Merge pull request RustPython#4642 from xiaozhiyan/fix-rsub-of-pyset-pyfrozenset

Fix `rsub` of `PySet` and `PyFrozenSet`

Author: youknowone

extra_tests/snippets/builtin_set.py

@@ -103,6 +103,9 @@ class S(set):
 assert set([1,2,3]) - set([1,2,3,4,5]) == set([])
 assert_raises(TypeError, lambda: set([1,2,3]) - [1,2,3,4,5])
 
+assert set([1,2]).__sub__(set([2,3])) == set([1])
+assert set([1,2]).__rsub__(set([2,3])) == set([3])
+
 assert set([1,2,3]).symmetric_difference(set([1,2])) == set([3])
 assert set([1,2,3]).symmetric_difference(set([5,6])) == set([1,2,3,5,6])
 assert set([1,2,3]).symmetric_difference([1,2]) == set([3])
@@ -271,6 +274,9 @@ class S(set):
 assert frozenset([1,2,3]) - frozenset([1,2,3,4,5]) == frozenset([])
 assert_raises(TypeError, lambda: frozenset([1,2,3]) - [1,2,3,4,5])
 
+assert frozenset([1,2]).__sub__(frozenset([2,3])) == frozenset([1])
+assert frozenset([1,2]).__rsub__(frozenset([2,3])) == frozenset([3])
+
 assert frozenset([1,2,3]).symmetric_difference(frozenset([1,2])) == frozenset([3])
 assert frozenset([1,2,3]).symmetric_difference(frozenset([5,6])) == frozenset([1,2,3,5,6])
 assert frozenset([1,2,3]).symmetric_difference([1,2]) == frozenset([3])
@@ -311,6 +317,11 @@ class S(set):
 assert frozenset([1,2,3]) - set([4,5]) == frozenset([1,2,3])
 assert set([1,2,3]) - frozenset([4,5]) == frozenset([1,2,3])
 
+assert frozenset([1,2]).__sub__(set([2,3])) == frozenset([1])
+assert frozenset([1,2]).__rsub__(set([2,3])) == set([3])
+assert set([1,2]).__sub__(frozenset([2,3])) == set([1])
+assert set([1,2]).__rsub__(frozenset([2,3])) == frozenset([3])
+
 assert frozenset([1,2,3]).symmetric_difference(set([1,2])) == frozenset([3])
 assert set([1,2,3]).symmetric_difference(frozenset([1,2])) == set([3])
 

vm/src/builtins/set.rs

@@ -604,8 +604,20 @@ impl PySet {
     }
 
     #[pymethod(magic)]
-    fn rsub(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyResult<PyArithmeticValue<Self>> {
-        self.sub(other, vm)
+    fn rsub(
+        zelf: PyRef<Self>,
+        other: PyObjectRef,
+        vm: &VirtualMachine,
+    ) -> PyResult<PyArithmeticValue<Self>> {
+        if let Ok(other) = AnySet::try_from_object(vm, other) {
+            Ok(PyArithmeticValue::Implemented(Self {
+                inner: other
+                    .as_inner()
+                    .difference(ArgIterable::try_from_object(vm, zelf.into())?, vm)?,
+            }))
+        } else {
+            Ok(PyArithmeticValue::NotImplemented)
+        }
     }
 
     #[pymethod(name = "__rxor__")]
@@ -1003,8 +1015,20 @@ impl PyFrozenSet {
     }
 
     #[pymethod(magic)]
-    fn rsub(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyResult<PyArithmeticValue<Self>> {
-        self.sub(other, vm)
+    fn rsub(
+        zelf: PyRef<Self>,
+        other: PyObjectRef,
+        vm: &VirtualMachine,
+    ) -> PyResult<PyArithmeticValue<Self>> {
+        if let Ok(other) = AnySet::try_from_object(vm, other) {
+            Ok(PyArithmeticValue::Implemented(Self {
+                inner: other
+                    .as_inner()
+                    .difference(ArgIterable::try_from_object(vm, zelf.into())?, vm)?,
+            }))
+        } else {
+            Ok(PyArithmeticValue::NotImplemented)
+        }
     }
 
     #[pymethod(name = "__rxor__")]