Issue #5180: Fixed a bug that prevented loading 2.x pickles in 3.x

python when they contain instances of old-style classes.

2 files changed, 74 insertions, 16 deletions

diff --git a/Lib/pickle.py b/Lib/pickle.py
index c4fc2c4..372d5b6 100644
--- a/Lib/pickle.py
+++ b/Lib/pickle.py
@@ -1034,19 +1034,15 @@ class _Unpickler:
     def _instantiate(self, klass, k):
         args = tuple(self.stack[k+1:])
         del self.stack[k:]
-        instantiated = False
-        if (not args and
-                isinstance(klass, type) and
-                not hasattr(klass, "__getinitargs__")):
-            value = _EmptyClass()
-            value.__class__ = klass
-            instantiated = True
-        if not instantiated:
+        if (args or not isinstance(klass, type) or
+            hasattr(klass, "__getinitargs__")):
             try:
                 value = klass(*args)
             except TypeError as err:
                 raise TypeError("in constructor for %s: %s" %
                                 (klass.__name__, str(err)), sys.exc_info()[2])
+        else:
+            value = klass.__new__(klass)
         self.append(value)
 
     def load_inst(self):
@@ -1239,14 +1235,7 @@ class _Unpickler:
         raise _Stop(value)
     dispatch[STOP[0]] = load_stop
 
-# Helper class for load_inst/load_obj
-
-class _EmptyClass:
-    pass
-
-# Encode/decode longs in linear time.
-
-import binascii as _binascii
+# Encode/decode longs.
 
 def encode_long(x):
     r"""Encode a long to a two's complement little-endian binary string.
diff --git a/Lib/test/pickletester.py b/Lib/test/pickletester.py
index dd0ed15..70e5ad0 100644
--- a/Lib/test/pickletester.py
+++ b/Lib/test/pickletester.py
@@ -65,9 +65,21 @@ class C:
     def __eq__(self, other):
         return self.__dict__ == other.__dict__
 
+class D(C):
+    def __init__(self, arg):
+        pass
+
+class E(C):
+    def __getinitargs__(self):
+        return ()
+
 import __main__
 __main__.C = C
 C.__module__ = "__main__"
+__main__.D = D
+D.__module__ = "__main__"
+__main__.E = E
+E.__module__ = "__main__"
 
 class myint(int):
     def __init__(self, x):
@@ -425,6 +437,63 @@ class AbstractPickleTests(unittest.TestCase):
     def test_load_from_data2(self):
         self.assertEqual(self._testdata, self.loads(DATA2))
 
+    def test_load_classic_instance(self):
+        # See issue5180.  Test loading 2.x pickles that
+        # contain an instance of old style class.
+        for X, args in [(C, ()), (D, ('x',)), (E, ())]:
+            xname = X.__name__.encode('ascii')
+            # Protocol 0 (text mode pickle):
+            """
+            0: (    MARK
+            1: i        INST       '__main__ X' (MARK at 0)
+            15: p    PUT        0
+            18: (    MARK
+            19: d        DICT       (MARK at 18)
+            20: p    PUT        1
+            23: b    BUILD
+            24: .    STOP
+            """
+            pickle0 = (b"(i__main__\n"
+                       b"X\n"
+                       b"p0\n"
+                       b"(dp1\nb.").replace(b'X', xname)
+            self.assertEqual(X(*args), self.loads(pickle0))
+
+            # Protocol 1 (binary mode pickle)
+            """
+            0: (    MARK
+            1: c        GLOBAL     '__main__ X'
+            15: q        BINPUT     0
+            17: o        OBJ        (MARK at 0)
+            18: q    BINPUT     1
+            20: }    EMPTY_DICT
+            21: q    BINPUT     2
+            23: b    BUILD
+            24: .    STOP
+            """
+            pickle1 = (b'(c__main__\n'
+                       b'X\n'
+                       b'q\x00oq\x01}q\x02b.').replace(b'X', xname)
+            self.assertEqual(X(*args), self.loads(pickle1))
+
+            # Protocol 2 (pickle2 = b'\x80\x02' + pickle1)
+            """
+            0: \x80 PROTO      2
+            2: (    MARK
+            3: c        GLOBAL     '__main__ X'
+            17: q        BINPUT     0
+            19: o        OBJ        (MARK at 2)
+            20: q    BINPUT     1
+            22: }    EMPTY_DICT
+            23: q    BINPUT     2
+            25: b    BUILD
+            26: .    STOP
+            """
+            pickle2 = (b'\x80\x02(c__main__\n'
+                       b'X\n'
+                       b'q\x00oq\x01}q\x02b.').replace(b'X', xname)
+            self.assertEqual(X(*args), self.loads(pickle2))
+
     # There are gratuitous differences between pickles produced by
     # pickle and cPickle, largely because cPickle starts PUT indices at
     # 1 and pickle starts them at 0.  See XXX comment in cPickle's put2() --