Re: [boost] Hi everybody, I found a bug of Boost.Typeof emulation mode

From: Atry (pop.atry_at_[hidden])
Date: 2007-06-02 14:38:08

Atry wrote:
> Giovanni Piero Deretta wrote:
>> On 6/2/07, Atry <pop.atry_at_[hidden]> wrote:
>>  
>>> #include <boost/typeof/typeof.hpp>
>>> #include <boost/static_assert.hpp>
>>> int a = 0;
>>> int& b = a;
>>> BOOST_STATIC_ASSERT((boost::is_same<BOOST_TYPEOF(b), int&>::value));
>>>
>>>     
>>
>> IIRC (do not have the docs at hand right now), BOOST_TYPEOF drops
>> toplevel references. So does gcc builtin typeof and, I think, the
>> proposed 'auto' type deduction (while decltype should preserve them).
>>
>> HTH,
>>
>> gpd
>> _______________________________________________
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>>
>>   
> Thanks. But is there any way to determine if an expression is reference?
>
>
In other word, how to know whether the expression is l-value;

#include <iostream>

void x(int&)
{
    std::cout << "l-value" << std::endl;
}

void x(int)
{
    std::cout << "r-value" << std::endl;
}

int main()
{
    x(1);    // r-value;
    int i = 1;
    int& j = i;
    x(i);    // expect l-value, but error.
    x(j);    // expect l-value, but error.
}