return "", err
	}

	tryGccgo := func() (string, error) {
		return readGccgoArchive(name, f)
	}

	// Archive header.
	for i := 0; ; i++ { // returns during i==3
		j := bytes.IndexByte(data, '\n')
		if j < 0 {
			return tryGccgo()
		}
		line := data[:j]
		data = data[j+1:]
		switch i {
		case 0:
			if !bytes.Equal(line, bangArch) {
				return tryGccgo()
			}
		case 1: