fix: tighten AST to call only, add docs

README.md

@@ -103,7 +103,7 @@ Options
 | **Build selection** | [`CIBW_PLATFORM`](https://cibuildwheel.readthedocs.io/en/stable/options/#platform)  | Override the auto-detected target platform |
 |   | [`CIBW_BUILD`](https://cibuildwheel.readthedocs.io/en/stable/options/#build-skip)  <br> [`CIBW_SKIP`](https://cibuildwheel.readthedocs.io/en/stable/options/#build-skip)  | Choose the Python versions to build |
 |   | [`CIBW_ARCHS_LINUX`](https://cibuildwheel.readthedocs.io/en/stable/options/#archs)  | Build non-native architectures |
-|   | [`CIBW_PROJECT_REQUIRES_PYTHON`](https://cibuildwheel.readthedocs.io/en/stable/options/#requires-python)  | Limit the Python versions to build |
+|   | [`CIBW_PROJECT_REQUIRES_PYTHON`](https://cibuildwheel.readthedocs.io/en/stable/options/#requires-python)  | Manually set the Python compatibility of your project |
 | **Build customization** | [`CIBW_ENVIRONMENT`](https://cibuildwheel.readthedocs.io/en/stable/options/#environment)  | Set environment variables needed during the build |
 |   | [`CIBW_BEFORE_ALL`](https://cibuildwheel.readthedocs.io/en/stable/options/#before-all)  | Execute a shell command on the build system before any wheels are built. |
 |   | [`CIBW_BEFORE_BUILD`](https://cibuildwheel.readthedocs.io/en/stable/options/#before-build)  | Execute a shell command preparing each wheel's build |
@@ -117,6 +117,7 @@ Options
 |   | [`CIBW_TEST_SKIP`](https://cibuildwheel.readthedocs.io/en/stable/options/#test-skip)  | Skip running tests on some builds |
 | **Other** | [`CIBW_BUILD_VERBOSITY`](https://cibuildwheel.readthedocs.io/en/stable/options/#build-verbosity)  | Increase/decrease the output of pip wheel |
 
+
 Working examples
 ----------------
 

cibuildwheel/__main__.py

@@ -159,12 +159,11 @@ def main() -> None:
     test_extras = get_option_from_environment('CIBW_TEST_EXTRAS', platform=platform, default='')
     build_verbosity_str = get_option_from_environment('CIBW_BUILD_VERBOSITY', platform=platform, default='')
 
-    setup_py = package_dir / 'setup.py'
-    setup_cfg = package_dir / 'setup.cfg'
-    pyproject_toml = package_dir / 'pyproject.toml'
+    package_files = {'setup.py', 'setup.cfg', 'pyproject.toml'}
 
-    if not pyproject_toml.exists() and not setup_cfg.exists() and not setup_py.exists():
-        print('cibuildwheel: Could not find setup.py, setup.cfg or pyproject.toml at root of package', file=sys.stderr)
+    if not any(package_dir.joinpath(name).exists() for name in package_files):
+        names = ', '.join(sorted(package_files, reverse=True))
+        print(f'cibuildwheel: Could not find any of {{{names}}} at root of package', file=sys.stderr)
         sys.exit(2)
 
     # Passing this in as an environment variable will override pyproject.toml, setup.cfg, or setup.py

cibuildwheel/projectfiles.py

@@ -2,7 +2,7 @@
 import sys
 from configparser import ConfigParser
 from pathlib import Path
-from typing import Any, Dict, Optional
+from typing import Any, Optional
 
 import toml
 
@@ -11,6 +11,8 @@
 
     def get_constant(x: ast.Str) -> str:
         return x.s
+
+
 else:
     Constant = ast.Constant
 
@@ -21,24 +23,23 @@ def get_constant(x: ast.Constant) -> Any:
 class Analyzer(ast.NodeVisitor):
     def __init__(self) -> None:
         self.requires_python: Optional[str] = None
-        self.constants: Dict[str, str] = {}
 
-    def visit_Assign(self, node: ast.Assign) -> None:
-        for target in node.targets:
-            if (
-                isinstance(target, ast.Name)
-                and isinstance(node.value, Constant)
-                and isinstance(get_constant(node.value), str)
-            ):
-                self.constants[target.id] = get_constant(node.value)
+    def visit(self, content: ast.AST) -> None:
+        for node in ast.walk(content):
+            for child in ast.iter_child_nodes(node):
+                child.parent = node  # type: ignore
+        super().visit(content)
 
     def visit_keyword(self, node: ast.keyword) -> None:
         self.generic_visit(node)
         if node.arg == "python_requires":
-            if isinstance(node.value, Constant):
+            # Must not be nested in an if or other structure
+            # This will be Module -> Expr -> Call -> keyword
+            if (
+                not hasattr(node.parent.parent.parent, "parent")  # type: ignore
+                and isinstance(node.value, Constant)
+            ):
                 self.requires_python = get_constant(node.value)
-            elif isinstance(node.value, ast.Name):
-                self.requires_python = self.constants.get(node.value.id)
 
 
 def setup_py_python_requires(content: str) -> Optional[str]:
@@ -54,27 +55,23 @@ def setup_py_python_requires(content: str) -> Optional[str]:
 def get_requires_python_str(package_dir: Path) -> Optional[str]:
     "Return the python requires string from the most canonical source available, or None"
 
-    setup_py = package_dir / 'setup.py'
-    setup_cfg = package_dir / 'setup.cfg'
-    pyproject_toml = package_dir / 'pyproject.toml'
-
     # Read in from pyproject.toml:project.requires-python
     try:
-        info = toml.load(pyproject_toml)
+        info = toml.load(package_dir / 'pyproject.toml')
         return str(info['project']['requires-python'])
     except (FileNotFoundError, KeyError, IndexError, TypeError):
         pass
 
     # Read in from setup.cfg:options.python_requires
     try:
         config = ConfigParser()
-        config.read(setup_cfg)
+        config.read(package_dir / 'setup.cfg')
         return str(config['options']['python_requires'])
     except (FileNotFoundError, KeyError, IndexError, TypeError):
         pass
 
     try:
-        with open(setup_py) as f:
+        with open(package_dir / 'setup.py') as f:
             return setup_py_python_requires(f.read())
     except FileNotFoundError:
         pass

docs/options.md

@@ -213,48 +213,49 @@ This option can also be set using the [command-line option](#command-line) `--ar
 
 By default, cibuildwheel reads your package's Python compatibility from
 `pyproject.toml` following [PEP621](https://www.python.org/dev/peps/pep-0621/)
-or from `setup.cfg`. If you need to override this behaviour for some reason,
-you can use this option.
+or from `setup.cfg`; finally it will try to inspect the AST of `setup.py` for a
+simple keyword assignment in a top level function call. If you need to override
+this behaviour for some reason, you can use this option.
 
 When setting this option, the syntax is the same as `project.requires-python`,
 using 'version specifiers' like `>=3.6`, according to
 [PEP440](https://www.python.org/dev/peps/pep-0440/#version-specifiers).
 
-Default: reads your package's Python compatibility from pyproject.toml
-(`project.requires-python`) or setup.cfg (`options.python_requires`). If not
-found, cibuildwheel assumes the package is compatible with all versions of
-Python that it can build.
-
-Platform-specific variants also available:<br/>
-`CIBW_PROJECT_REQUIRES_PYTHON_MACOS` | `CIBW_PROJECT_REQUIRES_PYTHON_WINDOWS` | `CIBW_PROJECT_REQUIRES_PYTHON_LINUX`
+Default: reads your package's Python compatibility from `pyproject.toml`
+(`project.requires-python`) or `setup.cfg` (`options.python_requires`) or
+`setup.py` `setup(python_requires="...")`. If not found, cibuildwheel assumes
+the package is compatible with all versions of Python that it can build.
 
 
 !!! note
     Rather than using this option, it's recommended you set
-    `project.requires-python` in `pyproject.toml` instead - that way, `pip`
-    knows which wheels are compatible when installing.
-
+    `project.requires-python` in `pyproject.toml` instead:
     Example `pyproject.toml`:
 
-    ~~~toml
-    [project]
-    requires-python = ">=3.6"
+        [project]
+        requires-python = ">=3.6"
+
+        # Aside - in pyproject.toml you should always specify minimal build
+        # system options, like this:
+
+        [build-system]
+        requires = ["setuptools>=42", "wheel"]
+        build-backend = "setuptools.build_meta"
 
-    # aside - in pyproject.toml you should always specify minimal build system
-    # options, like this:
 
-    [build-system]
-    requires = ["setuptools>=42", "wheel"]
-    build-backend = "setuptools.build_meta"
-    ~~~
+    Currently, setuptools has not yet added support for reading this value from
+    pyproject.toml yet, and so does not copy it to Requires-Python in the wheel
+    metadata. This mechanism is used by `pip` to scan through older versions of
+    your package until it finds a release compatible with the curernt version
+    of Python compatible when installing, so it is an important value to set if
+    you plan to drop support for a version of Python in the future.
 
-    If you don't want to use this yet, you can also use the currently
-    recommended location for setuptools in `setup.cfg`. Example `setup.cfg`:
+    If you don't want to list this value twice, you can also use the setuptools
+    specific location in `setup.cfg` and cibuildwheel will detect it from
+    there. Example `setup.cfg`:
 
-    ~~~ini
-    [options]
-    python_requires = ">=3.6"
-    ~~~
+        [options]
+        python_requires = ">=3.6"
 
 #### Examples
 

setup.cfg

@@ -46,13 +46,15 @@ dev =
     mypy
     pip-tools
     pygithub
+    ghapi
     pymdown-extensions
     pytest>=4
     pytest-timeout
     pyyaml
     requests
     typing-extensions
     rich>=9.6
+    mypy>=0.800
 
 [options.packages.find]
 include =

unit_test/projectfiles_test.py

@@ -54,8 +54,8 @@ def test_read_setup_py_assign(tmp_path):
             )
             """))
 
-    assert setup_py_python_requires(tmp_path.joinpath("setup.py").read_text()) == "3.21"
-    assert get_requires_python_str(tmp_path) == "3.21"
+    assert setup_py_python_requires(tmp_path.joinpath("setup.py").read_text()) is None
+    assert get_requires_python_str(tmp_path) is None
 
 
 def test_read_setup_py_None(tmp_path):