The better substitution would be not with eval, which won't perform as expected for all cases (for example, it doesn't have access to the lexical environment), and is also overkill (see here: https://stackoverflow.com/a/2571549/977052), but something using anonymous functions, like this:
(defun check (fn)
(report-result (funcall fn) (function-body fn)))
CL-USER> (check (lambda () (= 2 (+ 2 3))))
By the way, this is how such things are accomplished in Ruby (anonymous functions are called procs there).
But, as you see, it becomes somewhat less elegant (unless you add syntax sugar) and, there's actually a bigger problem: ther's no function-body function in Lisp (although there may be non-standard ways to get at it). Overall, as you see, for this particular task the alternative solutions are substantially worse, although in some cases such approach could work.
In general, though, if you want to do something with the source code of the expressions passed into the macro (and usually this is the primary reason of using macros), functions would not be sufficient.
