LD Changes To Implicit DSO Linking Update

[yersinia]

On Tue, Feb 9, 2010 at 3:38 PM, Adam Jackson <ajax at redhat.com> wrote:

> On Tue, 2010-02-09 at 08:06 +0000, Richard Hughes wrote:
> > On 8 February 2010 22:46, Kevin Kofler <kevin.kofler at chello.at> wrote:
> > > As a result, you'll be causing dozens of FTBFS bugs just before the
> feature
> > > freeze. I think this is entirely the wrong time in the release cycle to
> do
> > > such a change, if it is done at all.
> >
> > I've been fixing upstream projects for weeks to build with
> > --no-as-needed. The list of projects that fail to build should be much
> > smaller now, especially for GNOME and Freedesktop stuff.
>
> Just as a reminder, this change is --no-add-needed, not --no-as-needed.
> They have infuriatingly similar names; one of the changes is also to
> change the name of --{no-,}add-needed to be more obvious.
>
> --no-as-needed is already the default behaviour, and means "libraries
> specified with -lfoo will be emitted into the link output in a DT_NEEDED
> entry, regardless of whether any symbols from libfoo are used in the
> link output object itself".  This may mean your binary or library ends
> up with more dependencies than it needs, but is generally harmless.
>
Not so harmless, IMHO, causing unecessary deps in producing RPM. IIRC
there was some discussion on this in the past. Many of these errors was
caused from using AC_CHECK_LIB autoconf macro and not AC_SEARCH_LIB in
configure.ac

>
> --no-add-needed is quite different.  Your binary a.out uses symbols from
> libfoo and libbar.  libfoo is linked against libbar.  But your link line
> only says -lfoo.  --add-needed behaviour, the old default, would
> implicitly add a "-lbar" as well.  --no-add-needed, the new default,
> will not, and therefore your link will probably fail.
>
> This is the case described in the libtool manual
http://www.gnu.org/software/libtool/manual/html_node/Inter_002dlibrary-dependencies.html#Inter_002dlibrary-dependencies

Nice to know that Fedora will have the same behavior of the AIX libraries in
this area, if I understood correctly the topic under discussion.

Regards
Regards

> - ajax
>
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