bug#23648: [PATCH] `defun-declarations-alist' can be unintentionally modified

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Paul Pogonyshev <pogonyshev@gmail.com> writes:

> I quite often get the following messages:
>
> Warning: Unknown defun property ‘compiler-macro’ in ...
>
> As far as I could trace it, the problem is indirectly caused by
> `define-inline'. While definition of `defun-declarations-alist' does
> contain `compiler-macro' in its init form, it can be removed later.
> E.g. when I evaluated the variable, it was not there anymore, only
> `gv-setter' was there.
>
> It seems this is done unintentionally by `elisp-completion-at-point':
>
>                        (`declare
>                         (list t (mapcar (lambda (x) (symbol-name (car x)))
>                                         (delete-dups
>                                          ;; FIXME: We should include some
>                                          ;; docstring with each entry.
>                                          (append
>                                           macro-declarations-alist
>                                           defun-declarations-alist)))))
>
> Here `delete-dups' destructively modifies a list that includes
> `defun-declarations-alist' as its tail verbatim, not as a copy.
> Attached patch should fix that.

I agree with analysis and patch here.  Since this just appends another
nil, it should be safe for emacs-25, right?

>
> Paul
>
> * elisp-mode.el (elisp-completion-at-point): Fix to not alter
> `defun-declarations-alist' by side effect.

> -                                         (append
> -                                          macro-declarations-alist
> -                                          defun-declarations-alist)))))
> +                                         (append macro-declarations-alist
> +                                                 defun-declarations-alist
> +                                                 nil)))))