deprecate IPython.utils.signatures

and remove Python 2 backport code, since we don't use it anymore.

IPython/core/completer.py

@@ -843,18 +843,11 b' class IPCompleter(Completer):'
         ret += self._default_arguments_from_docstring(
                  getattr(call_obj, '__doc__', ''))
 
-        if PY3:
-            _keeps = (inspect.Parameter.KEYWORD_ONLY,
-                      inspect.Parameter.POSITIONAL_OR_KEYWORD)
-            signature = inspect.signature
-        else:
-            import IPython.utils.signatures
-            _keeps = (IPython.utils.signatures.Parameter.KEYWORD_ONLY,
-                      IPython.utils.signatures.Parameter.POSITIONAL_OR_KEYWORD)
-            signature = IPython.utils.signatures.signature
+        _keeps = (inspect.Parameter.KEYWORD_ONLY,
+                  inspect.Parameter.POSITIONAL_OR_KEYWORD)
 
         try:
-            sig = signature(call_obj)
+            sig = inspect.signature(call_obj)
             ret.extend(k for k, v in sig.parameters.items() if
                        v.kind in _keeps)
         except ValueError:

IPython/core/oinspect.py

@@ -14,6 +14,7 b" __all__ = ['Inspector','InspectColors']"
 
 # stdlib modules
 import inspect
+from inspect import signature
 import linecache
 import warnings
 import os
@@ -39,7 +40,6 b' from IPython.utils.text import indent'
 from IPython.utils.wildcard import list_namespace
 from IPython.utils.coloransi import TermColors, ColorScheme, ColorSchemeTable
 from IPython.utils.py3compat import cast_unicode, string_types, PY3
-from IPython.utils.signatures import signature
 from IPython.utils.colorable import Colorable
 
 from pygments import highlight

IPython/core/tests/test_oinspect.py

@@ -5,6 +5,7 b''
 # Distributed under the terms of the Modified BSD License.
 
 
+from inspect import Signature, Parameter
 import os
 import re
 import sys
@@ -17,11 +18,11 b' from IPython.core.magic import (Magics, magics_class, line_magic,'
                                 register_line_magic, register_cell_magic,
                                 register_line_cell_magic)
 from decorator import decorator
+from IPython import get_ipython
 from IPython.testing.decorators import skipif
 from IPython.testing.tools import AssertPrints
 from IPython.utils.path import compress_user
 from IPython.utils import py3compat
-from IPython.utils.signatures import Signature, Parameter
 
 
 #-----------------------------------------------------------------------------
@@ -39,7 +40,7 b' ip = get_ipython()'
 # defined, if any code is inserted above, the following line will need to be
 # updated.  Do NOT insert any whitespace between the next line and the function
 # definition below.
-THIS_LINE_NUMBER = 42  # Put here the actual number of this line
+THIS_LINE_NUMBER = 43  # Put here the actual number of this line
 
 from unittest import TestCase
 
@@ -68,7 +69,7 b' def test_find_file_decorated1():'
 
     @decorator
     def noop1(f):
-        def wrapper():
+        def wrapper(*a, **kw):
             return f(*a, **kw)
         return wrapper
 

IPython/utils/signatures.py

@@ -1,11 +1,11 b''
-"""Function signature objects for callables.
+"""DEPRECATED: Function signature objects for callables.
 
 Use the standard library version if available, as it is more up to date.
 Fallback on backport otherwise.
 """
 
+import warnings
+warnings.warn("{} backport for Python 2 is deprecated in IPython 6, which only supports Python 3".format(__name__),
+    DeprecationWarning, stacklevel=2)
 
-try:
-    from inspect import BoundArguments, Parameter, Signature, signature
-except ImportError:
-    from ._signatures import  BoundArguments, Parameter, Signature, signature
+from inspect import BoundArguments, Parameter, Signature, signature