Partially revert Clean up argparse hacks

Author: cdce8p

mypy/typeshed/stdlib/argparse.pyi

@@ -2,7 +2,7 @@ import sys
 from _typeshed import SupportsWrite, sentinel
 from collections.abc import Callable, Generator, Iterable, Sequence
 from re import Pattern
-from typing import IO, Any, ClassVar, Final, Generic, NoReturn, Protocol, TypeVar, overload
+from typing import IO, Any, ClassVar, Final, Generic, NewType, NoReturn, Protocol, TypeVar, overload
 from typing_extensions import Self, TypeAlias, deprecated
 
 __all__ = [
@@ -36,7 +36,9 @@ ONE_OR_MORE: Final = "+"
 OPTIONAL: Final = "?"
 PARSER: Final = "A..."
 REMAINDER: Final = "..."
-SUPPRESS: Final = "==SUPPRESS=="
+_SUPPRESS_T = NewType("_SUPPRESS_T", str)
+SUPPRESS: _SUPPRESS_T | str  # not using Literal because argparse sometimes compares SUPPRESS with is
+# the | str is there so that foo = argparse.SUPPRESS; foo = "test" checks out in mypy
 ZERO_OR_MORE: Final = "*"
 _UNRECOGNIZED_ARGS_ATTR: Final = "_unrecognized_args"  # undocumented
 
@@ -79,7 +81,7 @@ class _ActionsContainer:
         # more precisely, Literal["?", "*", "+", "...", "A...", "==SUPPRESS=="],
         # but using this would make it hard to annotate callers that don't use a
         # literal argument and for subclasses to override this method.
-        nargs: int | str | None = None,
+        nargs: int | str | _SUPPRESS_T | None = None,
         const: Any = ...,
         default: Any = ...,
         type: _ActionType = ...,