Merge #149: Remove unnecessary call to to_ascii_lowercase

b6233c8 Remove unnecessary call to to_ascii_lowercase (Tobin C. Harding)

Pull request description:

  We already iterate over lowercase characters when encoding a bech32 string, no need to call `to_ascii_lowercase`.

  Add a unit test as documentation of this behavior as well as to verify the change is correct.

ACKs for top commit:
  apoelstra:
    ACK b6233c8

Tree-SHA512: f2a7ef807645b00ae4d87cdeb138624b52b322fc51d9dd0c86076e7ce2c4408aee1333dda1fdf78ee4b59c57334b31f39c4ab0c2e1f2863dd4e2d80aa681c30e

Author: apoelstra

src/segwit.rs

@@ -221,12 +221,12 @@ pub fn encode_lower_to_writer_unchecked<W: std::io::Write>(
     match witness_version {
         VERSION_0 => {
             for c in iter.with_checksum::<Bech32>(hrp).with_witness_version(VERSION_0).chars() {
-                w.write_all(&[c.to_ascii_lowercase() as u8])?;
+                w.write_all(&[c as u8])?;
             }
         }
         version => {
             for c in iter.with_checksum::<Bech32m>(hrp).with_witness_version(version).chars() {
-                w.write_all(&[c.to_ascii_lowercase() as u8])?;
+                w.write_all(&[c as u8])?;
             }
         }
     }
@@ -416,4 +416,18 @@ mod tests {
         let want = "BC1QW508D6QEJXTDG4Y5R3ZARVARY0C5XW7KV8F3T4";
         assert_eq!(address, want);
     }
+
+    #[test]
+    #[cfg(feature = "std")]
+    fn encode_lower_to_writer_including_lowecaseing_hrp() {
+        let program = witness_program();
+        let mut buf = Vec::new();
+        let hrp = Hrp::parse_unchecked("BC");
+        encode_lower_to_writer_unchecked(&mut buf, &hrp, VERSION_0, &program)
+            .expect("failed to encode");
+
+        let address = std::str::from_utf8(&buf).expect("ascii is valid utf8");
+        let want = "bc1qw508d6qejxtdg4y5r3zarvary0c5xw7kv8f3t4";
+        assert_eq!(address, want);
+    }
 }