MAINT: remove typing backward compatibility with Python < 3.9

We support typing only with Python >= 3.9.

Author: dnicolodi

mesonpy/__init__.py

@@ -57,9 +57,11 @@
 
 
 if typing.TYPE_CHECKING:  # pragma: no cover
-    from typing import Any, Callable, ClassVar, DefaultDict, List, Optional, Sequence, TextIO, Tuple, Type, TypeVar, Union
+    from typing import (
+        Any, Callable, ClassVar, DefaultDict, List, Literal, Optional, Sequence, TextIO, Tuple, Type, TypeVar, Union
+    )
 
-    from mesonpy._compat import Iterator, Literal, ParamSpec, Path
+    from mesonpy._compat import Iterator, ParamSpec, Path
 
     P = ParamSpec('P')
     T = TypeVar('T')

mesonpy/_compat.py

@@ -41,11 +41,6 @@ def read_binary(package: str, resource: str) -> bytes:
     else:
         from typing_extensions import ParamSpec
 
-    if sys.version_info >= (3, 8):
-        from typing import Literal
-    else:
-        from typing_extensions import Literal
-
     Path = Union[str, os.PathLike]
 
 
@@ -65,7 +60,6 @@ def is_relative_to(path: pathlib.Path, other: Union[pathlib.Path, str]) -> bool:
     'Collection',
     'Iterable',
     'Iterator',
-    'Literal',
     'Mapping',
     'Path',
     'ParamSpec',