feat(halo2_proofs): add tachyon halo2 rust binding

halo2_proofs/Cargo.toml

@@ -75,6 +75,8 @@ log = "0.4.17"
 # timer
 ark-std = { version = "0.3.0" }
 
+# binding
+cxx = "1.0"
 
 # Legacy circuit compatibility
 halo2_legacy_pdqsort = { version = "0.1.0", optional = true }
@@ -87,6 +89,9 @@ gumdrop = "0.8"
 proptest = "1"
 rand_core = { version = "0.6", default-features = false, features = ["getrandom"] }
 
+[build-dependencies]
+cxx-build = "1.0"
+
 [target.'cfg(all(target_arch = "wasm32", target_os = "unknown"))'.dev-dependencies]
 getrandom = { version = "0.2", features = ["js"] }
 

halo2_proofs/build.rs

@@ -0,0 +1,48 @@
+fn main() {
+    let src_files = [
+        "src/bn254_blake2b_writer.cc",
+        "src/bn254_evals.cc",
+        "src/bn254_poly.cc",
+        "src/bn254_poseidon_writer.cc",
+        "src/bn254_prover.cc",
+        "src/bn254_proving_key.cc",
+        "src/bn254_rational_evals.cc",
+        "src/bn254_rational_evals_view.cc",
+        "src/bn254_sha256_writer.cc",
+        "src/bn254_snark_verifier_poseidon_writer.cc",
+        "src/cha_cha20_rng.cc",
+        "src/xor_shift_rng.cc",
+    ];
+    cxx_build::bridges([
+        "src/bn254.rs",
+        "src/cha_cha20_rng.rs",
+        "src/xor_shift_rng.rs",
+    ])
+    .files(src_files)
+    .flag_if_supported("-std=c++17")
+    .compile("halo2_proofs");
+
+    let mut dep_files = vec![
+        "include/bn254_blake2b_writer.h",
+        "include/bn254_evals.h",
+        "include/bn254_poly.h",
+        "include/bn254_poseidon_writer.h",
+        "include/bn254_prover.h",
+        "include/bn254_proving_key.h",
+        "include/bn254_rational_evals.h",
+        "include/bn254_rational_evals_view.h",
+        "include/bn254_sha256_writer.h",
+        "include/bn254_snark_verifier_poseidon_writer.h",
+        "include/cha_cha20_rng.h",
+        "include/xor_shift_rng.h",
+        "src/bn254.rs",
+        "src/rust_vec.h",
+        "src/xor_shift_rng.rs",
+    ];
+    dep_files.extend_from_slice(&src_files);
+    for file in dep_files {
+        println!("cargo:rerun-if-changed={file}");
+    }
+
+    println!("cargo:rustc-link-lib=dylib=tachyon");
+}