bug#8891: 23.3; save-buffer messages about writing files that may not be written

[Dave Abrahams]

on Sun Jul 03 2011, Lars Magne Ingebrigtsen <larsi-AT-gnus.org> wrote:

> Dave Abrahams <dave@boostpro.com> writes:
>
>> I have hooked write-file-functions for certain files to check the md5
>> sum of the file against what it was when last saved and simply mark the
>> file unmodified
>> (https://github.com/dabrahams/initsplit/blob/master/initsplit.el#L300)
>>
>> However, I get a message about saving these files even when there's been
>> no modification.  I think these lines in save-buffer come too early:
>>
>>     (if (and modp (buffer-file-name))
>>      (message "Saving file %s..." (buffer-file-name)))
>
> Hm.  If `modp' is true, then the buffer has been modified, hasn't it?

Yes... until `save-buffer' calls `basic-save-buffer' which invokes
`write-file-functions', one of which decides to override the notion of
"modified-ness" when it ascertains that the contents have not actually
changed.  So modp tells the truth at the time it's checked, but IMO it's
checked too early.

-- 
Dave Abrahams
BoostPro Computing
http://www.boostpro.com