Fix integer conversions and log2

crypto-primitives/src/merkle_tree/mod.rs

@@ -258,12 +258,6 @@ impl core::fmt::Display for Error {
 
 impl algebra_core::Error for Error {}
 
-/// Returns the log2 value of the given number.
-#[inline]
-fn log2(number: usize) -> usize {
-    algebra_core::log2(number) as usize
-}
-
 /// Returns the height of the tree, given the size of the tree.
 #[inline]
 fn tree_height(tree_size: usize) -> usize {
@@ -271,7 +265,7 @@ fn tree_height(tree_size: usize) -> usize {
         return 1;
     }
 
-    log2(tree_size)
+    algebra_core::log2(tree_size) as usize
 }
 
 /// Returns true iff the index represents the root.

r1cs-std/src/bits/boolean.rs

@@ -591,7 +591,7 @@ impl<F: Field> ToBytesGadget<F> for Boolean<F> {
     fn to_bytes(&self) -> Result<Vec<UInt8<F>>, SynthesisError> {
         let mut bits = vec![self.clone()];
         bits.extend(vec![Boolean::constant(false); 7]);
-        let value = self.value().map(|val| val as u8).ok();
+        let value = self.value().map(u8::from).ok();
         let byte = UInt8 { bits, value };
         Ok(vec![byte])
     }

r1cs-std/src/bits/uint.rs

@@ -3,6 +3,7 @@ macro_rules! make_uint {
         pub mod $mod_name {
             use algebra::{Field, FpParameters, PrimeField};
             use core::borrow::Borrow;
+            use core::convert::TryFrom;
 
             use r1cs_core::{
                 lc, ConstraintSystemRef, LinearCombination, Namespace, SynthesisError, Variable,
@@ -119,7 +120,9 @@ macro_rules! make_uint {
 
                     $name {
                         bits: new_bits,
-                        value: self.value.map(|v| v.rotate_right(by as u32)),
+                        value: self
+                            .value
+                            .map(|v| v.rotate_right(u32::try_from(by).unwrap())),
                     }
                 }
 

r1cs-std/src/fields/fp/mod.rs

@@ -476,8 +476,8 @@ impl<F: PrimeField> TwoBitLookupGadget<F> for AllocatedFp<F> {
         debug_assert_eq!(c.len(), 4);
         if let Some(cs) = b.cs() {
             let result = Self::new_witness(cs.clone(), || {
-                let lsb = b[0].value()? as usize;
+                let lsb = usize::from(b[0].value()?);
-                let msb = b[1].value()? as usize;
+                let msb = usize::from(b[1].value()?);
                 let index = lsb + (msb << 1);
                 Ok(c[index])
             })?;
@@ -509,8 +509,8 @@ impl<F: PrimeField> ThreeBitCondNegLookupGadget<F> for AllocatedFp<F> {
 
         if let Some(cs) = b.cs() {
             let result = Self::new_witness(cs.clone(), || {
-                let lsb = b[0].value()? as usize;
+                let lsb = usize::from(b[0].value()?);
-                let msb = b[1].value()? as usize;
+                let msb = usize::from(b[1].value()?);
                 let index = lsb + (msb << 1);
                 let intermediate = c[index];
 
@@ -893,8 +893,8 @@ impl<F: PrimeField> TwoBitLookupGadget<F> for FpVar<F> {
         if b.cs().is_some() {
             AllocatedFp::two_bit_lookup(b, c).map(Self::Var)
         } else {
-            let lsb = b[0].value()? as usize;
+            let lsb = usize::from(b[0].value()?);
-            let msb = b[1].value()? as usize;
+            let msb = usize::from(b[1].value()?);
             let index = lsb + (msb << 1);
             Ok(Self::Constant(c[index]))
         }
@@ -916,8 +916,8 @@ impl<F: PrimeField> ThreeBitCondNegLookupGadget<F> for FpVar<F> {
         if b.cs().or(b0b1.cs()).is_some() {
             AllocatedFp::three_bit_cond_neg_lookup(b, b0b1, c).map(Self::Var)
         } else {
-            let lsb = b[0].value()? as usize;
+            let lsb = usize::from(b[0].value()?);
-            let msb = b[1].value()? as usize;
+            let msb = usize::from(b[1].value()?);
             let index = lsb + (msb << 1);
             let intermediate = c[index];