Function jit_constant_convert 

pub unsafe extern "C" fn jit_constant_convert(
    result: *mut jit_constant_t,
    value: *const jit_constant_t,
    type_: jit_type_t,
    overflow_check: c_int,
) -> c_int

Convert a the constant value into a new type, and return its value in result. Returns zero if the conversion is not possible, usually due to overflow.