storage: ensure proper equality tests on Timestamp

Now that structural equality is different than semantic equality because
of the new flags field in Timestamp, we need to be careful about
comparing by value.

I detected these by adding a `_ func()` field to the struct and observed
what fell out when compiling.

pkg/ccl/changefeedccl/kvfeed/kv_feed.go

@@ -362,7 +362,7 @@ func copyFromSourceToSinkUntilTableEvent(
 					return false, false
 				}
 				frontier.Forward(resolved.Span, boundaryResolvedTimestamp)
-				return true, frontier.Frontier() == boundaryResolvedTimestamp
+				return true, frontier.Frontier().EqOrdering(boundaryResolvedTimestamp)
 			default:
 				log.Fatal(ctx, "unknown event type")
 				return false, false

pkg/kv/kvserver/liveness/livenesspb/liveness.go

@@ -53,7 +53,7 @@ func (l *Liveness) Compare(o Liveness) int {
 		}
 		return +1
 	}
-	if l.Expiration != o.Expiration {
+	if !l.Expiration.EqOrdering(o.Expiration) {
 		if l.Expiration.Less(o.Expiration) {
 			return -1
 		}

pkg/kv/kvserver/rangefeed/resolved_timestamp.go

@@ -312,7 +312,7 @@ func (h unresolvedTxnHeap) Less(i, j int) bool {
 	// container/heap constructs a min-heap by default, so prioritize the txn
 	// with the smaller timestamp. Break ties by comparing IDs to establish a
 	// total order.
-	if h[i].timestamp == h[j].timestamp {
+	if h[i].timestamp.EqOrdering(h[j].timestamp) {
 		return bytes.Compare(h[i].txnID.GetBytes(), h[j].txnID.GetBytes()) < 0
 	}
 	return h[i].timestamp.Less(h[j].timestamp)

pkg/kv/kvserver/replica_consistency_diff.go

@@ -112,7 +112,7 @@ func diffRange(l, r *roachpb.RaftSnapshotData) ReplicaSnapshotDiffSlice {
 		case 0:
 			// Timestamp sorting is weird. Timestamp{} sorts first, the
 			// remainder sort in descending order. See storage/engine/doc.go.
-			if e.Timestamp != v.Timestamp {
+			if !e.Timestamp.EqOrdering(v.Timestamp) {
 				if e.Timestamp.IsEmpty() {
 					addLeaseHolder()
 				} else if v.Timestamp.IsEmpty() {

pkg/sql/sem/tree/as_of.go

@@ -132,7 +132,7 @@ func DatumToHLC(evalCtx *EvalContext, stmtTimestamp time.Time, d Datum) (hlc.Tim
 		return ts, convErr
 	}
 	zero := hlc.Timestamp{}
-	if ts == zero {
+	if ts.EqOrdering(zero) {
 		return ts, errors.Errorf("zero timestamp is invalid")
 	} else if ts.Less(zero) {
 		return ts, errors.Errorf("timestamp before 1970-01-01T00:00:00Z is invalid")

pkg/storage/multi_iterator.go

@@ -155,7 +155,7 @@ func (f *multiIterator) advance() {
 			// The iterator at iterIdx has the same key as the current best, add
 			// it to itersWithCurrentKey and check how the timestamps compare.
 			f.itersWithCurrentKey = append(f.itersWithCurrentKey, iterIdx)
-			if proposedMVCCKey.Timestamp == iterMVCCKey.Timestamp {
+			if proposedMVCCKey.Timestamp.EqOrdering(iterMVCCKey.Timestamp) {
 				// We have two exactly equal mvcc keys (both key and timestamps
 				// match). The one in the later iterator takes precedence and
 				// the one in the earlier iterator should be omitted from

pkg/storage/mvcc.go

@@ -137,7 +137,7 @@ func (k MVCCKey) Less(l MVCCKey) bool {
 
 // Equal returns whether two keys are identical.
 func (k MVCCKey) Equal(l MVCCKey) bool {
-	return k.Key.Compare(l.Key) == 0 && k.Timestamp == l.Timestamp
+	return k.Key.Compare(l.Key) == 0 && k.Timestamp.EqOrdering(l.Timestamp)
 }
 
 // IsValue returns true iff the timestamp is non-zero.

pkg/util/span/frontier.go

@@ -60,7 +60,7 @@ func (h frontierHeap) Len() int { return len(h) }
 
 // Less implements heap.Interface.
 func (h frontierHeap) Less(i, j int) bool {
-	if h[i].ts == h[j].ts {
+	if h[i].ts.EqOrdering(h[j].ts) {
 		return h[i].span.Key.Compare(h[j].span.Key) < 0
 	}
 	return h[i].ts.Less(h[j].ts)