Error for Python objects as C++ class template parameters.

Cython/Compiler/PyrexTypes.py

@@ -3046,6 +3046,14 @@ class CppClassType(CType):
             error(pos, "%s templated type receives %d arguments, got %d" %
                   (self.name, len(self.templates), len(template_values)))
             return error_type
+        has_object_template_param = False
+        for value in template_values:
+            if value.is_pyobject:
+                has_object_template_param = True
+                error(pos,
+                      "Python object type '%s' cannot be used as a template argument" % value)
+        if has_object_template_param:
+            return error_type
         return self.specialize(dict(zip(self.templates, template_values)))
 
     def specialize(self, values):

tests/errors/cpp_object_template.pyx

+# mode: error
+
+from libcpp.vector cimport vector
+
+cdef class A:
+    pass
+
+def main():
+    cdef vector[object] vo
+    vo.push_back(object())
+    cdef vector[A] va
+    va.push_back(A())
+
+_ERRORS = u"""
+9:16: Python object type 'Python object' cannot be used as a template argument
+11:16: Python object type 'A' cannot be used as a template argument
+"""