Improving error information for address parser

Author: dr-orlovsky

src/util/address.rs

@@ -61,7 +61,12 @@ pub enum Error {
     /// The bech32 payload was empty
     EmptyBech32Payload,
     /// The wrong checksum algorithm was used. See BIP-0350.
-    InvalidBech32Variant,
+    InvalidBech32Variant {
+        /// Bech32 variant that is required by the used Witness version
+        expected: bech32::Variant,
+        /// The actual Bech32 variant encoded in the address representation
+        found: bech32::Variant
+    },
     /// Script version must be 0 to 16 inclusive
     InvalidWitnessVersion(u8),
     /// Unable to parse witness version from string
@@ -81,12 +86,12 @@ pub enum Error {
 impl fmt::Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {
-            Error::Base58(ref e) => write!(f, "base58: {}", e),
-            Error::Bech32(ref e) => write!(f, "bech32: {}", e),
+            Error::Base58(_) => write!(f, "base58 address encoding error"),
+            Error::Bech32(_) => write!(f, "bech32 address encoding error"),
             Error::EmptyBech32Payload => write!(f, "the bech32 payload was empty"),
-            Error::InvalidBech32Variant => write!(f, "invalid bech32 checksum variant"),
+            Error::InvalidBech32Variant { expected, found } => write!(f, "invalid bech32 checksum variant found {:?} when {:?} was expected", found, expected),
             Error::InvalidWitnessVersion(v) => write!(f, "invalid witness script version: {}", v),
-            Error::UnparsableWitnessVersion(ref e) => write!(f, "Incorrect format of a witness version byte: {}", e),
+            Error::UnparsableWitnessVersion(_) => write!(f, "incorrect format of a witness version byte"),
             Error::MalformedWitnessVersion => f.write_str("bitcoin script opcode does not match any known witness version, the script is malformed"),
             Error::InvalidWitnessProgramLength(l) => write!(f,
                 "the witness program must be between 2 and 40 bytes in length: length={}", l,
@@ -716,8 +721,9 @@ impl FromStr for Address {
             }
 
             // Encoding check
-            if version.bech32_variant() != variant {
-                return Err(Error::InvalidBech32Variant);
+            let expected = version.bech32_variant();
+            if expected != variant {
+                return Err(Error::InvalidBech32Variant { expected, found: variant });
             }
 
             return Ok(Address {