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Merge pull request #3478 from mejrs/auto 

Don't let auto trait syntax bleed through on stable Rust
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David Hewitt 2023-09-29 16:35:05 +00:00 committed by GitHub
parent 50cb41dd0b 0c8ab98760
commit b9e9859082
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1 changed files with 82 additions and 76 deletions
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158
src/marker.rs
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@ -185,84 +185,87 @@ pub unsafe trait Ungil {}
#[cfg(not(feature = "nightly"))]
unsafe impl<T: Send> Ungil for T {}
/// Types that are safe to access while the GIL is not held.
///
/// # Safety
///
/// The type must not carry borrowed Python references or, if it does, not allow access to them if
/// the GIL is not held.
///
/// See the [module-level documentation](self) for more information.
///
/// # Examples
///
/// Types which are `Ungil` cannot be used in contexts where the GIL was released, e.g.
///
/// ```compile_fail
/// # use pyo3::prelude::*;
/// # use pyo3::types::PyString;
/// Python::with_gil(|py| {
/// let string = PyString::new(py, "foo");
///
/// py.allow_threads(|| {
/// println!("{:?}", string);
/// });
/// });
/// ```
///
/// This applies to the GIL token `Python` itself as well, e.g.
///
/// ```compile_fail
/// # use pyo3::prelude::*;
/// Python::with_gil(|py| {
/// py.allow_threads(|| {
/// drop(py);
/// });
/// });
/// ```
///
/// On nightly Rust, this is not based on the [`Send`] auto trait and hence we are able
/// to prevent incorrectly circumventing it using e.g. the [`send_wrapper`](https://docs.rs/send_wrapper/) crate:
///
/// ```compile_fail
/// # use pyo3::prelude::*;
/// # use pyo3::types::PyString;
/// use send_wrapper::SendWrapper;
///
/// Python::with_gil(|py| {
/// let string = PyString::new(py, "foo");
///
/// let wrapped = SendWrapper::new(string);
///
/// py.allow_threads(|| {
/// let sneaky: &PyString = *wrapped;
///
/// println!("{:?}", sneaky);
/// });
/// });
/// ```
///
/// This also enables using non-[`Send`] types in `allow_threads`,
/// at least if they are not also bound to the GIL:
///
/// ```rust
/// # use pyo3::prelude::*;
/// use std::rc::Rc;
///
/// Python::with_gil(|py| {
/// let rc = Rc::new(42);
///
/// py.allow_threads(|| {
/// println!("{:?}", rc);
/// });
/// });
/// ```
#[cfg(feature = "nightly")]
pub unsafe auto trait Ungil {}
mod nightly {
macro_rules! define {
($($tt:tt)*) => { $($tt)* }
}
#[cfg(feature = "nightly")]
mod negative_impls {
use super::Ungil;
define! {
/// Types that are safe to access while the GIL is not held.
///
/// # Safety
///
/// The type must not carry borrowed Python references or, if it does, not allow access to them if
/// the GIL is not held.
///
/// See the [module-level documentation](self) for more information.
///
/// # Examples
///
/// Types which are `Ungil` cannot be used in contexts where the GIL was released, e.g.
///
/// ```compile_fail
/// # use pyo3::prelude::*;
/// # use pyo3::types::PyString;
/// Python::with_gil(|py| {
/// let string = PyString::new(py, "foo");
///
/// py.allow_threads(|| {
/// println!("{:?}", string);
/// });
/// });
/// ```
///
/// This applies to the GIL token `Python` itself as well, e.g.
///
/// ```compile_fail
/// # use pyo3::prelude::*;
/// Python::with_gil(|py| {
/// py.allow_threads(|| {
/// drop(py);
/// });
/// });
/// ```
///
/// On nightly Rust, this is not based on the [`Send`] auto trait and hence we are able
/// to prevent incorrectly circumventing it using e.g. the [`send_wrapper`](https://docs.rs/send_wrapper/) crate:
///
/// ```compile_fail
/// # use pyo3::prelude::*;
/// # use pyo3::types::PyString;
/// use send_wrapper::SendWrapper;
///
/// Python::with_gil(|py| {
/// let string = PyString::new(py, "foo");
///
/// let wrapped = SendWrapper::new(string);
///
/// py.allow_threads(|| {
/// let sneaky: &PyString = *wrapped;
///
/// println!("{:?}", sneaky);
/// });
/// });
/// ```
///
/// This also enables using non-[`Send`] types in `allow_threads`,
/// at least if they are not also bound to the GIL:
///
/// ```rust
/// # use pyo3::prelude::*;
/// use std::rc::Rc;
///
/// Python::with_gil(|py| {
/// let rc = Rc::new(42);
///
/// py.allow_threads(|| {
/// println!("{:?}", rc);
/// });
/// });
/// ```
pub unsafe auto trait Ungil {}
}
impl !Ungil for crate::Python<'_> {}
@ -289,6 +292,9 @@ mod negative_impls {
impl !Ungil for crate::ffi::PyArena {}
}
#[cfg(feature = "nightly")]
pub use nightly::Ungil;
/// A marker token that represents holding the GIL.
///
/// It serves three main purposes: