In compilers that implement GCC extensions (such as Clang), you can use the "poison" directive to achieve the same effect (but with a better error message):
Although GNU lighting is a JIT, it is probably not well-suited for this application (it has limited virtual registers, no register allocator, no optimizer).
Instead, gccjit would be a better option: https://gcc.gnu.org/onlinedocs/jit/