Fix regression property no member 2641

ChangeLog

@@ -6,6 +6,10 @@ What's New in astroid 2.5.0?
 ============================
 Release Date: TBA
 
+* Adds `attr_fset` in the `PropertyModel` class.
+
+  Fixes PyCQA/pylint#3480
+
 * Remove support for Python 3.5.
 * Remove the runtime dependency on ``six``. The ``six`` brain remains in
   astroid.

astroid/interpreter/objectmodel.py

@@ -32,11 +32,16 @@
 import os
 import types
 from functools import lru_cache
+from typing import Optional
 
 import astroid
 from astroid import context as contextmod
 from astroid import exceptions
 from astroid import node_classes
+from astroid import util
+
+# Prevents circular imports
+objects = util.lazy_import("objects")
 
 
 IMPL_PREFIX = "attr_"
@@ -715,9 +720,6 @@ def attr_items(self):
             elems.append(elem)
         obj.postinit(elts=elems)
 
-        # pylint: disable=import-outside-toplevel; circular import
-        from astroid import objects
-
         obj = objects.DictItems(obj)
         return self._generic_dict_attribute(obj, "items")
 
@@ -727,9 +729,6 @@ def attr_keys(self):
         obj = node_classes.List(parent=self._instance)
         obj.postinit(elts=keys)
 
-        # pylint: disable=import-outside-toplevel; circular import
-        from astroid import objects
-
         obj = objects.DictKeys(obj)
         return self._generic_dict_attribute(obj, "keys")
 
@@ -740,9 +739,6 @@ def attr_values(self):
         obj = node_classes.List(parent=self._instance)
         obj.postinit(values)
 
-        # pylint: disable=import-outside-toplevel; circular import
-        from astroid import objects
-
         obj = objects.DictValues(obj)
         return self._generic_dict_attribute(obj, "values")
 
@@ -794,6 +790,46 @@ def infer_call_result(self, caller=None, context=None):
         property_accessor.postinit(args=func.args, body=func.body)
         return property_accessor
 
+    @property
+    def attr_fset(self):
+        from astroid.scoped_nodes import FunctionDef
+
+        func = self._instance
+
+        def find_setter(func: objects.Property) -> Optional[astroid.FunctionDef]:
+            """
+            Given a property, find the corresponding setter function and returns it. 
+
+            :param func: property for which the setter has to be found
+            :return: the setter function or None
+            """
+            for target in [
+                t for t in func.parent.get_children() if t.name == func.function.name
+            ]:
+                for dec_name in target.decoratornames():
+                    if dec_name.endswith(func.function.name + ".setter"):
+                        return target
+            return None
+
+        func_setter = find_setter(func)
+        if not func_setter:
+            raise exceptions.InferenceError(
+                f"Unable to find the setter of property {func.function.name}"
+            )
+
+        class PropertyFuncAccessor(FunctionDef):
+            def infer_call_result(self, caller=None, context=None):
+                nonlocal func_setter
+                if caller and len(caller.args) != 2:
+                    raise exceptions.InferenceError(
+                        "fset() needs two arguments", target=self, context=context
+                    )
+                yield from func_setter.infer_call_result(caller=caller, context=context)
+
+        property_accessor = PropertyFuncAccessor(name="fset", parent=self._instance)
+        property_accessor.postinit(args=func_setter.args, body=func_setter.body)
+        return property_accessor
+
     @property
     def attr_setter(self):
         return self._init_function("setter")

tests/unittest_inference.py

@@ -5494,14 +5494,19 @@ class A:
         def test(self):
             return 42
 
+        @test.setter
+        def test(self, value):
+            return "banco"
+
     A.test #@
     A().test #@
     A.test.fget(A) #@
+    A.test.fset(A, "a_value") #@
     A.test.setter #@
     A.test.getter #@
     A.test.deleter #@
     """
-    prop, prop_result, prop_fget_result, prop_setter, prop_getter, prop_deleter = extract_node(
+    prop, prop_result, prop_fget_result, prop_fset_result, prop_setter, prop_getter, prop_deleter = extract_node(
         code
     )
 
@@ -5519,6 +5524,10 @@ def test(self):
     assert isinstance(inferred, nodes.Const)
     assert inferred.value == 42
 
+    inferred = next(prop_fset_result.infer())
+    assert isinstance(inferred, nodes.Const)
+    assert inferred.value == "banco"
+
     for prop_func in prop_setter, prop_getter, prop_deleter:
         inferred = next(prop_func.infer())
         assert isinstance(inferred, nodes.FunctionDef)