compiler bug

[Ares Lagae]

I have a strange problem with the code below. I _suspect_ a compiler
bug. When compiling the code below with 7.1, i get a number of
"undefined variable" errors, but the code should compile fine. However


1) If I remove the forward declaration

template <typename Ch, typename Tr>
std::basic_ostream<Ch,Tr>& operator<<(std::basic_ostream<Ch,Tr>&, const
timer&);

the same code compiles fine


2) If I change to forward declaration to include parameter names

template <typename Ch, typename Tr>
std::basic_ostream<Ch,Tr>& operator<<(std::basic_ostream<Ch,Tr>& os,
const timer& t);

the same code compiles fine


3) If I remove the stringstream part

replace

if (bResult == FALSE)
{
std::stringstream error_msg;
error_msg << "timer::now()"
<< ' ' << ':' << ' ' <<
"QueryPerformanceCounter() failed"
<< ' ' << '(' << "GetLastError() = " <<
::GetLastError() << ')'
<< ' ' << '(' << __FILE__ << '(' << __LINE__ <<
')' << ')';
throw std::runtime_error(error_msg.str());
}

in both timer::now() and timer::frequency()

by

if (bResult == FALSE)
{
throw std::runtime_error("");
}

the same code compiles fine.



Does anyone know what's going on here ?


Best regards,
Ares Lagae


------------------------------ BEGIN CODE ------------------------------


// declaration

#include <ostream>

class timer
{
public:
timer();
void start();
void stop();
long long elapsed() const;
long long frequency() const;
private:
long long now() const;
long long start_;
long long stop_;
bool running_;
};

template <typename Ch, typename Tr>
std::basic_ostream<Ch,Tr>& operator<<(std::basic_ostream<Ch,Tr>&, const
timer&);

// implementation

#include <stdexcept>
#include <sstream>
#include <cassert>
#include <windows.h>

timer::timer()
: start_(0), stop_(0), running_(false)
{
}

long long timer::now() const
{
LARGE_INTEGER liPerformanceCount;
BOOL bResult = QueryPerformanceCounter(&liPerformanceCount);
if (bResult == FALSE)
{
std::stringstream error_msg;
error_msg << "timer::now()"
<< ' ' << ':' << ' ' <<
"QueryPerformanceCounter() failed"
<< ' ' << '(' << "GetLastError() = " <<
::GetLastError() << ')'
<< ' ' << '(' << __FILE__ << '(' << __LINE__ <<
')' << ')';
throw std::runtime_error(error_msg.str());
}
return liPerformanceCount.QuadPart;
}

long long timer::frequency() const
{
LARGE_INTEGER liFrequency;
BOOL bResult = ::QueryPerformanceFrequency(&liFrequency);
if (bResult == FALSE)
{
std::stringstream error_msg;
error_msg << "timer::frequency()"
<< ' ' << ':' << ' ' <<
"QueryPerformanceFrequency() failed"
<< ' ' << '(' << "GetLastError() = " <<
::GetLastError() << ')'
<< ' ' << '(' << __FILE__ << '(' << __LINE__ <<
')' << ')';
throw std::runtime_error(error_msg.str());
}
return liFrequency.QuadPart;
}

void timer::start()
{
assert(running_ == false);
running_ = true;
start_ = now();
}

void timer::stop()
{
assert(running_ == true);
stop_ = now();
running_ = false;
}

long long timer::elapsed() const
{
return running_ ? now() - start_ : stop_ - start_;
}

template <typename Ch, typename Tr>
std::basic_ostream<Ch,Tr>& operator<<(std::basic_ostream<Ch,Tr>& os,
const timer& t)
{
return os << t.elapsed() << ' ' << '(' << t.frequency() << ')'
<< std::endl;
}

// program

#include <iostream>

int main(int argc, char* argv)
{
try
{
timer t;
t.start();
t.stop();
std::cout << t << std::endl;
}
catch (std::runtime_error & e)
{
std::cout << e.what() << std::endl;
}
}

 

[Carl Daniel [VC++ MVP]]

I have a strange problem with the code below. I _suspect_ a compiler
bug. When compiling the code below with 7.1, i get a number of
"undefined variable" errors, but the code should compile fine. However

2) If I change to forward declaration to include parameter names

This one cinches it as a compiler bug since formal parameter names in
function declarations that are not also definitions (i.e. 'prototypes' in
C-speak) are supposed to the ignored.

FWIW, this bug has been fixed in Whidbey. In the meantime, I'd use the
workaround of naming the formal parameters in the forward declaration to
match the actual function definition. Wierd bug.

-cd