Avoid introducing generic parameter with implied bounds from an associated type relation (#5638)

* avoid introducing generic parameter with implied bounds from an associated type relation

* newsfragment

Author: davidhewitt

newsfragments/5638.fixed.md

@@ -0,0 +1 @@
+Fix crash when compiling on Rust 1.92+ with both debug assertions and optimizations enabled.

src/pycell.rs

@@ -315,10 +315,10 @@ impl<'py, T: PyClass> PyRef<'py, T> {
     }
 }
 
-impl<'p, T, U> PyRef<'p, T>
+impl<'p, T> PyRef<'p, T>
 where
-    T: PyClass<BaseType = U>,
-    U: PyClass,
+    T: PyClass,
+    T::BaseType: PyClass,
 {
     /// Gets a `PyRef<T::BaseType>`.
     ///
@@ -365,10 +365,10 @@ where
     /// #     pyo3::py_run!(py, sub, "assert sub.name() == 'base1 base2 sub'")
     /// # });
     /// ```
-    pub fn into_super(self) -> PyRef<'p, U> {
+    pub fn into_super(self) -> PyRef<'p, T::BaseType> {
         let py = self.py();
         let t_not_frozen = !<T::Frozen as crate::pyclass::boolean_struct::private::Boolean>::VALUE;
-        let u_frozen = <U::Frozen as crate::pyclass::boolean_struct::private::Boolean>::VALUE;
+        let u_frozen = <<T::BaseType as PyClass>::Frozen as crate::pyclass::boolean_struct::private::Boolean>::VALUE;
         if t_not_frozen && u_frozen {
             // If `T` is mutable subclass of `U` differ, then it is possible that we need to
             // release the borrow count now. (e.g. `U` may have a noop borrow checker so
@@ -445,7 +445,7 @@ where
     /// #     pyo3::py_run!(py, sub, "assert sub.format_name_lengths() == '9 8'")
     /// # });
     /// ```
-    pub fn as_super(&self) -> &PyRef<'p, U> {
+    pub fn as_super(&self) -> &PyRef<'p, T::BaseType> {
         let ptr = NonNull::from(&self.inner)
             // `Bound<T>` has the same layout as `Bound<T::BaseType>`
             .cast::<Bound<'p, T::BaseType>>()
@@ -523,20 +523,20 @@ impl<'p, T: PyClass<Frozen = False>> PyRefMut<'p, T> {
     }
 }
 
-impl<T, U> AsRef<U> for PyRefMut<'_, T>
+impl<T> AsRef<T::BaseType> for PyRefMut<'_, T>
 where
-    T: PyClass<BaseType = U, Frozen = False>,
-    U: PyClass<Frozen = False>,
+    T: PyClass<Frozen = False>,
+    T::BaseType: PyClass<Frozen = False>,
 {
     fn as_ref(&self) -> &T::BaseType {
         PyRefMut::downgrade(self).as_super()
     }
 }
 
-impl<T, U> AsMut<U> for PyRefMut<'_, T>
+impl<T> AsMut<T::BaseType> for PyRefMut<'_, T>
 where
-    T: PyClass<BaseType = U, Frozen = False>,
-    U: PyClass<Frozen = False>,
+    T: PyClass<Frozen = False>,
+    T::BaseType: PyClass<Frozen = False>,
 {
     fn as_mut(&mut self) -> &mut T::BaseType {
         self.as_super()
@@ -589,15 +589,15 @@ impl<'py, T: PyClass<Frozen = False>> PyRefMut<'py, T> {
     }
 }
 
-impl<'p, T, U> PyRefMut<'p, T>
+impl<'p, T> PyRefMut<'p, T>
 where
-    T: PyClass<BaseType = U, Frozen = False>,
-    U: PyClass<Frozen = False>,
+    T: PyClass<Frozen = False>,
+    T::BaseType: PyClass<Frozen = False>,
 {
     /// Gets a `PyRef<T::BaseType>`.
     ///
     /// See [`PyRef::into_super`] for more.
-    pub fn into_super(self) -> PyRefMut<'p, U> {
+    pub fn into_super(self) -> PyRefMut<'p, T::BaseType> {
         let py = self.py();
         PyRefMut {
             inner: unsafe {
@@ -616,7 +616,7 @@ where
     /// can also be chained to access the super-superclass (and so on).
     ///
     /// See [`PyRef::as_super`] for more.
-    pub fn as_super(&mut self) -> &mut PyRefMut<'p, U> {
+    pub fn as_super(&mut self) -> &mut PyRefMut<'p, T::BaseType> {
         let mut ptr = NonNull::from(&mut self.inner)
             // `Bound<T>` has the same layout as `Bound<T::BaseType>`
             .cast::<Bound<'p, T::BaseType>>()

src/pyclass/guard.rs

@@ -142,10 +142,10 @@ impl<'a, T: PyClass> PyClassGuard<'a, T> {
     }
 }
 
-impl<'a, T, U> PyClassGuard<'a, T>
+impl<'a, T> PyClassGuard<'a, T>
 where
-    T: PyClass<BaseType = U>,
-    U: PyClass,
+    T: PyClass,
+    T::BaseType: PyClass,
 {
     /// Borrows a shared reference to `PyClassGuard<T::BaseType>`.
     ///
@@ -191,7 +191,7 @@ where
     /// #     pyo3::py_run!(py, sub, "assert sub.format_name_lengths() == '9 8'")
     /// # });
     /// ```
-    pub fn as_super(&self) -> &PyClassGuard<'a, U> {
+    pub fn as_super(&self) -> &PyClassGuard<'a, T::BaseType> {
         // SAFETY: `PyClassGuard<T>` and `PyClassGuard<U>` have the same layout
         unsafe { NonNull::from(self).cast().as_ref() }
     }
@@ -239,9 +239,10 @@ where
     /// #     pyo3::py_run!(py, sub, "assert sub.name() == 'base1 base2 sub'")
     /// # });
     /// ```
-    pub fn into_super(self) -> PyClassGuard<'a, U> {
+    pub fn into_super(self) -> PyClassGuard<'a, T::BaseType> {
         let t_not_frozen = !<T::Frozen as crate::pyclass::boolean_struct::private::Boolean>::VALUE;
-        let u_frozen = <U::Frozen as crate::pyclass::boolean_struct::private::Boolean>::VALUE;
+        let u_frozen =
+            <<T::BaseType as PyClass>::Frozen as crate::pyclass::boolean_struct::private::Boolean>::VALUE;
         if t_not_frozen && u_frozen {
             // If `T` is a mutable subclass of a frozen `U` base, then it is possible that we need
             // to release the borrow count now. (e.g. `U` may have a noop borrow checker so dropping
@@ -631,10 +632,10 @@ impl<'a, T: PyClass<Frozen = False>> PyClassGuardMut<'a, T> {
     }
 }
 
-impl<'a, T, U> PyClassGuardMut<'a, T>
+impl<'a, T> PyClassGuardMut<'a, T>
 where
-    T: PyClass<BaseType = U, Frozen = False>,
-    U: PyClass<Frozen = False>,
+    T: PyClass<Frozen = False>,
+    T::BaseType: PyClass<Frozen = False>,
 {
     /// Borrows a mutable reference to `PyClassGuardMut<T::BaseType>`.
     ///
@@ -644,15 +645,15 @@ where
     /// super-superclass (and so on).
     ///
     /// See [`PyClassGuard::as_super`] for more.
-    pub fn as_super(&mut self) -> &mut PyClassGuardMut<'a, U> {
+    pub fn as_super(&mut self) -> &mut PyClassGuardMut<'a, T::BaseType> {
         // SAFETY: `PyClassGuardMut<T>` and `PyClassGuardMut<U>` have the same layout
         unsafe { NonNull::from(self).cast().as_mut() }
     }
 
     /// Gets a `PyClassGuardMut<T::BaseType>`.
     ///
     /// See [`PyClassGuard::into_super`] for more.
-    pub fn into_super(self) -> PyClassGuardMut<'a, U> {
+    pub fn into_super(self) -> PyClassGuardMut<'a, T::BaseType> {
         // `PyClassGuardMut` is only available for non-frozen classes, so there
         // is no possibility of leaking borrows like `PyClassGuard`
         PyClassGuardMut {

src/pyclass_init.rs

@@ -138,8 +138,8 @@ impl<T: PyClass> PyClassInitializer<T> {
     #[inline]
     pub fn add_subclass<S>(self, subclass_value: S) -> PyClassInitializer<S>
     where
+        T: PyClassBaseType<Initializer = Self>,
         S: PyClass<BaseType = T>,
-        S::BaseType: PyClassBaseType<Initializer = Self>,
     {
         PyClassInitializer::new(subclass_value, self)
     }