On 01/31/2010 12:22 PM, Mike Frysinger wrote:
> On Saturday 30 January 2010 18:31:35 Nikos Chantziaras wrote:
>> What's the best way to have an ebuild abort if two mutually exclusive
>> USE flags are both set?
>>
>> I'm trying the modify the mozilla-firefox and xulrunner ebuilds to
>> support building with OSS instead of ALSA (sadly, the current versions
>> of the ebuilds in Portage only allow ALSA to be enabled, not OSS), but
>> the build system of Xulrunner/Firefox does not allow to build with both.
>> So I need to abort when both "alsa" and "oss" are set rather than having
>> the build proceed and the user getting a compilation error later on.
>
> put a check into pkg_setup() that does ewarn's on conflicting USE flags, and
> then have the rest of the ebuild pick a sensible default.  in the case of oss
> vs alsa, the latter would be the sensible default.
> -mike

OK, this what I ended up with.  Please note that my scripting skills are 
a bit rusty :P

(The wrong line breaks don't appear in the actual ebuild and tabs are 
used to indent.)


In pkg_setup():

   if use alsa && use oss ; then
     einfo
     ewarn "You have enabled both the \"alsa\" as well as the \"oss\" USE
           flags. It"
     ewarn "is not possible to build mozilla-firefox or xulrunner with
            support for"
     ewarn "both. ALSA will be used in this case. If you want OSS
            support, unset the"
     ewarn "\"alsa\" USE flag and leave only \"oss\" set."
   fi


In src_prepare():

   # Switch from ALSA to OSS
   if use oss && ! use alsa; then
     ebegin "Switching from ALSA to Open Sound System"
     sed -i 's/sydney_audio_alsa/sydney_audio_oss/' \
       media/libsydneyaudio/src/Makefile.in || die "sed failed!" \
     && sed -i '/alsa\//d' config/system-headers || die "sed failed!" \
     && sed -i '/alsa\//d' \
       js/src/config/system-headers || die "sed failed!" \
     && sed -i '/LIB(asound/d' configure.in || die "sed failed!"
   eend $?
   fi


In src_configure():

   # Enable/Disable audio in firefox
   if use alsa || use oss ; then
     mozconfig_annotate '' --enable-ogg
     mozconfig_annotate '' --enable-wave
   fi


In this last one, I'm not sure how to pass something to the first 
argument of mozconfig_annotate.  The original was:

   mozconfig_use_enable alsa ogg

which translates into:

   mozconfig_annotate 'alsa' --enable-ogg

The point is that the user will see which USE flags are responsible for 
"--enable-*" and "--disable-*" options.  Unfortunately, this:

   mozconfig_use_enable ( alsa || oss ) ogg

is not possible.  Should I therefore write the block twice in a nested 
if block or leave it as is (and losing the information about which USE 
flag resulted in "--enable-ogg|wave"?)