simplify s[:] to s where s is a slice

Found using https://go-critic.github.io/overview#unslice-ref

blockchain/chainio.go

@@ -120,7 +120,7 @@ func dbFetchVersion(dbTx database.Tx, key []byte) uint32 {
 		return 0
 	}
 
-	return byteOrder.Uint32(serialized[:])
+	return byteOrder.Uint32(serialized)
 }
 
 // dbPutVersion uses an existing database transaction to update the provided
@@ -943,7 +943,7 @@ func serializeBestChainState(state bestChainState) []byte {
 	byteOrder.PutUint32(serializedData[offset:], workSumBytesLen)
 	offset += 4
 	copy(serializedData[offset:], workSumBytes)
-	return serializedData[:]
+	return serializedData
 }
 
 // deserializeBestChainState deserializes the passed serialized best chain

database/ffldb/blockio.go

@@ -474,7 +474,7 @@ func (s *blockStore) writeBlock(rawBlock []byte) (blockLocation, error) {
 	_, _ = hasher.Write(scratch[:])
 
 	// Serialized block.
-	if err := s.writeData(rawBlock[:], "block"); err != nil {
+	if err := s.writeData(rawBlock, "block"); err != nil {
 		return blockLocation{}, err
 	}
 	_, _ = hasher.Write(rawBlock)

wire/fixedIO_test.go

@@ -68,7 +68,7 @@ func (fr *fixedReader) Read(p []byte) (n int, err error) {
 func newFixedReader(max int, buf []byte) io.Reader {
 	b := make([]byte, max)
 	if buf != nil {
-		copy(b[:], buf)
+		copy(b, buf)
 	}
 
 	iobuf := bytes.NewBuffer(b)

wire/message.go

@@ -401,7 +401,7 @@ func ReadMessageWithEncodingN(r io.Reader, pver uint32, btcnet BitcoinNet,
 
 	// Test checksum.
 	checksum := chainhash.DoubleHashB(payload)[0:4]
-	if !bytes.Equal(checksum[:], hdr.checksum[:]) {
+	if !bytes.Equal(checksum, hdr.checksum[:]) {
 		str := fmt.Sprintf("payload checksum failed - header "+
 			"indicates %v, but actual checksum is %v.",
 			hdr.checksum, checksum)