[libvirt] fix build failure with --disable-shared

[Jim Meyering]

Diego Elio “Flameeyes” Pettenò wrote:
> Il giorno gio, 07/01/2010 alle 21.29 +0100, Jim Meyering ha scritto:
>>
>> But --disable-shared is useful, and your change broke it.
>
> On the usefulness of that I have generally a lot to say, but that's
> another topic.
>
>> As such, I can't see how you would be using --disable-shared.
>
> Very simple: ./configure --disable-shared --without-python

So your change forced all other users of --disable-shared
to also configure with --without-python, but did not inform them
of the new constraint.  BTW, it also rendered build instructions
in the FAQ invalid.

>> Does the proposed patch cause you any difficulty?
>> If so, please tell us what/how, or propose an alternate patch.
>
> Without my patch you're building (and installing) an useless file with

I use --disable-shared only when debugging (and then only sometimes),
and certainly never install the result.

> the default configuration (--enable-shared). And _pretending_ to build
> Python bindings (that will never work even the slightest) with the
> configuration you suggested (--disable-shared --with-python).
>
> Your really can't get it both ways.

You're not considering my use case.
So far, whenever I've used --disable-shared, whether python support
is usable has been irrelevant to me.

> As Daniel (Berrange) said, the other option is to check whether shared
> libraries are enabled by libtool and either disable Python bindings or
> bail out earlier (configure rather than make) with the impossible
> combination of no-shared-libraries but-python-bindings.

I'll make --disable-shared imply --without-python
and silently override --with-python.  Here's what I'll
squash into the posted patch tomorrow:

diff --git a/configure.in b/configure.in
index 3f2f8ff..25df7a4 100644
--- a/configure.in
+++ b/configure.in
@@ -1813,6 +1813,10 @@ AC_ARG_WITH([qemu-group],
 AC_DEFINE_UNQUOTED([QEMU_USER], ["$QEMU_USER"], [QEMU user account])
 AC_DEFINE_UNQUOTED([QEMU_GROUP], ["$QEMU_GROUP"], [QEMU group account])

+if test "$enable_shared:$with_python" = no:yes; then
+  AC_MSG_WARN([you've selected --disable-shared; so disabling python support])
+  with_python=no
+fi

 # Only COPYING.LIB is under version control, yet COPYING
 # is included as part of the distribution tarball.