Add monkeypatch for root error ignore on Linux in cibuildwheel

Pretty terrible, but easier than figuring out rootless containers
in Github CI.

.github/workflows/wheels.yml

@@ -55,9 +55,6 @@ jobs:
           CIBW_ARCHS_LINUX: auto64 aarch64
           CIBW_ARCHS_WINDOWS: auto64
           CIBW_BEFORE_ALL_LINUX: bash .github/install_bazel.sh
-          # Rootless requirement of rules_python, see
-          # https://github.com/bazelbuild/rules_python/pull/713 .
-          CIBW_CONTAINER_ENGINE: podman
           # Grab the rootless Bazel installation inside the container.
           CIBW_ENVIRONMENT_LINUX: PATH=$PATH:$HOME/bin
           CIBW_TEST_COMMAND: python {project}/bindings/python/google_benchmark/example.py

MODULE.bazel

@@ -27,10 +27,6 @@ python.toolchain(
     is_default = True,
     python_version = "3.12",
 )
-use_repo(
-    python,
-    python = "python_versions",
-)
 
 pip = use_extension("@rules_python//python/extensions:pip.bzl", "pip", dev_dependency = True)
 pip.parse(

setup.py

@@ -1,13 +1,17 @@
+import contextlib
+import os
 import platform
+import re
 import shutil
 from pathlib import Path
-from typing import Any
+from typing import Any, Generator
 
 import setuptools
 from setuptools.command import build_ext
 
 IS_WINDOWS = platform.system() == "Windows"
 IS_MAC = platform.system() == "Darwin"
+IS_LINUX = platform.system() == "Linux"
 
 # hardcoded SABI-related options. Requires that each Python interpreter
 # (hermetic or not) participating is of the same major-minor version.
@@ -16,6 +20,34 @@
 options = {"bdist_wheel": {"py_limited_api": "cp312"}} if py_limited_api else {}
 
 
+def is_cibuildwheel() -> bool:
+    return os.getenv("CIBUILDWHEEL") is not None
+
+
+@contextlib.contextmanager
+def _maybe_patch_toolchains() -> Generator[None, None, None]:
+    """
+    Patch rules_python toolchains to ignore root user error
+    when run in a Docker container on Linux in cibuildwheel.
+    """
+    CIBW_LINUX = is_cibuildwheel() and IS_LINUX
+    try:
+        if CIBW_LINUX:
+            module_bazel = Path("MODULE.bazel")
+            content: str = module_bazel.read_text()
+            module_bazel.write_text(
+                re.sub(
+                    r"python.toolchain(.*)",
+                    r"python.toolchain(\1, ignore_root_user_error = True)",
+                    content,
+                )
+            )
+        yield
+    finally:
+        if CIBW_LINUX:
+            module_bazel.write_text(content)
+
+
 class BazelExtension(setuptools.Extension):
     """A C/C++ extension that is defined as a Bazel BUILD target."""
 
@@ -75,7 +107,8 @@ def bazel_build(self, ext: BazelExtension) -> None:
             # C++17 needs macOS 10.14 at minimum
             bazel_argv.append("--macos_minimum_os=10.14")
 
-        self.spawn(bazel_argv)
+        with _maybe_patch_toolchains():
+            self.spawn(bazel_argv)
 
         if IS_WINDOWS:
             suffix = ".pyd"