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List:       hpux-cxx-dev
Subject:    Re:  CXX-DEV: Linking order in HP 11.00
From:       Dennis Handly <dhandly () cup ! hp ! com>
Date:       2002-03-12 1:38:42
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>I have an archive library say libarchive.a. I have a shared library say
>libshared1.sl dependent on the archive library.

As mentioned, you should include the archive when you create the shared lib.

>aCC -o libarchive.a archive.o

Change to:
aCC +z -c archive.o
ar -cvr libarchive.a archive.o
aCC +z -b -o libshared1.sl shared1.cpp libarchive.a

>Two ways of making the final executable:
(1)  aCC -Wl,+s -L. -lshared1

Now you only have one way.

>Note even though libshared1.sl depends on libarchive.a I haven't linked
>the archive library with the shared library during its creation (and
>this doesn't crib !!!!).

You shouldn't do this.  If a shared lib is the only user of an archive,
then include the archive when you build the shared.
If the archive is used in multiple places, make a shared lib out of it.

>I had another shared library say libshared2.sl and repeated the same
>steps as given above, it wouldn't have mattered what the order of
>linking is

Right.  dld.sl looks at all of the libs.

>Can someone please tell me why the order of linking is important in case
>you have an archive library.

Mahesha and Mike explained it.  You can also use -Wl,+n to do multiple
pass over the link line.

>I read somewhere that aCC is a single pass compiler in contrast to say
>CC (Sun compiler) which is a multi-pass compiler.  Can someone please
>explain me if this has any bearing on the example I just discussed.
Aveek

No bearing at all.  aC++ is an N pass compiler.
I think you are talking about the linker instead and that is what the
difference occurs.

>From: "mahesha" <mahesha@india.hp.com>
>The linker searches libraries in the order in which they are specified on
>the command line - the link order.  Link order is important in that a
>library containing an external reference to another library must precede the
>library containing the definition.

>From: "Rich Rauenzahn" <rrauenza@cup.hp.com>
>This isn't doing at all what you think it's doing.  ar is used to create
>archive libraries.

Perhaps Aveek just explained it incorrectly?

>I don't see at all how libshared1.sl depends on libarchive from what you've
>shown above.

Depend is the wrong word.  It may be valid English but is isn't valid
Nerdese.  I.e. it isn't a shared library dependency.
It has unsats that the archive defines.

>Shouldn't you be linking the archive lib into the shared library when _it_
>is created?
Rich

It depends on how many people use it, or whether there is a PIC version.

>From: Mike Stroyan <stroyan@hpstryn.fc.hp.com>
>You can force all of an archive to be linked in using ld's -Fl or
>+forceload option.

Or add -Wl,-usym to only extract what is needed.  Or swap the order.
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