mIRC can start using 64-bit time_t values without becoming a 64-bit application. This wouldn't be that difficult to fix at all.
It looks like Windows has
solved this in quite a different way (see "Remarks", and read the entire thing) than *IX platforms have. So you are absolutely 100% correct and I am wrong.
Though it's
still quite a mess. As the poster there indicates at the bottom of his post, it's not always as easy as changing the declaration type; anything other code that uses hard-coded 32-bit numbers for time (e.g. not using time_t but instead using uint32_t or equivalent) would need to be changed, and that doesn't include any actual code that is written to assume the maximum value is 0x7fffffff. I can't comment on that part of mIRC (I have no visibility into the source, obviously).
