build: prefer 4Front OSS to native implementations

If sys/soundcard.h is actually linux/soundcard.h then it supports only OSSv3
API. This may happen when OSSLIBDIR == /usr while forgetting to replace
sys/soundcard.h from glibc.

However, after fa620ff waf prefers native implementation which is inferior
on Linux. To fix try making waf prefer oss-audio-4front. It's quite unusual
to have 4Front OSS installed where native implementation is superior, anyway.
Signed-off-by: bugmen0t <@>

Make the false positives path also undef the 4Front define.
Signed-off-by: Stefano Pigozzi <stefano.pigozzi@gmail.com>

Fixes #396

2 files changed, 14 insertions, 7 deletions

diff --git a/waftools/checks/custom.py b/waftools/checks/custom.py
index 09a5c01018..1b698ec086 100644
--- a/waftools/checks/custom.py
+++ b/waftools/checks/custom.py
@@ -1,3 +1,4 @@
+from waftools.inflectors import DependencyInflector
 from waftools.checks.generic import *
 from waflib import Utils
 import os
@@ -84,6 +85,12 @@ def __get_osslibdir():
 def check_oss_4front(ctx, dependency_identifier):
     oss_libdir = __get_osslibdir()
 
+    # avoid false positive from native sys/soundcard.h
+    if not oss_libdir:
+        defkey = DependencyInflector(dependency_identifier).define_key()
+        ctx.undefine(defkey)
+        return False
+
     soundcard_h = os.path.join(oss_libdir, "include/sys/soundcard.h")
     include_dir = os.path.join(oss_libdir, "include")
 
diff --git a/wscript b/wscript
index 290cbbe2fe..0da79b484c 100644
--- a/wscript
+++ b/wscript
@@ -383,12 +383,18 @@ audio_output_features = [
         'deps_neg': [ 'sdl2' ],
         'func': check_pkg_config('sdl')
     }, {
+        'name': 'oss-audio-4front',
+        'desc': 'OSS (implementation from opensound.com)',
+        'func': check_oss_4front,
+        'groups' : [ 'oss-audio' ]
+    }, {
         'name': 'oss-audio-native',
         'desc': 'OSS (platform-specific OSS implementation)',
         'func': check_cc(header_name='sys/soundcard.h',
                          defines=['PATH_DEV_DSP="/dev/dsp"',
                                   'PATH_DEV_MIXER="/dev/mixer"'],
                          fragment=load_fragment('oss_audio.c')),
+        'deps_neg': [ 'oss-audio-4front' ],
         'groups' : [ 'oss-audio' ]
     }, {
         'name': 'oss-audio-sunaudio',
@@ -398,13 +404,7 @@ audio_output_features = [
                          defines=['PATH_DEV_DSP="/dev/sound"',
                                   'PATH_DEV_MIXER="/dev/mixer"'],
                          fragment=load_fragment('oss_audio_sunaudio.c')),
-        'deps_neg': [ 'oss-audio-native' ],
-        'groups' : [ 'oss-audio' ]
-    }, {
-        'name': 'oss-audio-4front',
-        'desc': 'OSS (implementation from opensound.com)',
-        'func': check_oss_4front,
-        'deps_neg': [ 'oss-audio-native', 'oss-audio-sunaudio' ],
+        'deps_neg': [ 'oss-audio-4front', 'oss-audio-native' ],
         'groups' : [ 'oss-audio' ]
     }, {
         'name': '--oss-audio',