[Boost-users] Win32: Overloaded std::min and std::max

From: boost_at_[hidden]
Date: 2004-11-17 16:53:44

Hi all,

A day ago I stumbled upon a problem using std::min and std::max when having
included any boost header file on Win32 machine.

The following code should not compile, according to the C++ standard:

float f = 47.9999f;
long l = 47L;
std::max(f, l); // This should fail as the arguments aren't of the same
type.

But using boost (and Microsoft Visual C++ .NET 2003), it magically did. I
tracked down the problem and found a 'fix' in
<boost_1_31_0/boost/config/platform/win32.hpp> that looks like this:

-----8<----------8<----------8<----------8<----------8<-----

#ifdef BOOST_MSVC
#include <algorithm> // for existing std::min and std::max
namespace std{
  // Apparently, something in the Microsoft libraries requires the "long"
  // overload, because it calls the min/max functions with arguments of
  // slightly different type.  (If this proves to be incorrect, this
  // whole "BOOST_MSVC" section can be removed.)
  inline long min(long __a, long __b) {
    return __b < __a ? __b : __a;
  }
  inline long max(long __a, long __b) {
    return  __a < __b ? __b : __a;
  }
  // The "long double" overload is required, otherwise user code calling
  // min/max for floating-point numbers will use the "long" overload.
  // (SourceForge bug #495495)
  inline long double min(long double __a, long double __b) {
    return __b < __a ? __b : __a;
  }
  inline long double max(long double __a, long double __b) {
    return  __a < __b ? __b : __a;
  }
}
using std::min;
using std::max;
#     endif

-----8<----------8<----------8<----------8<----------8<-----

I think that that block of code should be removed as it is illegal to
overload any function in the standard library, according to the C++
standard, and that it also makes illegal code to compile.

Cheers,
Dalle