Drop support for Home and XDG config files

This has been a huge support burden for us. I seriously considered doing
this in 3.0 but caved to a vocal minority and the desire to keep as much
backwards compatibility as possible. At this point, however, I'm done
witnessing the abuse Anthony has to suffer over this and I'm done with
the undue hostility that people who don't bother to read the docs
display. Hopefully, this eases that a bit.

src/flake8/options/aggregator.py

@@ -38,7 +38,7 @@ def aggregate_options(
     default_values, _ = manager.parse_args([])
 
     # Make our new configuration file mergerator
-    config_parser = config.MergedConfigParser(
+    config_parser = config.ConfigParser(
         option_manager=manager, config_finder=config_finder
     )
 

src/flake8/options/config.py

@@ -11,7 +11,7 @@ from flake8 import utils
 
 LOG = logging.getLogger(__name__)
 
-__all__ = ("ConfigFileFinder", "MergedConfigParser")
+__all__ = ("ConfigFileFinder", "ConfigParser")
 
 
 class ConfigFileFinder:
@@ -48,26 +48,12 @@ class ConfigFileFinder:
 
         # User configuration file.
         self.program_name = program_name
-        self.user_config_file = self._user_config_file(program_name)
 
         # List of filenames to find in the local/project directory
         self.project_filenames = ("setup.cfg", "tox.ini", f".{program_name}")
 
         self.local_directory = os.path.abspath(os.curdir)
 
-    @staticmethod
-    def _user_config_file(program_name: str) -> str:
-        if utils.is_windows():
-            home_dir = os.path.expanduser("~")
-            config_file_basename = f".{program_name}"
-        else:
-            home_dir = os.environ.get(
-                "XDG_CONFIG_HOME", os.path.expanduser("~/.config")
-            )
-            config_file_basename = program_name
-
-        return os.path.join(home_dir, config_file_basename)
-
     @staticmethod
     def _read_config(
         *files: str,
@@ -146,15 +132,8 @@ class ConfigFileFinder:
         """Parse all local config files into one config object."""
         return self.local_configs_with_files()[0]
 
-    def user_config(self):
-        """Parse the user config file into a config object."""
-        config, found_files = self._read_config(self.user_config_file)
-        if found_files:
-            LOG.debug("Found user configuration files: %s", found_files)
-        return config
 
-
-class MergedConfigParser:
+class ConfigParser:
     """Encapsulate merging different types of configuration files.
 
     This parses out the options registered that were specified in the
@@ -167,7 +146,7 @@ class MergedConfigParser:
     GETBOOL_ACTIONS = {"store_true", "store_false"}
 
     def __init__(self, option_manager, config_finder):
-        """Initialize the MergedConfigParser instance.
+        """Initialize the ConfigParser instance.
 
         :param flake8.options.manager.OptionManager option_manager:
             Initialized OptionManager.
@@ -239,19 +218,6 @@ class MergedConfigParser:
         LOG.debug("Parsing local configuration files.")
         return self._parse_config(config)
 
-    def parse_user_config(self):
-        """Parse and return the user configuration files."""
-        config = self.config_finder.user_config()
-        if not self.is_configured_by(config):
-            LOG.debug(
-                "User configuration files have no %s section",
-                self.program_name,
-            )
-            return {}
-
-        LOG.debug("Parsing user configuration files.")
-        return self._parse_config(config)
-
     def parse_cli_config(self, config_path):
         """Parse and return the file specified by --config."""
         config = self.config_finder.cli_config(config_path)
@@ -265,28 +231,8 @@ class MergedConfigParser:
         LOG.debug("Parsing CLI configuration files.")
         return self._parse_config(config, os.path.dirname(config_path))
 
-    def merge_user_and_local_config(self):
-        """Merge the parsed user and local configuration files.
-
-        :returns:
-            Dictionary of the parsed and merged configuration options.
-        :rtype:
-            dict
-        """
-        user_config = self.parse_user_config()
-        config = self.parse_local_config()
-
-        for option, value in user_config.items():
-            config.setdefault(option, value)
-
-        return config
-
     def parse(self):
-        """Parse and return the local and user config files.
-
-        First this copies over the parsed local configuration and then
-        iterates over the options in the user configuration and sets them if
-        they were not set by the local configuration file.
+        """Parse and return the local config files.
 
         :returns:
             Dictionary of parsed configuration options
@@ -309,7 +255,7 @@ class MergedConfigParser:
             )
             return self.parse_cli_config(self.config_finder.config_file)
 
-        return self.merge_user_and_local_config()
+        return self.parse_local_config()
 
 
 def get_local_plugins(config_finder):