Introduce BuildPurpose concept

This allows deciding if build are allow to create editables or not.
It follows the PEP 660 principle stating that editables are only
meant as a transient artifact during installation.
It also makes the implementation of should_build slightly
easier to read.

src/pip/_internal/cli/req_command.py

@@ -30,7 +30,7 @@
     install_req_from_req_string,
 )
 from pip._internal.req.req_file import parse_requirements
-from pip._internal.req.req_install import InstallRequirement
+from pip._internal.req.req_install import BuildPurpose, InstallRequirement
 from pip._internal.req.req_tracker import RequirementTracker
 from pip._internal.resolution.base import BaseResolver
 from pip._internal.self_outdated_check import pip_self_version_check
@@ -234,6 +234,7 @@ def make_requirement_preparer(
         session: PipSession,
         finder: PackageFinder,
         use_user_site: bool,
+        purpose: BuildPurpose,
         download_dir: Optional[str] = None,
     ) -> RequirementPreparer:
         """
@@ -273,6 +274,7 @@ def make_requirement_preparer(
             use_user_site=use_user_site,
             lazy_wheel=lazy_wheel,
             in_tree_build="in-tree-build" in options.features_enabled,
+            purpose=purpose,
         )
 
     @classmethod

src/pip/_internal/commands/download.py

@@ -7,6 +7,7 @@
 from pip._internal.cli.cmdoptions import make_target_python
 from pip._internal.cli.req_command import RequirementCommand, with_cleanup
 from pip._internal.cli.status_codes import SUCCESS
+from pip._internal.req.req_install import BuildPurpose
 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
@@ -114,6 +115,7 @@ def run(self, options: Values, args: List[str]) -> int:
             finder=finder,
             download_dir=options.download_dir,
             use_user_site=False,
+            purpose=BuildPurpose.WHEEL,
         )
 
         resolver = self.make_resolver(

src/pip/_internal/commands/install.py

@@ -23,7 +23,7 @@
 from pip._internal.models.format_control import FormatControl
 from pip._internal.operations.check import ConflictDetails, check_install_conflicts
 from pip._internal.req import install_given_reqs
-from pip._internal.req.req_install import InstallRequirement
+from pip._internal.req.req_install import BuildPurpose, InstallRequirement
 from pip._internal.req.req_tracker import get_requirement_tracker
 from pip._internal.utils.compat import WINDOWS
 from pip._internal.utils.distutils_args import parse_distutils_args
@@ -315,6 +315,7 @@ def run(self, options: Values, args: List[str]) -> int:
                 session=session,
                 finder=finder,
                 use_user_site=options.use_user_site,
+                purpose=BuildPurpose.INSTALL,
             )
             resolver = self.make_resolver(
                 preparer=preparer,
@@ -359,6 +360,7 @@ def run(self, options: Values, args: List[str]) -> int:
                 verify=True,
                 build_options=[],
                 global_options=[],
+                purpose=BuildPurpose.INSTALL,
             )
 
             # If we're using PEP 517, we cannot do a direct install

src/pip/_internal/commands/wheel.py

@@ -9,7 +9,7 @@
 from pip._internal.cli.req_command import RequirementCommand, with_cleanup
 from pip._internal.cli.status_codes import SUCCESS
 from pip._internal.exceptions import CommandError
-from pip._internal.req.req_install import InstallRequirement
+from pip._internal.req.req_install import BuildPurpose, InstallRequirement
 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
@@ -121,11 +121,6 @@ def run(self, options: Values, args: List[str]) -> int:
 
         reqs = self.get_requirements(args, options, finder, session)
 
-        # Since we want to build regular wheels, disable the building of
-        # editable wheels.
-        for req in reqs:
-            req.no_build_editable = True
-
         preparer = self.make_requirement_preparer(
             temp_build_dir=directory,
             options=options,
@@ -134,6 +129,7 @@ def run(self, options: Values, args: List[str]) -> int:
             finder=finder,
             download_dir=options.wheel_dir,
             use_user_site=False,
+            purpose=BuildPurpose.WHEEL,
         )
 
         resolver = self.make_resolver(
@@ -163,6 +159,7 @@ def run(self, options: Values, args: List[str]) -> int:
             verify=(not options.no_verify),
             build_options=options.build_options or [],
             global_options=options.global_options or [],
+            purpose=BuildPurpose.WHEEL,
         )
         for req in build_successes:
             assert req.link and req.link.is_wheel

src/pip/_internal/distributions/base.py

@@ -2,7 +2,7 @@
 
 from pip._internal.index.package_finder import PackageFinder
 from pip._internal.metadata.base import BaseDistribution
-from pip._internal.req import InstallRequirement
+from pip._internal.req import BuildPurpose, InstallRequirement
 
 
 class AbstractDistribution(metaclass=abc.ABCMeta):
@@ -31,6 +31,6 @@ def get_metadata_distribution(self) -> BaseDistribution:
 
     @abc.abstractmethod
     def prepare_distribution_metadata(
-        self, finder: PackageFinder, build_isolation: bool
+        self, finder: PackageFinder, build_isolation: bool, purpose: BuildPurpose
     ) -> None:
         raise NotImplementedError()

src/pip/_internal/distributions/installed.py

@@ -1,6 +1,7 @@
 from pip._internal.distributions.base import AbstractDistribution
 from pip._internal.index.package_finder import PackageFinder
 from pip._internal.metadata import BaseDistribution
+from pip._internal.req import BuildPurpose
 
 
 class InstalledDistribution(AbstractDistribution):
@@ -15,6 +16,6 @@ def get_metadata_distribution(self) -> BaseDistribution:
         return self.req.satisfied_by
 
     def prepare_distribution_metadata(
-        self, finder: PackageFinder, build_isolation: bool
+        self, finder: PackageFinder, build_isolation: bool, purpose: BuildPurpose
     ) -> None:
         pass

src/pip/_internal/distributions/sdist.py

@@ -6,6 +6,7 @@
 from pip._internal.exceptions import InstallationError
 from pip._internal.index.package_finder import PackageFinder
 from pip._internal.metadata import BaseDistribution
+from pip._internal.req import BuildPurpose
 from pip._internal.utils.subprocess import runner_with_spinner_message
 
 logger = logging.getLogger(__name__)
@@ -24,19 +25,22 @@ def get_metadata_distribution(self) -> BaseDistribution:
         return _Dist(self.req.get_dist())
 
     def prepare_distribution_metadata(
-        self, finder: PackageFinder, build_isolation: bool
+        self,
+        finder: PackageFinder,
+        build_isolation: bool,
+        purpose: BuildPurpose,
     ) -> None:
         # Load pyproject.toml, to determine whether PEP 517 is to be used
         self.req.load_pyproject_toml()
 
         # Set up the build isolation, if this requirement should be isolated
         should_isolate = self.req.use_pep517 and build_isolation
         if should_isolate:
-            self._setup_isolation(finder)
+            self._setup_isolation(finder, purpose)
 
-        self.req.prepare_metadata()
+        self.req.prepare_metadata(purpose)
 
-    def _setup_isolation(self, finder: PackageFinder) -> None:
+    def _setup_isolation(self, finder: PackageFinder, purpose: BuildPurpose) -> None:
         def _raise_conflicts(
             conflicting_with: str, conflicting_reqs: Set[Tuple[str, str]]
         ) -> None:
@@ -90,7 +94,7 @@ def _raise_conflicts(
             backend = self.req.pep517_backend
             assert backend is not None
             with backend.subprocess_runner(runner):
-                if self.req.editable and not self.req.no_build_editable:
+                if self.req.editable and purpose == BuildPurpose.INSTALL:
                     reqs = backend.get_requires_for_build_editable()
                 else:
                     reqs = backend.get_requires_for_build_wheel()

src/pip/_internal/distributions/wheel.py

@@ -7,6 +7,7 @@
     FilesystemWheel,
     get_wheel_distribution,
 )
+from pip._internal.req import BuildPurpose
 
 
 class WheelDistribution(AbstractDistribution):
@@ -26,6 +27,6 @@ def get_metadata_distribution(self) -> BaseDistribution:
         return get_wheel_distribution(wheel, canonicalize_name(self.req.name))
 
     def prepare_distribution_metadata(
-        self, finder: PackageFinder, build_isolation: bool
+        self, finder: PackageFinder, build_isolation: bool, purpose: BuildPurpose
     ) -> None:
         pass

src/pip/_internal/operations/prepare.py

@@ -33,7 +33,7 @@
     dist_from_wheel_url,
 )
 from pip._internal.network.session import PipSession
-from pip._internal.req.req_install import InstallRequirement
+from pip._internal.req.req_install import BuildPurpose, InstallRequirement
 from pip._internal.req.req_tracker import RequirementTracker
 from pip._internal.utils.deprecation import deprecated
 from pip._internal.utils.filesystem import copy2_fixed
@@ -52,11 +52,12 @@ def _get_prepared_distribution(
     req_tracker: RequirementTracker,
     finder: PackageFinder,
     build_isolation: bool,
+    purpose: BuildPurpose,
 ) -> BaseDistribution:
     """Prepare a distribution for installation."""
     abstract_dist = make_distribution_for_install_requirement(req)
     with req_tracker.track(req):
-        abstract_dist.prepare_distribution_metadata(finder, build_isolation)
+        abstract_dist.prepare_distribution_metadata(finder, build_isolation, purpose)
     return abstract_dist.get_metadata_distribution()
 
 
@@ -279,6 +280,7 @@ def __init__(
         use_user_site: bool,
         lazy_wheel: bool,
         in_tree_build: bool,
+        purpose: BuildPurpose,
     ) -> None:
         super().__init__()
 
@@ -289,6 +291,7 @@ def __init__(
         self._download = Downloader(session, progress_bar)
         self._batch_download = BatchDownloader(session, progress_bar)
         self.finder = finder
+        self.purpose = purpose
 
         # Where still-packed archives should be written to. If None, they are
         # not saved, and are deleted immediately after unpacking.
@@ -558,6 +561,7 @@ def _prepare_linked_requirement(
             self.req_tracker,
             self.finder,
             self.build_isolation,
+            self.purpose,
         )
         return dist
 
@@ -611,6 +615,7 @@ def prepare_editable_requirement(
                 self.req_tracker,
                 self.finder,
                 self.build_isolation,
+                self.purpose,
             )
 
             req.check_if_exists(self.use_user_site)

src/pip/_internal/req/__init__.py

@@ -5,11 +5,12 @@
 from pip._internal.utils.logging import indent_log
 
 from .req_file import parse_requirements
-from .req_install import InstallRequirement
+from .req_install import BuildPurpose, InstallRequirement
 from .req_set import RequirementSet
 
 __all__ = [
     "RequirementSet",
+    "BuildPurpose",
     "InstallRequirement",
     "parse_requirements",
     "install_given_reqs",

src/pip/_internal/req/constructors.py

@@ -181,7 +181,6 @@ def install_req_from_editable(
     options: Optional[Dict[str, Any]] = None,
     constraint: bool = False,
     user_supplied: bool = False,
-    no_build_editable: bool = False,
 ) -> InstallRequirement:
 
     parts = parse_req_from_editable(editable_req)
@@ -191,7 +190,6 @@ def install_req_from_editable(
         comes_from=comes_from,
         user_supplied=user_supplied,
         editable=True,
-        no_build_editable=no_build_editable,
         link=parts.link,
         constraint=constraint,
         use_pep517=use_pep517,

src/pip/_internal/req/req_install.py

@@ -7,6 +7,7 @@
 import sys
 import uuid
 import zipfile
+from enum import Enum
 from typing import Any, Dict, Iterable, List, Optional, Sequence, Union
 
 from pip._vendor import pkg_resources
@@ -60,6 +61,11 @@
 logger = logging.getLogger(__name__)
 
 
+class BuildPurpose(Enum):
+    WHEEL = 1
+    INSTALL = 2
+
+
 def _get_dist(metadata_directory: str) -> Distribution:
     """Return a pkg_resources.Distribution for the provided
     metadata directory.
@@ -108,14 +114,12 @@ def __init__(
         constraint: bool = False,
         extras: Iterable[str] = (),
         user_supplied: bool = False,
-        no_build_editable: bool = False,
     ) -> None:
         assert req is None or isinstance(req, Requirement), req
         self.req = req
         self.comes_from = comes_from
         self.constraint = constraint
         self.editable = editable
-        self.no_build_editable = no_build_editable
         self.legacy_install_reason: Optional[int] = None
 
         # source_dir is the local directory where the linked requirement is
@@ -574,7 +578,7 @@ def _generate_metadata(self) -> str:
                 details=self.name or f"from {self.link}",
             )
 
-    def prepare_metadata(self) -> None:
+    def prepare_metadata(self, purpose: BuildPurpose) -> None:
         """Ensure that project metadata is available.
 
         Under PEP 517, call the backend hook to prepare the metadata.
@@ -583,7 +587,7 @@ def prepare_metadata(self) -> None:
         assert self.source_dir
 
         with indent_log():
-            if self.editable and not self.no_build_editable:
+            if self.editable and purpose == BuildPurpose.INSTALL:
                 self.metadata_directory = self._generate_metadata_for_editable()
             else:
                 self.metadata_directory = self._generate_metadata()

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

@@ -82,7 +82,6 @@ def make_install_req_from_editable(
         use_pep517=template.use_pep517,
         isolated=template.isolated,
         constraint=template.constraint,
-        no_build_editable=template.no_build_editable,
         options=dict(
             install_options=template.install_options,
             global_options=template.global_options,