Always use pep 517 when the 'wheel' package is absent

news/8559.removal.rst

@@ -0,0 +1,2 @@
+When the ``wheel`` package is not installed, pip now uses the default build backend
+instead of ``setup.py install`` for project without ``pyproject.toml``.

src/pip/_internal/cli/cmdoptions.py

@@ -783,10 +783,14 @@ def _handle_no_use_pep517(
         """
         raise_option_error(parser, option=option, msg=msg)
 
-    # If user doesn't wish to use pep517, we check if setuptools is installed
+    # If user doesn't wish to use pep517, we check if setuptools and wheel are installed
     # and raise error if it is not.
-    if not importlib.util.find_spec("setuptools"):
-        msg = "It is not possible to use --no-use-pep517 without setuptools installed."
+    packages = ("setuptools", "wheel")
+    if not all(importlib.util.find_spec(package) for package in packages):
+        msg = (
+            f"It is not possible to use --no-use-pep517 "
+            f"without {' and '.join(packages)} installed."
+        )
         raise_option_error(parser, option=option, msg=msg)
 
     # Otherwise, --no-use-pep517 was passed via the command-line.

src/pip/_internal/pyproject.py

@@ -93,12 +93,17 @@ def load_pyproject_toml(
     # we do so if the project has a pyproject.toml file
     # or if we cannot import setuptools.
 
-    # We fallback to PEP 517 when without setuptools,
+    # We fallback to PEP 517 when without setuptools or without the wheel package,
     # so setuptools can be installed as a default build backend.
     # For more info see:
     # https://discuss.python.org/t/pip-without-setuptools-could-the-experience-be-improved/11810/9
+    # https://github.com/pypa/pip/issues/8559
     elif use_pep517 is None:
-        use_pep517 = has_pyproject or not importlib.util.find_spec("setuptools")
+        use_pep517 = (
+            has_pyproject
+            or not importlib.util.find_spec("setuptools")
+            or not importlib.util.find_spec("wheel")
+        )
 
     # At this point, we know whether we're going to use PEP 517.
     assert use_pep517 is not None

src/pip/_internal/utils/deprecation.py

@@ -159,17 +159,3 @@ def emit_deprecation(self, name: str) -> None:
     issue=8368,
     emit_after_success=True,
 )
-
-
-LegacyInstallReasonMissingWheelPackage = LegacyInstallReason(
-    reason=(
-        "{name} is being installed using the legacy "
-        "'setup.py install' method, because it does not have a "
-        "'pyproject.toml' and the 'wheel' package "
-        "is not installed."
-    ),
-    replacement="to enable the '--use-pep517' option",
-    gone_in="23.1",
-    issue=8559,
-    emit_before_install=True,
-)

src/pip/_internal/utils/misc.py

@@ -614,18 +614,6 @@ def hash_file(path: str, blocksize: int = 1 << 20) -> Tuple[Any, int]:
     return h, length
 
 
-def is_wheel_installed() -> bool:
-    """
-    Return whether the wheel package is installed.
-    """
-    try:
-        import wheel  # noqa: F401
-    except ImportError:
-        return False
-
-    return True
-
-
 def pairwise(iterable: Iterable[Any]) -> Iterator[Tuple[Any, Any]]:
     """
     Return paired elements.

src/pip/_internal/wheel_builder.py

@@ -19,9 +19,8 @@
 from pip._internal.operations.build.wheel_editable import build_wheel_editable
 from pip._internal.operations.build.wheel_legacy import build_wheel_legacy
 from pip._internal.req.req_install import InstallRequirement
-from pip._internal.utils.deprecation import LegacyInstallReasonMissingWheelPackage
 from pip._internal.utils.logging import indent_log
-from pip._internal.utils.misc import ensure_dir, hash_file, is_wheel_installed
+from pip._internal.utils.misc import ensure_dir, hash_file
 from pip._internal.utils.setuptools_build import make_setuptools_clean_args
 from pip._internal.utils.subprocess import call_subprocess
 from pip._internal.utils.temp_dir import TempDirectory
@@ -73,14 +72,6 @@ def _should_build(
         # we only build PEP 660 editable requirements
         return req.supports_pyproject_editable()
 
-    if req.use_pep517:
-        return True
-
-    if not is_wheel_installed():
-        # we don't build legacy requirements if wheel is not installed
-        req.legacy_install_reason = LegacyInstallReasonMissingWheelPackage
-        return False
-
     return True
 
 

tests/conftest.py

@@ -429,6 +429,7 @@ def virtualenv_template(
     tmpdir_factory: pytest.TempPathFactory,
     pip_src: Path,
     setuptools_install: Path,
+    wheel_install: Path,
     coverage_install: Path,
 ) -> Iterator[VirtualEnvironment]:
 
@@ -442,8 +443,9 @@ def virtualenv_template(
     tmpdir = tmpdir_factory.mktemp("virtualenv")
     venv = VirtualEnvironment(tmpdir.joinpath("venv_orig"), venv_type=venv_type)
 
-    # Install setuptools and pip.
+    # Install setuptools, wheel and pip.
     install_pth_link(venv, "setuptools", setuptools_install)
+    install_pth_link(venv, "wheel", wheel_install)
     pip_editable = tmpdir_factory.mktemp("pip") / "pip"
     shutil.copytree(pip_src, pip_editable, symlinks=True)
     # noxfile.py is Python 3 only
@@ -501,11 +503,6 @@ def virtualenv(
     yield virtualenv_factory(tmpdir.joinpath("workspace", "venv"))
 
 
-@pytest.fixture
-def with_wheel(virtualenv: VirtualEnvironment, wheel_install: Path) -> None:
-    install_pth_link(virtualenv, "wheel", wheel_install)
-
-
 class ScriptFactory(Protocol):
     def __call__(
         self,

tests/data/packages/BrokenEmitsUTF8/setup.py

@@ -8,7 +8,7 @@ class FakeError(Exception):
     pass
 
 
-if sys.argv[1] == "install":
+if sys.argv[1] in ("install", "bdist_wheel"):
     if hasattr(sys.stdout, "buffer"):
         sys.stdout.buffer.write(
             "\nThis package prints out UTF-8 stuff like:\n".encode("utf-8")

tests/functional/test_download.py

@@ -659,7 +659,6 @@ def make_wheel_with_python_requires(
     return package_dir / "dist" / file_name
 
 
-@pytest.mark.usefixtures("with_wheel")
 def test_download__python_version_used_for_python_requires(
     script: PipTestEnvironment, data: TestData
 ) -> None:
@@ -700,7 +699,6 @@ def make_args(python_version: str) -> List[str]:
     script.pip(*args)  # no exception
 
 
-@pytest.mark.usefixtures("with_wheel")
 def test_download_ignore_requires_python_dont_fail_with_wrong_python(
     script: PipTestEnvironment,
 ) -> None:

tests/functional/test_freeze.py

@@ -104,7 +104,6 @@ def test_exclude_and_normalization(script: PipTestEnvironment, tmpdir: Path) ->
     assert "Normalizable_Name" not in result.stdout
 
 
-@pytest.mark.usefixtures("with_wheel")
 def test_freeze_multiple_exclude_with_all(script: PipTestEnvironment) -> None:
     result = script.pip("freeze", "--all")
     assert "pip==" in result.stdout
@@ -962,7 +961,6 @@ def test_freeze_path_multiple(
     _check_output(result.stdout, expected)
 
 
-@pytest.mark.usefixtures("with_wheel")
 def test_freeze_direct_url_archive(
     script: PipTestEnvironment, shared_data: TestData
 ) -> None:
@@ -1005,7 +1003,6 @@ def test_freeze_include_work_dir_pkg(script: PipTestEnvironment) -> None:
     assert "simple==1.0" in result.stdout
 
 
-@pytest.mark.usefixtures("with_wheel")
 def test_freeze_pep610_editable(script: PipTestEnvironment) -> None:
     """
     Test that a package installed with a direct_url.json with editable=true

tests/functional/test_inspect.py

@@ -31,11 +31,12 @@ def test_inspect_basic(simple_script: PipTestEnvironment) -> None:
     result = simple_script.pip("inspect")
     report = json.loads(result.stdout)
     installed = report["installed"]
-    assert len(installed) == 4
+    assert len(installed) == 5
     installed_by_name = {i["metadata"]["name"]: i for i in installed}
     assert installed_by_name.keys() == {
         "pip",
         "setuptools",
+        "wheel",
         "coverage",
         "simplewheel",
     }