Re: file-equal-p

[Po Lu <luangruo@yahoo.com>]

Michael Albinus <michael.albinus@gmx.de> writes:

> Andreas Schwab <schwab@suse.de> writes:
>
> Hi,
>
>> On Feb 16 2023, Po Lu wrote:
>>
>>> diff --git a/lisp/files.el b/lisp/files.el
>>> index b0ec6bb09d0..dcd17df166a 100644
>>> --- a/lisp/files.el
>>> +++ b/lisp/files.el
>>> @@ -6360,7 +6360,17 @@ file-equal-p
>>>        (let (f1-attr f2-attr)
>>>          (and (setq f1-attr (file-attributes (file-truename file1)))
>>>  	     (setq f2-attr (file-attributes (file-truename file2)))
>>> -	     (equal f1-attr f2-attr))))))
>>> +             (progn
>>> +               ;; Haiku systems change the file's last access timestamp
>>> +               ;; every time `stat' is called.  Make sure to not compare
>>> +               ;; the timestamps in that case.
>>> +               (when (and (eq system-type 'haiku)
>>> +                          (consp (nthcdr 4 f1-attr))
>>> +                          (consp (nthcdr 4 f2-attr)))
>>> +                 (ignore-errors
>>> +                   (setcar (nthcdr 4 f1-attr) nil)
>>> +                   (setcar (nthcdr 4 f2-attr) nil)))
>>> +	       (equal f1-attr f2-attr)))))))
>>
>> Why does that compare more than the inode and device number?  The other
>> attributes can change any time, if another process accesses the file or
>> modifies the inode between the two calls of file-attribute.
>
> For this we have file-attribute-file-identifier. So it might be
> sufficient to call
>
> (equal (file-attribute-file-identifier f1-attr) (file-attribute-file-identifier f2-attr))
>
> Best regards, Michael.

This looks like the better idea, yes.  Would using that be ok for Emacs
29?  Or is it something for master?