[utils] Remove Python 2

The library `six` provides compatibility between Python 2, and 3. It's no
longer necessary once we migrate of Python 2 completely.

Also remove any custom logic for Python 2 (the ones referenced by
a commentanyways).

https://bugs.swift.org/browse/SR-16025

Author: dduan

utils/GYBUnicodeDataUtils.py

@@ -355,9 +355,6 @@ def map_index(idx):
                 else:
                     return idx
 
-            # NOTE: Python 2's `map` function returns a list. Where Python 3's
-            # `map` function returns an iterator. To work around this the
-            # result of the `map` is explicitly converted to a `list`.
             return list(map(map_index, indexes))
 
         # If self.bmp_data contains identical data blocks, keep the first one,

utils/backtrace-check

@@ -72,10 +72,6 @@ def main():
     found_stack_trace_start = False
     found_stack_trace_entry = False
     for line in lines:
-        # In Python 2, string objects can contain Unicode characters.
-        if sys.version_info.major == 2:
-            line = line.decode('utf-8', 'replace')
-
         line = line.rstrip('\n')
 
         # First see if we found the start of our stack trace start. If so, set

utils/build-script

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # This source file is part of the Swift.org open source project
 #
@@ -32,8 +32,6 @@ from build_swift.build_swift.constants import SWIFT_BUILD_ROOT
 from build_swift.build_swift.constants import SWIFT_REPO_NAME
 from build_swift.build_swift.constants import SWIFT_SOURCE_ROOT
 
-import six
-
 from swift_build_support.swift_build_support import build_script_invocation
 from swift_build_support.swift_build_support import shell
 from swift_build_support.swift_build_support import targets
@@ -120,7 +118,7 @@ class JSONDumper(json.JSONEncoder):
     def default(self, o):
         if hasattr(o, '__dict__'):
             return vars(o)
-        return six.text_type(o)
+        return str(o)
 
 
 def print_xcodebuild_versions(file=sys.stdout):
@@ -499,7 +497,7 @@ def main_preset():
     try:
         preset_parser.read_files(args.preset_file_names)
     except presets.PresetError as e:
-        fatal_error(six.text_type(e))
+        fatal_error(str(e))
 
     if args.show_presets:
         for name in sorted(preset_parser.preset_names,
@@ -520,7 +518,7 @@ def main_preset():
             args.preset,
             vars=args.preset_substitutions)
     except presets.PresetError as e:
-        fatal_error(six.text_type(e))
+        fatal_error(str(e))
 
     preset_args = migration.migrate_swift_sdks(preset.args)
 

utils/build_swift/build_swift/argparse/actions.py

@@ -18,8 +18,6 @@
 import argparse
 import copy
 
-import six
-
 from .types import BoolType, PathType
 
 
@@ -81,7 +79,7 @@ def __init__(self,
         if dests == argparse.SUPPRESS:
             dests = []
             metavar = metavar or ''
-        elif isinstance(dests, six.string_types):
+        elif isinstance(dests, (str,)):
             dests = [dests]
             metavar = metavar or dests[0].upper()
 
@@ -138,7 +136,7 @@ def __init__(self, option_strings, join=None, **kwargs):
             **kwargs)
 
     def __call__(self, parser, namespace, values, option_string=None):
-        if isinstance(values, six.string_types):
+        if isinstance(values, (str,)):
             values = [values]
 
         for dest in self.dests:
@@ -343,5 +341,5 @@ def __call__(self, parser, namespace, values, option_string=None):
         if self.message is not None:
             parser.error(self.message)
 
-        arg = option_string or six.text_type(values)
+        arg = option_string or str(values)
         parser.error('unsupported argument: {}'.format(arg))

utils/build_swift/build_swift/argparse/parser.py

@@ -19,8 +19,6 @@
 import argparse
 from contextlib import contextmanager
 
-import six
-
 from . import Namespace, SUPPRESS, actions
 from .actions import Action
 
@@ -133,7 +131,7 @@ def thunk(**kwargs):
             *names, action=action, **kwargs)
 
     def add_positional(self, dests, action=None, **kwargs):
-        if isinstance(dests, six.string_types):
+        if isinstance(dests, (str,)):
             dests = [dests]
 
         if any(dest.startswith('-') for dest in dests):
@@ -145,7 +143,7 @@ def add_positional(self, dests, action=None, **kwargs):
         return self._add_argument(dests, action, **kwargs)
 
     def add_option(self, option_strings, *actions, **kwargs):
-        if isinstance(option_strings, six.string_types):
+        if isinstance(option_strings, (str,)):
             option_strings = [option_strings]
 
         if not all(opt.startswith('-') for opt in option_strings):

utils/build_swift/build_swift/argparse/types.py

@@ -19,8 +19,6 @@
 import re
 import shlex
 
-import six
-
 from . import ArgumentTypeError
 from ..versions import Version
 
@@ -42,7 +40,7 @@ def _repr(cls, args):
     """
 
     _args = []
-    for key, value in six.iteritems(args):
+    for key, value in args.items():
         _args.append('{}={}'.format(key, repr(value)))
 
     return '{}({})'.format(type(cls).__name__, ', '.join(_args))

utils/build_swift/build_swift/migration.py

@@ -17,9 +17,6 @@
 import itertools
 import subprocess
 
-import six
-from six.moves import map
-
 from swift_build_support.swift_build_support.targets import \
     StdlibDeploymentTarget
 
@@ -137,4 +134,4 @@ def check_impl_args(build_script_impl, args):
     _, err = pipe.communicate()
 
     if pipe.returncode != 0:
-        raise ValueError(six.text_type(err.splitlines()[0].decode()))
+        raise ValueError(str(err.splitlines()[0].decode()))

utils/build_swift/build_swift/presets.py

@@ -14,13 +14,11 @@
 
 from __future__ import absolute_import, unicode_literals
 
+import configparser
 import functools
 import io
 from collections import OrderedDict, namedtuple
 
-from six import StringIO
-from six.moves import configparser
-
 from . import class_utils
 
 
@@ -313,14 +311,9 @@ def read_string(self, string):
         """Reads and parses a string containing preset definintions.
         """
 
-        fp = StringIO(string)
-
-        # ConfigParser changes drastically from Python 2 to 3
-        if hasattr(self._parser, 'read_file'):
-            self._parser.read_file(fp)
-        else:
-            self._parser.readfp(fp)
+        fp = io.StringIO(string)
 
+        self._parser.read_file(fp)
         self._parse_raw_presets()
 
     # -------------------------------------------------------------------------

utils/build_swift/build_swift/shell.py

@@ -24,26 +24,11 @@
 import subprocess
 import sys
 from copy import copy as _copy
+from pathlib import Path
+from pipes import quote as _quote
 from shlex import split
 from subprocess import CalledProcessError
 
-import six
-from six.moves import map
-
-
-try:
-    # Python 2
-    from pipes import quote as _quote
-except ImportError:
-    from shutil import quote as _quote
-
-
-try:
-    # Python 3.4
-    from pathlib import Path
-except ImportError:
-    Path = None
-
 
 __all__ = [
     'CalledProcessError',
@@ -111,7 +96,7 @@ def _convert_pathlib_path(path):
         return path
 
     if isinstance(path, Path):
-        return six.text_type(path)
+        return str(path)
 
     return path
 
@@ -150,14 +135,14 @@ def _normalize_args(args):
     CommandWrapper instances into a one-dimensional list of strings.
     """
 
-    if isinstance(args, six.string_types):
+    if isinstance(args, (str,)):
         return shlex.split(args)
 
     def normalize_arg(arg):
         arg = _convert_pathlib_path(arg)
 
-        if isinstance(arg, six.string_types):
-            return [six.text_type(arg)]
+        if isinstance(arg, (str,)):
+            return [str(arg)]
         if isinstance(arg, AbstractWrapper):
             return list(map(_convert_pathlib_path, arg.command))
 
@@ -173,42 +158,14 @@ def normalize_arg(arg):
 # -----------------------------------------------------------------------------
 # Decorators
 
-def _backport_devnull(func):
-    """Decorator used to backport the subprocess.DEVNULL functionality from
-    Python 3 to Python 2.
-    """
-
-    # DEVNULL was introduced in Python 3.3
-    if _PY_VERSION >= (3, 3):
-        return func
-
-    @functools.wraps(func)
-    def wrapper(command, **kwargs):
-        stdout = kwargs.get('stdout', sys.stdout)
-        stderr = kwargs.get('stderr', sys.stderr)
-
-        if stdout != DEVNULL and stderr != DEVNULL:
-            return func(command, **kwargs)
-
-        with open(os.devnull, 'w') as devnull:
-            if stdout == DEVNULL:
-                kwargs['stdout'] = devnull
-            if stderr == DEVNULL:
-                kwargs['stderr'] = devnull
-
-            return func(command, **kwargs)
-
-    return wrapper
-
-
 def _normalize_command(func):
     """Decorator used to uniformly normalize the input command of the
     subprocess wrappers.
     """
 
     @functools.wraps(func)
     def wrapper(command, **kwargs):
-        if not isinstance(command, six.string_types):
+        if not isinstance(command, (str,)):
             command = _normalize_args(command)
 
         return func(command, **kwargs)
@@ -237,10 +194,9 @@ def wrapper(command, **kwargs):
 # Public Functions
 
 def quote(command):
-    """Extension of the standard pipes.quote (Python 2) or shutil.quote
-    (Python 3) that handles both strings and lists of strings. This mirrors
-    how the subprocess package can handle commands as both a standalone string
-    or list of strings.
+    """Extension of the standard shutil.quote that handles both strings and
+    lists of strings. This mirrors how the subprocess package can handle
+    commands as both a standalone string or list of strings.
 
     >>> quote('/Applications/App Store.app')
     "'/Applications/App Store.app'"
@@ -249,7 +205,7 @@ def quote(command):
     "rm -rf '~/Documents/My Homework'"
     """
 
-    if isinstance(command, six.string_types):
+    if isinstance(command, (str,)):
         return _quote(command)
 
     if isinstance(command, collections.Iterable):
@@ -288,7 +244,6 @@ def __init__(self, command, **kwargs):
         solution to this problem in the form of their `method_decorator`.
         """
 
-        @_backport_devnull
         @_normalize_command
         @_add_echo_kwarg
         def closure(command, **kwargs):
@@ -305,7 +260,6 @@ def __exit__(self, *exc):
             self.wait()
 
 
-@_backport_devnull
 @_normalize_command
 @_add_echo_kwarg
 def call(command, **kwargs):
@@ -316,7 +270,6 @@ def call(command, **kwargs):
     return subprocess.call(command, **kwargs)
 
 
-@_backport_devnull
 @_normalize_command
 @_add_echo_kwarg
 def check_call(command, **kwargs):
@@ -327,7 +280,6 @@ def check_call(command, **kwargs):
     return subprocess.check_call(command, **kwargs)
 
 
-@_backport_devnull
 @_normalize_command
 @_add_echo_kwarg
 def check_output(command, **kwargs):
@@ -337,16 +289,11 @@ def check_output(command, **kwargs):
     Output is returned as a unicode string.
     """
 
-    if six.PY3:
-        kwargs['encoding'] = 'utf-8'
+    kwargs['encoding'] = 'utf-8'
 
     output = subprocess.check_output(command, **kwargs)
 
-    if six.PY3:
-        return output
-
-    # Return unicode string rather than bytes in Python 2.
-    return six.text_type(output, errors='ignore')
+    return output
 
 
 # -----------------------------------------------------------------------------
@@ -484,8 +431,7 @@ def wraps(command):
     return CommandWrapper(command)
 
 
-@six.add_metaclass(abc.ABCMeta)
-class AbstractWrapper(object):
+class AbstractWrapper(object, metaclass=abc.ABCMeta):
     """Abstract base class for implementing wrappers around command line
     utilities and executables. Subclasses must implement the `command` method
     which returns a command list suitable for use with executor instances.
@@ -555,7 +501,7 @@ def __init__(self):
 
         self.EXECUTABLE = _convert_pathlib_path(self.EXECUTABLE)
 
-        if not isinstance(self.EXECUTABLE, six.string_types):
+        if not isinstance(self.EXECUTABLE, (str,)):
             raise AttributeError(
                 '{}.EXECUTABLE must be an executable name or path'.format(
                     type(self).__name__))