On transition from step 2 to step 3 there will be a great mess: some libraries in the OS distro are built with sizeof(time_t)=4 assumption and other libraries +

On transition from step 2 to step 3 there will be a great mess: some libraries in the OS distro are built with sizeof(time_t)=4 assumption and other libraries + application are built with sizeof(time_t)=8 assumption. ABI will break at random boundaries, and not just functions: structures will have incompatible layout etc. If step 2 is omitted, then similar great mess will happen on transition from step 1 to step 3. We need a better plan, like modifying compilers (for i686 and other 32-bit targets) to emit '32-bit time_t code' and '64-bit time_t code' simultaneously, and then resolve to proper functions later, at the link time.