mcf: impl Display for PasswordHashRef (#2114)

It's a `str` newtype, so make it possible to display the underlying
string

Author: tarcieri

mcf/src/lib.rs

@@ -20,6 +20,7 @@ mod base64;
 mod error;
 mod fields;
 
+use core::fmt;
 pub use error::{Error, Result};
 pub use fields::{Field, Fields};
 
@@ -71,6 +72,12 @@ impl<'a> PasswordHashRef<'a> {
     }
 }
 
+impl fmt::Display for PasswordHashRef<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(self.as_str())
+    }
+}
+
 impl<'a> From<PasswordHashRef<'a>> for &'a str {
     fn from(hash: PasswordHashRef<'a>) -> &'a str {
         hash.0