golang file1 代码
文件路径：/src/cmd/vet/testdata/tagtest/file1.go
/ Copyright 2015 The Go Authors. All rights reserved.
/ Use of this source code is governed by a BSD-style
/ license that can be found in the LICENSE file.
/go:build testtag
/ +build testtag
package main
import "fmt"
func main() {
fmt.Printf("%s", 0)
}