Allow no-arg constructor C++ classes as extension class members.

Cython/Compiler/ModuleNode.py

@@ -1036,6 +1036,10 @@ class ModuleNode(Nodes.Node, Nodes.BlockNode):
                 type.vtabslot_cname,
                 struct_type_cast, type.vtabptr_cname))
 
+        for entry in scope.var_entries:
+            if entry.type.is_cpp_class:
+                code.putln("new(&(p->%s)) %s();" % (entry.cname, entry.type.cname));
+
         for entry in py_attrs:
             if scope.is_internal or entry.name == "__weakref__":
                 # internal classes do not need None inits
@@ -1091,6 +1095,10 @@ class ModuleNode(Nodes.Node, Nodes.BlockNode):
         if weakref_slot in scope.var_entries:
             code.putln("if (p->__weakref__) PyObject_ClearWeakRefs(o);")
 
+        for entry in scope.var_entries:
+            if entry.type.is_cpp_class:
+                code.putln("p->%s.~%s();" % (entry.cname, entry.type.cname));
+
         for entry in py_attrs:
             code.put_xdecref("p->%s" % entry.cname, entry.type, nanny=False)
 

Cython/Compiler/Symtab.py

@@ -571,7 +571,7 @@ class Scope(object):
         if type.is_cpp_class and visibility != 'extern':
             constructor = type.scope.lookup(u'<init>')
             if constructor is not None and PyrexTypes.best_match([], constructor.all_alternatives()) is None:
-                error(pos, "C++ class must have a default constructor to be stack allocated")
+                error(pos, "C++ class must have a no-arg constructor to be stack allocated")
         entry = self.declare(name, cname, type, pos, visibility)
         entry.is_variable = 1
         if in_pxd and visibility != 'extern':
@@ -1770,7 +1770,10 @@ class CClassScope(ClassScope):
                 if visibility == 'private':
                     cname = c_safe_identifier(cname)
             if type.is_cpp_class and visibility != 'extern':
-                error(pos, "C++ classes not allowed as members of an extension type, use a pointer or reference instead")
+                constructor = type.scope.lookup(u'<init>')
+                if constructor is not None and \
+                        PyrexTypes.best_match([], constructor.all_alternatives()) is None:
+                    error(pos, "C++ class must have a no-arg constructor to be a member of an extension type; use a pointer instead")
             entry = self.declare(name, cname, type, pos, visibility)
             entry.is_variable = 1
             self.var_entries.append(entry)