bug#40431: 27.0.90; Can't edebug cl-defuns with &aux destructuring

[Philipp Stephani]

Am Sa., 4. Apr. 2020 um 18:19 Uhr schrieb Philipp Stephani
<p.stephani2@gmail.com>:
>
>
> Insert into *scratch*:
>
> (cl-defun foo (&aux ((a . b) '(1 . 2)))
>   (list a b))
>
> Now try to edebug this function (move point into it, hit C-u C-M-x).
> This gives an error:
>
> Debugger entered--Lisp error: (invalid-read-syntax "Expected one of" arg nil)

My guess is that in the specification

["&aux" &rest &or (symbolp &optional def-form) symbolp]

we should replace 'symbolp' with 'cl-macro-arg'. This might cause
other issues, however, as that specification is probably no longer
decidable.