gh-117692: Fix AttributeError in DocTestFinder on wrapped builtin_or_method (#117699)

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

Lib/doctest.py

@@ -1140,7 +1140,14 @@ def _find_lineno(self, obj, source_lines):
             obj = obj.fget
         if inspect.isfunction(obj) and getattr(obj, '__doc__', None):
             # We don't use `docstring` var here, because `obj` can be changed.
-            obj = inspect.unwrap(obj).__code__
+            obj = inspect.unwrap(obj)
+            try:
+                obj = obj.__code__
+            except AttributeError:
+                # Functions implemented in C don't necessarily
+                # have a __code__ attribute.
+                # If there's no code, there's no lineno
+                return None
         if inspect.istraceback(obj): obj = obj.tb_frame
         if inspect.isframe(obj): obj = obj.f_code
         if inspect.iscode(obj):

Lib/test/test_doctest/test_doctest.py

@@ -2553,6 +2553,20 @@ def test_look_in_unwrapped():
     'one other test'
     """
 
+@doctest_skip_if(support.check_impl_detail(cpython=False))
+def test_wrapped_c_func():
+    """
+    # https://github.com/python/cpython/issues/117692
+    >>> import binascii
+    >>> from test.test_doctest.decorator_mod import decorator
+
+    >>> c_func_wrapped = decorator(binascii.b2a_hex)
+    >>> tests = doctest.DocTestFinder(exclude_empty=False).find(c_func_wrapped)
+    >>> for test in tests:
+    ...    print(test.lineno, test.name)
+    None b2a_hex
+    """
+
 def test_unittest_reportflags():
     """Default unittest reporting flags can be set to control reporting
 

Misc/NEWS.d/next/Library/2024-04-09-23-22-21.gh-issue-117692.EciInD.rst

@@ -0,0 +1,2 @@
+Fixes a bug when :class:`doctest.DocTestFinder` was failing on wrapped
+``builtin_function_or_method``.