strong hash: Delete StrongHasher

Summary: I said this in code review at the time, but especially since D73095294 it's literally just dead code

Reviewed By: samkevich

Differential Revision: D73634797

fbshipit-source-id: e4db2ce5e16e5fc0198efd73a37ba709e437cbcc

Author: JakobDegen

gazebo/strong_hash/src/lib.rs

@@ -21,34 +21,6 @@ use crate as strong_hash;
 
 mod impls;
 
-/// `StrongHasher` is a trait for hashing functions that return more than 64
-/// bits of output.  The key difference between `std::hash::Hasher` and
-/// `StrongHasher` is that `StrongHasher` produces a vec of bytes as the hash.
-///
-/// For example, a `DefaultHasher` implementation of `StrongHasher` is as follows.
-///
-/// ```ignore
-/// struct DefaultHasher2 {
-///    hasher: DefaultHasher,
-/// }
-///
-/// impl StrongHasher for DefaultHasher2 {
-///     fn finish(self) -> Vec<u8> {
-///         self.hasher.finish().to_le_bytes().to_vec()
-///     }
-/// }
-/// ```
-pub trait StrongHasher: Hasher {
-    /// Finishes the hash and returns the hash in bytes as a `Vec<u8>`.
-    fn finish(&self) -> Vec<u8>;
-}
-
-impl<H: StrongHasher + ?Sized> StrongHasher for &mut H {
-    fn finish(&self) -> Vec<u8> {
-        StrongHasher::finish(*self)
-    }
-}
-
 /// `StrongHash`` is a trait that is notionally similar to `std::hash::Hash`,
 /// but carries the implicit expectation that the hash that will be produced
 /// should be as perturbed as possible.

gazebo/strong_hash_tests/src/lib.rs

@@ -12,7 +12,6 @@
 use std::hash::Hasher;
 
 use strong_hash::StrongHash;
-use strong_hash::StrongHasher;
 
 #[test]
 fn test_strong_hash_derive() {
@@ -60,16 +59,10 @@ fn test_strong_hash_derive() {
         }
     }
 
-    impl StrongHasher for Blake3StrongHasher {
-        fn finish(&self) -> Vec<u8> {
-            self.digest().as_bytes().into()
-        }
-    }
-
-    fn hash(hashable: &impl StrongHash) -> Vec<u8> {
+    fn hash(hashable: &impl StrongHash) -> u64 {
         let mut hasher = Blake3StrongHasher::new();
         hashable.strong_hash(&mut hasher);
-        StrongHasher::finish(&hasher)
+        Hasher::finish(&hasher)
     }
 
     // Now test that hashes are not equal