diff --git a/Lib/tempfile.py b/Lib/tempfile.py
index 6146235..083d9e4 100644
--- a/Lib/tempfile.py
+++ b/Lib/tempfile.py
@@ -447,7 +447,12 @@ class _TemporaryFileCloser:
 
         # Need to ensure the file is deleted on __del__
         def __del__(self):
-            self.close()
+            if not self.close_called and self.file is not None:
+                _warnings.warn(
+                    'unclosed file %r' % self, ResourceWarning,
+                    stacklevel=2,
+                    source=self)
+                self.close()
 
     else:
         def close(self):
diff --git a/Lib/test/test_tempfile.py b/Lib/test/test_tempfile.py
index 51df1ec..d918658 100644
--- a/Lib/test/test_tempfile.py
+++ b/Lib/test/test_tempfile.py
@@ -957,6 +957,15 @@ class TestNamedTemporaryFile(BaseTestCase):
             tempfile.NamedTemporaryFile(mode=2, dir=dir)
         self.assertEqual(os.listdir(dir), [])
 
+    def test_resource_warning_on_destructor(self):
+        def f():
+            tempfile.NamedTemporaryFile()
+        with warnings.catch_warnings(record=True) as w:
+            f()
+        self.assertEqual(len(w), 1)
+        self.assertEqual(w[-1].category, ResourceWarning)
+        self.assertIn('unclosed file', str(w[-1].message))
+
     # How to test the mode and bufsize parameters?
 
 class TestSpooledTemporaryFile(BaseTestCase):
diff --git a/Lib/test/test_urllib_response.py b/Lib/test/test_urllib_response.py
index 0eb5942..4de4aaf 100644
--- a/Lib/test/test_urllib_response.py
+++ b/Lib/test/test_urllib_response.py
@@ -16,8 +16,6 @@ class TestResponse(unittest.TestCase):
     def test_with(self):
         addbase = urllib.response.addbase(self.fp)
 
-        self.assertIsInstance(addbase, tempfile._TemporaryFileWrapper)
-
         def f():
             with addbase as spam:
                 pass
diff --git a/Lib/urllib/error.py b/Lib/urllib/error.py
index c5b675d..0b5fea4 100644
--- a/Lib/urllib/error.py
+++ b/Lib/urllib/error.py
@@ -44,14 +44,8 @@ class HTTPError(URLError, urllib.response.addinfourl):
         self.code = code
         self.msg = msg
         self.hdrs = hdrs
-        self.fp = fp
         self.filename = url
-        # The addinfourl classes depend on fp being a valid file
-        # object.  In some cases, the HTTPError may not have a valid
-        # file object.  If this happens, the simplest workaround is to
-        # not initialize the base classes.
-        if fp is not None:
-            self.__super_init(fp, hdrs, url, code)
+        self.__super_init(fp, hdrs, url, code)
 
     def __str__(self):
         return 'HTTP Error %s: %s' % (self.code, self.msg)
diff --git a/Lib/urllib/response.py b/Lib/urllib/response.py
index 4778118..ae559f6 100644
--- a/Lib/urllib/response.py
+++ b/Lib/urllib/response.py
@@ -6,18 +6,15 @@ addinfourl instance, which defines an info() method that returns
 headers and a geturl() method that returns the url.
 """
 
-import tempfile
-
 __all__ = ['addbase', 'addclosehook', 'addinfo', 'addinfourl']
 
 
-class addbase(tempfile._TemporaryFileWrapper):
+class addbase:
     """Base class for addinfo and addclosehook. Is a good idea for garbage collection."""
 
     # XXX Add a method to expose the timeout on the underlying socket?
 
     def __init__(self, fp):
-        super(addbase,  self).__init__(fp, '<urllib response>', delete=False)
         # Keep reference around as this was part of the original API.
         self.fp = fp
 
@@ -33,6 +30,23 @@ class addbase(tempfile._TemporaryFileWrapper):
     def __exit__(self, type, value, traceback):
         self.close()
 
+    def close(self):
+        self.fp.close()
+
+    def __getattr__(self, name):
+        # Attribute lookups are delegated to the underlying file.
+        return getattr(self.fp, name)
+
+    # iter() doesn't use __getattr__ to find the __iter__ method
+    def __iter__(self):
+        # Don't return iter(self.file), but yield from it to avoid closing file
+        # as long as it's being used as iterator (see issue #23700). We can't
+        # use 'yield from' here because iter(file) returns the file object
+        # itself, which has a close method, and thus the file would get closed
+        # when the generator is finalized, due to PEP380 semantics.
+        for line in self.fp:
+            yield line
+
 
 class addclosehook(addbase):
     """Class to add a close hook to an open file."""