add frontend features to reduce the amount of dependencies and compil…

…ation time

The reasoning behind this is that compilation time now is too long, in
part because dependencies on specific frontends, so if the compilation
don't use some frontend it can be turned off by default.

folding-schemes/Cargo.toml

@@ -15,7 +15,6 @@ ark-relations = { version = "^0.4.0", default-features = false }
 ark-r1cs-std = { version = "0.4.0", default-features = false } # this is patched at the workspace level
 ark-snark = { version = "^0.4.0"}
 ark-serialize = "^0.4.0"
-ark-circom = { git = "https://github.com/arnaucube/circom-compat" }
 thiserror = "1.0"
 rayon = "1.7.0"
 num-bigint = "0.4"
@@ -24,17 +23,20 @@ color-eyre = "=0.6.2"
 ark-bn254 = {version="0.4.0"}
 ark-groth16 = { version = "^0.4.0" }
 sha3 = "0.10"
-ark-noname = { git = "https://github.com/dmpierre/ark-noname", branch="feat/sonobe-integration" }
-noname = { git = "https://github.com/dmpierre/noname" }
 serde_json = "1.0.85"                                                                # to (de)serialize JSON
 serde = "1.0.203"
-acvm = { git = "https://github.com/noir-lang/noir", rev="2b4853e", default-features = false }
-arkworks_backend = { git = "https://github.com/dmpierre/arkworks_backend", branch="feat/sonobe-integration" }
 log = "0.4"
 
 # tmp import for espresso's sumcheck
 espresso_subroutines = {git="https://github.com/EspressoSystems/hyperplonk", package="subroutines"}
 
+# frontend dependencies:
+ark-circom = { git = "https://github.com/arnaucube/circom-compat", optional=true }
+noir_arkworks_backend = { package="arkworks_backend", git = "https://github.com/dmpierre/arkworks_backend", branch="feat/sonobe-integration", optional=true }
+acvm = { git = "https://github.com/noir-lang/noir", rev="2b4853e", default-features = false, optional=true }
+noname = { git = "https://github.com/dmpierre/noname", optional=true }
+ark-noname = { git = "https://github.com/dmpierre/ark-noname", branch="feat/sonobe-integration", optional=true }
+
 [dev-dependencies]
 ark-pallas = {version="0.4.0", features=["r1cs"]}
 ark-vesta = {version="0.4.0", features=["r1cs"]}
@@ -46,7 +48,14 @@ tracing-subscriber = { version = "0.2" }
 
 [features]
 default = ["parallel"]
+# 'light-test' is a feature disabled by default, that when enabled will affect
+# the DeciderEthCircuit implementations, skipping the heavy-weight parts of the
+# circuit, allowing to run light tests of it taking less time.
 light-test = []
+# frontend features:
+circom = ["dep:ark-circom"]
+noir = ["dep:acvm", "dep:noir_arkworks_backend"]
+noname = ["dep:noname", "dep:ark-noname"]
 
 parallel = [ 
     "ark-std/parallel", 

folding-schemes/src/frontend/mod.rs

@@ -4,8 +4,13 @@ use ark_r1cs_std::fields::fp::FpVar;
 use ark_relations::r1cs::{ConstraintSystemRef, SynthesisError};
 use ark_std::fmt::Debug;
 
+// we use features to activate specific frontends, to reduce the amount of dependencies and compile
+// time
+#[cfg(feature = "circom")]
 pub mod circom;
+#[cfg(feature = "noir")]
 pub mod noir;
+#[cfg(feature = "noname")]
 pub mod noname;
 
 /// FCircuit defines the trait of the circuit of the F function, which is the one being folded (ie.

folding-schemes/src/frontend/noir/mod.rs

@@ -16,7 +16,7 @@ use ark_ff::PrimeField;
 use ark_r1cs_std::{alloc::AllocVar, fields::fp::FpVar, R1CSVar};
 use ark_relations::r1cs::ConstraintSynthesizer;
 use ark_relations::r1cs::{ConstraintSystemRef, SynthesisError};
-use arkworks_backend::{read_program_from_file, sonobe_bridge::AcirCircuitSonobe};
+use noir_arkworks_backend::{read_program_from_file, sonobe_bridge::AcirCircuitSonobe};
 
 #[derive(Clone, Debug)]
 pub struct NoirFCircuit<F: PrimeField> {