Replace pip._internal.utils.typing with stdlib typing

The stdlib module has been available since Python 3.5 and the
TYPE_CHECKING constant has been available since 3.5.2.

By using stdlib, this removes the need for pip to maintain its own
Python 2 typing compatibility shim.

setup.cfg

@@ -91,7 +91,7 @@ exclude_lines =
     # it.
     pragma: no cover
     # This excludes typing-specific code, which will be validated by mypy anyway.
-    if MYPY_CHECK_RUNNING
+    if TYPE_CHECKING
     # Can be set to exclude e.g. `if PY2:` on Python 3
     ${PIP_CI_COVERAGE_EXCLUDES}
 

src/pip/__init__.py

@@ -1,6 +1,6 @@
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+from typing import TYPE_CHECKING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import List, Optional
 
 

src/pip/_internal/__init__.py

@@ -1,7 +1,8 @@
-import pip._internal.utils.inject_securetransport  # noqa
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+from typing import TYPE_CHECKING
 
-if MYPY_CHECK_RUNNING:
+import pip._internal.utils.inject_securetransport  # noqa
+
+if TYPE_CHECKING:
     from typing import List, Optional
 
 

src/pip/_internal/build_env.py

@@ -8,6 +8,7 @@ import textwrap
 from collections import OrderedDict
 from distutils.sysconfig import get_python_lib
 from sysconfig import get_paths
+from typing import TYPE_CHECKING
 
 from pip._vendor.pkg_resources import Requirement, VersionConflict, WorkingSet
 
@@ -15,9 +16,8 @@ from pip import __file__ as pip_location
 from pip._internal.cli.spinners import open_spinner
 from pip._internal.utils.subprocess import call_subprocess
 from pip._internal.utils.temp_dir import TempDirectory, tempdir_kinds
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from types import TracebackType
     from typing import Iterable, List, Optional, Set, Tuple, Type
 

src/pip/_internal/cache.py

@@ -5,6 +5,7 @@ import hashlib
 import json
 import logging
 import os
+from typing import TYPE_CHECKING
 
 from pip._vendor.packaging.tags import interpreter_name, interpreter_version
 from pip._vendor.packaging.utils import canonicalize_name
@@ -13,10 +14,9 @@ from pip._internal.exceptions import InvalidWheelFilename
 from pip._internal.models.link import Link
 from pip._internal.models.wheel import Wheel
 from pip._internal.utils.temp_dir import TempDirectory, tempdir_kinds
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.urls import path_to_url
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any, Dict, List, Optional, Set
 
     from pip._vendor.packaging.tags import Tag

src/pip/_internal/cli/autocompletion.py

@@ -5,13 +5,13 @@ import optparse
 import os
 import sys
 from itertools import chain
+from typing import TYPE_CHECKING
 
 from pip._internal.cli.main_parser import create_main_parser
 from pip._internal.commands import commands_dict, create_command
 from pip._internal.utils.misc import get_installed_distributions
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any, Iterable, List, Optional
 
 

src/pip/_internal/cli/base_command.py

@@ -6,6 +6,7 @@ import optparse
 import os
 import sys
 import traceback
+from typing import TYPE_CHECKING
 
 from pip._internal.cli import cmdoptions
 from pip._internal.cli.command_context import CommandContextMixIn
@@ -29,10 +30,9 @@ from pip._internal.utils.filesystem import check_path_owner
 from pip._internal.utils.logging import BrokenStdoutLoggingError, setup_logging
 from pip._internal.utils.misc import get_prog, normalize_path
 from pip._internal.utils.temp_dir import global_tempdir_manager, tempdir_registry
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.virtualenv import running_under_virtualenv
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import Values
     from typing import Any, List, Optional, Tuple
 

src/pip/_internal/cli/cmdoptions.py

@@ -16,6 +16,7 @@ import warnings
 from functools import partial
 from optparse import SUPPRESS_HELP, Option, OptionGroup
 from textwrap import dedent
+from typing import TYPE_CHECKING
 
 from pip._vendor.packaging.utils import canonicalize_name
 
@@ -27,9 +28,8 @@ from pip._internal.models.index import PyPI
 from pip._internal.models.target_python import TargetPython
 from pip._internal.utils.hashes import STRONG_HASHES
 from pip._internal.utils.misc import strtobool
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import OptionParser, Values
     from typing import Any, Callable, Dict, Optional, Tuple
 

src/pip/_internal/cli/command_context.py

@@ -1,10 +1,9 @@
 from contextlib import contextmanager
+from typing import TYPE_CHECKING
 
 from pip._vendor.contextlib2 import ExitStack
 
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
-
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import ContextManager, Iterator, TypeVar
 
     _T = TypeVar('_T', covariant=True)

src/pip/_internal/cli/main.py

@@ -4,15 +4,15 @@ import locale
 import logging
 import os
 import sys
+from typing import TYPE_CHECKING
 
 from pip._internal.cli.autocompletion import autocomplete
 from pip._internal.cli.main_parser import parse_command
 from pip._internal.commands import create_command
 from pip._internal.exceptions import PipError
 from pip._internal.utils import deprecation
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import List, Optional
 
 logger = logging.getLogger(__name__)

src/pip/_internal/cli/main_parser.py

@@ -3,15 +3,15 @@
 
 import os
 import sys
+from typing import TYPE_CHECKING
 
 from pip._internal.cli import cmdoptions
 from pip._internal.cli.parser import ConfigOptionParser, UpdatingDefaultsHelpFormatter
 from pip._internal.commands import commands_dict, get_similar_commands
 from pip._internal.exceptions import CommandError
 from pip._internal.utils.misc import get_pip_version, get_prog
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import List, Tuple
 
 

src/pip/_internal/cli/parser.py

@@ -8,15 +8,15 @@ import optparse
 import shutil
 import sys
 import textwrap
+from typing import TYPE_CHECKING
 
 from pip._vendor.contextlib2 import suppress
 
 from pip._internal.cli.status_codes import UNKNOWN_ERROR
 from pip._internal.configuration import Configuration, ConfigurationError
 from pip._internal.utils.misc import redact_auth_from_url, strtobool
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any
 
 logger = logging.getLogger(__name__)

src/pip/_internal/cli/progress_bars.py

@@ -1,6 +1,7 @@
 import itertools
 import sys
 from signal import SIGINT, default_int_handler, signal
+from typing import TYPE_CHECKING
 
 from pip._vendor.progress.bar import Bar, FillingCirclesBar, IncrementalBar
 from pip._vendor.progress.spinner import Spinner
@@ -8,9 +9,8 @@ from pip._vendor.progress.spinner import Spinner
 from pip._internal.utils.compat import WINDOWS
 from pip._internal.utils.logging import get_indentation
 from pip._internal.utils.misc import format_size
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any, Dict, List
 
 try:

src/pip/_internal/cli/req_command.py

@@ -8,6 +8,7 @@ PackageFinder machinery and all its vendored dependencies, etc.
 import logging
 import os
 from functools import partial
+from typing import TYPE_CHECKING
 
 from pip._internal.cli import cmdoptions
 from pip._internal.cli.base_command import Command
@@ -27,9 +28,8 @@ from pip._internal.req.constructors import (
 from pip._internal.req.req_file import parse_requirements
 from pip._internal.self_outdated_check import pip_self_version_check
 from pip._internal.utils.temp_dir import tempdir_kinds
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import Values
     from typing import Any, List, Optional, Tuple
 

src/pip/_internal/cli/spinners.py

@@ -3,14 +3,14 @@ import itertools
 import logging
 import sys
 import time
+from typing import TYPE_CHECKING
 
 from pip._vendor.progress import HIDE_CURSOR, SHOW_CURSOR
 
 from pip._internal.utils.compat import WINDOWS
 from pip._internal.utils.logging import get_indentation
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import IO, Iterator
 
 logger = logging.getLogger(__name__)

src/pip/_internal/commands/__init__.py

@@ -4,10 +4,9 @@ Package containing all pip commands
 
 import importlib
 from collections import OrderedDict, namedtuple
+from typing import TYPE_CHECKING
 
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
-
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any, Optional
 
     from pip._internal.cli.base_command import Command

src/pip/_internal/commands/cache.py

@@ -1,14 +1,14 @@
 import logging
 import os
 import textwrap
+from typing import TYPE_CHECKING
 
 import pip._internal.utils.filesystem as filesystem
 from pip._internal.cli.base_command import Command
 from pip._internal.cli.status_codes import ERROR, SUCCESS
 from pip._internal.exceptions import CommandError, PipError
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import Values
     from typing import Any, List
 

src/pip/_internal/commands/check.py

@@ -1,4 +1,5 @@
 import logging
+from typing import TYPE_CHECKING
 
 from pip._internal.cli.base_command import Command
 from pip._internal.cli.status_codes import ERROR, SUCCESS
@@ -7,11 +8,10 @@ from pip._internal.operations.check import (
     create_package_set_from_installed,
 )
 from pip._internal.utils.misc import write_output
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
 logger = logging.getLogger(__name__)
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import Values
     from typing import Any, List
 

src/pip/_internal/commands/completion.py

@@ -1,12 +1,12 @@
 import sys
 import textwrap
+from typing import TYPE_CHECKING
 
 from pip._internal.cli.base_command import Command
 from pip._internal.cli.status_codes import SUCCESS
 from pip._internal.utils.misc import get_prog
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import Values
     from typing import List
 

src/pip/_internal/commands/configuration.py

@@ -1,6 +1,7 @@
 import logging
 import os
 import subprocess
+from typing import TYPE_CHECKING
 
 from pip._internal.cli.base_command import Command
 from pip._internal.cli.status_codes import ERROR, SUCCESS
@@ -8,9 +9,8 @@ from pip._internal.configuration import Configuration, get_configuration_files,
 from pip._internal.exceptions import PipError
 from pip._internal.utils.logging import indent_log
 from pip._internal.utils.misc import get_prog, write_output
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import Values
     from typing import Any, List, Optional
 

src/pip/_internal/commands/debug.py

@@ -2,6 +2,7 @@ import locale
 import logging
 import os
 import sys
+from typing import TYPE_CHECKING
 
 import pip._vendor
 from pip._vendor.certifi import where
@@ -15,9 +16,8 @@ from pip._internal.cli.status_codes import SUCCESS
 from pip._internal.metadata import get_environment
 from pip._internal.utils.logging import indent_log
 from pip._internal.utils.misc import get_pip_version
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import Values
     from types import ModuleType
     from typing import Dict, List, Optional

src/pip/_internal/commands/download.py

@@ -1,5 +1,6 @@
 import logging
 import os
+from typing import TYPE_CHECKING
 
 from pip._internal.cli import cmdoptions
 from pip._internal.cli.cmdoptions import make_target_python
@@ -8,9 +9,8 @@ from pip._internal.cli.status_codes import SUCCESS
 from pip._internal.req.req_tracker import get_requirement_tracker
 from pip._internal.utils.misc import ensure_dir, normalize_path, write_output
 from pip._internal.utils.temp_dir import TempDirectory
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import Values
     from typing import List
 

src/pip/_internal/commands/freeze.py

@@ -1,4 +1,5 @@
 import sys
+from typing import TYPE_CHECKING
 
 from pip._internal.cli import cmdoptions
 from pip._internal.cli.base_command import Command
@@ -6,11 +7,10 @@ from pip._internal.cli.status_codes import SUCCESS
 from pip._internal.operations.freeze import freeze
 from pip._internal.utils.compat import stdlib_pkgs
 from pip._internal.utils.deprecation import deprecated
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
 DEV_PKGS = {'pip', 'setuptools', 'distribute', 'wheel'}
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import Values
     from typing import List
 

src/pip/_internal/commands/hash.py

@@ -1,14 +1,14 @@
 import hashlib
 import logging
 import sys
+from typing import TYPE_CHECKING
 
 from pip._internal.cli.base_command import Command
 from pip._internal.cli.status_codes import ERROR, SUCCESS
 from pip._internal.utils.hashes import FAVORITE_HASH, STRONG_HASHES
 from pip._internal.utils.misc import read_chunks, write_output
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import Values
     from typing import List
 

src/pip/_internal/commands/help.py

@@ -1,9 +1,10 @@
+from typing import TYPE_CHECKING
+
 from pip._internal.cli.base_command import Command
 from pip._internal.cli.status_codes import SUCCESS
 from pip._internal.exceptions import CommandError
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import Values
     from typing import List
 

src/pip/_internal/commands/install.py

@@ -5,6 +5,7 @@ import os
 import shutil
 import site
 from optparse import SUPPRESS_HELP
+from typing import TYPE_CHECKING
 
 from pip._vendor import pkg_resources
 from pip._vendor.packaging.utils import canonicalize_name
@@ -29,11 +30,10 @@ from pip._internal.utils.misc import (
     write_output,
 )
 from pip._internal.utils.temp_dir import TempDirectory
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.virtualenv import virtualenv_no_global
 from pip._internal.wheel_builder import build, should_build_for_install_command
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import Values
     from typing import Iterable, List, Optional
 

src/pip/_internal/commands/list.py

@@ -1,5 +1,6 @@
 import json
 import logging
+from typing import TYPE_CHECKING
 
 from pip._internal.cli import cmdoptions
 from pip._internal.cli.req_command import IndexGroupCommand
@@ -17,9 +18,8 @@ from pip._internal.utils.misc import (
 )
 from pip._internal.utils.packaging import get_installer
 from pip._internal.utils.parallel import map_multithread
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import Values
     from typing import Iterator, List, Set, Tuple
 

src/pip/_internal/commands/search.py

@@ -3,6 +3,7 @@ import shutil
 import sys
 import textwrap
 from collections import OrderedDict
+from typing import TYPE_CHECKING
 
 from pip._vendor.packaging.version import parse as parse_version
 
@@ -19,9 +20,8 @@ from pip._internal.models.index import PyPI
 from pip._internal.network.xmlrpc import PipXmlrpcTransport
 from pip._internal.utils.logging import indent_log
 from pip._internal.utils.misc import write_output
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import Values
     from typing import Dict, List, Optional
 

src/pip/_internal/commands/show.py

@@ -1,6 +1,7 @@
 import logging
 import os
 from email.parser import FeedParser
+from typing import TYPE_CHECKING
 
 from pip._vendor import pkg_resources
 from pip._vendor.packaging.utils import canonicalize_name
@@ -8,9 +9,8 @@ from pip._vendor.packaging.utils import canonicalize_name
 from pip._internal.cli.base_command import Command
 from pip._internal.cli.status_codes import ERROR, SUCCESS
 from pip._internal.utils.misc import write_output
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import Values
     from typing import Dict, Iterator, List
 

src/pip/_internal/commands/uninstall.py

@@ -1,3 +1,5 @@
+from typing import TYPE_CHECKING
+
 from pip._vendor.packaging.utils import canonicalize_name
 
 from pip._internal.cli.base_command import Command
@@ -10,9 +12,8 @@ from pip._internal.req.constructors import (
     install_req_from_parsed_requirement,
 )
 from pip._internal.utils.misc import protect_pip_from_modification_on_windows
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import Values
     from typing import List
 

src/pip/_internal/commands/wheel.py

@@ -1,6 +1,7 @@
 import logging
 import os
 import shutil
+from typing import TYPE_CHECKING
 
 from pip._internal.cache import WheelCache
 from pip._internal.cli import cmdoptions
@@ -10,10 +11,9 @@ from pip._internal.exceptions import CommandError
 from pip._internal.req.req_tracker import get_requirement_tracker
 from pip._internal.utils.misc import ensure_dir, normalize_path
 from pip._internal.utils.temp_dir import TempDirectory
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.wheel_builder import build, should_build_for_wheel_command
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import Values
     from typing import List
 

src/pip/_internal/configuration.py

@@ -16,6 +16,7 @@ import locale
 import logging
 import os
 import sys
+from typing import TYPE_CHECKING
 
 from pip._internal.exceptions import (
     ConfigurationError,
@@ -24,9 +25,8 @@ from pip._internal.exceptions import (
 from pip._internal.utils import appdirs
 from pip._internal.utils.compat import WINDOWS
 from pip._internal.utils.misc import ensure_dir, enum
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any, Dict, Iterable, List, NewType, Optional, Tuple
 
     RawConfigParser = configparser.RawConfigParser  # Shorthand

src/pip/_internal/distributions/__init__.py

@@ -1,8 +1,9 @@
+from typing import TYPE_CHECKING
+
 from pip._internal.distributions.sdist import SourceDistribution
 from pip._internal.distributions.wheel import WheelDistribution
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from pip._internal.distributions.base import AbstractDistribution
     from pip._internal.req.req_install import InstallRequirement
 

src/pip/_internal/distributions/base.py

@@ -1,8 +1,7 @@
 import abc
+from typing import TYPE_CHECKING
 
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
-
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Optional
 
     from pip._vendor.pkg_resources import Distribution

src/pip/_internal/distributions/installed.py

@@ -1,7 +1,8 @@
-from pip._internal.distributions.base import AbstractDistribution
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+from typing import TYPE_CHECKING
 
-if MYPY_CHECK_RUNNING:
+from pip._internal.distributions.base import AbstractDistribution
+
+if TYPE_CHECKING:
     from typing import Optional
 
     from pip._vendor.pkg_resources import Distribution

src/pip/_internal/distributions/sdist.py

@@ -1,12 +1,12 @@
 import logging
+from typing import TYPE_CHECKING
 
 from pip._internal.build_env import BuildEnvironment
 from pip._internal.distributions.base import AbstractDistribution
 from pip._internal.exceptions import InstallationError
 from pip._internal.utils.subprocess import runner_with_spinner_message
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Set, Tuple
 
     from pip._vendor.pkg_resources import Distribution

src/pip/_internal/distributions/wheel.py

@@ -1,10 +1,10 @@
+from typing import TYPE_CHECKING
 from zipfile import ZipFile
 
 from pip._internal.distributions.base import AbstractDistribution
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.wheel import pkg_resources_distribution_for_wheel
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from pip._vendor.pkg_resources import Distribution
 
     from pip._internal.index.package_finder import PackageFinder

src/pip/_internal/exceptions.py

@@ -1,10 +1,9 @@
 """Exceptions used throughout package"""
 
 from itertools import chain, groupby, repeat
+from typing import TYPE_CHECKING
 
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
-
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     import configparser
     from hashlib import _Hash
     from typing import Dict, List, Optional

src/pip/_internal/index/collector.py

@@ -12,6 +12,7 @@ import re
 import urllib.parse
 import urllib.request
 from collections import OrderedDict
+from typing import TYPE_CHECKING
 
 from pip._vendor import html5lib, requests
 from pip._vendor.distlib.compat import unescape
@@ -23,11 +24,10 @@ from pip._internal.models.search_scope import SearchScope
 from pip._internal.network.utils import raise_for_status
 from pip._internal.utils.filetypes import is_archive_file
 from pip._internal.utils.misc import pairwise, redact_auth_from_url
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.urls import path_to_url, url_to_path
 from pip._internal.vcs import is_url, vcs
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     import xml.etree.ElementTree
     from optparse import Values
     from typing import (

src/pip/_internal/index/package_finder.py

@@ -6,6 +6,7 @@
 import functools
 import logging
 import re
+from typing import TYPE_CHECKING
 
 from pip._vendor.packaging import specifiers
 from pip._vendor.packaging.utils import canonicalize_name
@@ -28,11 +29,10 @@ from pip._internal.utils.filetypes import WHEEL_EXTENSION
 from pip._internal.utils.logging import indent_log
 from pip._internal.utils.misc import build_netloc
 from pip._internal.utils.packaging import check_requires_python
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.unpacking import SUPPORTED_EXTENSIONS
 from pip._internal.utils.urls import url_to_path
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import FrozenSet, Iterable, List, Optional, Set, Tuple, Union
 
     from pip._vendor.packaging.tags import Tag

src/pip/_internal/locations.py

@@ -10,14 +10,14 @@ import sys
 import sysconfig
 from distutils.command.install import SCHEME_KEYS
 from distutils.command.install import install as distutils_install_command
+from typing import TYPE_CHECKING, cast
 
 from pip._internal.models.scheme import Scheme
 from pip._internal.utils import appdirs
 from pip._internal.utils.compat import WINDOWS
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING, cast
 from pip._internal.utils.virtualenv import running_under_virtualenv
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from distutils.cmd import Command as DistutilsCommand
     from typing import Dict, List, Optional, Union
 

src/pip/_internal/main.py

@@ -1,6 +1,6 @@
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+from typing import TYPE_CHECKING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import List, Optional
 
 

src/pip/_internal/metadata/__init__.py

@@ -1,6 +1,6 @@
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+from typing import TYPE_CHECKING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import List, Optional
 
     from .base import BaseDistribution, BaseEnvironment

src/pip/_internal/metadata/base.py

@@ -1,7 +1,8 @@
-from pip._internal.utils.misc import stdlib_pkgs  # TODO: Move definition here.
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+from typing import TYPE_CHECKING
 
-if MYPY_CHECK_RUNNING:
+from pip._internal.utils.misc import stdlib_pkgs  # TODO: Move definition here.
+
+if TYPE_CHECKING:
     from typing import Container, Iterator, List, Optional
 
     from pip._vendor.packaging.version import _BaseVersion

src/pip/_internal/metadata/pkg_resources.py

@@ -1,16 +1,16 @@
 import zipfile
+from typing import TYPE_CHECKING
 
 from pip._vendor import pkg_resources
 from pip._vendor.packaging.utils import canonicalize_name
 
 from pip._internal.utils import misc  # TODO: Move definition here.
 from pip._internal.utils.packaging import get_installer
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.wheel import pkg_resources_distribution_for_wheel
 
 from .base import BaseDistribution, BaseEnvironment
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Iterator, List, Optional
 
     from pip._vendor.packaging.version import _BaseVersion

src/pip/_internal/models/candidate.py

@@ -1,9 +1,10 @@
+from typing import TYPE_CHECKING
+
 from pip._vendor.packaging.version import parse as parse_version
 
 from pip._internal.utils.models import KeyBasedCompareMixin
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from pip._vendor.packaging.version import _BaseVersion
 
     from pip._internal.models.link import Link

src/pip/_internal/models/direct_url.py

@@ -2,10 +2,9 @@
 import json
 import re
 import urllib.parse
+from typing import TYPE_CHECKING
 
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
-
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any, Dict, Iterable, Optional, Type, TypeVar, Union
 
     T = TypeVar("T")
@@ -156,7 +155,7 @@ class DirInfo:
         return _filter_none(editable=self.editable or None)
 
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     InfoType = Union[ArchiveInfo, DirInfo, VcsInfo]
 
 

src/pip/_internal/models/format_control.py

@@ -1,9 +1,10 @@
+from typing import TYPE_CHECKING
+
 from pip._vendor.packaging.utils import canonicalize_name
 
 from pip._internal.exceptions import CommandError
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import FrozenSet, Optional, Set
 
 

src/pip/_internal/models/link.py

@@ -2,6 +2,7 @@ import os
 import posixpath
 import re
 import urllib.parse
+from typing import TYPE_CHECKING
 
 from pip._internal.utils.filetypes import WHEEL_EXTENSION
 from pip._internal.utils.misc import (
@@ -10,10 +11,9 @@ from pip._internal.utils.misc import (
     splitext,
 )
 from pip._internal.utils.models import KeyBasedCompareMixin
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.urls import path_to_url, url_to_path
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Optional, Tuple, Union
 
     from pip._internal.index.collector import HTMLPage

src/pip/_internal/models/search_scope.py

@@ -3,15 +3,15 @@ import logging
 import os
 import posixpath
 import urllib.parse
+from typing import TYPE_CHECKING
 
 from pip._vendor.packaging.utils import canonicalize_name
 
 from pip._internal.models.index import PyPI
 from pip._internal.utils.compat import has_tls
 from pip._internal.utils.misc import normalize_path, redact_auth_from_url
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import List
 
 

src/pip/_internal/models/selection_prefs.py

@@ -1,6 +1,6 @@
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+from typing import TYPE_CHECKING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Optional
 
     from pip._internal.models.format_control import FormatControl

src/pip/_internal/models/target_python.py

@@ -1,10 +1,10 @@
 import sys
+from typing import TYPE_CHECKING
 
 from pip._internal.utils.compatibility_tags import get_supported, version_info_to_nodot
 from pip._internal.utils.misc import normalize_version_info
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import List, Optional, Tuple
 
     from pip._vendor.packaging.tags import Tag

src/pip/_internal/models/wheel.py

@@ -2,13 +2,13 @@
 name that have meaning.
 """
 import re
+from typing import TYPE_CHECKING
 
 from pip._vendor.packaging.tags import Tag
 
 from pip._internal.exceptions import InvalidWheelFilename
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import List
 
 

src/pip/_internal/network/auth.py

@@ -6,6 +6,7 @@ providing credentials in the context of network requests.
 
 import logging
 import urllib.parse
+from typing import TYPE_CHECKING
 
 from pip._vendor.requests.auth import AuthBase, HTTPBasicAuth
 from pip._vendor.requests.utils import get_netrc_auth
@@ -17,9 +18,8 @@ from pip._internal.utils.misc import (
     remove_auth_from_url,
     split_auth_netloc_from_url,
 )
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any, Dict, List, Optional, Tuple
 
     from pip._vendor.requests.models import Request, Response

src/pip/_internal/network/cache.py

@@ -3,6 +3,7 @@
 
 import os
 from contextlib import contextmanager
+from typing import TYPE_CHECKING
 
 from pip._vendor.cachecontrol.cache import BaseCache
 from pip._vendor.cachecontrol.caches import FileCache
@@ -10,9 +11,8 @@ from pip._vendor.requests.models import Response
 
 from pip._internal.utils.filesystem import adjacent_tmp_file, replace
 from pip._internal.utils.misc import ensure_dir
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Iterator, Optional
 
 

src/pip/_internal/network/download.py

@@ -4,6 +4,7 @@ import cgi
 import logging
 import mimetypes
 import os
+from typing import TYPE_CHECKING
 
 from pip._vendor.requests.models import CONTENT_CHUNK_SIZE
 
@@ -13,9 +14,8 @@ from pip._internal.models.index import PyPI
 from pip._internal.network.cache import is_from_cache
 from pip._internal.network.utils import HEADERS, raise_for_status, response_chunks
 from pip._internal.utils.misc import format_size, redact_auth_from_url, splitext
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Iterable, Optional, Tuple
 
     from pip._vendor.requests.models import Response

src/pip/_internal/network/lazy_wheel.py

@@ -5,15 +5,15 @@ __all__ = ['HTTPRangeRequestUnsupported', 'dist_from_wheel_url']
 from bisect import bisect_left, bisect_right
 from contextlib import contextmanager
 from tempfile import NamedTemporaryFile
+from typing import TYPE_CHECKING
 from zipfile import BadZipfile, ZipFile
 
 from pip._vendor.requests.models import CONTENT_CHUNK_SIZE
 
 from pip._internal.network.utils import HEADERS, raise_for_status, response_chunks
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.wheel import pkg_resources_distribution_for_wheel
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any, Dict, Iterator, List, Optional, Tuple
 
     from pip._vendor.pkg_resources import Distribution

src/pip/_internal/network/session.py

@@ -15,6 +15,7 @@ import platform
 import sys
 import urllib.parse
 import warnings
+from typing import TYPE_CHECKING
 
 from pip._vendor import requests, urllib3
 from pip._vendor.cachecontrol import CacheControlAdapter
@@ -35,10 +36,9 @@ from pip._internal.utils.misc import (
     get_installed_version,
     parse_netloc,
 )
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.urls import url_to_path
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any, Iterator, List, Optional, Sequence, Tuple, Union
 
     from pip._internal.models.link import Link

src/pip/_internal/network/utils.py

@@ -1,9 +1,10 @@
+from typing import TYPE_CHECKING
+
 from pip._vendor.requests.models import CONTENT_CHUNK_SIZE, Response
 
 from pip._internal.exceptions import NetworkConnectionError
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Dict, Iterator
 
 # The following comments and HTTP headers were originally added by

src/pip/_internal/network/xmlrpc.py

@@ -3,6 +3,7 @@
 
 import logging
 import urllib.parse
+from typing import TYPE_CHECKING
 
 # NOTE: XMLRPC Client is not annotated in typeshed as on 2017-07-17, which is
 #       why we ignore the type on this import
@@ -10,9 +11,8 @@ from pip._vendor.six.moves import xmlrpc_client  # type: ignore
 
 from pip._internal.exceptions import NetworkConnectionError
 from pip._internal.network.utils import raise_for_status
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Dict
 
     from pip._internal.network.session import PipSession

src/pip/_internal/operations/build/metadata.py

@@ -2,12 +2,12 @@
 """
 
 import os
+from typing import TYPE_CHECKING
 
 from pip._internal.utils.subprocess import runner_with_spinner_message
 from pip._internal.utils.temp_dir import TempDirectory
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from pip._vendor.pep517.wrappers import Pep517HookCaller
 
     from pip._internal.build_env import BuildEnvironment

src/pip/_internal/operations/build/metadata_legacy.py

@@ -3,14 +3,14 @@
 
 import logging
 import os
+from typing import TYPE_CHECKING
 
 from pip._internal.exceptions import InstallationError
 from pip._internal.utils.setuptools_build import make_setuptools_egg_info_args
 from pip._internal.utils.subprocess import call_subprocess
 from pip._internal.utils.temp_dir import TempDirectory
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from pip._internal.build_env import BuildEnvironment
 
 logger = logging.getLogger(__name__)

src/pip/_internal/operations/build/wheel.py

@@ -1,10 +1,10 @@
 import logging
 import os
+from typing import TYPE_CHECKING
 
 from pip._internal.utils.subprocess import runner_with_spinner_message
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import List, Optional
 
     from pip._vendor.pep517.wrappers import Pep517HookCaller

src/pip/_internal/operations/build/wheel_legacy.py

@@ -1,5 +1,6 @@
 import logging
 import os.path
+from typing import TYPE_CHECKING
 
 from pip._internal.cli.spinners import open_spinner
 from pip._internal.utils.setuptools_build import make_setuptools_bdist_wheel_args
@@ -8,9 +9,8 @@ from pip._internal.utils.subprocess import (
     call_subprocess,
     format_command_args,
 )
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import List, Optional
 
 logger = logging.getLogger(__name__)

src/pip/_internal/operations/check.py

@@ -3,17 +3,17 @@
 
 import logging
 from collections import namedtuple
+from typing import TYPE_CHECKING
 
 from pip._vendor.packaging.utils import canonicalize_name
 from pip._vendor.pkg_resources import RequirementParseError
 
 from pip._internal.distributions import make_distribution_for_install_requirement
 from pip._internal.utils.misc import get_installed_distributions
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
 logger = logging.getLogger(__name__)
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any, Callable, Dict, List, Optional, Set, Tuple
 
     from pip._internal.req.req_install import InstallRequirement

src/pip/_internal/operations/freeze.py

@@ -1,6 +1,7 @@
 import collections
 import logging
 import os
+from typing import TYPE_CHECKING
 
 from pip._vendor.packaging.utils import canonicalize_name
 from pip._vendor.pkg_resources import RequirementParseError
@@ -16,9 +17,8 @@ from pip._internal.utils.direct_url_helpers import (
     dist_get_direct_url,
 )
 from pip._internal.utils.misc import dist_is_editable, get_installed_distributions
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import (
         Container,
         Dict,

src/pip/_internal/operations/install/editable_legacy.py

@@ -1,13 +1,13 @@
 """Legacy editable installation process, i.e. `setup.py develop`.
 """
 import logging
+from typing import TYPE_CHECKING
 
 from pip._internal.utils.logging import indent_log
 from pip._internal.utils.setuptools_build import make_setuptools_develop_args
 from pip._internal.utils.subprocess import call_subprocess
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import List, Optional, Sequence
 
     from pip._internal.build_env import BuildEnvironment

src/pip/_internal/operations/install/legacy.py

@@ -5,6 +5,7 @@ import logging
 import os
 import sys
 from distutils.util import change_root
+from typing import TYPE_CHECKING
 
 from pip._internal.exceptions import InstallationError
 from pip._internal.utils.logging import indent_log
@@ -12,9 +13,8 @@ from pip._internal.utils.misc import ensure_dir
 from pip._internal.utils.setuptools_build import make_setuptools_install_args
 from pip._internal.utils.subprocess import runner_with_spinner_message
 from pip._internal.utils.temp_dir import TempDirectory
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import List, Optional, Sequence
 
     from pip._internal.build_env import BuildEnvironment

src/pip/_internal/operations/install/wheel.py

@@ -14,6 +14,7 @@ import sys
 import warnings
 from base64 import urlsafe_b64encode
 from itertools import chain, filterfalse, starmap
+from typing import TYPE_CHECKING, cast
 from zipfile import ZipFile
 
 from pip._vendor import pkg_resources
@@ -27,7 +28,6 @@ from pip._internal.models.direct_url import DIRECT_URL_METADATA_NAME, DirectUrl
 from pip._internal.models.scheme import SCHEME_KEYS
 from pip._internal.utils.filesystem import adjacent_tmp_file, replace
 from pip._internal.utils.misc import captured_stdout, ensure_dir, hash_file, partition
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.unpacking import (
     current_umask,
     is_within_directory,
@@ -36,12 +36,7 @@ from pip._internal.utils.unpacking import (
 )
 from pip._internal.utils.wheel import parse_wheel, pkg_resources_distribution_for_wheel
 
-# Use the custom cast function at runtime to make cast work,
-# and import typing.cast when performing pre-commit and type
-# checks
-if not MYPY_CHECK_RUNNING:
-    from pip._internal.utils.typing import cast
-else:
+if TYPE_CHECKING:
     from email.message import Message
     from typing import (
         IO,
@@ -59,7 +54,6 @@ else:
         Set,
         Tuple,
         Union,
-        cast,
     )
     from zipfile import ZipInfo
 

src/pip/_internal/operations/prepare.py

@@ -8,6 +8,7 @@ import logging
 import mimetypes
 import os
 import shutil
+from typing import TYPE_CHECKING
 
 from pip._vendor.packaging.utils import canonicalize_name
 
@@ -33,11 +34,10 @@ from pip._internal.utils.hashes import MissingHashes
 from pip._internal.utils.logging import indent_log
 from pip._internal.utils.misc import display_path, hide_url, path_to_display, rmtree
 from pip._internal.utils.temp_dir import TempDirectory
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.unpacking import unpack_file
 from pip._internal.vcs import vcs
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Dict, Iterable, List, Optional, Tuple
 
     from pip._vendor.pkg_resources import Distribution

src/pip/_internal/pyproject.py

@@ -1,13 +1,13 @@
 import os
 from collections import namedtuple
+from typing import TYPE_CHECKING
 
 from pip._vendor import toml
 from pip._vendor.packaging.requirements import InvalidRequirement, Requirement
 
 from pip._internal.exceptions import InstallationError
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any, List, Optional
 
 

src/pip/_internal/req/__init__.py

@@ -1,14 +1,14 @@
 import collections
 import logging
+from typing import TYPE_CHECKING
 
 from pip._internal.utils.logging import indent_log
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
 from .req_file import parse_requirements
 from .req_install import InstallRequirement
 from .req_set import RequirementSet
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Iterator, List, Optional, Sequence, Tuple
 
 __all__ = [

src/pip/_internal/req/constructors.py

@@ -11,6 +11,7 @@ InstallRequirement.
 import logging
 import os
 import re
+from typing import TYPE_CHECKING
 
 from pip._vendor.packaging.markers import Marker
 from pip._vendor.packaging.requirements import InvalidRequirement, Requirement
@@ -25,11 +26,10 @@ from pip._internal.pyproject import make_pyproject_path
 from pip._internal.req.req_install import InstallRequirement
 from pip._internal.utils.filetypes import is_archive_file
 from pip._internal.utils.misc import is_installable_dir
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.urls import path_to_url
 from pip._internal.vcs import is_url, vcs
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any, Dict, Optional, Set, Tuple, Union
 
     from pip._internal.req.req_file import ParsedRequirement

src/pip/_internal/req/req_file.py

@@ -7,16 +7,16 @@ import os
 import re
 import shlex
 import urllib.parse
+from typing import TYPE_CHECKING
 
 from pip._internal.cli import cmdoptions
 from pip._internal.exceptions import InstallationError, RequirementsFileParseError
 from pip._internal.models.search_scope import SearchScope
 from pip._internal.network.utils import raise_for_status
 from pip._internal.utils.encoding import auto_decode
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.urls import get_url_scheme, url_to_path
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from optparse import Values
     from typing import (
         Any,

src/pip/_internal/req/req_install.py

@@ -7,6 +7,7 @@ import shutil
 import sys
 import uuid
 import zipfile
+from typing import TYPE_CHECKING
 
 from pip._vendor import pkg_resources, six
 from pip._vendor.packaging.requirements import Requirement
@@ -48,11 +49,10 @@ from pip._internal.utils.misc import (
 )
 from pip._internal.utils.packaging import get_metadata
 from pip._internal.utils.temp_dir import TempDirectory, tempdir_kinds
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.virtualenv import running_under_virtualenv
 from pip._internal.vcs import vcs
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any, Dict, Iterable, List, Optional, Sequence, Union
 
     from pip._vendor.packaging.markers import Marker

src/pip/_internal/req/req_set.py

@@ -1,14 +1,14 @@
 import logging
 from collections import OrderedDict
+from typing import TYPE_CHECKING
 
 from pip._vendor.packaging.utils import canonicalize_name
 
 from pip._internal.exceptions import InstallationError
 from pip._internal.models.wheel import Wheel
 from pip._internal.utils import compatibility_tags
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Dict, Iterable, List, Optional, Tuple
 
     from pip._internal.req.req_install import InstallRequirement

src/pip/_internal/req/req_tracker.py

@@ -2,13 +2,13 @@ import contextlib
 import hashlib
 import logging
 import os
+from typing import TYPE_CHECKING
 
 from pip._vendor import contextlib2
 
 from pip._internal.utils.temp_dir import TempDirectory
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from types import TracebackType
     from typing import Dict, Iterator, Optional, Set, Type, Union
 

src/pip/_internal/req/req_uninstall.py

@@ -5,6 +5,7 @@ import os
 import sys
 import sysconfig
 from importlib.util import cache_from_source
+from typing import TYPE_CHECKING
 
 from pip._vendor import pkg_resources
 
@@ -23,9 +24,8 @@ from pip._internal.utils.misc import (
     rmtree,
 )
 from pip._internal.utils.temp_dir import AdjacentTempDirectory, TempDirectory
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import (
         Any,
         Callable,

src/pip/_internal/resolution/base.py

@@ -1,6 +1,6 @@
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+from typing import TYPE_CHECKING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Callable, List
 
     from pip._internal.req.req_install import InstallRequirement

src/pip/_internal/resolution/legacy/resolver.py

@@ -18,6 +18,7 @@ import logging
 import sys
 from collections import defaultdict
 from itertools import chain
+from typing import TYPE_CHECKING
 
 from pip._vendor.packaging import specifiers
 
@@ -35,9 +36,8 @@ from pip._internal.utils.compatibility_tags import get_supported
 from pip._internal.utils.logging import indent_log
 from pip._internal.utils.misc import dist_in_usersite, normalize_version_info
 from pip._internal.utils.packaging import check_requires_python, get_requires_python
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import DefaultDict, List, Optional, Set, Tuple
 
     from pip._vendor.pkg_resources import Distribution

src/pip/_internal/resolution/resolvelib/base.py

@@ -1,11 +1,12 @@
+from typing import TYPE_CHECKING
+
 from pip._vendor.packaging.specifiers import SpecifierSet
 from pip._vendor.packaging.utils import canonicalize_name
 
 from pip._internal.req.req_install import InstallRequirement
 from pip._internal.utils.hashes import Hashes
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import FrozenSet, Iterable, Optional, Tuple
 
     from pip._vendor.packaging.version import _BaseVersion

src/pip/_internal/resolution/resolvelib/candidates.py

@@ -1,5 +1,6 @@
 import logging
 import sys
+from typing import TYPE_CHECKING
 
 from pip._vendor.packaging.specifiers import InvalidSpecifier, SpecifierSet
 from pip._vendor.packaging.utils import canonicalize_name
@@ -14,11 +15,10 @@ from pip._internal.req.constructors import (
 from pip._internal.req.req_install import InstallRequirement
 from pip._internal.utils.misc import dist_is_editable, normalize_version_info
 from pip._internal.utils.packaging import get_requires_python
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
 from .base import Candidate, format_name
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any, FrozenSet, Iterable, Optional, Tuple, Union
 
     from pip._vendor.packaging.version import _BaseVersion

src/pip/_internal/resolution/resolvelib/factory.py

@@ -1,5 +1,6 @@
 import functools
 import logging
+from typing import TYPE_CHECKING
 
 from pip._vendor.packaging.utils import canonicalize_name
 
@@ -20,7 +21,6 @@ from pip._internal.utils.misc import (
     dist_in_usersite,
     get_installed_distributions,
 )
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.virtualenv import running_under_virtualenv
 
 from .base import Constraint
@@ -39,7 +39,7 @@ from .requirements import (
     UnsatisfiableRequirement,
 )
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import (
         Dict,
         FrozenSet,

src/pip/_internal/resolution/resolvelib/found_candidates.py

@@ -9,12 +9,11 @@ something.
 """
 
 import functools
+from typing import TYPE_CHECKING
 
 from pip._vendor.six.moves import collections_abc  # type: ignore
 
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
-
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Callable, Iterator, Optional, Set, Tuple
 
     from pip._vendor.packaging.version import _BaseVersion

src/pip/_internal/resolution/resolvelib/provider.py

@@ -1,10 +1,10 @@
-from pip._vendor.resolvelib.providers import AbstractProvider
+from typing import TYPE_CHECKING
 
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+from pip._vendor.resolvelib.providers import AbstractProvider
 
 from .base import Constraint
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any, Dict, Iterable, Optional, Sequence, Tuple, Union
 
     from .base import Candidate, Requirement

src/pip/_internal/resolution/resolvelib/reporter.py

@@ -1,11 +1,10 @@
 from collections import defaultdict
 from logging import getLogger
+from typing import TYPE_CHECKING
 
 from pip._vendor.resolvelib.reporters import BaseReporter
 
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
-
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any, DefaultDict
 
     from .base import Candidate, Requirement

src/pip/_internal/resolution/resolvelib/requirements.py

@@ -1,10 +1,10 @@
-from pip._vendor.packaging.utils import canonicalize_name
+from typing import TYPE_CHECKING
 
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+from pip._vendor.packaging.utils import canonicalize_name
 
 from .base import Requirement, format_name
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from pip._vendor.packaging.specifiers import SpecifierSet
 
     from pip._internal.req.req_install import InstallRequirement

src/pip/_internal/resolution/resolvelib/resolver.py

@@ -1,6 +1,7 @@
 import functools
 import logging
 import os
+from typing import TYPE_CHECKING
 
 from pip._vendor import six
 from pip._vendor.packaging.utils import canonicalize_name
@@ -19,12 +20,11 @@ from pip._internal.resolution.resolvelib.reporter import (
 from pip._internal.utils.deprecation import deprecated
 from pip._internal.utils.filetypes import is_archive_file
 from pip._internal.utils.misc import dist_is_editable
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
 from .base import Constraint
 from .factory import Factory
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Dict, List, Optional, Set, Tuple
 
     from pip._vendor.resolvelib.resolvers import Result

src/pip/_internal/self_outdated_check.py

@@ -4,6 +4,7 @@ import json
 import logging
 import os.path
 import sys
+from typing import TYPE_CHECKING
 
 from pip._vendor.packaging import version as packaging_version
 
@@ -13,9 +14,8 @@ from pip._internal.metadata import get_default_environment
 from pip._internal.models.selection_prefs import SelectionPreferences
 from pip._internal.utils.filesystem import adjacent_tmp_file, check_path_owner, replace
 from pip._internal.utils.misc import ensure_dir, get_installed_version
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     import optparse
     from typing import Any, Dict
 

src/pip/_internal/utils/appdirs.py

@@ -7,12 +7,11 @@ and eventually drop this after all usages are changed.
 """
 
 import os
+from typing import TYPE_CHECKING
 
 from pip._vendor import appdirs as _appdirs
 
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
-
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import List
 
 

src/pip/_internal/utils/compat.py

@@ -9,10 +9,9 @@ import locale
 import logging
 import os
 import sys
+from typing import TYPE_CHECKING
 
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
-
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Optional, Union
 
 

src/pip/_internal/utils/compatibility_tags.py

@@ -2,6 +2,7 @@
 """
 
 import re
+from typing import TYPE_CHECKING
 
 from pip._vendor.packaging.tags import (
     Tag,
@@ -13,9 +14,7 @@ from pip._vendor.packaging.tags import (
     mac_platforms,
 )
 
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
-
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import List, Optional, Tuple
 
     from pip._vendor.packaging.tags import PythonVersion

src/pip/_internal/utils/deprecation.py

@@ -7,13 +7,13 @@ A module that implements tooling to enable easy warnings about deprecations.
 
 import logging
 import warnings
+from typing import TYPE_CHECKING
 
 from pip._vendor.packaging.version import parse
 
 from pip import __version__ as current_version
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any, Optional
 
 

src/pip/_internal/utils/direct_url_helpers.py

@@ -1,5 +1,6 @@
 import json
 import logging
+from typing import TYPE_CHECKING
 
 from pip._internal.models.direct_url import (
     DIRECT_URL_METADATA_NAME,
@@ -9,10 +10,9 @@ from pip._internal.models.direct_url import (
     DirInfo,
     VcsInfo,
 )
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.vcs import vcs
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Optional
 
     from pip._vendor.pkg_resources import Distribution

src/pip/_internal/utils/distutils_args.py

@@ -1,9 +1,8 @@
 from distutils.errors import DistutilsArgError
 from distutils.fancy_getopt import FancyGetopt
+from typing import TYPE_CHECKING
 
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
-
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Dict, List
 
 

src/pip/_internal/utils/encoding.py

@@ -2,10 +2,9 @@ import codecs
 import locale
 import re
 import sys
+from typing import TYPE_CHECKING
 
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
-
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import List, Tuple
 
 BOMS = [

src/pip/_internal/utils/entrypoints.py

@@ -1,9 +1,9 @@
 import sys
+from typing import TYPE_CHECKING
 
 from pip._internal.cli.main import main
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import List, Optional
 
 

src/pip/_internal/utils/filesystem.py

@@ -7,6 +7,7 @@ import stat
 import sys
 from contextlib import contextmanager
 from tempfile import NamedTemporaryFile
+from typing import TYPE_CHECKING, cast
 
 # NOTE: retrying is not annotated in typeshed as on 2017-07-17, which is
 #       why we ignore the type on this import.
@@ -14,9 +15,8 @@ from pip._vendor.retrying import retry  # type: ignore
 
 from pip._internal.utils.compat import get_path_uid
 from pip._internal.utils.misc import format_size
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING, cast
 
-if MYPY_CHECK_RUNNING:
+if TYPE_CHECKING:
     from typing import Any, BinaryIO, Iterator, List, Union
 
 

src/pip/_internal/utils/filetypes.py

@@ -1,9 +1,10 @@
 """Filetype information.
 """
-from pip._internal.utils.misc import splitext
-from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+from typing import TYPE_CHECKING
 
-if MYPY_CHECK_RUNNING:
+from pip._internal.utils.misc import splitext
+
+if TYPE_CHECKING:
     from typing import Tuple
 
 WHEEL_EXTENSION = '.whl'