Bug 1278415 - Make the buildconfig module use MozbuildObject.from_environment. r=gps

The buildconfig module predates MozbuildObject.from_environment, and
it's about time to start factoring things out such that we only have
one way to get config.status data. This is step 1: making the
buildconfig module use MozbuildObject.from_environment.

Eventually, we'll want to remove the buildconfig module uses everywhere.

build/buildconfig.py

@@ -2,29 +2,19 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-import imp
 import os
 import sys
+from mozbuild.base import MozbuildObject
 
-path = os.path.dirname(sys.executable)
-while not os.path.exists(os.path.join(path, 'config.status')):
-    parent = os.path.normpath(os.path.join(path, os.pardir))
-    if parent == path:
-        raise Exception("Can't find config.status")
-    path = parent
+config = MozbuildObject.from_environment()
 
-path = os.path.join(path, 'config.status')
-config = imp.load_module('_buildconfig', open(path), path, ('', 'r', imp.PY_SOURCE))
-
-# Copy values from the config.status namespace into this module namespace.
-# This effectively imports topsrcdir, topobjdir, defines, substs, files,
-# headers and non_global_defines
-for var in config.__all__:
+for var in ('topsrcdir', 'topobjdir', 'defines', 'non_global_defines',
+            'substs'):
     value = getattr(config, var)
-    if isinstance(value, list) and value and isinstance(value[0], tuple):
-        value = dict(value)
     setattr(sys.modules[__name__], var, value)
 
+substs = dict(substs)
+
 for var in os.environ:
     if var != 'SHELL' and var in substs:
         substs[var] = os.environ[var]

python/mozbuild/mozbuild/base.py

@@ -269,6 +269,10 @@ class MozbuildObject(ProcessExecutionMixin):
     def defines(self):
         return self.config_environment.defines
 
+    @property
+    def non_global_defines(self):
+        return self.config_environment.non_global_defines
+
     @property
     def substs(self):
         return self.config_environment.substs