Template function don't work as inline function. Why?

[iQChange]

I have this:

string input;
unsigned short choice;
...
istringstream valid(input);
...
if(!(valid >> choice))
{
   //some error
}

Ok. My code is almost 1000 lines, and I have splited some functions in headers. But the same function doesn't work:

template <typename T> bool valid_input(const string& input, T var)
{
    istringstream valid(input);
    return (valid >> var);
}

You can check it here: http://coliru.stacked-crooked.com/a/0f22981e72360f6f
The output is correct, but in my machine with C++11, MinGW 4.8 (64 bit in a 64bit-Windows8), the output is incorrect. Why?

If you want more specific info, the problem is that I use input, I think. I use std::getline(std::cin, some_string).

[MiiNiPaa]

Is your program fails on same test you posted on Coliru? Because there should not be errors, and it works with 64bit MinGW GCC 8.8.1 compiler on 64bit Win7.

[iQChange]

No, it doesn't. By that I think that the error appears because of the input...

[MiiNiPaa]

ON what input it fails?

[long double main]

Shouldn't it be
template <typename T> bool valid_input(const string& input, T& var) // <-- T&, not T
?