175 lines
6.8 KiB
Python
175 lines
6.8 KiB
Python
import importlib.util
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import os
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from collections import namedtuple
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from typing import Any, List, Optional
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from pip._vendor import tomli
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from pip._vendor.packaging.requirements import InvalidRequirement, Requirement
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from pip._internal.exceptions import (
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InstallationError,
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InvalidPyProjectBuildRequires,
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MissingPyProjectBuildRequires,
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)
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def _is_list_of_str(obj: Any) -> bool:
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return isinstance(obj, list) and all(isinstance(item, str) for item in obj)
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def make_pyproject_path(unpacked_source_directory: str) -> str:
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return os.path.join(unpacked_source_directory, "pyproject.toml")
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BuildSystemDetails = namedtuple(
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"BuildSystemDetails", ["requires", "backend", "check", "backend_path"]
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)
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def load_pyproject_toml(
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use_pep517: Optional[bool], pyproject_toml: str, setup_py: str, req_name: str
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) -> Optional[BuildSystemDetails]:
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"""Load the pyproject.toml file.
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Parameters:
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use_pep517 - Has the user requested PEP 517 processing? None
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means the user hasn't explicitly specified.
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pyproject_toml - Location of the project's pyproject.toml file
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setup_py - Location of the project's setup.py file
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req_name - The name of the requirement we're processing (for
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error reporting)
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Returns:
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None if we should use the legacy code path, otherwise a tuple
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(
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requirements from pyproject.toml,
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name of PEP 517 backend,
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requirements we should check are installed after setting
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up the build environment
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directory paths to import the backend from (backend-path),
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relative to the project root.
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)
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"""
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has_pyproject = os.path.isfile(pyproject_toml)
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has_setup = os.path.isfile(setup_py)
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if not has_pyproject and not has_setup:
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raise InstallationError(
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f"{req_name} does not appear to be a Python project: "
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f"neither 'setup.py' nor 'pyproject.toml' found."
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)
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if has_pyproject:
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with open(pyproject_toml, encoding="utf-8") as f:
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pp_toml = tomli.loads(f.read())
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build_system = pp_toml.get("build-system")
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else:
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build_system = None
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# The following cases must use PEP 517
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# We check for use_pep517 being non-None and falsey because that means
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# the user explicitly requested --no-use-pep517. The value 0 as
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# opposed to False can occur when the value is provided via an
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# environment variable or config file option (due to the quirk of
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# strtobool() returning an integer in pip's configuration code).
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if has_pyproject and not has_setup:
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if use_pep517 is not None and not use_pep517:
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raise InstallationError(
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"Disabling PEP 517 processing is invalid: "
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"project does not have a setup.py"
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)
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use_pep517 = True
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elif build_system and "build-backend" in build_system:
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if use_pep517 is not None and not use_pep517:
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raise InstallationError(
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"Disabling PEP 517 processing is invalid: "
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"project specifies a build backend of {} "
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"in pyproject.toml".format(build_system["build-backend"])
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)
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use_pep517 = True
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# If we haven't worked out whether to use PEP 517 yet,
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# and the user hasn't explicitly stated a preference,
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# we do so if the project has a pyproject.toml file
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# or if we cannot import setuptools.
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# We fallback to PEP 517 when without setuptools,
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# so setuptools can be installed as a default build backend.
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# For more info see:
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# https://discuss.python.org/t/pip-without-setuptools-could-the-experience-be-improved/11810/9
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elif use_pep517 is None:
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use_pep517 = has_pyproject or not importlib.util.find_spec("setuptools")
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# At this point, we know whether we're going to use PEP 517.
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assert use_pep517 is not None
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# If we're using the legacy code path, there is nothing further
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# for us to do here.
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if not use_pep517:
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return None
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if build_system is None:
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# Either the user has a pyproject.toml with no build-system
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# section, or the user has no pyproject.toml, but has opted in
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# explicitly via --use-pep517.
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# In the absence of any explicit backend specification, we
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# assume the setuptools backend that most closely emulates the
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# traditional direct setup.py execution, and require wheel and
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# a version of setuptools that supports that backend.
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build_system = {
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"requires": ["setuptools>=40.8.0", "wheel"],
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"build-backend": "setuptools.build_meta:__legacy__",
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}
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# If we're using PEP 517, we have build system information (either
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# from pyproject.toml, or defaulted by the code above).
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# Note that at this point, we do not know if the user has actually
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# specified a backend, though.
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assert build_system is not None
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# Ensure that the build-system section in pyproject.toml conforms
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# to PEP 518.
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# Specifying the build-system table but not the requires key is invalid
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if "requires" not in build_system:
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raise MissingPyProjectBuildRequires(package=req_name)
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# Error out if requires is not a list of strings
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requires = build_system["requires"]
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if not _is_list_of_str(requires):
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raise InvalidPyProjectBuildRequires(
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package=req_name,
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reason="It is not a list of strings.",
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)
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# Each requirement must be valid as per PEP 508
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for requirement in requires:
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try:
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Requirement(requirement)
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except InvalidRequirement as error:
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raise InvalidPyProjectBuildRequires(
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package=req_name,
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reason=f"It contains an invalid requirement: {requirement!r}",
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) from error
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backend = build_system.get("build-backend")
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backend_path = build_system.get("backend-path", [])
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check: List[str] = []
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if backend is None:
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# If the user didn't specify a backend, we assume they want to use
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# the setuptools backend. But we can't be sure they have included
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# a version of setuptools which supplies the backend. So we
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# make a note to check that this requirement is present once
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# we have set up the environment.
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# This is quite a lot of work to check for a very specific case. But
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# the problem is, that case is potentially quite common - projects that
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# adopted PEP 518 early for the ability to specify requirements to
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# execute setup.py, but never considered needing to mention the build
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# tools themselves. The original PEP 518 code had a similar check (but
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# implemented in a different way).
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backend = "setuptools.build_meta:__legacy__"
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check = ["setuptools>=40.8.0"]
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return BuildSystemDetails(requires, backend, check, backend_path)
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