WIP: Lightweight version of ark-circom (#41)

* remove ethers-core

* test

* return ethereum and add a feature

* lint fixes

---------

Co-authored-by: s1fr0 <28568419+s1fr0@users.noreply.github.com>
Co-authored-by: tyshkor <tyshko1@gmail.com>

src/circom/r1cs_reader.rs

@@ -73,7 +73,7 @@ impl<E: PairingEngine> R1CSFile<E> {
         for _ in 0..num_sections {
             let sec_type = reader.read_u32::<LittleEndian>()?;
             let sec_size = reader.read_u64::<LittleEndian>()?;
-            let offset = reader.seek(SeekFrom::Current(0))?;
+            let offset = reader.stream_position()?;
             sec_offsets.insert(sec_type, offset);
             sec_sizes.insert(sec_type, sec_size);
             reader.seek(SeekFrom::Current(sec_size as i64))?;

src/lib.rs

@@ -7,6 +7,7 @@ pub use witness::WitnessCalculator;
 pub mod circom;
 pub use circom::{CircomBuilder, CircomCircuit, CircomConfig, CircomReduction};
 
+#[cfg(feature = "full")]
 pub mod ethereum;
 
 mod zkey;

src/witness/witness_calculator.rs

@@ -313,8 +313,7 @@ mod runtime {
             // NOTE: We can also get more information why it is failing, see p2str etc here:
             // https://github.com/iden3/circom_runtime/blob/master/js/witness_calculator.js#L52-L64
             println!(
-                "runtime error, exiting early: {0} {1} {2} {3} {4} {5}",
-                a, b, c, d, e, f
+                "runtime error, exiting early: {a} {b} {c} {d} {e} {f}",
             );
             Err(RuntimeError::user(Box::new(ExitCode(1))))
         }