util: Remove Python 2.7 glue code

Remove uses of six and from __future__ imports as they are no longer
needed.

Change-Id: I8d6aae84d8192b301d541b8dc81275f4932f9f2f
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/39756
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

util/build_cross_gcc/build_cross_gcc.py

@@ -32,7 +32,6 @@ import os
 import os.path
 import pickle
 import shutil
-import six
 import subprocess
 import textwrap
 
@@ -145,9 +144,9 @@ def run_commands(working_dir, *cmds):
 # Settings.
 #
 
-class MetaSetting(type):
+class MetaSetting(abc.ABCMeta):
     def __new__(mcls, name, bases, d):
-        cls = super(MetaSetting, mcls).__new__(mcls, name, bases, d)
+        cls = super().__new__(mcls, name, bases, d)
         key = d.get('key', None)
         if key is not None:
             assert('default' in d)
@@ -157,9 +156,7 @@ class MetaSetting(type):
             all_settings[key] = instance
         return cls
 
-@six.add_metaclass(MetaSetting)
-@six.add_metaclass(abc.ABCMeta)
-class Setting(object):
+class Setting(object, metaclass=MetaSetting):
     key = None
 
     @abc.abstractmethod
@@ -420,17 +417,15 @@ class Parallelism(Setting):
 # Steps of the build process.
 #
 
-class MetaStep(type):
+class MetaStep(abc.ABCMeta):
     def __new__(mcls, name, bases, d):
-        cls = super(MetaStep, mcls).__new__(mcls, name, bases, d)
+        cls = super().__new__(mcls, name, bases, d)
         number = d.get('number', None)
         if number is not None:
             all_steps[number] = cls()
         return cls
 
-@six.add_metaclass(MetaStep)
-@six.add_metaclass(abc.ABCMeta)
-class Step(object):
+class Step(object, metaclass=MetaStep):
     'Steps to set up a cross compiling gcc.'
     number = None
 

util/cpt_upgrader.py

@@ -69,8 +69,7 @@
 # upgraders in private branches.
 
 
-
-from six.moves import configparser
+import configparser
 import glob, types, sys, os
 import os.path as osp
 

util/style/verifiers.py

@@ -47,8 +47,6 @@ import os
 import re
 import sys
 
-from six import add_metaclass
-
 from . import style
 from . import sort_includes
 from .region import *
@@ -102,8 +100,7 @@ def _modified_regions(old, new):
     return regions
 
 
-@add_metaclass(ABCMeta)
-class Verifier(object):
+class Verifier(object, metaclass=ABCMeta):
     """Base class for style verifiers
 
     Verifiers check for style violations and optionally fix such
@@ -224,7 +221,6 @@ class Verifier(object):
         """
         pass
 
-@add_metaclass(ABCMeta)
 class LineVerifier(Verifier):
     def check(self, filename, regions=all_regions, fobj=None, silent=False):
         close = False