Reconcile computation of isolated build environment paths

news/11740.bugfix.rst

@@ -0,0 +1,3 @@
+Improve handling of isolated build environments on platforms that
+customize the Python's installation schemes, such as Debian and
+Homebrew.

src/pip/_internal/build_env.py

@@ -9,20 +9,15 @@
 import textwrap
 from collections import OrderedDict
 from types import TracebackType
-from typing import TYPE_CHECKING, Iterable, List, Optional, Set, Tuple, Type
+from typing import TYPE_CHECKING, Iterable, List, Optional, Set, Tuple, Type, Union
 
 from pip._vendor.certifi import where
 from pip._vendor.packaging.requirements import Requirement
 from pip._vendor.packaging.version import Version
 
 from pip import __file__ as pip_location
 from pip._internal.cli.spinners import open_spinner
-from pip._internal.locations import (
-    get_isolated_environment_bin_path,
-    get_isolated_environment_lib_paths,
-    get_platlib,
-    get_purelib,
-)
+from pip._internal.locations import get_platlib, get_purelib, get_scheme
 from pip._internal.metadata import get_default_environment, get_environment
 from pip._internal.utils.subprocess import call_subprocess
 from pip._internal.utils.temp_dir import TempDirectory, tempdir_kinds
@@ -33,12 +28,17 @@
 logger = logging.getLogger(__name__)
 
 
+def _dedup(a: str, b: str) -> Union[Tuple[str], Tuple[str, str]]:
+    return (a, b) if a != b else (a,)
+
+
 class _Prefix:
     def __init__(self, path: str) -> None:
         self.path = path
         self.setup = False
-        self.bin_dir = get_isolated_environment_bin_path(path)
-        self.lib_dirs = get_isolated_environment_lib_paths(path)
+        scheme = get_scheme("", prefix=path)
+        self.bin_dir = scheme.scripts
+        self.lib_dirs = _dedup(scheme.purelib, scheme.platlib)
 
 
 def get_runnable_pip() -> str:

src/pip/_internal/locations/__init__.py

@@ -4,7 +4,7 @@
 import pathlib
 import sys
 import sysconfig
-from typing import Any, Dict, Generator, List, Optional, Tuple
+from typing import Any, Dict, Generator, Optional, Tuple
 
 from pip._internal.models.scheme import SCHEME_KEYS, Scheme
 from pip._internal.utils.compat import WINDOWS
@@ -25,8 +25,6 @@
     "USER_CACHE_DIR",
     "get_bin_prefix",
     "get_bin_user",
-    "get_isolated_environment_bin_path",
-    "get_isolated_environment_lib_paths",
     "get_major_minor_version",
     "get_platlib",
     "get_purelib",
@@ -467,67 +465,3 @@ def get_platlib() -> str:
     if _warn_if_mismatch(pathlib.Path(old), pathlib.Path(new), key="platlib"):
         _log_context()
     return old
-
-
-def _deduplicated(v1: str, v2: str) -> List[str]:
-    """Deduplicate values from a list."""
-    if v1 == v2:
-        return [v1]
-    return [v1, v2]
-
-
-def _looks_like_apple_library(path: str) -> bool:
-    """Apple patches sysconfig to *always* look under */Library/Python*."""
-    if sys.platform[:6] != "darwin":
-        return False
-    return path == f"/Library/Python/{get_major_minor_version()}/site-packages"
-
-
-def get_isolated_environment_lib_paths(prefix: str) -> List[str]:
-    """Return the lib locations under ``prefix``."""
-    new_pure, new_plat = _sysconfig.get_isolated_environment_lib_paths(prefix)
-    if _USE_SYSCONFIG:
-        return _deduplicated(new_pure, new_plat)
-
-    old_pure, old_plat = _distutils.get_isolated_environment_lib_paths(prefix)
-    old_lib_paths = _deduplicated(old_pure, old_plat)
-
-    # Apple's Python (shipped with Xcode and Command Line Tools) hard-code
-    # platlib and purelib to '/Library/Python/X.Y/site-packages'. This will
-    # cause serious build isolation bugs when Apple starts shipping 3.10 because
-    # pip will install build backends to the wrong location. This tells users
-    # who is at fault so Apple may notice it and fix the issue in time.
-    if all(_looks_like_apple_library(p) for p in old_lib_paths):
-        deprecated(
-            reason=(
-                "Python distributed by Apple's Command Line Tools incorrectly "
-                "patches sysconfig to always point to '/Library/Python'. This "
-                "will cause build isolation to operate incorrectly on Python "
-                "3.10 or later. Please help report this to Apple so they can "
-                "fix this. https://developer.apple.com/bug-reporting/"
-            ),
-            replacement=None,
-            gone_in=None,
-        )
-        return old_lib_paths
-
-    warned = [
-        _warn_if_mismatch(
-            pathlib.Path(old_pure),
-            pathlib.Path(new_pure),
-            key="prefixed-purelib",
-        ),
-        _warn_if_mismatch(
-            pathlib.Path(old_plat),
-            pathlib.Path(new_plat),
-            key="prefixed-platlib",
-        ),
-    ]
-    if any(warned):
-        _log_context(prefix=prefix)
-
-    return old_lib_paths
-
-
-def get_isolated_environment_bin_path(prefix: str) -> str:
-    return _sysconfig.get_isolated_environment_paths(prefix)["scripts"]

src/pip/_internal/locations/_distutils.py

@@ -21,7 +21,7 @@
 from distutils.command.install import SCHEME_KEYS
 from distutils.command.install import install as distutils_install_command
 from distutils.sysconfig import get_python_lib
-from typing import Dict, List, Optional, Tuple, Union, cast
+from typing import Dict, List, Optional, Union, cast
 
 from pip._internal.models.scheme import Scheme
 from pip._internal.utils.compat import WINDOWS
@@ -171,10 +171,3 @@ def get_purelib() -> str:
 
 def get_platlib() -> str:
     return get_python_lib(plat_specific=True)
-
-
-def get_isolated_environment_lib_paths(prefix: str) -> Tuple[str, str]:
-    return (
-        get_python_lib(plat_specific=False, prefix=prefix),
-        get_python_lib(plat_specific=True, prefix=prefix),
-    )

src/pip/_internal/locations/_sysconfig.py

@@ -211,15 +211,3 @@ def get_purelib() -> str:
 
 def get_platlib() -> str:
     return sysconfig.get_paths()["platlib"]
-
-
-def get_isolated_environment_paths(prefix: str) -> typing.Dict[str, str]:
-    variables = {"base": prefix, "platbase": prefix}
-    if "venv" in sysconfig.get_scheme_names():
-        return sysconfig.get_paths(vars=variables, scheme="venv")
-    return sysconfig.get_paths(vars=variables)
-
-
-def get_isolated_environment_lib_paths(prefix: str) -> typing.Tuple[str, str]:
-    paths = get_isolated_environment_paths(prefix)
-    return (paths["purelib"], paths["platlib"])