From 34cce21d29f9692a34fec22a76bee70939e628a5 Mon Sep 17 00:00:00 2001
From: Matus Valo <matusvalo@gmail.com>
Date: Sat, 20 Feb 2021 22:01:03 +0100
Subject: Move message definition to the DeprecatedMixin class

---
 examples/deprecation_checker.py | 20 ++++++--------------
 pylint/checkers/deprecated.py   |  9 +++++++++
 pylint/checkers/stdlib.py       |  2 +-
 3 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/examples/deprecation_checker.py b/examples/deprecation_checker.py
index a6a8e3963..7059c89ab 100644
--- a/examples/deprecation_checker.py
+++ b/examples/deprecation_checker.py
@@ -33,25 +33,17 @@ from pylint.checkers import BaseChecker, DeprecatedMixin, utils
 from pylint.interfaces import IAstroidChecker
 
 
-class DeprecationChecker(BaseChecker, DeprecatedMixin):
+class DeprecationChecker(DeprecatedMixin, BaseChecker):
     """Class implementing deprecation checker."""
 
+    # DeprecationMixin class is Mixin class implementing logic for searching deprecated methods and functions.
+    # The list of deprecated methods/functions is defined by implemeting class via deprecated_methods callback.
+    # DeprecatedMixin class is overriding attrigutes of BaseChecker hence must be specified *before* BaseChecker
+    # in list of base classes.
+
     __implements__ = (IAstroidChecker,)
     # The name defines a custom section of the config for this checker.
     name = "deprecated"
-    # This class variable declares the messages (ie the warnings and errors)
-    # that the checker can emit.
-    msgs = {
-        # Each message has a code, a message that the user will see,
-        # a unique symbol that identifies the message,
-        # and a detailed help message
-        # that will be included in the documentation.
-        "W1505": (
-            "Using deprecated method %s()",
-            "deprecated-method",
-            "The method is marked as deprecated and will be removed in the future.",
-        ),
-    }
 
     @utils.check_messages(
         "deprecated-method",
diff --git a/pylint/checkers/deprecated.py b/pylint/checkers/deprecated.py
index 0bbad05ee..54254340d 100644
--- a/pylint/checkers/deprecated.py
+++ b/pylint/checkers/deprecated.py
@@ -4,6 +4,7 @@
 """Checker mixin for deprecated functionality."""
 
 import abc
+from typing import Any
 
 import astroid
 
@@ -19,6 +20,14 @@ class DeprecatedMixin(metaclass=abc.ABCMeta):
     A class imlementing mixin must define "deprecated-method" Message.
     """
 
+    msgs: Any = {
+        "W1505": (
+            "Using deprecated method %s()",
+            "deprecated-method",
+            "The method is marked as deprecated and will be removed in the future.",
+        ),
+    }
+
     @abc.abstractmethod
     def deprecated_methods(self):
         """Callback returning the deprecated methods/functions.
diff --git a/pylint/checkers/stdlib.py b/pylint/checkers/stdlib.py
index ad6e4f855..26bce9435 100644
--- a/pylint/checkers/stdlib.py
+++ b/pylint/checkers/stdlib.py
@@ -80,7 +80,7 @@ def _check_mode_str(mode):
     return True
 
 
-class StdlibChecker(BaseChecker, DeprecatedMixin):
+class StdlibChecker(DeprecatedMixin, BaseChecker):
     __implements__ = (IAstroidChecker,)
     name = "stdlib"
 
-- 
cgit v1.2.1