Left-hand operands are fellback to RH ones for type mismatching

pyo3-derive-backend/src/defs.rs

@@ -65,18 +65,13 @@ pub struct SlotSetter {
     pub proto_names: &'static [&'static str],
     /// The name of the setter called to the method table.
     pub set_function: &'static str,
-    /// Represents a set of setters disabled by this setter.
-    /// E.g., `set_setdelitem` have to disable `set_setitem` and `set_delitem`.
-    pub skipped_setters: &'static [&'static str],
 }
 
 impl SlotSetter {
-    const EMPTY_SETTERS: &'static [&'static str] = &[];
     const fn new(names: &'static [&'static str], set_function: &'static str) -> Self {
         SlotSetter {
             proto_names: names,
             set_function,
-            skipped_setters: Self::EMPTY_SETTERS,
         }
     }
 }
@@ -144,11 +139,7 @@ pub const OBJECT: Proto = Proto {
         SlotSetter::new(&["__hash__"], "set_hash"),
         SlotSetter::new(&["__getattr__"], "set_getattr"),
         SlotSetter::new(&["__richcmp__"], "set_richcompare"),
-        SlotSetter {
+        SlotSetter::new(&["__setattr__", "__delattr__"], "set_setdelattr"),
-            proto_names: &["__setattr__", "__delattr__"],
-            set_function: "set_setdelattr",
-            skipped_setters: &["set_setattr", "set_delattr"],
-        },
         SlotSetter::new(&["__setattr__"], "set_setattr"),
         SlotSetter::new(&["__delattr__"], "set_delattr"),
         SlotSetter::new(&["__bool__"], "set_bool"),
@@ -379,11 +370,7 @@ pub const MAPPING: Proto = Proto {
     slot_setters: &[
         SlotSetter::new(&["__len__"], "set_length"),
         SlotSetter::new(&["__getitem__"], "set_getitem"),
-        SlotSetter {
+        SlotSetter::new(&["__setitem__", "__delitem__"], "set_setdelitem"),
-            proto_names: &["__setitem__", "__delitem__"],
-            set_function: "set_setdelitem",
-            skipped_setters: &["set_setitem", "set_delitem"],
-        },
         SlotSetter::new(&["__setitem__"], "set_setitem"),
         SlotSetter::new(&["__delitem__"], "set_delitem"),
     ],
@@ -446,11 +433,7 @@ pub const SEQ: Proto = Proto {
         SlotSetter::new(&["__concat__"], "set_concat"),
         SlotSetter::new(&["__repeat__"], "set_repeat"),
         SlotSetter::new(&["__getitem__"], "set_getitem"),
-        SlotSetter {
+        SlotSetter::new(&["__setitem__", "__delitem__"], "set_setdelitem"),
-            proto_names: &["__setitem__", "__delitem__"],
-            set_function: "set_setdelitem",
-            skipped_setters: &["set_setitem", "set_delitem"],
-        },
         SlotSetter::new(&["__setitem__"], "set_setitem"),
         SlotSetter::new(&["__delitem__"], "set_delitem"),
         SlotSetter::new(&["__contains__"], "set_contains"),
@@ -766,71 +749,40 @@ pub const NUM: Proto = Proto {
         ),
     ],
     slot_setters: &[
-        SlotSetter {
+        SlotSetter::new(&["__add__", "__radd__"], "set_add_radd"),
-            proto_names: &["__add__"],
+        SlotSetter::new(&["__add__"], "set_add"),
-            set_function: "set_add",
-            skipped_setters: &["set_radd"],
-        },
         SlotSetter::new(&["__radd__"], "set_radd"),
-        SlotSetter {
+        SlotSetter::new(&["__sub__", "__rsub__"], "set_sub_rsub"),
-            proto_names: &["__sub__"],
+        SlotSetter::new(&["__sub__"], "set_sub"),
-            set_function: "set_sub",
-            skipped_setters: &["set_rsub"],
-        },
         SlotSetter::new(&["__rsub__"], "set_rsub"),
-        SlotSetter {
+        SlotSetter::new(&["__mul__", "__rmul__"], "set_mul_rmul"),
-            proto_names: &["__mul__"],
+        SlotSetter::new(&["__mul__"], "set_mul"),
-            set_function: "set_mul",
-            skipped_setters: &["set_rmul"],
-        },
         SlotSetter::new(&["__rmul__"], "set_rmul"),
         SlotSetter::new(&["__mod__"], "set_mod"),
-        SlotSetter {
+        SlotSetter::new(&["__divmod__", "__rdivmod__"], "set_divmod_rdivmod"),
-            proto_names: &["__divmod__"],
+        SlotSetter::new(&["__divmod__"], "set_divmod"),
-            set_function: "set_divmod",
-            skipped_setters: &["set_rdivmod"],
-        },
         SlotSetter::new(&["__rdivmod__"], "set_rdivmod"),
-        SlotSetter {
+        SlotSetter::new(&["__pow__", "__rpow__"], "set_pow_rpow"),
-            proto_names: &["__pow__"],
+        SlotSetter::new(&["__pow__"], "set_pow"),
-            set_function: "set_pow",
-            skipped_setters: &["set_rpow"],
-        },
         SlotSetter::new(&["__rpow__"], "set_rpow"),
         SlotSetter::new(&["__neg__"], "set_neg"),
         SlotSetter::new(&["__pos__"], "set_pos"),
         SlotSetter::new(&["__abs__"], "set_abs"),
         SlotSetter::new(&["__invert__"], "set_invert"),
-        SlotSetter::new(&["__rdivmod__"], "set_rdivmod"),
+        SlotSetter::new(&["__lshift__", "__rlshift__"], "set_lshift_rlshift"),
-        SlotSetter {
+        SlotSetter::new(&["__lshift__"], "set_lshift"),
-            proto_names: &["__lshift__"],
-            set_function: "set_lshift",
-            skipped_setters: &["set_rlshift"],
-        },
         SlotSetter::new(&["__rlshift__"], "set_rlshift"),
-        SlotSetter {
+        SlotSetter::new(&["__rshift__", "__rrshift__"], "set_rshift_rrshift"),
-            proto_names: &["__rshift__"],
+        SlotSetter::new(&["__rshift__"], "set_rshift"),
-            set_function: "set_rshift",
-            skipped_setters: &["set_rrshift"],
-        },
         SlotSetter::new(&["__rrshift__"], "set_rrshift"),
-        SlotSetter {
+        SlotSetter::new(&["__and__", "__rand__"], "set_and_rand"),
-            proto_names: &["__and__"],
+        SlotSetter::new(&["__and__"], "set_and"),
-            set_function: "set_and",
-            skipped_setters: &["set_rand"],
-        },
         SlotSetter::new(&["__rand__"], "set_rand"),
-        SlotSetter {
+        SlotSetter::new(&["__xor__", "__rxor__"], "set_xor_rxor"),
-            proto_names: &["__xor__"],
+        SlotSetter::new(&["__xor__"], "set_xor"),
-            set_function: "set_xor",
-            skipped_setters: &["set_rxor"],
-        },
         SlotSetter::new(&["__rxor__"], "set_rxor"),
-        SlotSetter {
+        SlotSetter::new(&["__or__", "__ror__"], "set_or_ror"),
-            proto_names: &["__or__"],
+        SlotSetter::new(&["__or__"], "set_or"),
-            set_function: "set_or",
-            skipped_setters: &["set_ror"],
-        },
         SlotSetter::new(&["__ror__"], "set_ror"),
         SlotSetter::new(&["__int__"], "set_int"),
         SlotSetter::new(&["__float__"], "set_float"),
@@ -844,26 +796,17 @@ pub const NUM: Proto = Proto {
         SlotSetter::new(&["__iand__"], "set_iand"),
         SlotSetter::new(&["__ixor__"], "set_ixor"),
         SlotSetter::new(&["__ior__"], "set_ior"),
-        SlotSetter {
+        SlotSetter::new(&["__floordiv__", "__rfloordiv__"], "set_floordiv_rfloordiv"),
-            proto_names: &["__floordiv__"],
+        SlotSetter::new(&["__floordiv__"], "set_floordiv"),
-            set_function: "set_floordiv",
-            skipped_setters: &["set_rfloordiv"],
-        },
         SlotSetter::new(&["__rfloordiv__"], "set_rfloordiv"),
-        SlotSetter {
+        SlotSetter::new(&["__truediv__", "__rtruediv__"], "set_truediv_rtruediv"),
-            proto_names: &["__truediv__"],
+        SlotSetter::new(&["__truediv__"], "set_truediv"),
-            set_function: "set_truediv",
-            skipped_setters: &["set_rtruediv"],
-        },
         SlotSetter::new(&["__rtruediv__"], "set_rtruediv"),
         SlotSetter::new(&["__ifloordiv__"], "set_ifloordiv"),
         SlotSetter::new(&["__itruediv__"], "set_itruediv"),
         SlotSetter::new(&["__index__"], "set_index"),
-        SlotSetter {
+        SlotSetter::new(&["__matmul__", "__rmatmul__"], "set_matmul_rmatmul"),
-            proto_names: &["__matmul__"],
+        SlotSetter::new(&["__matmul__"], "set_matmul"),
-            set_function: "set_matmul",
-            skipped_setters: &["set_rmatmul"],
-        },
         SlotSetter::new(&["__rmatmul__"], "set_rmatmul"),
         SlotSetter::new(&["__imatmul__"], "set_imatmul"),
     ],

pyo3-derive-backend/src/pyproto.rs

@@ -134,23 +134,22 @@ fn slot_initialization(
     ty: &syn::Type,
     proto: &defs::Proto,
 ) -> syn::Result<TokenStream> {
-    // Some setters cannot coexist.
+    // To skip used protocols.
-    // E.g., if we have `__add__`, we need to skip `set_radd`.
+    // E.g., if __set__ and __del__ exist, we use set_set_del and skip set_set.
-    let mut skipped_setters = Vec::new();
+    let mut used_protocols = HashSet::new();
     // Collect initializers
     let mut initializers: Vec<TokenStream> = vec![];
-    'outer_loop: for m in proto.slot_setters {
+    for m in proto.slot_setters {
-        if skipped_setters.contains(&m.set_function) {
+        // Skip if any required protocol are not implemented or already used.
+        if m.proto_names
+            .iter()
+            .any(|name| !method_names.contains(*name) || used_protocols.contains(name))
+        {
             continue;
         }
         for name in m.proto_names {
-            // If this `#[pyproto]` block doesn't provide all required methods,
+            used_protocols.insert(name);
-            // let's skip implementing this method.
-            if !method_names.contains(*name) {
-                continue 'outer_loop;
         }
-        }
-        skipped_setters.extend_from_slice(m.skipped_setters);
         // Add slot methods to PyProtoRegistry
         let set = syn::Ident::new(m.set_function, Span::call_site());
         initializers.push(quote! { table.#set::<#ty>(); });

src/class/macros.rs

@@ -112,10 +112,39 @@ macro_rules! py_binary_reversed_num_func {
         {
             $crate::callback_body!(py, {
                 // Swap lhs <-> rhs
-                let slf = py.from_borrowed_ptr::<$crate::PyCell<T>>(rhs);
+                let slf: &$crate::PyCell<T> = extract_or_return_not_implemented!(py, rhs);
-                let arg = py.from_borrowed_ptr::<$crate::PyAny>(lhs);
+                let arg = extract_or_return_not_implemented!(py, lhs);
+                $class::$f(&*slf.try_borrow()?, arg).convert(py)
+            })
+        }
+        Some(wrap::<$class>)
+    }};
+}
 
-                $class::$f(&*slf.try_borrow()?, arg.extract()?).convert(py)
+#[macro_export]
+#[doc(hidden)]
+macro_rules! py_binary_fallbacked_num_func {
+    ($class:ident, $lop_trait: ident :: $lop: ident, $rop_trait: ident :: $rop: ident) => {{
+        unsafe extern "C" fn wrap<T>(
+            lhs: *mut ffi::PyObject,
+            rhs: *mut ffi::PyObject,
+        ) -> *mut $crate::ffi::PyObject
+        where
+            T: for<'p> $lop_trait<'p> + for<'p> $rop_trait<'p>,
+        {
+            $crate::callback_body!(py, {
+                let lhs = py.from_borrowed_ptr::<$crate::PyAny>(lhs);
+                let rhs = py.from_borrowed_ptr::<$crate::PyAny>(rhs);
+                // First, try the left hand method (e.g., __add__)
+                match (lhs.extract(), rhs.extract()) {
+                    (Ok(l), Ok(r)) => $class::$lop(l, r).convert(py),
+                    _ => {
+                        // Next, try the right hand method (e.g., __add__)
+                        let slf: &$crate::PyCell<T> = extract_or_return_not_implemented!(rhs);
+                        let arg = extract_or_return_not_implemented!(lhs);
+                        $class::$rop(&*slf.try_borrow()?, arg).convert(py)
+                    }
+                }
             })
         }
         Some(wrap::<$class>)
@@ -205,57 +234,6 @@ macro_rules! py_ternarys_func {
     };
 }
 
-#[macro_export]
-#[doc(hidden)]
-macro_rules! py_ternary_num_func {
-    ($trait:ident, $class:ident :: $f:ident) => {{
-        unsafe extern "C" fn wrap<T>(
-            arg1: *mut $crate::ffi::PyObject,
-            arg2: *mut $crate::ffi::PyObject,
-            arg3: *mut $crate::ffi::PyObject,
-        ) -> *mut $crate::ffi::PyObject
-        where
-            T: for<'p> $trait<'p>,
-        {
-            $crate::callback_body!(py, {
-                let arg1 = py
-                    .from_borrowed_ptr::<$crate::types::PyAny>(arg1)
-                    .extract()?;
-                let arg2 = extract_or_return_not_implemented!(py, arg2);
-                let arg3 = extract_or_return_not_implemented!(py, arg3);
-                $class::$f(arg1, arg2, arg3).convert(py)
-            })
-        }
-
-        Some(wrap::<T>)
-    }};
-}
-
-#[macro_export]
-#[doc(hidden)]
-macro_rules! py_ternary_reversed_num_func {
-    ($trait:ident, $class:ident :: $f:ident) => {{
-        unsafe extern "C" fn wrap<T>(
-            arg1: *mut $crate::ffi::PyObject,
-            arg2: *mut $crate::ffi::PyObject,
-            arg3: *mut $crate::ffi::PyObject,
-        ) -> *mut $crate::ffi::PyObject
-        where
-            T: for<'p> $trait<'p>,
-        {
-            $crate::callback_body!(py, {
-                // Swap lhs <-> rhs
-                let slf = py.from_borrowed_ptr::<$crate::PyCell<T>>(arg2);
-                let arg1 = py.from_borrowed_ptr::<$crate::PyAny>(arg1);
-                let arg2 = py.from_borrowed_ptr::<$crate::PyAny>(arg3);
-
-                $class::$f(&*slf.try_borrow()?, arg1.extract()?, arg2.extract()?).convert(py)
-            })
-        }
-        Some(wrap::<$class>)
-    }};
-}
-
 // NOTE(kngwyu): Somehow __ipow__ causes SIGSEGV in Python < 3.8 when we extract arg2,
 // so we ignore it. It's the same as what CPython does.
 #[macro_export]
@@ -370,6 +348,16 @@ macro_rules! py_func_set_del {
 }
 
 macro_rules! extract_or_return_not_implemented {
+    ($arg: ident) => {
+        match $arg.extract() {
+            Ok(value) => value,
+            Err(_) => {
+                let res = $crate::ffi::Py_NotImplemented();
+                ffi::Py_INCREF(res);
+                return Ok(res);
+            }
+        }
+    };
     ($py: ident, $arg: ident) => {
         match $py
             .from_borrowed_ptr::<$crate::types::PyAny>($arg)

src/class/number.rs

@@ -585,6 +585,16 @@ impl ffi::PyNumberMethods {
         nm.nb_bool = Some(nb_bool);
         Box::into_raw(Box::new(nm))
     }
+    pub fn set_add_radd<T>(&mut self)
+    where
+        T: for<'p> PyNumberAddProtocol<'p> + for<'p> PyNumberRAddProtocol<'p>,
+    {
+        self.nb_add = py_binary_fallbacked_num_func!(
+            T,
+            PyNumberAddProtocol::__add__,
+            PyNumberRAddProtocol::__radd__
+        );
+    }
     pub fn set_add<T>(&mut self)
     where
         T: for<'p> PyNumberAddProtocol<'p>,
@@ -597,6 +607,16 @@ impl ffi::PyNumberMethods {
     {
         self.nb_add = py_binary_reversed_num_func!(PyNumberRAddProtocol, T::__radd__);
     }
+    pub fn set_sub_rsub<T>(&mut self)
+    where
+        T: for<'p> PyNumberSubProtocol<'p> + for<'p> PyNumberRSubProtocol<'p>,
+    {
+        self.nb_subtract = py_binary_fallbacked_num_func!(
+            T,
+            PyNumberSubProtocol::__sub__,
+            PyNumberRSubProtocol::__rsub__
+        );
+    }
     pub fn set_sub<T>(&mut self)
     where
         T: for<'p> PyNumberSubProtocol<'p>,
@@ -609,6 +629,16 @@ impl ffi::PyNumberMethods {
     {
         self.nb_subtract = py_binary_reversed_num_func!(PyNumberRSubProtocol, T::__rsub__);
     }
+    pub fn set_mul_rmul<T>(&mut self)
+    where
+        T: for<'p> PyNumberMulProtocol<'p> + for<'p> PyNumberRMulProtocol<'p>,
+    {
+        self.nb_multiply = py_binary_fallbacked_num_func!(
+            T,
+            PyNumberMulProtocol::__mul__,
+            PyNumberRMulProtocol::__rmul__
+        );
+    }
     pub fn set_mul<T>(&mut self)
     where
         T: for<'p> PyNumberMulProtocol<'p>,
@@ -627,6 +657,16 @@ impl ffi::PyNumberMethods {
     {
         self.nb_remainder = py_binary_num_func!(PyNumberModProtocol, T::__mod__);
     }
+    pub fn set_divmod_rdivmod<T>(&mut self)
+    where
+        T: for<'p> PyNumberDivmodProtocol<'p> + for<'p> PyNumberRDivmodProtocol<'p>,
+    {
+        self.nb_divmod = py_binary_fallbacked_num_func!(
+            T,
+            PyNumberDivmodProtocol::__divmod__,
+            PyNumberRDivmodProtocol::__rdivmod__
+        );
+    }
     pub fn set_divmod<T>(&mut self)
     where
         T: for<'p> PyNumberDivmodProtocol<'p>,
@@ -639,17 +679,78 @@ impl ffi::PyNumberMethods {
     {
         self.nb_divmod = py_binary_reversed_num_func!(PyNumberRDivmodProtocol, T::__rdivmod__);
     }
+    pub fn set_pow_rpow<T>(&mut self)
+    where
+        T: for<'p> PyNumberPowProtocol<'p> + for<'p> PyNumberRPowProtocol<'p>,
+    {
+        unsafe extern "C" fn wrap_pow_and_rpow<T>(
+            lhs: *mut crate::ffi::PyObject,
+            rhs: *mut crate::ffi::PyObject,
+            modulo: *mut crate::ffi::PyObject,
+        ) -> *mut crate::ffi::PyObject
+        where
+            T: for<'p> PyNumberPowProtocol<'p> + for<'p> PyNumberRPowProtocol<'p>,
+        {
+            crate::callback_body!(py, {
+                let lhs = py.from_borrowed_ptr::<crate::PyAny>(lhs);
+                let rhs = py.from_borrowed_ptr::<crate::PyAny>(rhs);
+                let modulo = py.from_borrowed_ptr::<crate::PyAny>(modulo);
+                // First, try __pow__
+                match (lhs.extract(), rhs.extract(), modulo.extract()) {
+                    (Ok(l), Ok(r), Ok(m)) => T::__pow__(l, r, m).convert(py),
+                    _ => {
+                        // Then try __rpow__
+                        let slf: &crate::PyCell<T> = extract_or_return_not_implemented!(rhs);
+                        let arg = extract_or_return_not_implemented!(lhs);
+                        let modulo = extract_or_return_not_implemented!(modulo);
+                        slf.try_borrow()?.__rpow__(arg, modulo).convert(py)
+                    }
+                }
+            })
+        }
+        self.nb_power = Some(wrap_pow_and_rpow::<T>);
+    }
     pub fn set_pow<T>(&mut self)
     where
         T: for<'p> PyNumberPowProtocol<'p>,
     {
-        self.nb_power = py_ternary_num_func!(PyNumberPowProtocol, T::__pow__);
+        unsafe extern "C" fn wrap_pow<T>(
+            lhs: *mut crate::ffi::PyObject,
+            rhs: *mut crate::ffi::PyObject,
+            modulo: *mut crate::ffi::PyObject,
+        ) -> *mut crate::ffi::PyObject
+        where
+            T: for<'p> PyNumberPowProtocol<'p>,
+        {
+            crate::callback_body!(py, {
+                let lhs = extract_or_return_not_implemented!(py, lhs);
+                let rhs = extract_or_return_not_implemented!(py, rhs);
+                let modulo = extract_or_return_not_implemented!(py, modulo);
+                T::__pow__(lhs, rhs, modulo).convert(py)
+            })
+        }
+        self.nb_power = Some(wrap_pow::<T>);
     }
     pub fn set_rpow<T>(&mut self)
     where
         T: for<'p> PyNumberRPowProtocol<'p>,
     {
-        self.nb_power = py_ternary_reversed_num_func!(PyNumberRPowProtocol, T::__rpow__);
+        unsafe extern "C" fn wrap_rpow<T>(
+            arg: *mut crate::ffi::PyObject,
+            slf: *mut crate::ffi::PyObject,
+            modulo: *mut crate::ffi::PyObject,
+        ) -> *mut crate::ffi::PyObject
+        where
+            T: for<'p> PyNumberRPowProtocol<'p>,
+        {
+            crate::callback_body!(py, {
+                let slf: &crate::PyCell<T> = extract_or_return_not_implemented!(py, slf);
+                let arg = extract_or_return_not_implemented!(py, arg);
+                let modulo = extract_or_return_not_implemented!(py, modulo);
+                slf.try_borrow()?.__rpow__(arg, modulo).convert(py)
+            })
+        }
+        self.nb_power = Some(wrap_rpow::<T>);
     }
     pub fn set_neg<T>(&mut self)
     where
@@ -675,6 +776,16 @@ impl ffi::PyNumberMethods {
     {
         self.nb_invert = py_unary_func!(PyNumberInvertProtocol, T::__invert__);
     }
+    pub fn set_lshift_rlshift<T>(&mut self)
+    where
+        T: for<'p> PyNumberLShiftProtocol<'p> + for<'p> PyNumberRLShiftProtocol<'p>,
+    {
+        self.nb_lshift = py_binary_fallbacked_num_func!(
+            T,
+            PyNumberLShiftProtocol::__lshift__,
+            PyNumberRLShiftProtocol::__rlshift__
+        );
+    }
     pub fn set_lshift<T>(&mut self)
     where
         T: for<'p> PyNumberLShiftProtocol<'p>,
@@ -687,6 +798,16 @@ impl ffi::PyNumberMethods {
     {
         self.nb_lshift = py_binary_reversed_num_func!(PyNumberRLShiftProtocol, T::__rlshift__);
     }
+    pub fn set_rshift_rrshift<T>(&mut self)
+    where
+        T: for<'p> PyNumberRShiftProtocol<'p> + for<'p> PyNumberRRShiftProtocol<'p>,
+    {
+        self.nb_rshift = py_binary_fallbacked_num_func!(
+            T,
+            PyNumberRShiftProtocol::__rshift__,
+            PyNumberRRShiftProtocol::__rrshift__
+        );
+    }
     pub fn set_rshift<T>(&mut self)
     where
         T: for<'p> PyNumberRShiftProtocol<'p>,
@@ -699,6 +820,16 @@ impl ffi::PyNumberMethods {
     {
         self.nb_rshift = py_binary_reversed_num_func!(PyNumberRRShiftProtocol, T::__rrshift__);
     }
+    pub fn set_and_rand<T>(&mut self)
+    where
+        T: for<'p> PyNumberAndProtocol<'p> + for<'p> PyNumberRAndProtocol<'p>,
+    {
+        self.nb_and = py_binary_fallbacked_num_func!(
+            T,
+            PyNumberAndProtocol::__and__,
+            PyNumberRAndProtocol::__rand__
+        );
+    }
     pub fn set_and<T>(&mut self)
     where
         T: for<'p> PyNumberAndProtocol<'p>,
@@ -711,6 +842,16 @@ impl ffi::PyNumberMethods {
     {
         self.nb_and = py_binary_reversed_num_func!(PyNumberRAndProtocol, T::__rand__);
     }
+    pub fn set_xor_rxor<T>(&mut self)
+    where
+        T: for<'p> PyNumberXorProtocol<'p> + for<'p> PyNumberRXorProtocol<'p>,
+    {
+        self.nb_xor = py_binary_fallbacked_num_func!(
+            T,
+            PyNumberXorProtocol::__xor__,
+            PyNumberRXorProtocol::__rxor__
+        );
+    }
     pub fn set_xor<T>(&mut self)
     where
         T: for<'p> PyNumberXorProtocol<'p>,
@@ -723,6 +864,16 @@ impl ffi::PyNumberMethods {
     {
         self.nb_xor = py_binary_reversed_num_func!(PyNumberRXorProtocol, T::__rxor__);
     }
+    pub fn set_or_ror<T>(&mut self)
+    where
+        T: for<'p> PyNumberOrProtocol<'p> + for<'p> PyNumberROrProtocol<'p>,
+    {
+        self.nb_or = py_binary_fallbacked_num_func!(
+            T,
+            PyNumberOrProtocol::__or__,
+            PyNumberROrProtocol::__ror__
+        );
+    }
     pub fn set_or<T>(&mut self)
     where
         T: for<'p> PyNumberOrProtocol<'p>,
@@ -807,6 +958,16 @@ impl ffi::PyNumberMethods {
     {
         self.nb_inplace_or = py_binary_self_func!(PyNumberIOrProtocol, T::__ior__);
     }
+    pub fn set_floordiv_rfloordiv<T>(&mut self)
+    where
+        T: for<'p> PyNumberFloordivProtocol<'p> + for<'p> PyNumberRFloordivProtocol<'p>,
+    {
+        self.nb_floor_divide = py_binary_fallbacked_num_func!(
+            T,
+            PyNumberFloordivProtocol::__floordiv__,
+            PyNumberRFloordivProtocol::__rfloordiv__
+        );
+    }
     pub fn set_floordiv<T>(&mut self)
     where
         T: for<'p> PyNumberFloordivProtocol<'p>,
@@ -820,6 +981,16 @@ impl ffi::PyNumberMethods {
         self.nb_floor_divide =
             py_binary_reversed_num_func!(PyNumberRFloordivProtocol, T::__rfloordiv__);
     }
+    pub fn set_truediv_rtruediv<T>(&mut self)
+    where
+        T: for<'p> PyNumberTruedivProtocol<'p> + for<'p> PyNumberRTruedivProtocol<'p>,
+    {
+        self.nb_true_divide = py_binary_fallbacked_num_func!(
+            T,
+            PyNumberTruedivProtocol::__truediv__,
+            PyNumberRTruedivProtocol::__rtruediv__
+        );
+    }
     pub fn set_truediv<T>(&mut self)
     where
         T: for<'p> PyNumberTruedivProtocol<'p>,
@@ -853,6 +1024,16 @@ impl ffi::PyNumberMethods {
     {
         self.nb_index = py_unary_func!(PyNumberIndexProtocol, T::__index__);
     }
+    pub fn set_matmul_rmatmul<T>(&mut self)
+    where
+        T: for<'p> PyNumberMatmulProtocol<'p> + for<'p> PyNumberRMatmulProtocol<'p>,
+    {
+        self.nb_matrix_multiply = py_binary_fallbacked_num_func!(
+            T,
+            PyNumberMatmulProtocol::__matmul__,
+            PyNumberRMatmulProtocol::__rmatmul__
+        );
+    }
     pub fn set_matmul<T>(&mut self)
     where
         T: for<'p> PyNumberMatmulProtocol<'p>,

tests/test_arithmetics.rs

@@ -332,6 +332,58 @@ fn lhs_override_rhs() {
     py_run!(py, c, "assert 1 ** c == '1 ** BA'");
 }
 
+#[pyclass]
+#[derive(Debug)]
+struct Lhs2Rhs {}
+
+#[pyproto]
+impl PyNumberProtocol for Lhs2Rhs {
+    fn __add__(lhs: PyRef<Lhs2Rhs>, rhs: &PyAny) -> String {
+        format!("{:?} + {:?}", lhs, rhs)
+    }
+    fn __sub__(lhs: PyRef<Lhs2Rhs>, rhs: &PyAny) -> String {
+        format!("{:?} - {:?}", lhs, rhs)
+    }
+    fn __pow__(lhs: PyRef<Lhs2Rhs>, rhs: &PyAny, _mod: Option<usize>) -> String {
+        format!("{:?} ** {:?}", lhs, rhs)
+    }
+    fn __matmul__(lhs: PyRef<Lhs2Rhs>, rhs: &PyAny) -> String {
+        format!("{:?} @ {:?}", lhs, rhs)
+    }
+
+    fn __radd__(&self, other: &PyAny) -> String {
+        format!("{:?} + RA", other)
+    }
+    fn __rsub__(&self, rhs: &PyAny) -> String {
+        format!("{:?} - RA", rhs)
+    }
+    fn __rpow__(&self, rhs: &PyAny, _mod: Option<usize>) -> String {
+        format!("{:?} ** RA", rhs)
+    }
+    fn __rmatmul__(&self, rhs: &PyAny) -> String {
+        format!("{:?} @ RA", rhs)
+    }
+}
+
+#[pyproto]
+impl PyObjectProtocol for Lhs2Rhs {
+    fn __repr__(&self) -> &'static str {
+        "BA"
+    }
+}
+
+#[test]
+fn lhs_fallbacked_to_rhs() {
+    let gil = Python::acquire_gil();
+    let py = gil.python();
+
+    let c = PyCell::new(py, Lhs2Rhs {}).unwrap();
+    // Fallbacked to RHS because of type mismatching
+    py_run!(py, c, "assert 1 + c == '1 + RA'");
+    py_run!(py, c, "assert 1 - c == '1 - RA'");
+    py_run!(py, c, "assert 1 ** c == '1 ** RA'");
+}
+
 #[pyclass]
 struct RichComparisons {}