configure, missing libraries and overwrites

[mmitch]

What do we want configure to do, when somebody says --enable-this and libthis.h is not available?

With the new dsound plugin, configure says it can't find the include but does honor --enable-dsound and enables it in the config. This later fails during the build:

$ ./configure --enable-dsound
[…]
checking for alsa/asoundlib.h:  ok
checking for dsound.h:  not found
checking for dsound.h in /usr/local/include:  not found
checking for pulse/simple.h:  ok
[…]
optional modules: +contrib +test -xmmsplugin
optional features: +i18n -sharedlibgbs -regparm +ssp -debug +stdout +devdsp +alsa +nas +pulse +midi +dsound
EXTRA_CFLAGS=-Wdeclaration-after-statement -fstack-protector --param=ssp-buffer-size=4 -Os -pipe -fomit-frame-pointer
EXTRA_LDFLAGS=-fstack-protector

$ make
DEP gbsinfo.c -o gbsinfo.d
DEP plugout_dsound.c -o plugout_dsound.d
plugout_dsound.c:12:22: fatal error: initguid.h: No such file or directory
 #include <initguid.h>
                      ^
compilation terminated.

We could debate whether failing the build is okay or the configure script should already fail, but at least this is consistent: Telling configure to add something that is not there will fail.

The pulse plugout (and propably alsa, too) behaves differently: When the headers are missing and --enable-pulse is given, configure silently decided to go with --disable-pulse – despite being told the opposite:

$ ./configure --enable-pulse
[…]
checking for dsound.h in /usr/local/include:  not found
checking for pulse/simple.h:  not found
checking for pulse/simple.h in /usr/local/include:  not found
checking for audio/audiolib.h:  ok
[…]
optional modules: +contrib +test -xmmsplugin
optional features: +i18n -sharedlibgbs -regparm +ssp -debug +stdout +devdsp +alsa +nas -pulse +midi
EXTRA_CFLAGS=-Wdeclaration-after-statement -fstack-protector --param=ssp-buffer-size=4 -Os -pipe -fomit-frame-pointer
EXTRA_LDFLAGS=-fstack-protector

I consider this a bug.

In the gbsplay Debian package, I have --enabled all plugouts and wanted the configure script to tell me "hey, you're missing a build dependency" during a package build in a clean environment – but instead configure disabled everything that should have been enabled and carried on - without most of the plugins.

[ranma]

Yeah, I agree --enable-foo should fail at configure time if we detect that the build-dependencies for foo are missing.