Extra arg for "method" (self) and "classmethod" (cls)

doc/whatsnew/fragments/8675.false_negative

@@ -0,0 +1,3 @@
+Fix a false positive for `too-many-arguments` in (non static) method and classmethod.
+
+Closes #8675

pylint/checkers/design_analysis.py

@@ -561,20 +561,28 @@
                 ignored_args_num = ignored_pos_args_num + ignored_kwonly_args_num
 
             argnum = len(args) - ignored_args_num
-            if argnum > self.linter.config.max_args:
+            if node.type in {"function", "staticmethod"}:
+                max_args = self.linter.config.max_args
+                max_positional_arguments = self.linter.config.max_positional_arguments
+            elif node.type in {"method", "classmethod"}:
+                max_args = self.linter.config.max_args + 1
+                max_positional_arguments = (
+                    self.linter.config.max_positional_arguments + 1
+                )
+            if argnum > max_args:
                 self.add_message(
                     "too-many-arguments",
                     node=node,
-                    args=(len(args), self.linter.config.max_args),
+                    args=(len(args), max_args),
                 )
             pos_args_count = (
                 len(args) - len(node.args.kwonlyargs) - ignored_pos_args_num
             )
-            if pos_args_count > self.linter.config.max_positional_arguments:
+            if pos_args_count > max_positional_arguments:
                 self.add_message(
                     "too-many-positional-arguments",
                     node=node,
-                    args=(pos_args_count, self.linter.config.max_positional_arguments),
+                    args=(pos_args_count, max_positional_arguments),
                     confidence=HIGH,
                 )
         else:

tests/functional/t/too/too_many_positional_arguments.py

@@ -1,9 +1,9 @@
 # pylint: disable=missing-function-docstring, missing-module-docstring
-class FiveArgumentMethods:
-    """The max positional arguments default is 5."""
-    def fail1(self, a, b, c, d, e):  # [too-many-arguments, too-many-positional-arguments]
+class SixArgumentMethods:
+    """The max positional arguments default is 5, so 6 for a method because of self."""
+    def fail1(self, a, b, c, d, e, f):  # [too-many-arguments, too-many-positional-arguments]
         pass
-    def fail2(self, a, b, c, d, /, e):  # [too-many-arguments, too-many-positional-arguments]
+    def fail2(self, a, b, c, d, e, /, f):  # [too-many-arguments, too-many-positional-arguments]
         pass
-    def okay1(self, a, b, c, d, *, e=True):  # [too-many-arguments]
+    def okay1(self, a, b, c, d, e, *, f=True):  # [too-many-arguments]
         pass

tests/functional/t/too/too_many_positional_arguments.txt

@@ -1,5 +1,5 @@
-too-many-arguments:4:4:4:13:FiveArgumentMethods.fail1:Too many arguments (6/5):UNDEFINED
-too-many-positional-arguments:4:4:4:13:FiveArgumentMethods.fail1:Too many positional arguments (6/5):HIGH
-too-many-arguments:6:4:6:13:FiveArgumentMethods.fail2:Too many arguments (6/5):UNDEFINED
-too-many-positional-arguments:6:4:6:13:FiveArgumentMethods.fail2:Too many positional arguments (6/5):HIGH
-too-many-arguments:8:4:8:13:FiveArgumentMethods.okay1:Too many arguments (6/5):UNDEFINED
+too-many-arguments:4:4:4:13:SixArgumentMethods.fail1:Too many arguments (7/6):UNDEFINED
+too-many-positional-arguments:4:4:4:13:SixArgumentMethods.fail1:Too many positional arguments (7/6):HIGH
+too-many-arguments:6:4:6:13:SixArgumentMethods.fail2:Too many arguments (7/6):UNDEFINED
+too-many-positional-arguments:6:4:6:13:SixArgumentMethods.fail2:Too many positional arguments (7/6):HIGH
+too-many-arguments:8:4:8:13:SixArgumentMethods.okay1:Too many arguments (7/6):UNDEFINED