Ahoy,
On the weekend I tried actually /using/ SLIME. It's not bad but, gee
wiz, it isn't hard to run into trouble :-). A couple of notes.
If you have your own reader-macros then make sure they respect
*READ-SUPPRESS*. We set this while searching for source locations, and
it took me a while to realise that some of my reader-macros were
broken: they couldn't handle their recursive READs returning NIL. This
is confusing to debug if you didn't know that *READ-SUPPRESS* exists,
so read the Hyperspec if in doubt.
I generally had some trouble working with majorly broken packages that
want to bring up the debugger lots of times while failing to
compile. It helped to add a new ABORT restart that aborts compilation
but still presents the compiler messages that have been gathered so
far.
I also hit a bug in the May snapshot of CMUCL that is triggered by my
"cache source files as strings for location-finding" change:
reader-errors coming from non-file streams hit a type error before the
real error is reported. Raymond Toy says it should be fixed in 19A,
and meanwhile here is a "hotfix" (might only apply to May snapshot):
;;; Avoid calling FILE-LENGTH on STREAM. It might not be a file stream.
(in-package :c)
(defun careful-read (stream eof pos)
(handler-case (let ((*features* (backend-features *target-backend*)))
(read stream nil eof))
(error (condition)
(if (null (peek-char nil stream nil))
(unexpected-eof-error stream pos condition)
(progn (normal-read-error stream pos condition)
(ignore-error-form stream pos)))
'(cerror "Skip this form."
"Attempt to load a file having a compile-time read error."))))
(defun unexpected-eof-error (stream pos condition)
(declare (type stream stream) (type unsigned-byte pos))
(let ((eof-pos (file-position stream))
(res nil))
(file-position stream pos)
(loop
(let ((line (read-line stream nil nil)))
(unless line (return))
(when (or (find #\" line) (find #\( line))
(setq res line)
(return))
(unless (or res (zerop (length line)))
(setq res line))))
(compiler-error-message
"Read error in form starting at ~D:~%~@[ \"~A\"~%~]~A"
pos res condition)
(file-position stream eof-pos)
(undefined-value)))