plugin: drop deprecated Plugin constructor wrapper

Streamlink 5.0.0 added this compatibility wrapper for the Plugin class
constructor after its signature got changed.

src/streamlink/plugin/plugin.py

@@ -1,10 +1,8 @@
 import ast
-import inspect
 import logging
 import operator
 import re
 import time
-import warnings
 from contextlib import suppress
 from functools import partial
 from http.cookiejar import Cookie
@@ -218,16 +216,6 @@ class Matches(_MCollection[Optional[Match]]):
         return next(((matcher.pattern, match) for matcher, match in matches if match is not None), (None, None))
 
 
-# Add front- and back-wrappers to the deprecated plugin's method resolution order (see Plugin.__new__)
-class PluginWrapperMeta(type):
-    def mro(cls):
-        # cls.__base__ is the PluginWrapperFront which is based on the deprecated plugin class
-        mro = list(cls.__base__.__mro__)
-        # cls is the PluginWrapperBack and needs to be inserted after the deprecated plugin class
-        mro.insert(2, cls)
-        return mro
-
-
 class Plugin:
     """
     Plugin base class for retrieving streams and metadata from the URL specified.
@@ -277,45 +265,6 @@ class Plugin:
     # deprecated
     priority: Callable[[str], int]
 
-    # Handle deprecated plugin constructors which only take the url argument
-    def __new__(cls, *args, **kwargs):
-        # Ignore plugins without custom constructors or wrappers
-        if cls.__init__ is Plugin.__init__ or hasattr(cls, "_IS_DEPRECATED_PLUGIN_WRAPPER"):
-            return super().__new__(cls)
-
-        # Ignore custom constructors which have a formal "session" parameter or a variable positional parameter
-        sig = inspect.signature(cls.__init__).parameters
-        if "session" in sig or any(param.kind == inspect.Parameter.VAR_POSITIONAL for param in sig.values()):
-            return super().__new__(cls)
-
-        # Wrapper class which overrides the very first constructor in the MRO
-        # noinspection PyAbstractClass
-        class PluginWrapperFront(cls):
-            _IS_DEPRECATED_PLUGIN_WRAPPER = True
-
-            # The __module__ value needs to be copied
-            __module__ = cls.__module__
-
-            def __init__(self, session, url):
-                # Take any arguments, but only pass the URL to the custom constructor of the deprecated plugin
-                # noinspection PyArgumentList
-                super().__init__(url)
-                warnings.warn(
-                    f"Initialized {self.module} plugin with deprecated constructor",
-                    FutureWarning,
-                    stacklevel=2,
-                )
-
-        # Wrapper class which comes after the deprecated plugin in the MRO
-        # noinspection PyAbstractClass
-        class PluginWrapperBack(PluginWrapperFront, metaclass=PluginWrapperMeta):
-            def __init__(self, *_, **__):
-                # Take any arguments from the super() call of the constructor of the deprecated plugin,
-                # but pass the right args and keywords to the Plugin constructor
-                super().__init__(*args, **kwargs)
-
-        return cls.__new__(PluginWrapperBack, *args, **kwargs)
-
     def __init__(self, session: "Streamlink", url: str, options: Optional[Options] = None):
         """
         :param session: The Streamlink session instance

tests/test_plugin.py

@@ -44,12 +44,6 @@ class CustomConstructorTwoPlugin(FakePlugin):
         super().__init__(session, url)
 
 
-class DeprecatedPlugin(FakePlugin):
-    def __init__(self, url):
-        super().__init__(url)  # type: ignore[call-arg]
-        self.custom_attribute = url.upper()
-
-
 class TestPlugin:
     @pytest.mark.parametrize(("pluginclass", "module", "logger"), [
         (Plugin, "plugin", "streamlink.plugin.plugin"),
@@ -79,35 +73,6 @@ class TestPlugin:
 
         assert mock_load_cookies.call_args_list == [call()]
 
-    def test_constructor_wrapper(self, recwarn: pytest.WarningsRecorder):
-        session = Mock()
-        with patch("streamlink.plugin.plugin.Cache") as mock_cache, \
-             patch.object(DeprecatedPlugin, "load_cookies") as mock_load_cookies:
-            plugin = DeprecatedPlugin(session, "http://localhost")  # type: ignore[call-arg]
-
-        assert isinstance(plugin, DeprecatedPlugin)
-        assert plugin.custom_attribute == "HTTP://LOCALHOST"
-        assert [(record.category, str(record.message), record.filename) for record in recwarn.list] == [
-            (
-                FutureWarning,
-                "Initialized test_plugin plugin with deprecated constructor",
-                __file__,
-            ),
-        ]
-
-        assert plugin.session is session
-        assert plugin.url == "http://localhost"
-
-        assert plugin.module == "test_plugin"
-
-        assert isinstance(plugin.logger, logging.Logger)
-        assert plugin.logger.name == "tests.test_plugin"
-
-        assert mock_cache.call_args_list == [call(filename="plugin-cache.json", key_prefix="test_plugin")]
-        assert plugin.cache == mock_cache()
-
-        assert mock_load_cookies.call_args_list == [call()]
-
     def test_constructor_options(self):
         one = FakePlugin(Mock(), "https://mocked", Options({"key": "val"}))
         two = FakePlugin(Mock(), "https://mocked")