Fix false positive for no-self-argument

doc/whatsnew/fragments/7300.false_positive

@@ -0,0 +1,3 @@
+Fix false positive for `no-self-argument` when a staticmethod is applied to a function but uses a different name.
+
+Closes #7300

pylint/checkers/classes/class_checker.py

@@ -1926,6 +1926,9 @@ def _check_first_arg_for_type(
                 self.add_message("bad-staticmethod-argument", args=first, node=node)
                 return
             self._first_attrs[-1] = None
+        elif any(name == "builtins.staticmethod" for name in node.decoratornames()):
+            # Check if there is a decorator which is not named `staticmethod` but is assigned to one.
+            return
         # class / regular method with no args
         elif not node.args.args and not node.args.posonlyargs:
             self.add_message("no-method-argument", node=node)

tests/functional/n/no/no_self_argument.py

@@ -1,8 +1,15 @@
 """Check for method without self as first argument"""
-# pylint: disable=useless-object-inheritance
-from __future__ import print_function
 
-class NoSelfArgument(object):
+
+MYSTATICMETHOD = staticmethod
+
+
+def returns_staticmethod(my_function):
+    """Create a staticmethod from function `my_function`"""
+    return staticmethod(my_function)
+
+
+class NoSelfArgument:
     """dummy class"""
 
     def __init__(truc):  # [no-self-argument]
@@ -16,3 +23,18 @@ def abdc(yoo):  # [no-self-argument]
     def edf(self):
         """just another method"""
         print('yapudju in', self)
+
+    @staticmethod
+    def say_hello():
+        """A standard staticmethod"""
+        print("hello!")
+
+    @MYSTATICMETHOD
+    def say_goodbye():
+        """A staticmethod but using a different name"""
+        print("goodbye!")
+
+    @returns_staticmethod
+    def sum_strings(string1, string2):
+        """A staticmethod created by `returns_staticmethod` function"""
+        return string1 + string2

tests/functional/n/no/no_self_argument.txt

@@ -1,2 +1,2 @@
-no-self-argument:8:4:8:16:NoSelfArgument.__init__:"Method should have ""self"" as first argument":UNDEFINED
-no-self-argument:12:4:12:12:NoSelfArgument.abdc:"Method should have ""self"" as first argument":UNDEFINED
+no-self-argument:15:4:15:16:NoSelfArgument.__init__:"Method should have ""self"" as first argument":UNDEFINED
+no-self-argument:19:4:19:12:NoSelfArgument.abdc:"Method should have ""self"" as first argument":UNDEFINED