Add Fe32::ZERO const

src/primitives/checksum.rs

@@ -463,7 +463,7 @@ impl<'hrp> Iterator for HrpFe32Iter<'hrp> {
                 Some(high) => return Some(Fe32(high >> 5)),
                 None => {
                     self.high_iter = None;
-                    return Some(Fe32::Q);
+                    return Some(Fe32::ZERO);
                 }
             }
         }

src/primitives/decode.rs

@@ -180,7 +180,7 @@ impl<'s> UncheckedHrpstring<'s> {
     ///
     /// let mut unchecked = UncheckedHrpstring::new(&addr).unwrap();
     /// let witness_version = unchecked.remove_witness_version().unwrap();
-    /// assert_eq!(witness_version, Fe32::Q);
+    /// assert_eq!(witness_version, Fe32::ZERO);
     /// assert!(unchecked.data_part_ascii().iter().eq(ascii.as_bytes().iter()))
     /// ```
     #[inline]
@@ -210,7 +210,7 @@ impl<'s> UncheckedHrpstring<'s> {
     /// let addr = "bc1qar0srrr7xfkvy5l643lydnw9re59gtzzffffff";
     ///
     /// let unchecked = UncheckedHrpstring::new(&addr).unwrap();
-    /// assert_eq!(unchecked.witness_version(), Some(Fe32::Q));
+    /// assert_eq!(unchecked.witness_version(), Some(Fe32::ZERO));
     /// ```
     #[inline]
     pub fn witness_version(&self) -> Option<Fe32> {

src/primitives/gf32.rs

@@ -71,6 +71,9 @@ const CHARS_INV: [i8; 128] = [
 pub struct Fe32(pub(crate) u8);
 
 impl Fe32 {
+    /// The Zero element is 0 numeric (character 'Q')
+    pub const ZERO: Fe32 = Fe32(0);
+
     // These are a little gratuitous for a reference implementation, but it makes me happy to do it.
     /// Numeric value maps to bech32 character: 0 == "q".
     pub const Q: Fe32 = Fe32(0);
@@ -257,7 +260,7 @@ impl AsRef<u8> for Fe32 {
 }
 
 impl super::Field for Fe32 {
-    const ZERO: Self = Fe32::Q;
+    const ZERO: Self = Fe32::ZERO;
     const ONE: Self = Fe32::P;
     const GENERATOR: Self = Fe32::Z;
     const MULTIPLICATIVE_ORDER: usize = 31;
@@ -487,6 +490,12 @@ mod tests {
             assert_eq!(fe * Fe32::P, fe) // Fe32::P == Fe32(1)
         }
     }
+
+    #[test]
+    fn const_zero() {
+        assert_eq!(Fe32::ZERO.to_u8(), 0);
+        assert_eq!(Fe32::ZERO.to_char(), 'q');
+    }
 }
 
 #[cfg(kani)]

src/primitives/segwit.rs

@@ -18,7 +18,7 @@ use crate::primitives::gf32::Fe32;
 pub const MAX_STRING_LENGTH: usize = 90;
 
 /// The field element representing segwit version 0.
-pub const VERSION_0: Fe32 = Fe32::Q;
+pub const VERSION_0: Fe32 = Fe32::ZERO;
 /// The field element representing segwit version 1 (taproot).
 pub const VERSION_1: Fe32 = Fe32::P;
 

tests/bip_173_test_vectors.rs

@@ -59,7 +59,7 @@ macro_rules! check_valid_address_roundtrip {
                 // bech32 checksum algorithm can be used with any witness version, and this is
                 // tested by the test vectors. However when BIP-350 came into effect only witness
                 // version 0 uses bech32 (and this is enforced by encode/decode).
-                if let Ok((hrp, bech32::Fe32::Q, program)) = bech32::segwit::decode($addr) {
+                if let Ok((hrp, bech32::Fe32::ZERO, program)) = bech32::segwit::decode($addr) {
                     let encoded = bech32::segwit::encode_v0(hrp, &program).expect("failed to encode address");
                     // The bips specifically say that encoder should output lowercase characters so we uppercase manually.
                     if encoded != $addr {