bug#33201: 26.1; Edebug doesn't work on closures with edebug-unwrap-results

[Alan Mackenzie]

Hello, Allen.

In article <mailman.3074.1540882208.1284.bug-gnu-emacs@gnu.org> you wrote:
> Reproduce:

> 1. emacs -Q
> 2. Evaluate in *scratch*:

> (setq edebug-unwrap-results t)

> (defun foobar (x)
>   (funcall x))

> 3. Evaluate to confirm it works:

> (foobar '(closure ((x . 5) t) nil x))

> 4. Instrument foobar (C-u C-M-x with point on defun).
> 5. Evaluate:

> (foobar '(closure ((x . 5) t) nil x))

> 5. Step through with SPC

> Expected:

> Evaluates to 5 with no error

> Actual:

> edebug-signal: Wrong type argument: listp, 5

> In GNU Emacs 26.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.30)
>  of 2018-07-05 built on juergen
> Windowing system distributor 'The X.Org Foundation', version 11.0.12003000

Yes.  There is no handling for closures in 26.1's edebug.

Handling for closures was added to the Emacs master branch on 2018-06-19
by Gemini Lasswell, as an incidental enhancement when introducing better
backtrace handling.  Your scenario above works fine in master.

This fix could probably be backported to the emacs-26 branch, but how
important is it?  What were you actually trying to do when you uncovered
this bug?

-- 
Alan Mackenzie (Nuremberg, Germany).