macro returning more than one form

[Paul Tarvydas]

On 14-03-14 12:00 PM, Dave Cooper wrote:
> ...
> What does LW and SBCL hate about wrapping toplevel forms in progn?

The LW debugger can't set breakpoints unless I remove the progn 
wrapper.  A user of my code is complaining that "it doesn't work" in 
SBCL (:-) (I guess I'll get more detail later).

Asking the question got me to think of an experiment.  I typed

(defstruct hello a b )

Into a file, then asked LW to macroexpand it.  What is the result?

(in-package "COMMON-LISP-USER")

(dspec ...)

i.e. two forms without a wrapper!

And the answer in SBCL is a progn!  With a an onerous-looking ...LOCK... 
as the first form.

pt