Only implement CheckNamedValue for go1.8+

Author: pushrax

connection.go

@@ -459,8 +459,3 @@ func (mc *mysqlConn) finish() {
 	case <-mc.closech:
 	}
 }
-
-func (mc *mysqlConn) CheckNamedValue(nv *driver.NamedValue) (err error) {
-	nv.Value, err = converter{}.ConvertValue(nv.Value)
-	return
-}

connection_go18.go

@@ -195,3 +195,8 @@ func (mc *mysqlConn) startWatcher() {
 		}
 	}()
 }
+
+func (mc *mysqlConn) CheckNamedValue(nv *driver.NamedValue) (err error) {
+	nv.Value, err = converter{}.ConvertValue(nv.Value)
+	return
+}

connection_go18_test.go

@@ -0,0 +1,30 @@
+// Go MySQL Driver - A MySQL-Driver for Go's database/sql package
+//
+// Copyright 2017 The Go-MySQL-Driver Authors. All rights reserved.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at http://mozilla.org/MPL/2.0/.
+
+// +build go1.8
+
+package mysql
+
+import (
+	"database/sql/driver"
+	"testing"
+)
+
+func TestCheckNamedValue(t *testing.T) {
+	value := driver.NamedValue{Value: ^uint64(0)}
+	x := &mysqlConn{}
+	err := x.CheckNamedValue(&value)
+
+	if err != nil {
+		t.Fatal("High-bit set uint64 not supported", err)
+	}
+
+	if value.Value != "18446744073709551615" {
+		t.Fatal("High-bit set uint64 not supported", value.Value)
+	}
+}