From a12975bd8f4a6cdbd05b94bdc4f86a3408061db0 Mon Sep 17 00:00:00 2001
From: Jakob Stadler <127443735+Jakob-Stadler@users.noreply.github.com>
Date: Fri, 30 Jun 2023 10:49:54 +0200
Subject: [PATCH 1/4] Fix namespace argument regression in argparse.parse_args

The previous commit [1] explicitly added `Namespace` to the first overload, which causes a false-postive when the used `namespace=` argument is a subclass of  `Namespace`.

Example code, flagged both in pyright and mypy (with most recent typeshed):

```python
import argparse
import sys

# Explicit subclass of Namepsace
# not strictly necessary, but it conveys intent better than a standalone class
class ExampleNamespace(argparse.Namespace):
  example_argument: str

parser = argparse.ArgumentParser()
parser.add_argument('example_argument')


ns = parser.parse_args(sys.argv, ExampleNamespace())
reveal_type(ns)  # Revealed type is "Namespace"


# error: Incompatible types in assignment (expression has type "Namespace", variable has type "ExampleNamespace")  [assignment]
ens: ExampleNamespace = parser.parse_args(sys.argv, ExampleNamespace())
reveal_type(ens)  # Revealed type is "ExampleNamespace"
```

[1] https://github.com/python/typeshed/pull/10307
---
 stdlib/argparse.pyi | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/stdlib/argparse.pyi b/stdlib/argparse.pyi
index e41048516dd9..182f96bd0432 100644
--- a/stdlib/argparse.pyi
+++ b/stdlib/argparse.pyi
@@ -171,7 +171,7 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
         ) -> None: ...
 
     @overload
-    def parse_args(self, args: Sequence[str] | None = None, namespace: Namespace | None = None) -> Namespace: ...  # type: ignore[misc]
+    def parse_args(self, args: Sequence[str] | None = None, namespace: None = None) -> Namespace: ...  # type: ignore[misc]
     @overload
     def parse_args(self, args: Sequence[str] | None, namespace: _N) -> _N: ...
     @overload
@@ -210,7 +210,7 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
     def format_usage(self) -> str: ...
     def format_help(self) -> str: ...
     @overload
-    def parse_known_args(self, args: Sequence[str] | None = None, namespace: Namespace | None = None) -> tuple[Namespace, list[str]]: ...  # type: ignore[misc]
+    def parse_known_args(self, args: Sequence[str] | None = None, namespace: None = None) -> tuple[Namespace, list[str]]: ...  # type: ignore[misc]
     @overload
     def parse_known_args(self, args: Sequence[str] | None, namespace: _N) -> tuple[_N, list[str]]: ...
     @overload
@@ -219,13 +219,13 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
     def exit(self, status: int = 0, message: str | None = None) -> NoReturn: ...
     def error(self, message: str) -> NoReturn: ...
     @overload
-    def parse_intermixed_args(self, args: Sequence[str] | None = None, namespace: Namespace | None = None) -> Namespace: ...  # type: ignore[misc]
+    def parse_intermixed_args(self, args: Sequence[str] | None = None, namespace: None = None) -> Namespace: ...  # type: ignore[misc]
     @overload
     def parse_intermixed_args(self, args: Sequence[str] | None, namespace: _N) -> _N: ...
     @overload
     def parse_intermixed_args(self, *, namespace: _N) -> _N: ...
     @overload
-    def parse_known_intermixed_args(self, args: Sequence[str] | None = None, namespace: Namespace | None = None) -> tuple[Namespace, list[str]]: ...  # type: ignore[misc]
+    def parse_known_intermixed_args(self, args: Sequence[str] | None = None, namespace: None = None) -> tuple[Namespace, list[str]]: ...  # type: ignore[misc]
     @overload
     def parse_known_intermixed_args(self, args: Sequence[str] | None, namespace: _N) -> tuple[_N, list[str]]: ...
     @overload

From 79ac38f8221e362487c1e664ce334c36c04d34d0 Mon Sep 17 00:00:00 2001
From: Jakob Stadler <127443735+Jakob-Stadler@users.noreply.github.com>
Date: Thu, 6 Jul 2023 17:41:42 +0200
Subject: [PATCH 2/4] Second attempt to fix argparse regression

This solution may be overly verbose.

The real problem is that the TypeVar _N should be bound to "mutable objects" that allow adding attributes via setattr(), and ignore builtin immutable objects like None.
---
 stdlib/argparse.pyi | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/stdlib/argparse.pyi b/stdlib/argparse.pyi
index 182f96bd0432..cc8f96e162d9 100644
--- a/stdlib/argparse.pyi
+++ b/stdlib/argparse.pyi
@@ -173,8 +173,14 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
     @overload
     def parse_args(self, args: Sequence[str] | None = None, namespace: None = None) -> Namespace: ...  # type: ignore[misc]
     @overload
+    def parse_args(self, args: Sequence[str] | None, namespace: _N | None) -> _N | Namespace: ...
+    @overload
     def parse_args(self, args: Sequence[str] | None, namespace: _N) -> _N: ...
     @overload
+    def parse_args(self, *, namespace: None) -> Namespace: ...
+    @overload
+    def parse_args(self, *, namespace: _N | None) -> _N | Namespace: ...
+    @overload
     def parse_args(self, *, namespace: _N) -> _N: ...
     @overload
     def add_subparsers(
@@ -212,8 +218,14 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
     @overload
     def parse_known_args(self, args: Sequence[str] | None = None, namespace: None = None) -> tuple[Namespace, list[str]]: ...  # type: ignore[misc]
     @overload
+    def parse_known_args(self, args: Sequence[str] | None, namespace: _N | None) -> tuple[_N | Namespace, list[str]]: ...
+    @overload
     def parse_known_args(self, args: Sequence[str] | None, namespace: _N) -> tuple[_N, list[str]]: ...
     @overload
+    def parse_known_args(self, *, namespace: None) -> tuple[Namespace, list[str]]: ...
+    @overload
+    def parse_known_args(self, *, namespace: _N | None) -> tuple[_N | Namespace, list[str]]: ...
+    @overload
     def parse_known_args(self, *, namespace: _N) -> tuple[_N, list[str]]: ...
     def convert_arg_line_to_args(self, arg_line: str) -> list[str]: ...
     def exit(self, status: int = 0, message: str | None = None) -> NoReturn: ...
@@ -221,14 +233,26 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
     @overload
     def parse_intermixed_args(self, args: Sequence[str] | None = None, namespace: None = None) -> Namespace: ...  # type: ignore[misc]
     @overload
+    def parse_intermixed_args(self, args: Sequence[str] | None, namespace: _N | None) -> _N | Namespace: ...
+    @overload
     def parse_intermixed_args(self, args: Sequence[str] | None, namespace: _N) -> _N: ...
     @overload
+    def parse_intermixed_args(self, *, namespace: None) -> Namespace: ...
+    @overload
+    def parse_intermixed_args(self, *, namespace: _N | None) -> _N | Namespace: ...
+    @overload
     def parse_intermixed_args(self, *, namespace: _N) -> _N: ...
     @overload
     def parse_known_intermixed_args(self, args: Sequence[str] | None = None, namespace: None = None) -> tuple[Namespace, list[str]]: ...  # type: ignore[misc]
     @overload
+    def parse_known_intermixed_args(self, args: Sequence[str] | None, namespace: _N | None) -> tuple[_N | Namespace, list[str]]: ...
+    @overload
     def parse_known_intermixed_args(self, args: Sequence[str] | None, namespace: _N) -> tuple[_N, list[str]]: ...
     @overload
+    def parse_known_intermixed_args(self, *, namespace: None) -> tuple[Namespace, list[str]]: ...
+    @overload
+    def parse_known_intermixed_args(self, *, namespace: _N | None) -> tuple[_N | Namespace, list[str]]: ...
+    @overload
     def parse_known_intermixed_args(self, *, namespace: _N) -> tuple[_N, list[str]]: ...
     # undocumented
     def _get_optional_actions(self) -> list[Action]: ...

From eef5a7e97cec47907e7b2966998b18682dcc6e04 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Thu, 6 Jul 2023 15:43:02 +0000
Subject: [PATCH 3/4] [pre-commit.ci] auto fixes from pre-commit.com hooks

---
 stdlib/argparse.pyi | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/stdlib/argparse.pyi b/stdlib/argparse.pyi
index cc8f96e162d9..3c5c5f5c7dab 100644
--- a/stdlib/argparse.pyi
+++ b/stdlib/argparse.pyi
@@ -245,7 +245,9 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
     @overload
     def parse_known_intermixed_args(self, args: Sequence[str] | None = None, namespace: None = None) -> tuple[Namespace, list[str]]: ...  # type: ignore[misc]
     @overload
-    def parse_known_intermixed_args(self, args: Sequence[str] | None, namespace: _N | None) -> tuple[_N | Namespace, list[str]]: ...
+    def parse_known_intermixed_args(
+        self, args: Sequence[str] | None, namespace: _N | None
+    ) -> tuple[_N | Namespace, list[str]]: ...
     @overload
     def parse_known_intermixed_args(self, args: Sequence[str] | None, namespace: _N) -> tuple[_N, list[str]]: ...
     @overload

From a45041ef30b8fc3b75b0975514356d2dd050067f Mon Sep 17 00:00:00 2001
From: Jakob Stadler <127443735+Jakob-Stadler@users.noreply.github.com>
Date: Thu, 6 Jul 2023 18:00:02 +0200
Subject: [PATCH 4/4] Revert second attempt

---
 stdlib/argparse.pyi | 26 --------------------------
 1 file changed, 26 deletions(-)

diff --git a/stdlib/argparse.pyi b/stdlib/argparse.pyi
index 3c5c5f5c7dab..182f96bd0432 100644
--- a/stdlib/argparse.pyi
+++ b/stdlib/argparse.pyi
@@ -173,14 +173,8 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
     @overload
     def parse_args(self, args: Sequence[str] | None = None, namespace: None = None) -> Namespace: ...  # type: ignore[misc]
     @overload
-    def parse_args(self, args: Sequence[str] | None, namespace: _N | None) -> _N | Namespace: ...
-    @overload
     def parse_args(self, args: Sequence[str] | None, namespace: _N) -> _N: ...
     @overload
-    def parse_args(self, *, namespace: None) -> Namespace: ...
-    @overload
-    def parse_args(self, *, namespace: _N | None) -> _N | Namespace: ...
-    @overload
     def parse_args(self, *, namespace: _N) -> _N: ...
     @overload
     def add_subparsers(
@@ -218,14 +212,8 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
     @overload
     def parse_known_args(self, args: Sequence[str] | None = None, namespace: None = None) -> tuple[Namespace, list[str]]: ...  # type: ignore[misc]
     @overload
-    def parse_known_args(self, args: Sequence[str] | None, namespace: _N | None) -> tuple[_N | Namespace, list[str]]: ...
-    @overload
     def parse_known_args(self, args: Sequence[str] | None, namespace: _N) -> tuple[_N, list[str]]: ...
     @overload
-    def parse_known_args(self, *, namespace: None) -> tuple[Namespace, list[str]]: ...
-    @overload
-    def parse_known_args(self, *, namespace: _N | None) -> tuple[_N | Namespace, list[str]]: ...
-    @overload
     def parse_known_args(self, *, namespace: _N) -> tuple[_N, list[str]]: ...
     def convert_arg_line_to_args(self, arg_line: str) -> list[str]: ...
     def exit(self, status: int = 0, message: str | None = None) -> NoReturn: ...
@@ -233,28 +221,14 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
     @overload
     def parse_intermixed_args(self, args: Sequence[str] | None = None, namespace: None = None) -> Namespace: ...  # type: ignore[misc]
     @overload
-    def parse_intermixed_args(self, args: Sequence[str] | None, namespace: _N | None) -> _N | Namespace: ...
-    @overload
     def parse_intermixed_args(self, args: Sequence[str] | None, namespace: _N) -> _N: ...
     @overload
-    def parse_intermixed_args(self, *, namespace: None) -> Namespace: ...
-    @overload
-    def parse_intermixed_args(self, *, namespace: _N | None) -> _N | Namespace: ...
-    @overload
     def parse_intermixed_args(self, *, namespace: _N) -> _N: ...
     @overload
     def parse_known_intermixed_args(self, args: Sequence[str] | None = None, namespace: None = None) -> tuple[Namespace, list[str]]: ...  # type: ignore[misc]
     @overload
-    def parse_known_intermixed_args(
-        self, args: Sequence[str] | None, namespace: _N | None
-    ) -> tuple[_N | Namespace, list[str]]: ...
-    @overload
     def parse_known_intermixed_args(self, args: Sequence[str] | None, namespace: _N) -> tuple[_N, list[str]]: ...
     @overload
-    def parse_known_intermixed_args(self, *, namespace: None) -> tuple[Namespace, list[str]]: ...
-    @overload
-    def parse_known_intermixed_args(self, *, namespace: _N | None) -> tuple[_N | Namespace, list[str]]: ...
-    @overload
     def parse_known_intermixed_args(self, *, namespace: _N) -> tuple[_N, list[str]]: ...
     # undocumented
     def _get_optional_actions(self) -> list[Action]: ...