[libvirt] [PATCH v2] Check for --no-copy-dt-needed linker flag

[Daniel P. Berrange]

On Mon, Aug 19, 2013 at 08:07:42PM +0200, Guido Günther wrote:
> On Mon, Aug 19, 2013 at 11:37:24AM -0600, Eric Blake wrote:
> > On 08/19/2013 11:28 AM, Guido Günther wrote:
> > > and use it when available
> > > ---
> > >  configure.ac                  |  1 +
> > >  m4/virt-linker-no-indirect.m4 | 30 ++++++++++++++++++++++++++++++
> > >  src/Makefile.am               |  9 +++++++++
> > >  tests/Makefile.am             |  1 +
> > >  4 files changed, 41 insertions(+)
> > >  create mode 100644 m4/virt-linker-no-indirect.m4
> > > 
> > 
> > > +AC_DEFUN([LIBVIRT_LINKER_NO_INDIRECT],[
> > > +    AC_MSG_CHECKING([for how to avoid indirect lib deps])
> > > +
> > > +    NO_INDIRECT_LDFLAGS=
> > > +    `$LD --help 2>&1 | grep -- "--no-copy-dt-needed-entries" >/dev/null` && \
> > 
> > Doesn't do what you think (it tries to execute the output of grep -
> > which is thankfully empty on both success and failure).  Also wastes a
> > fork on grep, compared to the simpler:
> 
> I was looking following virt-linker-relro.m4 and I'm getting the correct
> result since the output is always empty but for the non matching case
> grep exits with 1. However
> 
> > 
> > case `$LD --help 2>&1` in
> >   *--no-copy-dt-needed-entries*) NO_INDIRECT_LDFLAGS=... ;;
> > esac
> 
> this looks nicer.
> 
> > 
> > > +++ b/src/Makefile.am
> > > @@ -1813,6 +1813,7 @@ libvirt_la_LDFLAGS = \
> > >  		$(LIBVIRT_NODELETE) \
> > >  		$(AM_LDFLAGS) \
> > >  		$(RELRO_LDFLAGS) \
> > > +		$(NO_INDIRECT_LDFLAGS) \
> > 
> > Why aren't you building this directly into $(AM_LDFLAGS) once, rather
> > than having to copy it into each and every library recipe?
> > 
> > Why only src/ and tests/? What about tools/ and daemon/?
> 
> Again following the above example. I'll come up with a v3.
> Cheers,

Personally I prefer to see things explicitly listed rather than hide
them behind AM_LDFLAGS.

Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|