userhash: don't use pointers for no reason

privmsg.go

@@ -212,9 +212,9 @@ func (robo *Robot) learn(ctx context.Context, log *slog.Logger, ch *channel.Chan
 		log.DebugContext(ctx, "no learn tag")
 		return
 	}
-	user := hasher.Hash(new(userhash.Hash), msg.Sender, msg.To, msg.Time())
+	user := hasher.Hash(msg.Sender, msg.To, msg.Time())
 	start := time.Now()
-	if err := brain.Learn(ctx, robo.brain, ch.Learn, msg.ID, *user, msg.Time(), msg.Text); err != nil {
+	if err := brain.Learn(ctx, robo.brain, ch.Learn, msg.ID, user, msg.Time(), msg.Text); err != nil {
 		log.ErrorContext(ctx, "failed to learn", slog.Any("err", err))
 		return
 	}

userhash/hash.go

@@ -52,15 +52,16 @@ func New(prk []byte) Hasher {
 	}
 }
 
-// Hash computes a userhash and writes it into dst.
-func (h Hasher) Hash(dst *Hash, uid, where string, when time.Time) *Hash {
+// Hash computes a userhash.
+func (h Hasher) Hash(uid, where string, when time.Time) Hash {
 	h.mac.Reset()
 	t := when.UnixNano() / TimeQuantum.Nanoseconds()
 	b := make([]byte, 8, 8+len(uid)+1+len(where))
+	dst := make([]byte, 0, Size)
 	binary.LittleEndian.PutUint64(b, uint64(t))
 	b = append(b, uid...)
 	b = append(b, 0xaa)
 	b = append(b, where...)
 	h.mac.Write(b)
-	return (*Hash)(h.mac.Sum(dst[:0]))
+	return Hash(h.mac.Sum(dst))
 }

userhash/hash_test.go

@@ -36,12 +36,12 @@ func TestHasher(t *testing.T) {
 			for _, loc := range locs {
 				for _, when := range times {
 					hr := userhash.New([]byte(key))
-					a := *hr.Hash(new(userhash.Hash), user, loc, when)
+					a := hr.Hash(user, loc, when)
 					if u[a] {
 						t.Errorf("duplicate hash: %s/%s/%s/%v gave %x", key, user, loc, when, a)
 					}
 					u[a] = true
-					b := *hr.Hash(new(userhash.Hash), user, loc, when)
+					b := hr.Hash(user, loc, when)
 					if a != b {
 						t.Errorf("repeated hash changed: %s/%s/%s/%v gave first %x then %x", key, user, loc, when, a, b)
 					}