Make pairing and groth16 optional 🎉

Cargo.toml

@@ -22,6 +22,13 @@ byteorder = "1"
 [dependencies.pairing]
 git = "https://github.com/str4d/pairing"
 rev = "3d41ee5abaa4888ff3607689aba007be8856816d"
+optional = true
 
 [features]
-default = []
+groth16 = ["pairing"]
+default = ["groth16"]
+
+[[test]]
+name = "mimc"
+path = "tests/mimc.rs"
+required-features = ["groth16"]

src/domain.rs

@@ -371,6 +371,7 @@ fn parallel_fft<E: ScalarEngine, T: Group<E>>(
 
 // Test multiplying various (low degree) polynomials together and
 // comparing with naive evaluations.
+#[cfg(feature = "pairing")]
 #[test]
 fn polynomial_arith() {
     use pairing::bls12_381::Bls12;
@@ -418,6 +419,7 @@ fn polynomial_arith() {
     test_mul::<Bls12, _>(rng);
 }
 
+#[cfg(feature = "pairing")]
 #[test]
 fn fft_composition() {
     use pairing::bls12_381::Bls12;
@@ -456,6 +458,7 @@ fn fft_composition() {
     test_comp::<Bls12, _>(rng);
 }
 
+#[cfg(feature = "pairing")]
 #[test]
 fn parallel_fft_consistency() {
     use pairing::bls12_381::Bls12;

src/lib.rs

@@ -1,5 +1,6 @@
 extern crate ff;
 extern crate group;
+#[cfg(feature = "pairing")]
 extern crate pairing;
 extern crate rand;
 extern crate num_cpus;
@@ -12,6 +13,7 @@ extern crate byteorder;
 pub mod multicore;
 mod multiexp;
 pub mod domain;
+#[cfg(feature = "groth16")]
 pub mod groth16;
 
 use ff::{Field, ScalarEngine};

src/multiexp.rs

@@ -255,6 +255,7 @@ pub fn multiexp<Q, D, G, S>(
     multiexp_inner(pool, bases, density_map, exponents, 0, c, true)
 }
 
+#[cfg(feature = "pairing")]
 #[test]
 fn test_with_bls12() {
     fn naive_multiexp<G: CurveAffine>(