[MinGW-dvlpr] 64-bit compatibility with msvc [Was: (no subject)]

[Greg C. <chi...@co...>]

On 2006-9-26 7:36 UTC, Kai Tietz wrote:
> 
> [...] the major problem is the ISO definition of the pointer 
> difference, which lead to a long type. What implicit means, that a long 
> needs to have the same size as a pointer itself. Even MS reflect this by 
> defining intptr_t to an __int64 type.

The C standard, ISO/IEC 9899, says at 6.5.6/9

  When two pointers are subtracted, [...] the size of the result
  is implementation-defined, and its type (a signed integer type)
  is ptrdiff_t

6.2.5/4 defines signed integer types to include implementation-
defined extended types. Thus, ptrdiff_t does not need to be the
same as long int.

> If we change the ISO-C type "long", it means that programmer needs to 
> learn that pointer differences are "__int64" not "long", which for my 
> opinion looks more worse.

Programmers should use ptrdiff_t directly, and not assume that
it's the same as any particular type.