这是编译器错误还是我的代码？

Question

这是一个示例代码:

#include <iostream>
#include <stdexcept>
#include <cstring>
#include <ctime>
#include <sstream>

using std::cout;
using std::endl;

std::size_t const BUF_SIZE(1000);

std::ostream& operator<<(std::ostream& os, std::tm const& rhs)
{   
    os << asctime(&rhs);
    return os; 
}   

std::istream& operator>>(std::istream& is, std::tm& rhs)
{   
    while (is.peek() == ' ' || is.peek() == '\t')
    {   
        is.get();
    }   
    std::streampos curPos = is.tellg();
    char buf[BUF_SIZE];
    is.getline(buf, BUF_SIZE);
    char* ptr = strptime(buf, "%D %T", &rhs);
    if (ptr == 0)
    {   
        throw std::runtime_error("strptime() failed!");
    }   
    std::size_t processed = ptr - buf;
    is.seekg(curPos + static_cast<std::streampos>(processed));
    return is; 
}   

int main()
{   
    std::istringstream is("10101 07/09/12 07:30:00 123.24");
    int uuid(0);
    double price(0);
    std::tm ptime; std::memset(&ptime, 0, sizeof(tm));

    is >> uuid >> ptime >> price;
    cout << "UUID: " << uuid << endl;
    cout << "Time: " << ptime;
    cout << "Price: " << price << endl;
} 

我正在尝试重载struct tm的<<和>>运算符!如果我使用g ++编译我的代码并运行它,我得到:

UUID: 10101
Time: Sun Jul  9 07:30:00 2012
Price: 123.24

完善!

但是,如果我使用clang ++编译它,我得到:

UUID: 10101
Time: Sun Jul  9 07:30:00 2012
Price: 0

OOPS!

到底是怎么回事？这是clang的一个问题,还是我处理istream的方式？

Answer 1

我能够重现这个(g ++ 4.7.0和clang ++ 3.1与libc ++ - svn),并且一个简短的调试会话显示clang ++设置了eofbitafter getline(这是正常的),然后以某种方式导致seekg设置failbit.这听起来像一个bug,鉴于seekg first clears eofbit(§27.7.2.3/ 41)

要解决,请插入和is.clear()之间的任何位置.getlineseekg