Re: [boost] Proposal for cleanup of INT64 macros

From: John Maddock (john_at_[hidden])
Date: 2004-10-15 05:14:18

Marcus,

There seems to be a lot of confusion about these macros, so let me try and 
give you the full lowdown:

BOOST_HAS_LONG_LONG

Indicates that [unsigned] long long is a valid type, use only when 
overloading a function or specialising a template for all intrinsic integral 
types (see is_integral for example).  Do not use this macro (or long long) 
if you want a 64-bit interal type.

BOOST_HAS_MS_INT64

Indicates that [unsigned] __int64 is a valid type, use only when overloading 
a function or specialising a template for all intrinsic integral types (see 
is_integral for example).  Do not use this macro (or long long) if you want 
a 64-bit interal type.  Do not use if BOOST_HAS_LONG_LONG is set since 
__int64 is the same type as long long on all compilers that have both.

BOOST_NO_INT64

Indicates that boost::int64_t and boost_uint64_t do not exist in 
boost/cstdint.hpp.  It's a defect macro because these types are documented 
as existing; it doesn't indicate a defect in the compiler, although if we're 
being picky, neither these types nor *any* of the exact width types in 
boost/cstdint.hpp are required to be supported by C99.  If you need a 64-bit 
integer type then this macro is the one to check (and then use [u]int64_t).

BOOST_NO_INTEGRAL_INT64_T

Indicates that int64_t and uint64_t can not be used in integral constant 
expressions (that includes their use as non-type template parameters). 
Contrary to what Marcus suggested there are several compilers that have this 
defect - a quick grep through the config system will show you which ones - 
in fact until recently is was the exception rather than the rule for 
compilers to accept types wider than int in integral constant expressions, 
and especially in enum types.

Those macros are needed IMO, and should also be sufficient.

The macros BOOST_NO_INTRINSIC_INT64_T and BOOST_NO_INTRINSIC_UINT64_T appear 
to have been removed, so no cleanup necessary :-)

John.