Fix integer conversions and log2

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())),
                     }
                 }