Don't introspect __call__ for simple callables

Closes gh-5164

IPython/core/oinspect.py

@@ -48,6 +48,9 b' _object_init_docstring = object.__init__.__doc__'
 _builtin_type_docstrings = {
     t.__doc__ for t in (types.ModuleType, types.MethodType, types.FunctionType)
 }
+
+_builtin_func_type = type(all)
+_builtin_meth_type = type(str.upper)  # Bound methods have the same type as builtin functions
 #****************************************************************************
 # Builtin color schemes
 
@@ -180,6 +183,13 b' def getsource(obj,is_binary=False):'
         encoding = get_encoding(obj)
         return cast_unicode(src, encoding=encoding)
 
+
+def is_simple_callable(obj):
+    """True if obj is a function ()"""
+    return (inspect.isfunction(obj) or inspect.ismethod(obj) or \
+            isinstance(obj, _builtin_func_type) or isinstance(obj, _builtin_meth_type))
+
+
 def getargspec(obj):
     """Wrapper around :func:`inspect.getfullargspec` on Python 3, and
     :func:inspect.getargspec` on Python 2.
@@ -187,8 +197,7 b' def getargspec(obj):'
     In addition to functions and methods, this can also handle objects with a
     ``__call__`` attribute.
     """
-    if not (inspect.isfunction(obj) or inspect.ismethod(obj)) \
-            and safe_hasattr(obj, '__call__'):
+    if safe_hasattr(obj, '__call__') and not is_simple_callable(obj):
         obj = obj.__call__
 
     return inspect.getfullargspec(obj) if PY3 else inspect.getargspec(obj)
@@ -767,7 +776,7 b' class Inspector:'
                 out['init_docstring'] = init_ds
 
             # Call form docstring for callable instances
-            if safe_hasattr(obj, '__call__'):
+            if safe_hasattr(obj, '__call__') and not is_simple_callable(obj):
                 call_def = self._getdef(obj.__call__, oname)
                 if call_def is not None:
                     out['call_def'] = self.format(call_def)

IPython/core/tests/test_oinspect.py

@@ -115,6 +115,10 b' class Call(object):'
     def method(self, x, z=2):
         """Some method's docstring"""
 
+class SimpleClass(object):
+    def method(self, x, z=2):
+        """Some method's docstring"""
+
 
 class OldStyle:
     """An old-style class for testing."""
@@ -271,6 +275,13 b' def test_info_awkward():'
     # Just test that this doesn't throw an error.
     i = inspector.info(Awkward())
 
+def test_calldef_none():
+    # We should ignore __call__ for all of these.
+    for obj in [f, SimpleClass().method, any, str.upper]:
+        print(obj)
+        i = inspector.info(obj)
+        nt.assert_is(i['call_def'], None)
+
 if py3compat.PY3:
     exec("def f_kwarg(pos, *, kwonly): pass")