When deleting a variable from an OverrideEnvironment, do not throw an exception if the underlying Environment does not have a variable we deleted.

3 files changed, 33 insertions, 2 deletions

diff --git a/src/CHANGES.txt b/src/CHANGES.txt
index 8fd81cc..68d1b48 100644
--- a/src/CHANGES.txt
+++ b/src/CHANGES.txt
@@ -340,6 +340,10 @@ RELEASE 0.97 - XXX
   - Don't fail when writing signatures if the .sconsign.dblite file is
     owned by a different user (e.g. root) from a previous run.
 
+  - When deleting variables from stacked OverrideEnvironments, don't
+    throw a KeyError if we were able to delte the variable from any
+    Environment in the stack.
+
   From Chen Lee:
 
   - Handle Visual Studio project and solution files in Unicode.
diff --git a/src/engine/SCons/Environment.py b/src/engine/SCons/Environment.py
index 0833f5f..08e085d 100644
--- a/src/engine/SCons/Environment.py
+++ b/src/engine/SCons/Environment.py
@@ -1509,8 +1509,16 @@ class OverrideEnvironment(Base):
         try:
             del self.__dict__['overrides'][key]
         except KeyError:
-            pass
-        return self.__dict__['__subject'].__delitem__(key)
+            deleted = 0
+        else:
+            deleted = 1
+        try:
+            result = self.__dict__['__subject'].__delitem__(key)
+        except KeyError:
+            if not deleted:
+                raise
+            result = None
+        return result
     def get(self, key, default=None):
         """Emulates the get() method of dictionaries."""
         try:
diff --git a/src/engine/SCons/EnvironmentTests.py b/src/engine/SCons/EnvironmentTests.py
index 55dfb3a..4b222b8 100644
--- a/src/engine/SCons/EnvironmentTests.py
+++ b/src/engine/SCons/EnvironmentTests.py
@@ -2847,6 +2847,25 @@ class OverrideEnvironmentTestCase(unittest.TestCase):
         assert env2['YYY'] == 'y', env2['YYY']
         assert env3['YYY'] == 'y3', env3['YYY']
 
+    def test___delitem__(self):
+        """Test deleting variables from an OverrideEnvironment"""
+        env, env2, env3 = self.envs
+
+        del env3['XXX']
+        assert not env.has_key('XXX'), "env has XXX?"
+        assert not env2.has_key('XXX'), "env2 has XXX?"
+        assert not env3.has_key('XXX'), "env3 has XXX?"
+
+        del env3['YYY']
+        assert not env.has_key('YYY'), "env has YYY?"
+        assert not env2.has_key('YYY'), "env2 has YYY?"
+        assert not env3.has_key('YYY'), "env3 has YYY?"
+
+        del env3['ZZZ']
+        assert not env.has_key('ZZZ'), "env has ZZZ?"
+        assert not env2.has_key('ZZZ'), "env2 has ZZZ?"
+        assert not env3.has_key('ZZZ'), "env3 has ZZZ?"
+
     def test_get(self):
         """Test the OverrideEnvironment get() method"""
         env, env2, env3 = self.envs