Remove unnecessary uses of six.ensure_(binary|str|text)

Now that Python 2 is not supported, the bytes/str boundaries are more
clear and explicit. Using six.ensure_* methods for backwards
compatibility is no longer necessary as the types are known and verified
using mypy.

One exception is tests/lib/wheel.py which allows tests to pass test
setup data as either bytes or str.

The module operations.install.wheel also remains untouched as it is
especially delicate to bytes/str mixups and the current version is
working.

src/pip/_internal/network/session.py

@@ -16,7 +16,7 @@ import sys
 import urllib.parse
 import warnings
 
-from pip._vendor import requests, six, urllib3
+from pip._vendor import requests, urllib3
 from pip._vendor.cachecontrol import CacheControlAdapter
 from pip._vendor.requests.adapters import BaseAdapter, HTTPAdapter
 from pip._vendor.requests.models import Response
@@ -367,14 +367,8 @@ class PipSession(requests.Session):
                 continue
 
             try:
-                addr = ipaddress.ip_address(
+                addr = ipaddress.ip_address(origin_host)
-                    None
+                network = ipaddress.ip_network(secure_host)
-                    if origin_host is None
-                    else six.ensure_text(origin_host)
-                )
-                network = ipaddress.ip_network(
-                    six.ensure_text(secure_host)
-                )
             except ValueError:
                 # We don't have both a valid address or a valid network, so
                 # we'll check this origin against hostnames.

src/pip/_internal/req/req_install.py

@@ -255,7 +255,7 @@ class InstallRequirement:
         # type: () -> Optional[str]
         if self.req is None:
             return None
-        return six.ensure_str(pkg_resources.safe_name(self.req.name))
+        return pkg_resources.safe_name(self.req.name)
 
     @property
     def specifier(self):

src/pip/_internal/self_outdated_check.py

@@ -6,7 +6,6 @@ import os.path
 import sys
 
 from pip._vendor.packaging import version as packaging_version
-from pip._vendor.six import ensure_binary
 
 from pip._internal.index.collector import LinkCollector
 from pip._internal.index.package_finder import PackageFinder
@@ -31,7 +30,7 @@ logger = logging.getLogger(__name__)
 
 def _get_statefile_name(key):
     # type: (str) -> str
-    key_bytes = ensure_binary(key)
+    key_bytes = key.encode()
     name = hashlib.sha224(key_bytes).hexdigest()
     return name
 
@@ -85,7 +84,7 @@ class SelfCheckState:
         text = json.dumps(state, sort_keys=True, separators=(",", ":"))
 
         with adjacent_tmp_file(self.statefile_path) as f:
-            f.write(ensure_binary(text))
+            f.write(text.encode())
 
         try:
             # Since we have a prefix-specific state file, we can just

src/pip/_internal/utils/pkg_resources.py

@@ -1,5 +1,4 @@
 from pip._vendor.pkg_resources import yield_lines
-from pip._vendor.six import ensure_str
 
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
@@ -21,7 +20,7 @@ class DictMetadata:
     def get_metadata(self, name):
         # type: (str) -> str
         try:
-            return ensure_str(self._metadata[name])
+            return self._metadata[name].decode()
         except UnicodeDecodeError as e:
             # Mirrors handling done in pkg_resources.NullProvider.
             e.reason += f" in {name} file"

src/pip/_internal/utils/temp_dir.py

@@ -6,9 +6,7 @@ import tempfile
 from contextlib import contextmanager
 
 from pip._vendor.contextlib2 import ExitStack
-from pip._vendor.six import ensure_text
 
-from pip._internal.utils.compat import WINDOWS
 from pip._internal.utils.misc import enum, rmtree
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
@@ -196,15 +194,7 @@ class TempDirectory:
         self._deleted = True
         if not os.path.exists(self._path):
             return
-        # Make sure to pass unicode on Python 2 to make the contents also
+        rmtree(self._path)
-        # use unicode, ensuring non-ASCII names and can be represented.
-        # This is only done on Windows because POSIX platforms use bytes
-        # natively for paths, and the bytes-text conversion omission avoids
-        # errors caused by the environment configuring encodings incorrectly.
-        if WINDOWS:
-            rmtree(ensure_text(self._path))
-        else:
-            rmtree(self._path)
 
 
 class AdjacentTempDirectory(TempDirectory):

src/pip/_internal/utils/wheel.py

@@ -7,7 +7,6 @@ from zipfile import BadZipFile, ZipFile
 
 from pip._vendor.packaging.utils import canonicalize_name
 from pip._vendor.pkg_resources import DistInfoDistribution
-from pip._vendor.six import ensure_str
 
 from pip._internal.exceptions import UnsupportedWheel
 from pip._internal.utils.pkg_resources import DictMetadata
@@ -62,17 +61,10 @@ def pkg_resources_distribution_for_wheel(wheel_zip, name, location):
 
     metadata_text = {}  # type: Dict[str, bytes]
     for path in metadata_files:
-        # If a flag is set, namelist entries may be unicode in Python 2.
+        _, metadata_name = path.split("/", 1)
-        # We coerce them to native str type to match the types used in the rest
-        # of the code. This cannot fail because unicode can always be encoded
-        # with UTF-8.
-        full_path = ensure_str(path)
-        _, metadata_name = full_path.split("/", 1)
 
         try:
-            metadata_text[metadata_name] = read_wheel_metadata_file(
+            metadata_text[metadata_name] = read_wheel_metadata_file(wheel_zip, path)
-                wheel_zip, full_path
-            )
         except UnsupportedWheel as e:
             raise UnsupportedWheel(
                 "{} has an invalid wheel, {}".format(name, str(e))
@@ -139,9 +131,7 @@ def wheel_dist_info_dir(source, name):
             )
         )
 
-    # Zip file paths can be unicode or str depending on the zip entry flags,
+    return info_dir
-    # so normalize it.
-    return ensure_str(info_dir)
 
 
 def read_wheel_metadata_file(source, path):
@@ -166,7 +156,7 @@ def wheel_metadata(source, dist_info_dir):
     wheel_contents = read_wheel_metadata_file(source, path)
 
     try:
-        wheel_text = ensure_str(wheel_contents)
+        wheel_text = wheel_contents.decode()
     except UnicodeDecodeError as e:
         raise UnsupportedWheel(f"error decoding {path!r}: {e!r}")
 

tests/lib/__init__.py

@@ -13,7 +13,6 @@ from textwrap import dedent
 from zipfile import ZipFile
 
 import pytest
-from pip._vendor.six import ensure_binary
 from scripttest import FoundDir, TestFileEnvironment
 
 from pip._internal.index.collector import LinkCollector
@@ -1095,7 +1094,7 @@ def create_basic_sdist_for_package(
     for fname in files:
         path = script.temp_path / fname
         path.parent.mkdir(exist_ok=True, parents=True)
-        path.write_bytes(ensure_binary(files[fname]))
+        path.write_bytes(files[fname].encode("utf-8"))
 
     retval = script.scratch_path / archive_name
     generated = shutil.make_archive(

tests/lib/test_wheel.py

@@ -5,8 +5,6 @@ from email import message_from_string
 from functools import partial
 from zipfile import ZipFile
 
-from pip._vendor.six import ensure_text
-
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from tests.lib.wheel import (
     _default,
@@ -164,7 +162,7 @@ def test_make_wheel_default_record():
         extra_data_files={"purelib/info.txt": "c"},
     ).as_zipfile() as z:
         record_bytes = z.read("simple-0.1.0.dist-info/RECORD")
-        record_text = ensure_text(record_bytes)
+        record_text = record_bytes.decode()
         record_rows = list(csv.reader(record_text.splitlines()))
         records = {
             row[0]: row[1:] for row in record_rows

tests/lib/wheel.py

@@ -13,7 +13,6 @@ from zipfile import ZipFile
 
 import csv23
 from pip._vendor.requests.structures import CaseInsensitiveDict
-from pip._vendor.six import ensure_binary, ensure_text
 
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from tests.lib.path import Path
@@ -61,6 +60,13 @@ if MYPY_CHECK_RUNNING:
         pass
 
 
+def ensure_binary(value):
+    # type: (AnyStr) -> bytes
+    if isinstance(value, bytes):
+        return value
+    return value.encode()
+
+
 def message_from_dict(headers):
     # type: (Dict[str, HeaderValue]) -> Message
     """Plain key-value pairs are set in the returned message.
@@ -110,7 +116,7 @@ def make_metadata_file(
     if body is not _default:
         message.set_payload(body)
 
-    return File(path, ensure_binary(message_from_dict(metadata).as_string()))
+    return File(path, message_from_dict(metadata).as_bytes())
 
 
 def make_wheel_metadata_file(
@@ -139,7 +145,7 @@ def make_wheel_metadata_file(
     if updates is not _default:
         metadata.update(updates)
 
-    return File(path, ensure_binary(message_from_dict(metadata).as_string()))
+    return File(path, message_from_dict(metadata).as_bytes())
 
 
 def make_entry_points_file(
@@ -167,7 +173,7 @@ def make_entry_points_file(
 
     return File(
         dist_info_path(name, version, "entry_points.txt"),
-        ensure_binary("\n".join(lines)),
+        "\n".join(lines).encode(),
     )
 
 
@@ -243,7 +249,7 @@ def record_file_maker_wrapper(
     with StringIO(newline="") as buf:
         writer = csv23.writer(buf)
         for record in records:
-            writer.writerow(map(ensure_text, record))
+            writer.writerow(record)
         contents = buf.getvalue().encode("utf-8")
 
     yield File(record_path, contents)

tests/unit/test_utils_pkg_resources.py

@@ -2,7 +2,6 @@ from email.message import Message
 
 import pytest
 from pip._vendor.pkg_resources import DistInfoDistribution, Requirement
-from pip._vendor.six import ensure_binary
 
 from pip._internal.utils.packaging import get_metadata, get_requires_python
 from pip._internal.utils.pkg_resources import DictMetadata
@@ -26,9 +25,7 @@ def test_dict_metadata_works():
         metadata["Provides-Extra"] = extra
     metadata["Requires-Python"] = requires_python
 
-    inner_metadata = DictMetadata({
+    inner_metadata = DictMetadata({"METADATA": metadata.as_bytes()})
-        "METADATA": ensure_binary(metadata.as_string())
-    })
     dist = DistInfoDistribution(
         location="<in-memory>", metadata=inner_metadata, project_name=name
     )