Timestamps in libraries created by GNU ar

Hi,

I have a question regarding timestamps in libraries that are created
by GNU ar (I asked this question yesterday in gnu.gcc but it seems to
me this group is not very frequented).
Everytime a library is created by ar the timestamps of the object
files are included in the resulting library.
Is there a way to prevent the timestamps in the library?
The problem with the timestamps is that one cannot see directly in a
diff if only the timestamps have changed but also functionality has
changed.

Thanks in advance
Karl-Heinz

KHR wrote:

> Everytime a library is created by ar the timestamps of the object
> files are included in the resulting library.

Of course it is --- after all, the second(!) paragraph of info 'ar' says 
this:

    The original files' contents, mode (permissions), timestamp, owner,
and group are preserved in the archive, and can be restored on
extraction.

How could it do that, if it didn't store the timestamps?

> Is there a way to prevent the timestamps in the library?

I don't think so.

> The problem with the timestamps is that one cannot see directly in a
> diff if only the timestamps have changed but also functionality has
> changed.

So don't do that.  Un-ar them to separate directories, and diff the 
object files instead.

And don't be too surprised if that doesn't work like you want it to, 
either.  Some object file formats have timestamps inside, too!

On 11 Jul., 23:44, Hans-Bernhard Br=F6ker <HBBroe...@t-online.de> wrote:
> KHR wrote:
> > Everytime a library is created by ar the timestamps of the object
> > files are included in the resulting library.
>
> Of course it is --- after all, the second(!) paragraph of info 'ar' says
> this:
>
>     The original files' contents, mode (permissions), timestamp, owner,
> and group are preserved in the archive, and can be restored on
> extraction.
>
> How could it do that, if it didn't store the timestamps?
>
> > Is there a way to prevent the timestamps in the library?
>
> I don't think so.
>
> > The problem with the timestamps is that one cannot see directly in a
> > diff if only the timestamps have changed but also functionality has
> > changed.
>
> So don't do that.  Un-ar them to separate directories, and diff the
> object files instead.
>
> And don't be too surprised if that doesn't work like you want it to,
> either.  Some object file formats have timestamps inside, too!

Thank you for your answer.
I will try the procedure to un-ar the libs to separate directories. It
seems to be the only option.