Re: Accepted sdl-image1.2 1.2.2-1 (i386 source)
>> Jérôme Marant <email@example.com> writes:
> On Thu, Jul 25, 2002 at 01:26:23PM +0200, Marcelo E. Magallon wrote:
> > For the maintainers of the above mentioned packages, it'd be
> > worthwhile figuring out why these packages depend on libpng2. They
> > shouldn't.
> Speaking about libsdl-ocaml, should it build-depend on libpng-dev
> or libpng3-dev?
It should build depend on libsdl-image1.2-dev and let that package
state what it wants to have.
In general it looks like this:
Programs linking against libbar, should do it like this:
$ cc -o myprogram myprogram.o -lbar
and *not* like either of:
$ cc -o myprogram myprogram.o -lbar -lfoo
$ cc -o myprogram myprogram.o -lbar -lfoo -lpng
the library libbar has a dependency on libfoo which in turn has a
dependency on libpng. Your program only cares about libbar, not libfoo
Now, *if* your program *does* care about libfoo, that is, it uses
functions from libfoo directly (and not via libbar), *then* it should
include libfoo in the link line. (This is the reason why I said
"figure out why your library depends on libpng2", there might be a
valid reason for that)
This, of course, depends on libfoo declaring its depencencies. If
libfoo is linked like this:
$ cc -o libfoo.so -Wl,-soname,libfoo.so -shared foo.o
$ cc -o libfoo.so -Wl,-soname,libfoo.so -shared foo.o -lpng
then /of course/ you are going to get an error from either the dynamic
linker or the linker stating that png_* is undefined.
On Debian we tend to get this right, for example, on Debian it's
possible to write:
$ cc -o myglutprogram myglutprogram.o -lglut -lGL
and have it work without having to specify -lX11 -lXext -lXi -lXmu -lm
and something else I forget right now. glut is called a wrapper for a
Last but not least, this is /extremely/ Linux specific behaviour (and
is valid in the context of dynamic linking). A lot of other linkers
are amazingly brain dead in this respect. Out of memory, the Solaris
linker gets things right, too.
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