Fix typo that causes several NaT methods to have incorrect docstrings (pandas-dev#17327)

Author: jbrockmendel

doc/source/whatsnew/v0.21.0.txt

@@ -428,3 +428,4 @@ Other
 - The ``Series`` constructor with no arguments would have an index like ``Index([], dtype='object')`` instead of ``RangeIndex(start=0, stop=0, step=1)``
 - Bug in ``.isin()`` in which checking membership in empty ``Series`` objects raised an error (:issue:`16991`)
 - Bug in :func:`unique` where checking a tuple of strings raised a ``TypeError`` (:issue:`17108`)
+- Several ``NaT`` method docstrings (e.g. :func:`NaT.ctime`) were incorrect (:issue:`17327`)

pandas/_libs/tslib.pyx

@@ -1,3 +1,4 @@
+# -*- coding: utf-8 -*-
 # cython: profile=False
 
 import warnings
@@ -3922,7 +3923,7 @@ for _method_name in _nat_methods:
         def f(*args, **kwargs):
             return NaT
         f.__name__ = func_name
-        f.__doc__ = _get_docstring(_method_name)
+        f.__doc__ = _get_docstring(func_name)
         return f
 
     setattr(NaTType, _method_name, _make_nat_func(_method_name))
@@ -3934,7 +3935,7 @@ for _method_name in _nan_methods:
         def f(*args, **kwargs):
             return np.nan
         f.__name__ = func_name
-        f.__doc__ = _get_docstring(_method_name)
+        f.__doc__ = _get_docstring(func_name)
         return f
 
     setattr(NaTType, _method_name, _make_nan_func(_method_name))
@@ -3952,7 +3953,7 @@ for _maybe_method_name in dir(NaTType):
             def f(*args, **kwargs):
                 raise ValueError("NaTType does not support " + func_name)
             f.__name__ = func_name
-            f.__doc__ = _get_docstring(_method_name)
+            f.__doc__ = _get_docstring(func_name)
             return f
 
         setattr(NaTType, _maybe_method_name,

pandas/tests/scalar/test_nat.py

@@ -247,3 +247,8 @@ def test_nat_arithmetic_index():
         tm.assert_index_equal(right + left, exp)
         tm.assert_index_equal(left - right, exp)
         tm.assert_index_equal(right - left, exp)
+
+
+def test_nat_pinned_docstrings():
+    # GH17327
+    assert NaT.ctime.__doc__ == datetime.ctime.__doc__