len := runtime.Callers(3, pcs[:])
	frames := runtime.CallersFrames(pcs[:len])
	for i := 0; i < len; i++ {
		// second return value is "more", not "ok"
		frame, _ := frames.Next()
		if (!strings.HasPrefix(frame.File, gormSourceDir) ||
			strings.HasSuffix(frame.File, "_test.go")) && !strings.HasSuffix(frame.File, ".gen.go") {
			return string(strconv.AppendInt(append([]byte(frame.File), ':'), int64(frame.Line), 10))
		}
	}

		isSameType  = fullDataType == realDataType
	)

	if !field.PrimaryKey {
		// check type
		if !strings.HasPrefix(fullDataType, realDataType) {
			// check type aliases
			aliases := m.DB.Migrator().GetTypeAliases(realDataType)
			for _, alias := range aliases {
				if strings.HasPrefix(fullDataType, alias) {
					isSameType = true
					break
				}
			}

			if !isSameType {
				alterColumn = true

		Int8 Smallint
	}

	tracer := Tracer{
		Logger: DB.Config.Logger,
		Test: func(ctx context.Context, begin time.Time, fc func() (sql string, rowsAffected int64), err error) {
			sql, _ := fc()
			if strings.HasPrefix(sql, "ALTER TABLE \"migrate_ints\" ALTER COLUMN \"int8\" TYPE smallint") {
				t.Fatalf("shouldn't execute ALTER COLUMN TYPE if such type is already existed in DB schema: sql: %s",
					sql)
			}
		},
	}