input bit decomposition check
     num_to_bits_le_bounded::<F>(cs.clone(), input, self.num_bits)?;

src/spartan/snark.rs

@@ -25,7 +25,7 @@ use crate::{
 };
 use ark_ff::{AdditiveGroup, Field};
 use ark_relations::lc;
-use ark_relations::r1cs::{ConstraintSynthesizer, ConstraintSystem, ConstraintSystemRef};
+use ark_relations::r1cs::{ConstraintSynthesizer, ConstraintSystem};
 use once_cell::sync::OnceCell;
 use rayon::prelude::*;
 use serde::{Deserialize, Serialize};
@@ -120,7 +120,7 @@ impl<G: Group, EE: EvaluationEngineTrait<G>> RelaxedR1CSSNARKTrait<G> for Relaxe
 
     let num_vars = cs.num_witness_variables();
     (num_vars..num_vars.next_power_of_two()).for_each(|i| {
-      cs.enforce_constraint(lc!(), lc!(), lc!())
+      cs.new_witness_variable(|| Ok(G::Scalar::ZERO))
         .expect(&format!("Failed to enforce padding variable {i}"));
     });
 
@@ -146,18 +146,17 @@ impl<G: Group, EE: EvaluationEngineTrait<G>> RelaxedR1CSSNARKTrait<G> for Relaxe
     pk: &Self::ProverKey,
     circuit: C,
   ) -> Result<Self, SpartanError> {
-    let cs = ConstraintSystem::<G::Scalar>::new();
-    let cs_ref = ConstraintSystemRef::new(cs.clone());
+    let cs_ref = ConstraintSystem::new_ref();
     circuit
       .generate_constraints(cs_ref.clone())
       .expect("TODO: Handle error");
 
-    // Padding the variables
-    let num_vars = cs_ref.num_instance_variables();
+    // Padding the witness variables
+    let num_vars = cs_ref.num_witness_variables();
     (num_vars..num_vars.next_power_of_two()).for_each(|i| {
       cs_ref
-        .enforce_constraint(lc!(), lc!(), lc!())
-        .expect(&format!("Failed to enforce padding constraint {i}"));
+        .new_witness_variable(|| Ok(G::Scalar::ZERO))
+        .expect(&format!("Failed to enforce padding variable {i}"));
     });
 
     let cs = cs_ref.borrow().unwrap();