bug#13949: 24.4.1; `fill-paragraph' should not always put the buffer as modified

[Óscar Fuentes]

Dmitry Gutov <dgutov@yandex.ru> writes:

> On 03/27/2016 06:28 PM, Óscar Fuentes wrote:
>
>> The docs say:
>>
>>
>>   This shows two dashes (‘--’) if the buffer displayed in the window has
>>   the same contents as the corresponding file on the disk; i.e., if the
>>   buffer is unmodified.
>
> That might be a documentation bug. Switch to an unmodified buffer.
> Type `a', and then backspace. What do you see in the status?

When you type `a', you changed the buffer. Checking that your subsequent
actions gives a result that is identical to the saved file is something
that would be nice to have, but I guess that few users would think that
it is a reasonable requirement.

OTOH, `undo' clears the `modified' flag.

>> AFAIK, a file-visiting buffer is not marked as modified when text
>> properties are applied to it.
>
> It is. If you're thinking of font-lock, then it uses
> with-silent-modifications.

And why it does use with-silent-modifications? Is there a case where the
user is benefited from marking the buffer as modified after applying
text properties?