I'm guessing that this is already known, but, in case it isn't, the standard compilation procedures on macOS and 64-bit Linux generate code that uses 64-bit integers for s32b and u32b.
Modifying h-config.h so L64 is set for those systems would fix that (and presumably make it easier to transfer savefiles between macOS or 64-bit Linux and Windows or 32-bit Linux) but break backwards compatibility with savefiles previously generated on macOS or 64-bit Linux.
I'm guessing that this is already known, but, in case it isn't, the standard compilation procedures on macOS and 64-bit Linux generate code that uses 64-bit integers for s32b and u32b.
Modifying h-config.h so L64 is set for those systems would fix that (and presumably make it easier to transfer savefiles between macOS or 64-bit Linux and Windows or 32-bit Linux) but break backwards compatibility with savefiles previously generated on macOS or 64-bit Linux.