Backtraces to use macro information from edebug-specs?

["Tobias C. Rittweiler" <tcr@freebits.de>]

Let's take the following code

  (defun foo (list)
    (destructuring-bind (key slot1 slot2) list
      (case key
        (:foo (quux slot1)
              (:bar (quux slot2))))))

  (defun quux (x)
    (error "QUUX -- %S" x))

Now evaluating

  (foo '(:foo 23 42))

results in the following backtrace

  Debugger entered--Lisp error: (error "QUUX -- 23")
    signal(error ("QUUX -- 23"))
    error("QUUX -- %S" 23)
    quux(23)
    (cond ((eql key ...) (quux slot1) (:bar ...)))
    (case key (:foo (quux slot1) (:bar ...)))
    (let* ((--cl-rest-- list) (key ...) (slot1 ...) (slot2 ...)) (case ...)
    (progn (let* (... ... ... ...) (case key ...)))
    (destructuring-bind (key slot1 slot2) list (case key (:foo ... ...)))
    foo((:foo 23 42))

Given the information form edebug-specs (which are defined for all `cl'
macros), it may perhaps be possible to find out that

  `quux(23)' comes from the body of case, but `(cond ((eql ...' doesn't.

  `(case key ...' appears in the body of destructuring-bind, but the
  `(let* ... ' and `(progn ...' do not.

As a result the backtrace could be presented as follows

  Debugger entered--Lisp error: (error "QUUX -- 23")
    signal(error ("QUUX -- 23"))
    error("QUUX -- %S" 23)
    quux(23)
      (cond ((eql key ...) (quux slot1) (:bar ...)))
    (case key (:foo (quux slot1) (:bar ...)))
      (let* ((--cl-rest-- list) (key ...) (slot1 ...) (slot2 ...)) (case ...)
      (progn (let* (... ... ... ...) (case key ...)))
    (destructuring-bind (key slot1 slot2) list (case key (:foo ... ...)))
    foo((:foo 23 42))

Of course, they may be better ways to do this, depending on how much
debug information is available.

Has anyone worked on something like that?

  -T.