INCLUDE(CheckCXXSourceCompiles)

# This compiler test checks to see if the compiler supports a intrinic
# datatype __int64, such as on some 64 bit Windows compilers.
#
# The below test program checks to see that __int64 is defined, different from
# any existing standard intrinsic 'int' types, except for 'long long int'.
# This is necessasry because Teuchos and other Trilinos packages require usage
# of trait class specializations for datatypes like ptrdiff_t and size_t which
# turn out to be a typedefs to the non-standard __int64 datatype on 64 bit
# Windows compilers.  See Trilinos bug 5801 for all of the details.  However,
# we don't include 'long long int' in this below test because on these windows
# platforms it seems that 'long long int' is treated as the same type as
# __int64 with respect to template specializations (again, see Trilinos bug
# 5801).
#
FUNCTION(CHECK_FOR___INT64 VARNAME)

  SET(SOURCE
  "
template<typename T> struct MyOrdinalTraits {};

template<> struct MyOrdinalTraits<int> { static inline int zero() { return 0; } };
template<> struct MyOrdinalTraits<long int> { static inline long int zero() { return 0; } };
template<> struct MyOrdinalTraits<__int64> { static inline __int64 zero() { return 0; } };

int main()
{
  MyOrdinalTraits<int>::zero();
  MyOrdinalTraits<long int>::zero();
  MyOrdinalTraits<__int64>::zero();
  return 0;
}
"
  )

  CHECK_CXX_SOURCE_COMPILES("${SOURCE}" ${VARNAME})

ENDFUNCTION()