Modified config to explicitly update cumulative attributes in targets

Modified '_process_config_and_overrides' to update cumulative
attributes based on cumulative overrides found during walking config
files.

This should remove most of the disparity between the config target
cumulative overrides and cumulative attributes set in targets.json.
These cumulative overrides are updated after the global target
instantiation though, which may cause internal build tool state
dependent on cumulative attributes to not correctly reflect all
cumulative overrides.

Author: geky

tools/config.py

@@ -146,7 +146,7 @@ def __init__(self, name, additions=set(), removals=set(), strict=False):
         self.strict = strict
 
     # Add attr to the cumulative override
-    def remove_cumulative_override(self, overrides):
+    def remove_cumulative_overrides(self, overrides):
         for override in overrides:
             if override in self.additions:
                 raise ConfigException("Configuration conflict. The %s %s both added and removed." % (self.name, override))
@@ -163,12 +163,13 @@ def add_cumulative_overrides(self, overrides):
 
     # Enable strict set of cumulative overrides for the specified attr
     def strict_cumulative_overrides(self, overrides):
-        self.remove_cumulative_override(self.additions - set(overrides))
-        self.add_cumulative_override(overrides)
+        self.remove_cumulative_overrides(self.additions - set(overrides))
+        self.add_cumulative_overrides(overrides)
         self.strict = True
 
-    def get_cumulative_overrides(self, target):
-        return set(getattr(target, self.name)) | self.additions - self.removals
+    def update_target(self, target):
+        setattr(target, self.name, list(
+                set(getattr(target, self.name, [])) | self.additions - self.removals))
 
 
 # 'Config' implements the mbed configuration mechanism
@@ -290,6 +291,10 @@ def _process_config_and_overrides(self, data, params, unit_name, unit_kind):
                     else:
                         self.config_errors.append(ConfigException("Attempt to override undefined parameter '%s' in '%s'"
                             % (full_name, ConfigParameter.get_display_name(unit_name, unit_kind, label))))
+
+        for cumulatives in self.cumulative_overrides.itervalues():
+            cumulatives.update_target(Target.get_target(self.target))
+
         return params
 
     # Read and interpret configuration data defined by targets
@@ -400,20 +405,12 @@ def config_to_macros(config):
     def get_config_data_macros(self):
         return self.config_to_macros(self.get_config_data())
 
-    # Returns any cumulative overrides in the configuration data
-    def get_cumulative_overrides(self, attr):
-        if attr not in self.cumulative_overrides:
-            return None
-
-        params, _ = self.get_config_data()
-        self._check_required_parameters(params)
-
-        return self.cumulative_overrides[attr].get_cumulative_overrides(
-                Target.get_target(self.target))
-
     # Returns any features in the configuration data
     def get_features(self):
-        features = self.get_cumulative_overrides('features')
+        params, _ = self.get_config_data()
+        self._check_required_parameters(params)
+        self.cumulative_overrides['features'].update_target(Target.get_target(self.target))
+        features = Target.get_target(self.target).features
 
         for feature in features:
             if feature not in self.__allowed_features: