initialise all fields to 0 when using object structs from the freelist

--HG--
extra : rebase_source : 346e99306b247c116d988b58802ed7e7eb62754c

Cython/Compiler/ModuleNode.py

@@ -1076,10 +1076,14 @@ class ModuleNode(Nodes.Node, Nodes.BlockNode):
         else:
             code.putln("PyObject *o;")
             if freelist_size:
+                code.globalstate.use_utility_code(
+                    UtilityCode.load_cached("IncludeStringH", "StringTools.c"))
+                obj_struct = type.declaration_code("", deref=True)
                 code.putln("if ((%s > 0) & (t->tp_basicsize == sizeof(%s))) {" % (
-                    freecount_name, type.declaration_code("", deref=True)))
+                    freecount_name, obj_struct))
                 code.putln("o = (PyObject*)%s[--%s];" % (
                     freelist_name, freecount_name))
+                code.putln("memset(o, 0, sizeof(%s));" % obj_struct)
                 code.putln("PyObject_INIT(o, t);")
                 if scope.needs_gc():
                     code.putln("PyObject_GC_Track(o);")

tests/run/exttype_freelist.pyx

@@ -69,6 +69,52 @@ cdef class LargerExtSubType(ExtSubType):
         self.attribute2 = object()
 
 
+@cython.freelist(8)
+cdef class ExtTypeWithCAttr:
+    """
+    >>> obj = ExtTypeWithCAttr()
+    >>> obj = ExtTypeWithCAttr()
+    >>> obj = ExtTypeWithCAttr()
+    >>> obj = ExtTypeWithCAttr()
+    >>> obj = ExtTypeWithCAttr()
+    >>> obj = ExtTypeWithCAttr()
+    """
+    cdef int cattr
+
+    def __cinit__(self):
+        assert self.cattr == 0
+        self.cattr = 1
+
+
+cdef class ExtSubTypeWithCAttr(ExtTypeWithCAttr):
+    """
+    >>> obj = ExtSubTypeWithCAttr()
+    >>> obj = ExtSubTypeWithCAttr()
+    >>> obj = ExtSubTypeWithCAttr()
+    >>> obj = ExtSubTypeWithCAttr()
+    >>> obj = ExtSubTypeWithCAttr()
+    >>> obj = ExtSubTypeWithCAttr()
+    """
+
+
+cdef class ExtTypeWithCAttrNoFreelist:
+    """
+    For comparison with normal CPython instantiation.
+
+    >>> obj = ExtTypeWithCAttrNoFreelist()
+    >>> obj = ExtTypeWithCAttrNoFreelist()
+    >>> obj = ExtTypeWithCAttrNoFreelist()
+    >>> obj = ExtTypeWithCAttrNoFreelist()
+    >>> obj = ExtTypeWithCAttrNoFreelist()
+    >>> obj = ExtTypeWithCAttrNoFreelist()
+    """
+    cdef int cattr
+
+    def __cinit__(self):
+        assert self.cattr == 0
+        self.cattr = 1
+
+
 @cython.freelist(8)
 cdef class ExtTypeWithRefCycle:
     """