better fix for issue 2821 -- avoid direct copies of the BuilderDict as it is ambiguous/corrupts the original environment

2 files changed, 18 insertions, 15 deletions

diff --git a/src/engine/SCons/Environment.py b/src/engine/SCons/Environment.py
index b308765..529e3a3 100644
--- a/src/engine/SCons/Environment.py
+++ b/src/engine/SCons/Environment.py
@@ -72,6 +72,7 @@ CleanTargets = {}
 CalculatorArgs = {}
 
 semi_deepcopy = SCons.Util.semi_deepcopy
+semi_deepcopy_dict = SCons.Util.semi_deepcopy_dict
 
 # Pull UserError into the global name space for the benefit of
 # Environment().SourceSignatures(), which has some import statements
@@ -303,7 +304,9 @@ class BuilderDict(UserDict):
         UserDict.__init__(self, dict)
 
     def __semi_deepcopy__(self):
-        return self.__class__(self.data, self.env)
+        # These cannot be copied since they would both modify the same builder object, and indeed
+        # just copying would modify the original builder
+        raise TypeError( 'cannot semi_deepcopy a BuilderDict' )
 
     def __setitem__(self, item, val):
         try:
@@ -1374,15 +1377,15 @@ class Base(SubstitutionEnvironment):
         (like a function).  There are no references to any mutable
         objects in the original Environment.
         """
-        clone = copy.copy(self)
-        clone._dict = semi_deepcopy(self._dict)
-
         try:
-            cbd = clone._dict['BUILDERS']
+            builders = self._dict['BUILDERS']
         except KeyError:
             pass
-        else:
-            clone._dict['BUILDERS'] = BuilderDict(cbd, clone)
+            
+        clone = copy.copy(self)
+        # BUILDERS is not safe to do a simple copy
+        clone._dict = semi_deepcopy_dict(self._dict, ['BUILDERS'])
+        clone._dict['BUILDERS'] = BuilderDict(builders, clone)
 
         # Check the methods added via AddMethod() and re-bind them to
         # the cloned environment.  Only do this if the attribute hasn't
@@ -1733,7 +1736,7 @@ class Base(SubstitutionEnvironment):
         except KeyError:
             pass
         else:
-            kwbd = semi_deepcopy(kwbd)
+            kwbd = BuilderDict(kwbd,self)
             del kw['BUILDERS']
             self.__setitem__('BUILDERS', kwbd)
         kw = copy_non_reserved_keywords(kw)
diff --git a/src/engine/SCons/Util.py b/src/engine/SCons/Util.py
index 2523eda..822d524 100644
--- a/src/engine/SCons/Util.py
+++ b/src/engine/SCons/Util.py
@@ -430,15 +430,15 @@ def to_String_for_signature(obj, to_String_for_subst=to_String_for_subst,
 # references to anything else it finds.
 #
 # A special case is any object that has a __semi_deepcopy__() method,
-# which we invoke to create the copy, which is used by the BuilderDict
-# class because of its extra initialization argument.
+# which we invoke to create the copy. Currently only used by
+# BuilderDict to actually prevent the copy operation (as invalid on that object)
 #
 # The dispatch table approach used here is a direct rip-off from the
 # normal Python copy module.
 
 _semi_deepcopy_dispatch = d = {}
 
-def _semi_deepcopy_dict(x):
+def semi_deepcopy_dict(x, exclude = [] ):
     copy = {}
     for key, val in x.items():
         # The regular Python copy.deepcopy() also deepcopies the key,
@@ -447,9 +447,10 @@ def _semi_deepcopy_dict(x):
         #    copy[semi_deepcopy(key)] = semi_deepcopy(val)
         #
         # Doesn't seem like we need to, but we'll comment it just in case.
-        copy[key] = semi_deepcopy(val)
+        if key not in exclude:
+            copy[key] = semi_deepcopy(val)
     return copy
-d[dict] = _semi_deepcopy_dict
+d[dict] = semi_deepcopy_dict
 
 def _semi_deepcopy_list(x):
     return list(map(semi_deepcopy, x))
@@ -467,14 +468,13 @@ def semi_deepcopy(x):
         if hasattr(x, '__semi_deepcopy__') and callable(x.__semi_deepcopy__):
             return x.__semi_deepcopy__()
         elif isinstance(x, UserDict):
-            return x.__class__(_semi_deepcopy_dict(x))
+            return x.__class__(semi_deepcopy_dict(x))
         elif isinstance(x, UserList):
             return x.__class__(_semi_deepcopy_list(x))
         
         return x
 
 
-
 class Proxy(object):
     """A simple generic Proxy class, forwarding all calls to
     subject.  So, for the benefit of the python newbie, what does