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FlickerSouldavidhewitt
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davidhewitt
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Prevent building in GIL-less environment (#4327)
* Prevent building in GIL-less environment * Add change log * add "yet" to phrasing * Add testing to build script * add link to issue * Fix formatting issues --------- Co-authored-by: David Hewitt <mail@davidhewitt.dev>
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Lines changed: 41 additions & 4 deletions

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‎newsfragments/4327.packaging.md‎

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This PR lets PyO3 checks `Py_GIL_DISABLED` build flag and prevents `pyo3-ffi` crate building against GIL-less Python,
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unless
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explicitly opt using the `UNSAFE_PYO3_BUILD_FREE_THREADED` environment flag.

‎noxfile.py‎

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@@ -9,7 +9,7 @@
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from functools import lru_cache
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from glob import glob
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from pathlib import Path
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from typing import Any, Callable, Dict, Iterator, List, Optional, Tuple
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from typing import Any, Callable, Dict, Iterable, Iterator, List, Optional, Tuple
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import nox
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import nox.command
@@ -655,6 +655,14 @@ def test_version_limits(session: nox.Session):
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config_file.set("PyPy", "3.11")
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_run_cargo(session, "check", env=env, expect_error=True)
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# Python build with GIL disabled should fail building
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config_file.set("CPython", "3.13", build_flags=["Py_GIL_DISABLED"])
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_run_cargo(session, "check", env=env, expect_error=True)
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# Python build with GIL disabled should pass with env flag on
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env["UNSAFE_PYO3_BUILD_FREE_THREADED"] = "1"
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_run_cargo(session, "check", env=env)
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@nox.session(name="check-feature-powerset", venv_backend="none")
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def check_feature_powerset(session: nox.Session):
@@ -919,14 +927,17 @@ class _ConfigFile:
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def __init__(self, config_file) -> None:
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self._config_file = config_file
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def set(self, implementation: str, version: str) -> None:
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def set(
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self, implementation: str, version: str, build_flags: Iterable[str] = ()
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) -> None:
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"""Set the contents of this config file to the given implementation and version."""
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self._config_file.seek(0)
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self._config_file.truncate(0)
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self._config_file.write(
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f"""\
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implementation={implementation}
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version={version}
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build_flags={','.join(build_flags)}
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suppress_build_script_link_lines=true
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"""
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)

‎pyo3-build-config/src/impl_.rs‎

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@@ -996,6 +996,7 @@ pub enum BuildFlag {
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Py_DEBUG,
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Py_REF_DEBUG,
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Py_TRACE_REFS,
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Py_GIL_DISABLED,
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COUNT_ALLOCS,
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Other(String),
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}
@@ -1016,6 +1017,7 @@ impl FromStr for BuildFlag {
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"Py_DEBUG" => Ok(BuildFlag::Py_DEBUG),
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"Py_REF_DEBUG" => Ok(BuildFlag::Py_REF_DEBUG),
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"Py_TRACE_REFS" => Ok(BuildFlag::Py_TRACE_REFS),
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"Py_GIL_DISABLED" => Ok(BuildFlag::Py_GIL_DISABLED),
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"COUNT_ALLOCS" => Ok(BuildFlag::COUNT_ALLOCS),
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other => Ok(BuildFlag::Other(other.to_owned())),
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}
@@ -1039,10 +1041,11 @@ impl FromStr for BuildFlag {
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pub struct BuildFlags(pub HashSet<BuildFlag>);
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impl BuildFlags {
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const ALL: [BuildFlag; 4] = [
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const ALL: [BuildFlag; 5] = [
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BuildFlag::Py_DEBUG,
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BuildFlag::Py_REF_DEBUG,
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BuildFlag::Py_TRACE_REFS,
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BuildFlag::Py_GIL_DISABLED,
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BuildFlag::COUNT_ALLOCS,
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];
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‎pyo3-ffi/build.rs‎

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@@ -4,8 +4,9 @@ use pyo3_build_config::{
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cargo_env_var, env_var, errors::Result, is_linking_libpython, resolve_interpreter_config,
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InterpreterConfig, PythonVersion,
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},
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warn, PythonImplementation,
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warn, BuildFlag, PythonImplementation,
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};
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use std::ops::Not;
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/// Minimum Python version PyO3 supports.
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struct SupportedVersions {
@@ -120,6 +121,24 @@ fn ensure_python_version(interpreter_config: &InterpreterConfig) -> Result<()> {
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Ok(())
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}
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fn ensure_gil_enabled(interpreter_config: &InterpreterConfig) -> Result<()> {
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let gil_enabled = interpreter_config
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.build_flags
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.0
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.contains(&BuildFlag::Py_GIL_DISABLED)
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.not();
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ensure!(
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gil_enabled || std::env::var("UNSAFE_PYO3_BUILD_FREE_THREADED").map_or(false, |os_str| os_str == "1"),
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"the Python interpreter was built with the GIL disabled, which is not yet supported by PyO3\n\
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= help: see https://github.com/PyO3/pyo3/issues/4265 for more information\n\
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= help: please check if an updated version of PyO3 is available. Current version: {}\n\
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= help: set UNSAFE_PYO3_BUILD_FREE_THREADED=1 to suppress this check and build anyway for free-threaded Python",
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std::env::var("CARGO_PKG_VERSION").unwrap()
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);
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Ok(())
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}
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fn ensure_target_pointer_width(interpreter_config: &InterpreterConfig) -> Result<()> {
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if let Some(pointer_width) = interpreter_config.pointer_width {
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// Try to check whether the target architecture matches the python library
@@ -185,6 +204,7 @@ fn configure_pyo3() -> Result<()> {
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ensure_python_version(&interpreter_config)?;
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ensure_target_pointer_width(&interpreter_config)?;
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ensure_gil_enabled(&interpreter_config)?;
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// Serialize the whole interpreter config into DEP_PYTHON_PYO3_CONFIG env var.
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interpreter_config.to_cargo_dep_env()?;

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