What is a compiler (vol. 63827) meets what are gensyms.

[Gregor.pa@Xerox.COM]

In this issue the subject of what compile file is required to do with
top-level forms meets the subject of top-level calls to macros which
expand into code containing gensyms.

Suppose I have the following macro.

(defmacro foo (x y)
  (let ((var (gensym))
	(nv-var (gensym)))
    `(progn
       (defun ,x ..)
       (defun ,y ..)
       (defsetf ,x (,var) (,nv-var) `(,',y ,,var ,,nv-var)))))

And I have a file that includes the form:

 (FOO BAR SET-BAR)

[ For clarities sake, the point is that the macro expands
  to a progn that includes a defsetf that has gensyms for
  the access-function-args and storing-variables, like this:

  (DEFSETF BAR (#:G1890) (#:G1891) `(SET-BAR ,#:G1890 ,#:G1891))
]

Is compiling and loading the file legal Common Lisp?

Is the original foo macro legal Common Lisp?

I claim that the answer to both questions is yes.  After all, it is
clearly legal interpreted/compiled to core Common Lisp.

I believe that CLtL is "silent" on this issue.

I got bit by a Common Lisp compiler which macroexpands top-level forms,
but which does not necessarily compile the entire result of the
macroexpansion.  In this particular case the compiler expanded the two
defuns, but left the defsetf as (store-setf '<list with gensyms in it>)
Then the dumper dumped that list in such a way that when the file was
loaded the gensyms which should have been eq were not.
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