fix: correct batch inversion implementation (#121)

src/fns/constrained_ops.nr

@@ -31,7 +31,7 @@ global TWO_POW_120: Field = 0x1000000000000000000000000000000;
  */
 
 pub(crate) fn limbs_to_field<let N: u32, let MOD_BITS: u32>(
-    params: P<N, MOD_BITS>,
+    _params: P<N, MOD_BITS>,
     limbs: [Field; N],
 ) -> Field {
     let TWO_POW_120 = 0x1000000000000000000000000000000;
@@ -58,7 +58,7 @@ pub(crate) fn limbs_to_field<let N: u32, let MOD_BITS: u32>(
 }
 
 pub(crate) fn from_field<let N: u32, let MOD_BITS: u32>(
-    params: P<N, MOD_BITS>,
+    _params: P<N, MOD_BITS>,
     field: Field,
 ) -> [Field; N] {
     // Safety: we check that the resulting limbs represent the intended field element

src/fns/unconstrained_ops.nr

@@ -237,7 +237,7 @@ pub(crate) unconstrained fn __batch_invert<let N: u32, let MOD_BITS: u32, let M:
 ) -> [[Field; N]; M] {
     // TODO: ugly! Will fail if input slice is empty
     let mut accumulator: [Field; N] = __one::<N>();
-    let mut temporaries: [[Field; N]; N] = std::mem::zeroed();
+    let mut temporaries: [[Field; N]; M] = std::mem::zeroed();
     for i in 0..M {
         temporaries[i] = accumulator;
         if (!__is_zero(x[i])) {

src/tests/bignum_test.nr

@@ -950,9 +950,7 @@ where
 #[test]
 unconstrained fn test_batch_inversion_BN381(seeds: [[u8; 2]; 3]) {
     let fields = seeds.map(|seed| BN381::derive_from_seed(seed));
-    unsafe {
-        test_batch_inversion(fields)
-    }
+    test_batch_inversion(fields)
 }
 
 unconstrained fn test_batch_inversion_slice<BN>(fields: [BN])
@@ -969,7 +967,5 @@ where
 #[test]
 unconstrained fn test_batch_inversion_slice_BN381(seeds: [[u8; 2]; 3]) {
     let fields = seeds.map(|seed| BN381::derive_from_seed(seed)).as_slice();
-    unsafe {
-        test_batch_inversion_slice(fields)
-    }
+    test_batch_inversion_slice(fields)
 }