waf: mavgen: use output_dir instead of target

The option target for the waf task generator is meant for actual files that are
going to be build. Since our target files are dynamic, let's change the code to
use a new parameter output_dir instead.

Tools/ardupilotwaf/mavgen.py

@@ -13,7 +13,7 @@ import os
 class mavgen(Task.Task):
     """generate mavlink header files"""
     color   = 'GREEN'
-    run_str = '${PYTHON} ${MAVGEN} --lang=C --wire-protocol=1.0 --output ${TGT} ${SRC}'
+    run_str = '${PYTHON} ${MAVGEN} --lang=C --wire-protocol=1.0 --output ${OUTPUT_DIR} ${SRC}'
     before  = 'cxx c'
 
     def post_run(self):
@@ -27,18 +27,19 @@ def options(opt):
 @feature('mavgen')
 @before_method('process_source')
 def process_mavgen(self):
+    if not hasattr(self, 'output_dir'):
+        self.bld.fatal('mavgen: missing option output_dir')
+
     inputs = self.to_nodes(self.source)
     outputs = []
 
-    self.target = Utils.to_list(getattr(self, 'target', []))
-    for t in self.target:
-        if not isinstance(t, Node.Node):
-            t = self.bld.bldnode.find_or_declare(t)
-        outputs.append(t)
-
     self.source = []
 
+    if not isinstance(self.output_dir, Node.Node):
+        self.output_dir = self.bld.bldnode.find_or_declare(self.output_dir)
+
     task = self.create_task('mavgen', inputs, outputs)
+    task.env['OUTPUT_DIR'] = self.output_dir.abspath()
 
     task.env.env = dict(os.environ)
     task.env.env['PYTHONPATH'] = task.env.MAVLINK_DIR

wscript

@@ -122,7 +122,7 @@ def build(bld):
     bld(
         features='mavgen',
         source='modules/mavlink/message_definitions/v1.0/ardupilotmega.xml',
-        target='libraries/GCS_MAVLink/include/mavlink/v1.0/',
+        output_dir='libraries/GCS_MAVLink/include/mavlink/v1.0/',
         name='mavlink',
         # this below is not ideal, mavgen tool should set this, but that's not
         # currently possible