The last Unisys release, the Dorado from 2015 (ClearPath Dorado 8300 to be exact), used Xeon processors (which are 64-bit x86_64). But, for argument’s sake, let’s suppose there’s a Unisys 2200 out there with 36-bit registers and GCC/clang makes a C2y compiler for it.

If so, then said compiler should still have support for (u)int_8/16/32/64_t. Said compiler already needs to have that support with (unsigned) _BitInt(8/16/32/64)—and, yes, one can also have 36-bit ints on x86_64 in C23 with _BitInt(36) if one must—and allowing stuff like int32_t and uint32_t will allow said (imaginary) 2200 system to cleanly compile a lot of pre-C23 open source code out there. Yes, uint32_t will look a little ugly at the assembly level, just as _BitInt(36) will look a little ugly on, say, a Xeon processor, but the code will compile and run the same.

Of course, these days they can buy tokens so an agent can do any relevant porting, but still.