_MSC_VER not defined on mingw32

From: omnizionic (omnizionic_at_[hidden])
Date: 2003-06-12 04:55:08

I downloaded and unzipped the latest boost (1.30.0) and tried using it 
in a simple file like this:

#include <boost/smart_ptr.hpp>
int main()
{
      boost::shared_ptr<int> p(new int);

  return 0;
}

I compiled it, and got the following output:
gcc -c -Wall -W -Werror -Wundef -Wfloat-equal -Wshadow -Wpointer-arith 
-Wcast-qual -Wwrite-strings -Wconversion -idirafter c:
/programming/lib/kakefisk -Ic:/programming/boost_1_30_0 -O3 
-fomit-frame-pointer -ffast-math btest.cpp -o btest.o
In file included from c:/programming/boost_1_30_0/boost/scoped_ptr.
hpp:16,
                 from c:/programming/boost_1_30_0/boost/smart_ptr.hpp:
17,
                 from btest.cpp:1:
c:/programming/boost_1_30_0/boost/checked_delete.hpp:4:5: "_MSC_VER" 
is not defined
In file included from c:/programming/boost_1_30_0/boost/shared_ptr.
hpp:26,
                 from c:/programming/boost_1_30_0/boost/smart_ptr.hpp:
19,
                 from btest.cpp:1:
c:/programming/boost_1_30_0/boost/throw_exception.hpp:4:5: "_MSC_VER" 
is not defined
In file included from c:/programming/boost_1_30_0/boost/shared_ptr.
hpp:27,
                 from c:/programming/boost_1_30_0/boost/smart_ptr.hpp:
19,
                 from btest.cpp:1:
c:/programming/boost_1_30_0/boost/detail/shared_count.hpp:4:5: 
"_MSC_VER" is not defined
In file included from c:
/programming/boost_1_30_0/boost/detail/shared_count.hpp:27,
                 from c:/programming/boost_1_30_0/boost/shared_ptr.
hpp:27,
                 from c:/programming/boost_1_30_0/boost/smart_ptr.hpp:
19,
                 from btest.cpp:1:
c:/programming/boost_1_30_0/boost/detail/lightweight_mutex.hpp:4:5: 
"_MSC_VER" is not defined
In file included from c:
/programming/boost_1_30_0/boost/detail/lightweight_mutex.hpp:68,
                 from c:
/programming/boost_1_30_0/boost/detail/shared_count.hpp:27,
                 from c:/programming/boost_1_30_0/boost/shared_ptr.
hpp:27,
                 from c:/programming/boost_1_30_0/boost/smart_ptr.hpp:
19,
                 from btest.cpp:1:
c:/programming/boost_1_30_0/boost/detail/lwm_nop.hpp:4:5: "_MSC_VER" 
is not defined
In file included from c:/programming/boost_1_30_0/boost/smart_ptr.hpp:
19,
                 from btest.cpp:1:
c:/programming/boost_1_30_0/boost/shared_ptr.hpp:390:60: "BOOST_MSVC" 
is not defined
mingw32-make.exe: *** [btest.o] Error 1

I also tried compiling after setting the following in 
<boost/config/user.hpp> 
with no apparent effect:
// define this to locate a compiler config file:
#define BOOST_COMPILER_CONFIG <boost/config/compiler/gcc.hpp>
// define this to locate a stdlib config file:
#define BOOST_STDLIB_CONFIG   <boost/config/stdlib/libstdcpp3.hpp>
// define this to locate a platform config file:
#define BOOST_PLATFORM_CONFIG <boost/config/platform/win32.hpp>

Does anyone have any ideas as to where the problem might lie?