Use overload to type get_global_option (pylint-dev#4978)

* Use ``overload`` to type ``get_global_option``
* Use type alias and TypeVar

Co-authored-by: Marc Mueller <30130371+cdce8p@users.noreply.github.com>

pylint/extensions/code_style.py

@@ -77,7 +77,7 @@ def __init__(self, linter: PyLinter) -> None:
         super().__init__(linter=linter)
 
     def open(self) -> None:
-        py_version: Tuple[int, int] = get_global_option(self, "py-version")
+        py_version = get_global_option(self, "py-version")
         self._py38_plus = py_version >= (3, 8)
         self._max_length: int = (
             self.config.max_line_length_suggestions

pylint/extensions/typing.py

@@ -1,4 +1,4 @@
-from typing import Dict, List, NamedTuple, Set, Tuple, Union
+from typing import Dict, List, NamedTuple, Set, Union
 
 import astroid.bases
 from astroid import nodes
@@ -139,7 +139,7 @@ def __init__(self, linter: PyLinter) -> None:
         self._consider_using_alias_msgs: List[DeprecatedTypingAliasMsg] = []
 
     def open(self) -> None:
-        py_version: Tuple[int, int] = get_global_option(self, "py-version")
+        py_version = get_global_option(self, "py-version")
         self._py37_plus = py_version >= (3, 7)
         self._py39_plus = py_version >= (3, 9)
         self._py310_plus = py_version >= (3, 10)

pylint/utils/utils.py

@@ -17,13 +17,55 @@
 import sys
 import textwrap
 import tokenize
+from typing import (
+    TYPE_CHECKING,
+    List,
+    Optional,
+    Pattern,
+    Tuple,
+    TypeVar,
+    Union,
+    overload,
+)
 
 from astroid import Module, modutils
 
 from pylint.constants import PY_EXTS
 
+if sys.version_info >= (3, 8):
+    from typing import Literal
+else:
+    from typing_extensions import Literal
+
+if TYPE_CHECKING:
+    from pylint.checkers.base_checker import BaseChecker
+
 DEFAULT_LINE_LENGTH = 79
 
+# These are types used to overload get_global_option() and refer to the options type
+GLOBAL_OPTION_BOOL = Literal[
+    "ignore-mixin-members",
+    "suggestion-mode",
+    "analyse-fallback-blocks",
+    "allow-global-unused-variables",
+]
+GLOBAL_OPTION_INT = Literal["max-line-length", "docstring-min-length"]
+GLOBAL_OPTION_LIST = Literal["ignored-modules"]
+GLOBAL_OPTION_PATTERN = Literal[
+    "no-docstring-rgx", "dummy-variables-rgx", "ignored-argument-names"
+]
+GLOBAL_OPTION_TUPLE_INT = Literal["py-version"]
+GLOBAL_OPTION_NAMES = Union[
+    GLOBAL_OPTION_BOOL,
+    GLOBAL_OPTION_INT,
+    GLOBAL_OPTION_LIST,
+    GLOBAL_OPTION_PATTERN,
+    GLOBAL_OPTION_TUPLE_INT,
+]
+T_GlobalOptionReturnTypes = TypeVar(
+    "T_GlobalOptionReturnTypes", bool, int, List[str], Pattern, Tuple[int, ...]
+)
+
 
 def normalize_text(text, line_len=DEFAULT_LINE_LENGTH, indent=""):
     """Wrap the text on the given line length."""
@@ -148,7 +190,52 @@ def register_plugins(linter, directory):
                     imported[base] = 1
 
 
-def get_global_option(checker, option, default=None):
+@overload
+def get_global_option(
+    checker: "BaseChecker", option: GLOBAL_OPTION_BOOL, default: Optional[bool] = None
+) -> bool:
+    ...
+
+
+@overload
+def get_global_option(
+    checker: "BaseChecker", option: GLOBAL_OPTION_INT, default: Optional[int] = None
+) -> int:
+    ...
+
+
+@overload
+def get_global_option(
+    checker: "BaseChecker",
+    option: GLOBAL_OPTION_LIST,
+    default: Optional[List[str]] = None,
+) -> List[str]:
+    ...
+
+
+@overload
+def get_global_option(
+    checker: "BaseChecker",
+    option: GLOBAL_OPTION_PATTERN,
+    default: Optional[Pattern] = None,
+) -> Pattern:
+    ...
+
+
+@overload
+def get_global_option(
+    checker: "BaseChecker",
+    option: GLOBAL_OPTION_TUPLE_INT,
+    default: Optional[Tuple[int, ...]] = None,
+) -> Tuple[int, ...]:
+    ...
+
+
+def get_global_option(
+    checker: "BaseChecker",
+    option: GLOBAL_OPTION_NAMES,
+    default: Optional[T_GlobalOptionReturnTypes] = None,
+) -> Optional[T_GlobalOptionReturnTypes]:
     """Retrieve an option defined by the given *checker* or
     by all known option providers.