allow borrowed extracts with `gil-refs` disabled (#3959)

src/conversion.rs

@@ -6,7 +6,9 @@ use crate::pyclass::boolean_struct::False;
 use crate::type_object::PyTypeInfo;
 use crate::types::any::PyAnyMethods;
 use crate::types::PyTuple;
-use crate::{ffi, gil, Bound, Py, PyAny, PyClass, PyNativeType, PyObject, PyRef, PyRefMut, Python};
+use crate::{
+    ffi, gil, Borrowed, Bound, Py, PyAny, PyClass, PyNativeType, PyObject, PyRef, PyRefMut, Python,
+};
 use std::ptr::NonNull;
 
 /// Returns a borrowed pointer to a Python object.
@@ -288,7 +290,7 @@ pub trait FromPyObjectBound<'a, 'py>: Sized + from_py_object_bound_sealed::Seale
     ///
     /// Users are advised against calling this method directly: instead, use this via
     /// [`Bound<'_, PyAny>::extract`] or [`Py::extract`].
-    fn from_py_object_bound(ob: &'a Bound<'py, PyAny>) -> PyResult<Self>;
+    fn from_py_object_bound(ob: Borrowed<'a, 'py, PyAny>) -> PyResult<Self>;
 
     /// Extracts the type hint information for this type when it appears as an argument.
     ///
@@ -307,8 +309,8 @@ impl<'py, T> FromPyObjectBound<'_, 'py> for T
 where
     T: FromPyObject<'py>,
 {
-    fn from_py_object_bound(ob: &Bound<'py, PyAny>) -> PyResult<Self> {
-        Self::extract_bound(ob)
+    fn from_py_object_bound(ob: Borrowed<'_, 'py, PyAny>) -> PyResult<Self> {
+        Self::extract_bound(&ob)
     }
 
     #[cfg(feature = "experimental-inspect")]

src/conversions/std/slice.rs

@@ -2,11 +2,9 @@ use std::borrow::Cow;
 
 #[cfg(feature = "experimental-inspect")]
 use crate::inspect::types::TypeInfo;
-#[cfg(not(feature = "gil-refs"))]
-use crate::types::PyBytesMethods;
 use crate::{
-    types::{PyAnyMethods, PyByteArray, PyByteArrayMethods, PyBytes},
-    Bound, IntoPy, Py, PyAny, PyObject, PyResult, Python, ToPyObject,
+    types::{PyByteArray, PyByteArrayMethods, PyBytes},
+    IntoPy, Py, PyAny, PyObject, PyResult, Python, ToPyObject,
 };
 
 impl<'a> IntoPy<PyObject> for &'a [u8] {
@@ -34,7 +32,7 @@ impl<'py> crate::FromPyObject<'py> for &'py [u8] {
 
 #[cfg(not(feature = "gil-refs"))]
 impl<'a> crate::conversion::FromPyObjectBound<'a, '_> for &'a [u8] {
-    fn from_py_object_bound(obj: &'a Bound<'_, PyAny>) -> PyResult<Self> {
+    fn from_py_object_bound(obj: crate::Borrowed<'a, '_, PyAny>) -> PyResult<Self> {
         Ok(obj.downcast::<PyBytes>()?.as_bytes())
     }
 
@@ -51,7 +49,8 @@ impl<'a> crate::conversion::FromPyObjectBound<'a, '_> for &'a [u8] {
 /// If it is a `bytearray`, its contents will be copied to an owned `Cow`.
 #[cfg(feature = "gil-refs")]
 impl<'py> crate::FromPyObject<'py> for Cow<'py, [u8]> {
-    fn extract_bound(ob: &Bound<'py, PyAny>) -> PyResult<Self> {
+    fn extract_bound(ob: &crate::Bound<'py, PyAny>) -> PyResult<Self> {
+        use crate::types::PyAnyMethods;
         if let Ok(bytes) = ob.downcast::<PyBytes>() {
             return Ok(Cow::Borrowed(bytes.clone().into_gil_ref().as_bytes()));
         }
@@ -63,7 +62,7 @@ impl<'py> crate::FromPyObject<'py> for Cow<'py, [u8]> {
 
 #[cfg(not(feature = "gil-refs"))]
 impl<'a> crate::conversion::FromPyObjectBound<'a, '_> for Cow<'a, [u8]> {
-    fn from_py_object_bound(ob: &'a Bound<'_, PyAny>) -> PyResult<Self> {
+    fn from_py_object_bound(ob: crate::Borrowed<'a, '_, PyAny>) -> PyResult<Self> {
         if let Ok(bytes) = ob.downcast::<PyBytes>() {
             return Ok(Cow::Borrowed(bytes.as_bytes()));
         }

src/conversions/std/string.rs

@@ -128,7 +128,7 @@ impl<'py> FromPyObject<'py> for &'py str {
 
 #[cfg(all(not(feature = "gil-refs"), any(Py_3_10, not(Py_LIMITED_API))))]
 impl<'a> crate::conversion::FromPyObjectBound<'a, '_> for &'a str {
-    fn from_py_object_bound(ob: &'a Bound<'_, PyAny>) -> PyResult<Self> {
+    fn from_py_object_bound(ob: crate::Borrowed<'a, '_, PyAny>) -> PyResult<Self> {
         ob.downcast::<PyString>()?.to_str()
     }
 
@@ -152,7 +152,7 @@ impl<'py> FromPyObject<'py> for Cow<'py, str> {
 
 #[cfg(not(feature = "gil-refs"))]
 impl<'a> crate::conversion::FromPyObjectBound<'a, '_> for Cow<'a, str> {
-    fn from_py_object_bound(ob: &'a Bound<'_, PyAny>) -> PyResult<Self> {
+    fn from_py_object_bound(ob: crate::Borrowed<'a, '_, PyAny>) -> PyResult<Self> {
         ob.downcast::<PyString>()?.to_cow()
     }
 

src/err/mod.rs

@@ -7,7 +7,7 @@ use crate::{
     exceptions::{self, PyBaseException},
     ffi,
 };
-use crate::{IntoPy, Py, PyAny, PyNativeType, PyObject, Python, ToPyObject};
+use crate::{Borrowed, IntoPy, Py, PyAny, PyNativeType, PyObject, Python, ToPyObject};
 use std::borrow::Cow;
 use std::cell::UnsafeCell;
 use std::ffi::CString;
@@ -65,17 +65,16 @@ impl<'a> PyDowncastError<'a> {
     /// Compatibility API to convert the Bound variant `DowncastError` into the
     /// gil-ref variant
     pub(crate) fn from_downcast_err(DowncastError { from, to }: DowncastError<'a, 'a>) -> Self {
-        Self {
-            from: from.as_gil_ref(),
-            to,
-        }
+        #[allow(deprecated)]
+        let from = unsafe { from.py().from_borrowed_ptr(from.as_ptr()) };
+        Self { from, to }
     }
 }
 
 /// Error that indicates a failure to convert a PyAny to a more specific Python type.
 #[derive(Debug)]
 pub struct DowncastError<'a, 'py> {
-    from: &'a Bound<'py, PyAny>,
+    from: Borrowed<'a, 'py, PyAny>,
     to: Cow<'static, str>,
 }
 
@@ -83,6 +82,16 @@ impl<'a, 'py> DowncastError<'a, 'py> {
     /// Create a new `PyDowncastError` representing a failure to convert the object
     /// `from` into the type named in `to`.
     pub fn new(from: &'a Bound<'py, PyAny>, to: impl Into<Cow<'static, str>>) -> Self {
+        DowncastError {
+            from: from.as_borrowed(),
+            to: to.into(),
+        }
+    }
+    #[cfg(not(feature = "gil-refs"))]
+    pub(crate) fn new_from_borrowed(
+        from: Borrowed<'a, 'py, PyAny>,
+        to: impl Into<Cow<'static, str>>,
+    ) -> Self {
         DowncastError {
             from,
             to: to.into(),
@@ -1036,7 +1045,7 @@ impl std::error::Error for DowncastError<'_, '_> {}
 
 impl std::fmt::Display for DowncastError<'_, '_> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
-        display_downcast_error(f, self.from, &self.to)
+        display_downcast_error(f, &self.from, &self.to)
     }
 }
 

src/instance.rs

@@ -579,6 +579,20 @@ impl<'a, 'py> Borrowed<'a, 'py, PyAny> {
         Self(NonNull::new_unchecked(ptr), PhantomData, py)
     }
 
+    #[inline]
+    #[cfg(not(feature = "gil-refs"))]
+    pub(crate) fn downcast<T>(self) -> Result<Borrowed<'a, 'py, T>, DowncastError<'a, 'py>>
+    where
+        T: PyTypeCheck,
+    {
+        if T::type_check(&self) {
+            // Safety: type_check is responsible for ensuring that the type is correct
+            Ok(unsafe { self.downcast_unchecked() })
+        } else {
+            Err(DowncastError::new_from_borrowed(self, T::NAME))
+        }
+    }
+
     /// Converts this `PyAny` to a concrete Python type without checking validity.
     ///
     /// # Safety

src/types/any.rs

@@ -1,5 +1,5 @@
 use crate::class::basic::CompareOp;
-use crate::conversion::{AsPyPointer, FromPyObject, FromPyObjectBound, IntoPy, ToPyObject};
+use crate::conversion::{AsPyPointer, FromPyObjectBound, IntoPy, ToPyObject};
 use crate::err::{DowncastError, DowncastIntoError, PyDowncastError, PyErr, PyResult};
 use crate::exceptions::{PyAttributeError, PyTypeError};
 use crate::ffi_ptr_ext::FfiPtrExt;
@@ -799,13 +799,14 @@ impl PyAny {
 
     /// Extracts some type from the Python object.
     ///
-    /// This is a wrapper function around [`FromPyObject::extract()`].
+    /// This is a wrapper function around
+    /// [`FromPyObject::extract()`](crate::FromPyObject::extract).
     #[inline]
     pub fn extract<'py, D>(&'py self) -> PyResult<D>
     where
-        D: FromPyObject<'py>,
+        D: FromPyObjectBound<'py, 'py>,
     {
-        FromPyObject::extract(self)
+        FromPyObjectBound::from_py_object_bound(self.as_borrowed())
     }
 
     /// Returns the reference count for the Python object.
@@ -1641,7 +1642,8 @@ pub trait PyAnyMethods<'py>: crate::sealed::Sealed {
 
     /// Extracts some type from the Python object.
     ///
-    /// This is a wrapper function around [`FromPyObject::extract()`].
+    /// This is a wrapper function around
+    /// [`FromPyObject::extract()`](crate::FromPyObject::extract).
     fn extract<'a, T>(&'a self) -> PyResult<T>
     where
         T: FromPyObjectBound<'a, 'py>;
@@ -2182,7 +2184,7 @@ impl<'py> PyAnyMethods<'py> for Bound<'py, PyAny> {
     where
         T: FromPyObjectBound<'a, 'py>,
     {
-        FromPyObjectBound::from_py_object_bound(self)
+        FromPyObjectBound::from_py_object_bound(self.as_borrowed())
     }
 
     fn get_refcnt(&self) -> isize {

src/types/bytes.rs

@@ -158,7 +158,7 @@ impl<'py> PyBytesMethods<'py> for Bound<'py, PyBytes> {
 impl<'a> Borrowed<'a, '_, PyBytes> {
     /// Gets the Python string as a byte slice.
     #[allow(clippy::wrong_self_convention)]
-    fn as_bytes(self) -> &'a [u8] {
+    pub(crate) fn as_bytes(self) -> &'a [u8] {
         unsafe {
             let buffer = ffi::PyBytes_AsString(self.as_ptr()) as *const u8;
             let length = ffi::PyBytes_Size(self.as_ptr()) as usize;

src/types/string.rs

@@ -369,7 +369,7 @@ impl<'a> Borrowed<'a, '_, PyString> {
     }
 
     #[allow(clippy::wrong_self_convention)]
-    fn to_cow(self) -> PyResult<Cow<'a, str>> {
+    pub(crate) fn to_cow(self) -> PyResult<Cow<'a, str>> {
         // TODO: this method can probably be deprecated once Python 3.9 support is dropped,
         // because all versions then support the more efficient `to_str`.
         #[cfg(any(Py_3_10, not(Py_LIMITED_API)))]