add Bound::from_owned_ptr_unchecked (crate-private for now) (#4596)

* add `Bound::from_owned_ptr_unchecked` (crate-private for now)

* Update src/instance.rs

Co-authored-by: Icxolu <10486322+Icxolu@users.noreply.github.com>

---------

Co-authored-by: Icxolu <10486322+Icxolu@users.noreply.github.com>

src/ffi_ptr_ext.rs

@@ -6,10 +6,20 @@ use crate::{
 };
 
 pub(crate) trait FfiPtrExt: Sealed {
+    /// Assumes this pointer carries a Python reference which needs to be decref'd.
+    ///
+    /// If the pointer is NULL, this function will fetch an error.
     unsafe fn assume_owned_or_err(self, py: Python<'_>) -> PyResult<Bound<'_, PyAny>>;
+
+    /// Same as `assume_owned_or_err`, but doesn't fetch an error on NULL.
     unsafe fn assume_owned_or_opt(self, py: Python<'_>) -> Option<Bound<'_, PyAny>>;
+
+    /// Same as `assume_owned_or_err`, but panics on NULL.
     unsafe fn assume_owned(self, py: Python<'_>) -> Bound<'_, PyAny>;
 
+    /// Same as `assume_owned_or_err`, but does not check for NULL.
+    unsafe fn assume_owned_unchecked(self, py: Python<'_>) -> Bound<'_, PyAny>;
+
     /// Assumes this pointer is borrowed from a parent object.
     ///
     /// Warning: the lifetime `'a` is not bounded by the function arguments; the caller is
@@ -44,6 +54,11 @@ impl FfiPtrExt for *mut ffi::PyObject {
         Bound::from_owned_ptr(py, self)
     }
 
+    #[inline]
+    unsafe fn assume_owned_unchecked(self, py: Python<'_>) -> Bound<'_, PyAny> {
+        Bound::from_owned_ptr_unchecked(py, self)
+    }
+
     #[inline]
     unsafe fn assume_borrowed_or_err<'a>(
         self,

src/instance.rs

@@ -134,6 +134,19 @@ impl<'py> Bound<'py, PyAny> {
         Py::from_owned_ptr_or_err(py, ptr).map(|obj| Self(py, ManuallyDrop::new(obj)))
     }
 
+    /// Constructs a new `Bound<'py, PyAny>` from a pointer without checking for null.
+    ///
+    /// # Safety
+    ///
+    /// - `ptr` must be a valid pointer to a Python object
+    /// - `ptr` must be a strong/owned reference
+    pub(crate) unsafe fn from_owned_ptr_unchecked(
+        py: Python<'py>,
+        ptr: *mut ffi::PyObject,
+    ) -> Self {
+        Self(py, ManuallyDrop::new(Py::from_owned_ptr_unchecked(ptr)))
+    }
+
     /// Constructs a new `Bound<'py, PyAny>` from a pointer by creating a new Python reference.
     /// Panics if `ptr` is null.
     ///
@@ -1630,6 +1643,15 @@ impl<T> Py<T> {
         NonNull::new(ptr).map(|nonnull_ptr| Py(nonnull_ptr, PhantomData))
     }
 
+    /// Constructs a new `Py<T>` instance by taking ownership of the given FFI pointer.
+    ///
+    /// # Safety
+    ///
+    /// - `ptr` must be a non-null pointer to a Python object or type `T`.
+    pub(crate) unsafe fn from_owned_ptr_unchecked(ptr: *mut ffi::PyObject) -> Self {
+        Py(NonNull::new_unchecked(ptr), PhantomData)
+    }
+
     /// Create a `Py<T>` instance by creating a new reference from the given FFI pointer.
     ///
     /// # Safety

src/pycell.rs

@@ -370,7 +370,7 @@ where
             inner: unsafe {
                 ManuallyDrop::new(self)
                     .as_ptr()
-                    .assume_owned(py)
+                    .assume_owned_unchecked(py)
                     .downcast_into_unchecked()
             },
         }
@@ -587,7 +587,7 @@ where
             inner: unsafe {
                 ManuallyDrop::new(self)
                     .as_ptr()
-                    .assume_owned(py)
+                    .assume_owned_unchecked(py)
                     .downcast_into_unchecked()
             },
         }

src/types/dict.rs

@@ -261,7 +261,11 @@ impl<'py> PyDictMethods<'py> for Bound<'py, PyDict> {
             } {
                 std::os::raw::c_int::MIN..=-1 => Err(PyErr::fetch(py)),
                 0 => Ok(None),
-                1..=std::os::raw::c_int::MAX => Ok(Some(unsafe { result.assume_owned(py) })),
+                1..=std::os::raw::c_int::MAX => {
+                    // Safety: PyDict_GetItemRef positive return value means the result is a valid
+                    // owned reference
+                    Ok(Some(unsafe { result.assume_owned_unchecked(py) }))
+                }
             }
         }
 

src/types/weakref/anyref.rs

@@ -395,7 +395,9 @@ impl<'py> PyWeakrefMethods<'py> for Bound<'py, PyWeakref> {
         match unsafe { ffi::compat::PyWeakref_GetRef(self.as_ptr(), &mut obj) } {
             std::os::raw::c_int::MIN..=-1 => panic!("The 'weakref' weak reference instance should be valid (non-null and actually a weakref reference)"),
             0 => PyNone::get(self.py()).to_owned().into_any(),
-            1..=std::os::raw::c_int::MAX => unsafe { obj.assume_owned(self.py()) },
+            // Safety: positive return value from `PyWeakRef_GetRef` guarantees the return value is
+            // a valid strong reference.
+            1..=std::os::raw::c_int::MAX => unsafe { obj.assume_owned_unchecked(self.py()) },
         }
     }
 }

src/types/weakref/proxy.rs

@@ -187,7 +187,9 @@ impl<'py> PyWeakrefMethods<'py> for Bound<'py, PyWeakrefProxy> {
         match unsafe { ffi::compat::PyWeakref_GetRef(self.as_ptr(), &mut obj) } {
             std::os::raw::c_int::MIN..=-1 => panic!("The 'weakref.ProxyType' (or `weakref.CallableProxyType`) instance should be valid (non-null and actually a weakref reference)"),
             0 => PyNone::get(self.py()).to_owned().into_any(),
-            1..=std::os::raw::c_int::MAX => unsafe { obj.assume_owned(self.py()) },
+            // Safety: positive return value from `PyWeakRef_GetRef` guarantees the return value is
+            // a valid strong reference.
+            1..=std::os::raw::c_int::MAX => unsafe { obj.assume_owned_unchecked(self.py()) },
         }
     }
 }

src/types/weakref/reference.rs

@@ -196,7 +196,9 @@ impl<'py> PyWeakrefMethods<'py> for Bound<'py, PyWeakrefReference> {
         match unsafe { ffi::compat::PyWeakref_GetRef(self.as_ptr(), &mut obj) } {
             std::os::raw::c_int::MIN..=-1 => panic!("The 'weakref.ReferenceType' instance should be valid (non-null and actually a weakref reference)"),
             0 => PyNone::get(self.py()).to_owned().into_any(),
-            1..=std::os::raw::c_int::MAX => unsafe { obj.assume_owned(self.py()) },
+            // Safety: positive return value from `PyWeakRef_GetRef` guarantees the return value is
+            // a valid strong reference.
+            1..=std::os::raw::c_int::MAX => unsafe { obj.assume_owned_unchecked(self.py()) },
         }
     }
 }