struct tm -> time_t converter wanted

[Alan J Rosenthal]

In article <12418 at steinmetz.ge.com> davidsen at crdos1.UUCP (bill davidsen) writes:
>changing the epoch or going to 64 bits would break existing programs.

How could going to 64 bits break an existing program?  Only if it _depended_ on
2147483647 + 1 being -2147483648, as far as I can tell.  This is, of course,
assuming that longs have become 64 bits; time_t has to be typedefed as
_something_.

Or, of course, if it did stuff like "int *p = (int *)malloc(4)" instead of
using sizeof(int)...

But, show us a program which isn't broken already which will break when longs
become 64 bits.