On 08/26/2016 01:41 AM, Peter Rosin wrote:
It is wrong to assume that pointers fit in long int.
Not in GNU code. <https://www.gnu.org/prep/standards/html_node/CPU-Portability.html says that GNU programs should not make any effort to cater to the possibility that 'long' will be narrower than ptrdiff_t.
(It should be safe to convert ptrdiff_t to long in an LP64 system, so I assume you meant to write "LLP64" in the Subject: line. Also, the values in questions are offsets, not pointers, so I assume you meant to write "pointer differences" not "pointers" in the above-quoted sentence.)
A problem with the proposed patch is that it uses PRIdPTR, and thus won't work on platforms with older C libraries that lack support for PRIdPTR. Although this can be worked around with some effort, as a general rule we prefer to avoid the effort.
Every POSIX platform is supposed to provide a compilation environment where 'long' is no wider than ptrdiff_t, so if you're using a POSIX platform you should be able to build diffutils without modifying its source code. See:
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/c99.html
