Fifth draft of the Y2038 design document

[Paul Eggert]

One other question: how set-in-stone is this business about _TIME_BITS 
defaulting to 32-bit time_t?

I'm asking because the applications I help maintain (coreutils, grep, 
Emacs, etc.) don't want to use "backward-compatibility mode". That is, 
I'd prefer a default where the implementation defaults to 64-bit time_t 
if I don't do anything special. (If I really want 32-bit time_t, which I 
don't, I can compile with -D_TIME_BITS=32.)

I wish _FILE_OFFSET_BITS worked this way; it would have saved me hassle 
back in the day. Is there some reason we can't do better this time 
around, and have _TIME_BITS default to 64?