[Gcl-devel] debugging with and without dbl

[Dan Muresan]

Hi all,

I need some help using the GCL debugging facility (preferably from
DBL). I'm using 2.6.7 (from the Ubuntu feisty package).

My problem is simple to state: I have a long program (generated
automatically) that wields lots of closures and deeply nested calls.
At some point during the execution, I get

Error: LAMBDA-CLOSURE [or a callee] requires less than three arguments.
Error signalled by LAMBDA-CLOSURE.

I want to find out where in the source code that particular lambda
closure is, and preferably which arguments it received. All code is
interpreted (meaning I haven't compiled anything).

I've figured out that :ihs, :bt and :vs do useful things, but I get
lost in their output (particularly since, as I mentioned, the Lisp
code is an automatically generated behemoth). :vs prints an
overwhelming amount of information. Both :bt and :ihs tend to print
things like

#30   FUNCALL {loc0=(lambda-closure ((winders nil) (f #) (k #) ...)
nil ...)} [ihs=15]

That # seems to stand for something, but I don't know what. Is there
any documentation on the format of these reports? What are the lists
after lambda-closure?

As far as DBL -- after figuring out that readline support must be
disabled in Emacs to avoid annoying control chars from showing up -- I
still don't know what to do. Typing (si::dbl) (randomly found that in
the dbl.el code) at the break prompt gets me a mode where some
:commands don't work any more:

dbl:>>:bt
Error: NIL is an illegal ihs index.

As usual, there seems to be no documentation on the magical
incantations that I'm supposed to type in to get something useful...

Really, it seems that the biggest problem is the lack of even minimal
debugging documentation. Google doesn't seem to help much either.
Hopefully this list can point me in the right direction.

Dan Muresan
http://alumnus.caltech.edu/~muresan/