From 6060876c3945f2443efb44a48b98f834e89d8aa8 Mon Sep 17 00:00:00 2001
From: Max Muoto <maxmuoto@gmail.com>
Date: Thu, 8 May 2025 18:57:41 -0500
Subject: [PATCH 01/17] feat: Improve `json.dumps`, `json.dump`  typing

---
 stdlib/json/__init__.pyi | 47 +++++++++++++++++++++++++++++++++++-----
 1 file changed, 42 insertions(+), 5 deletions(-)

diff --git a/stdlib/json/__init__.pyi b/stdlib/json/__init__.pyi
index 63e9718ee151..ee1b3d6af714 100644
--- a/stdlib/json/__init__.pyi
+++ b/stdlib/json/__init__.pyi
@@ -1,14 +1,34 @@
 from _typeshed import SupportsRead, SupportsWrite
 from collections.abc import Callable
-from typing import Any
+from typing import Any, TypeAlias, TypeVar, overload
 
 from .decoder import JSONDecodeError as JSONDecodeError, JSONDecoder as JSONDecoder
 from .encoder import JSONEncoder as JSONEncoder
 
 __all__ = ["dump", "dumps", "load", "loads", "JSONDecoder", "JSONDecodeError", "JSONEncoder"]
 
+_T = TypeVar("_T")
+
+_JSON: TypeAlias = dict[str, _JSON] | list[_JSON] | str | int | float | bool | None
+
+@overload
+def dumps(
+    obj: _JSON,
+    *,
+    skipkeys: bool = False,
+    ensure_ascii: bool = True,
+    check_circular: bool = True,
+    allow_nan: bool = True,
+    cls: type[JSONEncoder] | None = None,
+    indent: None | int | str = None,
+    separators: tuple[str, str] | None = None,
+    default: None = None,
+    sort_keys: bool = False,
+    **kwds: Any,
+) -> str: ...
+@overload
 def dumps(
-    obj: Any,
+    obj: _T,
     *,
     skipkeys: bool = False,
     ensure_ascii: bool = True,
@@ -17,12 +37,29 @@ def dumps(
     cls: type[JSONEncoder] | None = None,
     indent: None | int | str = None,
     separators: tuple[str, str] | None = None,
-    default: Callable[[Any], Any] | None = None,
+    default: Callable[[_T], _JSON],
     sort_keys: bool = False,
     **kwds: Any,
 ) -> str: ...
+@overload
+def dump(
+    obj: _JSON,
+    fp: SupportsWrite[str],
+    *,
+    skipkeys: bool = False,
+    ensure_ascii: bool = True,
+    check_circular: bool = True,
+    allow_nan: bool = True,
+    cls: type[JSONEncoder] | None = None,
+    indent: None | int | str = None,
+    separators: tuple[str, str] | None = None,
+    default: None = None,
+    sort_keys: bool = False,
+    **kwds: Any,
+) -> None: ...
+@overload
 def dump(
-    obj: Any,
+    obj: _T,
     fp: SupportsWrite[str],
     *,
     skipkeys: bool = False,
@@ -32,7 +69,7 @@ def dump(
     cls: type[JSONEncoder] | None = None,
     indent: None | int | str = None,
     separators: tuple[str, str] | None = None,
-    default: Callable[[Any], Any] | None = None,
+    default: Callable[[_T], _JSON],
     sort_keys: bool = False,
     **kwds: Any,
 ) -> None: ...

From f7c16d0745a3762e3b327c80fcd156fa87cda80b Mon Sep 17 00:00:00 2001
From: Max Muoto <maxmuoto@gmail.com>
Date: Thu, 8 May 2025 18:59:52 -0500
Subject: [PATCH 02/17] Tweak

---
 stdlib/json/__init__.pyi | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/stdlib/json/__init__.pyi b/stdlib/json/__init__.pyi
index ee1b3d6af714..9160a102c1de 100644
--- a/stdlib/json/__init__.pyi
+++ b/stdlib/json/__init__.pyi
@@ -1,6 +1,7 @@
 from _typeshed import SupportsRead, SupportsWrite
 from collections.abc import Callable
-from typing import Any, TypeAlias, TypeVar, overload
+from typing import Any, TypeVar, overload
+from typing_extensions import TypeAlias
 
 from .decoder import JSONDecodeError as JSONDecodeError, JSONDecoder as JSONDecoder
 from .encoder import JSONEncoder as JSONEncoder

From c741607d2e38c5099ccbae6c843a29b4bfbd379b Mon Sep 17 00:00:00 2001
From: Max Muoto <maxmuoto@gmail.com>
Date: Thu, 8 May 2025 19:09:10 -0500
Subject: [PATCH 03/17] Add test

---
 stdlib/@tests/test_cases/check_json.py | 55 ++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 stdlib/@tests/test_cases/check_json.py

diff --git a/stdlib/@tests/test_cases/check_json.py b/stdlib/@tests/test_cases/check_json.py
new file mode 100644
index 000000000000..49db8ea16242
--- /dev/null
+++ b/stdlib/@tests/test_cases/check_json.py
@@ -0,0 +1,55 @@
+import json
+from decimal import Decimal
+
+
+# By default, json.dumps() will not accept any non-serializable objects.
+class CustomClass: ...
+
+
+json.dumps(CustomClass())  # Error
+json.dumps(object())  # Error
+json.dumps(Decimal(1))  # Error
+
+# Serializable types are supported, included nested JSON.
+json.dumps(
+    {
+        "a": 34,
+        "b": [1, 2, 3],
+        "c": {
+            "d": "hello",
+            "e": False,
+        },
+    }
+)
+json.dumps(
+    {
+        "numbers": [1, 2, 3, 4, 5],
+        "strings": ["hello", "world"],
+        "booleans": [True, False],
+        "null": None,
+        "nested": {"array": [[1, 2], [3, 4.34]], "object": {"x": 1, "y": 2}},
+    }
+)
+json.dumps({"empty_array": [], "empty_object": {}, "float": 3.14, "scientific": 1.23e-4, "unicode": "Hello 世界"})
+json.dumps(1)
+json.dumps(1.23)
+json.dumps(True)
+json.dumps(False)
+json.dumps(None)
+json.dumps("hello")
+
+
+# Custom types are supported when a custom encoder is provided.
+def decimal_encoder(obj: Decimal) -> float:
+    return float(obj)
+
+
+json.dumps(Decimal(1), default=decimal_encoder)
+
+
+# If the custom encoder doesn't return JSON, it will raise.
+def custom_encoder(obj: Decimal) -> Decimal:
+    return obj
+
+
+json.dumps(Decimal(1), default=custom_encoder)  #  type: ignore

From 2a034188ff0ad6b6118b6be86625ef21a285bb23 Mon Sep 17 00:00:00 2001
From: Max Muoto <maxmuoto@gmail.com>
Date: Thu, 8 May 2025 19:10:37 -0500
Subject: [PATCH 04/17] Fixes

---
 stdlib/@tests/test_cases/check_json.py | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/stdlib/@tests/test_cases/check_json.py b/stdlib/@tests/test_cases/check_json.py
index 49db8ea16242..c3bcf58c05f2 100644
--- a/stdlib/@tests/test_cases/check_json.py
+++ b/stdlib/@tests/test_cases/check_json.py
@@ -2,13 +2,13 @@
 from decimal import Decimal
 
 
-# By default, json.dumps() will not accept any non-serializable objects.
+# By default, json.dumps() will not accept any non JSON-serializable objects.
 class CustomClass: ...
 
 
-json.dumps(CustomClass())  # Error
-json.dumps(object())  # Error
-json.dumps(Decimal(1))  # Error
+json.dumps(CustomClass())  # type: ignore
+json.dumps(object())  # type: ignore
+json.dumps(Decimal(1))  # type: ignore
 
 # Serializable types are supported, included nested JSON.
 json.dumps(
@@ -47,7 +47,7 @@ def decimal_encoder(obj: Decimal) -> float:
 json.dumps(Decimal(1), default=decimal_encoder)
 
 
-# If the custom encoder doesn't return JSON, it will raise.
+# If the custom encoder doesn't return JSON, it will lead a typing error..
 def custom_encoder(obj: Decimal) -> Decimal:
     return obj
 

From 07f1922acffa4b9a7ad9a0ca9b1c40e2359cfb55 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Fri, 9 May 2025 00:10:50 +0000
Subject: [PATCH 05/17] [pre-commit.ci] auto fixes from pre-commit.com hooks

---
 stdlib/@tests/test_cases/check_json.py | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/stdlib/@tests/test_cases/check_json.py b/stdlib/@tests/test_cases/check_json.py
index c3bcf58c05f2..2d000f662843 100644
--- a/stdlib/@tests/test_cases/check_json.py
+++ b/stdlib/@tests/test_cases/check_json.py
@@ -11,16 +11,7 @@ class CustomClass: ...
 json.dumps(Decimal(1))  # type: ignore
 
 # Serializable types are supported, included nested JSON.
-json.dumps(
-    {
-        "a": 34,
-        "b": [1, 2, 3],
-        "c": {
-            "d": "hello",
-            "e": False,
-        },
-    }
-)
+json.dumps({"a": 34, "b": [1, 2, 3], "c": {"d": "hello", "e": False}})
 json.dumps(
     {
         "numbers": [1, 2, 3, 4, 5],

From 87b10d5b50c4240723decbef14f6d309bc55ff01 Mon Sep 17 00:00:00 2001
From: Max Muoto <maxmuoto@gmail.com>
Date: Thu, 8 May 2025 19:12:31 -0500
Subject: [PATCH 06/17] Tweak test

---
 stdlib/@tests/test_cases/check_json.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/stdlib/@tests/test_cases/check_json.py b/stdlib/@tests/test_cases/check_json.py
index 2d000f662843..bad385adad23 100644
--- a/stdlib/@tests/test_cases/check_json.py
+++ b/stdlib/@tests/test_cases/check_json.py
@@ -21,7 +21,6 @@ class CustomClass: ...
         "nested": {"array": [[1, 2], [3, 4.34]], "object": {"x": 1, "y": 2}},
     }
 )
-json.dumps({"empty_array": [], "empty_object": {}, "float": 3.14, "scientific": 1.23e-4, "unicode": "Hello 世界"})
 json.dumps(1)
 json.dumps(1.23)
 json.dumps(True)

From 9d548a65799803444924a4e2c814df107d99bdd3 Mon Sep 17 00:00:00 2001
From: Max Muoto <maxmuoto@gmail.com>
Date: Thu, 8 May 2025 19:26:34 -0500
Subject: [PATCH 07/17] Tweak

---
 stdlib/json/__init__.pyi | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/stdlib/json/__init__.pyi b/stdlib/json/__init__.pyi
index 9160a102c1de..57436855170d 100644
--- a/stdlib/json/__init__.pyi
+++ b/stdlib/json/__init__.pyi
@@ -10,7 +10,11 @@ __all__ = ["dump", "dumps", "load", "loads", "JSONDecoder", "JSONDecodeError", "
 
 _T = TypeVar("_T")
 
-_JSON: TypeAlias = dict[str, _JSON] | list[_JSON] | str | int | float | bool | None
+# We could use `_JSON: TypeAlias = dict[str, _JSON] | list[_JSON] | str | int | float | bool | None`
+# as the type, but that forces users to define their own custom JSON types when using `json.dumps()
+# or `json.dump()` on a passed in value. Instead we opt for a more permissive type that focuses on
+# checking non-nested structures.
+_JSON: TypeAlias = dict[str, Any] | list[Any] | str | int | float | bool | None
 
 @overload
 def dumps(

From 07cf9d06e5359d2689e8346e51cbbecae7959394 Mon Sep 17 00:00:00 2001
From: Max Muoto <maxmuoto@gmail.com>
Date: Thu, 8 May 2025 19:27:14 -0500
Subject: [PATCH 08/17] Tweak

---
 stdlib/json/__init__.pyi | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/stdlib/json/__init__.pyi b/stdlib/json/__init__.pyi
index 57436855170d..1a06b12e5d2c 100644
--- a/stdlib/json/__init__.pyi
+++ b/stdlib/json/__init__.pyi
@@ -14,7 +14,8 @@ _T = TypeVar("_T")
 # as the type, but that forces users to define their own custom JSON types when using `json.dumps()
 # or `json.dump()` on a passed in value. Instead we opt for a more permissive type that focuses on
 # checking non-nested structures.
-_JSON: TypeAlias = dict[str, Any] | list[Any] | str | int | float | bool | None
+_JSONValue: TypeAlias = str | int | float | bool | None
+_JSON: TypeAlias = dict[str, Any] | list[_JSONValue] | str | int | float | bool | None
 
 @overload
 def dumps(

From c51d852f862e655560b54b628e3ca2d35cfa6fbb Mon Sep 17 00:00:00 2001
From: Max Muoto <maxmuoto@gmail.com>
Date: Thu, 8 May 2025 19:29:58 -0500
Subject: [PATCH 09/17] Tweak

---
 stdlib/@tests/test_cases/check_json.py | 3 +++
 stdlib/json/__init__.pyi               | 7 +------
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/stdlib/@tests/test_cases/check_json.py b/stdlib/@tests/test_cases/check_json.py
index bad385adad23..2f0b3a3e5bc2 100644
--- a/stdlib/@tests/test_cases/check_json.py
+++ b/stdlib/@tests/test_cases/check_json.py
@@ -28,6 +28,9 @@ class CustomClass: ...
 json.dumps(None)
 json.dumps("hello")
 
+x: dict[str, float | int] = {"a": 1, "b": 2.0}
+json.dumps(x)
+
 
 # Custom types are supported when a custom encoder is provided.
 def decimal_encoder(obj: Decimal) -> float:
diff --git a/stdlib/json/__init__.pyi b/stdlib/json/__init__.pyi
index 1a06b12e5d2c..ed615b48329c 100644
--- a/stdlib/json/__init__.pyi
+++ b/stdlib/json/__init__.pyi
@@ -10,12 +10,7 @@ __all__ = ["dump", "dumps", "load", "loads", "JSONDecoder", "JSONDecodeError", "
 
 _T = TypeVar("_T")
 
-# We could use `_JSON: TypeAlias = dict[str, _JSON] | list[_JSON] | str | int | float | bool | None`
-# as the type, but that forces users to define their own custom JSON types when using `json.dumps()
-# or `json.dump()` on a passed in value. Instead we opt for a more permissive type that focuses on
-# checking non-nested structures.
-_JSONValue: TypeAlias = str | int | float | bool | None
-_JSON: TypeAlias = dict[str, Any] | list[_JSONValue] | str | int | float | bool | None
+_JSON: TypeAlias = dict[str, _JSON] | list[_JSON] | str | float | bool | None
 
 @overload
 def dumps(

From 454786b624649f8ca901717601f0ecc47b9fb5e5 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Fri, 9 May 2025 00:32:01 +0000
Subject: [PATCH 10/17] [pre-commit.ci] auto fixes from pre-commit.com hooks

---
 stdlib/@tests/test_cases/check_json.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/stdlib/@tests/test_cases/check_json.py b/stdlib/@tests/test_cases/check_json.py
index 2f0b3a3e5bc2..9e0f165f1b13 100644
--- a/stdlib/@tests/test_cases/check_json.py
+++ b/stdlib/@tests/test_cases/check_json.py
@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import json
 from decimal import Decimal
 

From 6d07be5ad61d66c7ee8b4bf24fb441371604f3fc Mon Sep 17 00:00:00 2001
From: Max Muoto <maxmuoto@gmail.com>
Date: Thu, 8 May 2025 19:32:06 -0500
Subject: [PATCH 11/17] Further broaden

---
 stdlib/@tests/test_cases/check_json.py | 3 +++
 stdlib/json/__init__.pyi               | 4 ++--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/stdlib/@tests/test_cases/check_json.py b/stdlib/@tests/test_cases/check_json.py
index 9e0f165f1b13..292ba00faaa7 100644
--- a/stdlib/@tests/test_cases/check_json.py
+++ b/stdlib/@tests/test_cases/check_json.py
@@ -33,6 +33,9 @@ class CustomClass: ...
 x: dict[str, float | int] = {"a": 1, "b": 2.0}
 json.dumps(x)
 
+z: dict[str, dict[str, dict[str, list[int]]]] = {"a": {"b": {"c": [1, 2, 3]}}}
+json.dumps(z)
+
 
 # Custom types are supported when a custom encoder is provided.
 def decimal_encoder(obj: Decimal) -> float:
diff --git a/stdlib/json/__init__.pyi b/stdlib/json/__init__.pyi
index ed615b48329c..9b58c12a6a7d 100644
--- a/stdlib/json/__init__.pyi
+++ b/stdlib/json/__init__.pyi
@@ -1,5 +1,5 @@
 from _typeshed import SupportsRead, SupportsWrite
-from collections.abc import Callable
+from collections.abc import Callable, Mapping, Sequence
 from typing import Any, TypeVar, overload
 from typing_extensions import TypeAlias
 
@@ -10,7 +10,7 @@ __all__ = ["dump", "dumps", "load", "loads", "JSONDecoder", "JSONDecodeError", "
 
 _T = TypeVar("_T")
 
-_JSON: TypeAlias = dict[str, _JSON] | list[_JSON] | str | float | bool | None
+_JSON: TypeAlias = Mapping[str, _JSON] | Sequence[_JSON] | str | float | bool | None
 
 @overload
 def dumps(

From a05d94a6dbe3ae7e519b94ca880157bc3fc0c67d Mon Sep 17 00:00:00 2001
From: Max Muoto <maxmuoto@gmail.com>
Date: Thu, 8 May 2025 19:39:22 -0500
Subject: [PATCH 12/17] Add json.dump tests

---
 stdlib/@tests/test_cases/check_json.py | 34 ++++++++++++++++++++++----
 1 file changed, 29 insertions(+), 5 deletions(-)

diff --git a/stdlib/@tests/test_cases/check_json.py b/stdlib/@tests/test_cases/check_json.py
index 292ba00faaa7..e870bd14f2c0 100644
--- a/stdlib/@tests/test_cases/check_json.py
+++ b/stdlib/@tests/test_cases/check_json.py
@@ -1,19 +1,28 @@
-from __future__ import annotations
-
 import json
 from decimal import Decimal
 
 
+class _File:
+    def write(self, s: str) -> int: ...
+
+
+fp = _File()
+
+
 # By default, json.dumps() will not accept any non JSON-serializable objects.
 class CustomClass: ...
 
 
 json.dumps(CustomClass())  # type: ignore
+json.dump(CustomClass(), fp)  # type: ignore
 json.dumps(object())  # type: ignore
+json.dump(object(), fp)  # type: ignore
 json.dumps(Decimal(1))  # type: ignore
+json.dump(Decimal(1), fp)  # type: ignore
 
 # Serializable types are supported, included nested JSON.
 json.dumps({"a": 34, "b": [1, 2, 3], "c": {"d": "hello", "e": False}})
+json.dump({"a": 34, "b": [1, 2, 3], "c": {"d": "hello", "e": False}}, fp)
 json.dumps(
     {
         "numbers": [1, 2, 3, 4, 5],
@@ -23,18 +32,31 @@ class CustomClass: ...
         "nested": {"array": [[1, 2], [3, 4.34]], "object": {"x": 1, "y": 2}},
     }
 )
+json.dump(
+    {
+        "numbers": [1, 2, 3, 4, 5],
+        "strings": ["hello", "world"],
+        "booleans": [True, False],
+        "null": None,
+        "nested": {"array": [[1, 2], [3, 4.34]], "object": {"x": 1, "y": 2}},
+    },
+    fp,
+)
 json.dumps(1)
+json.dump(1, fp)
 json.dumps(1.23)
+json.dump(1.23, fp)
 json.dumps(True)
-json.dumps(False)
-json.dumps(None)
-json.dumps("hello")
+json.dump(True, fp)
 
+# Test explicit nested types that might cause variance issues.
 x: dict[str, float | int] = {"a": 1, "b": 2.0}
 json.dumps(x)
+json.dump(x, fp)
 
 z: dict[str, dict[str, dict[str, list[int]]]] = {"a": {"b": {"c": [1, 2, 3]}}}
 json.dumps(z)
+json.dump(z, fp)
 
 
 # Custom types are supported when a custom encoder is provided.
@@ -43,6 +65,7 @@ def decimal_encoder(obj: Decimal) -> float:
 
 
 json.dumps(Decimal(1), default=decimal_encoder)
+json.dump(Decimal(1), fp, default=decimal_encoder)
 
 
 # If the custom encoder doesn't return JSON, it will lead a typing error..
@@ -51,3 +74,4 @@ def custom_encoder(obj: Decimal) -> Decimal:
 
 
 json.dumps(Decimal(1), default=custom_encoder)  #  type: ignore
+json.dump(Decimal(1), fp, default=custom_encoder)  #  type: ignore

From fe7076771ec53976e309a9b676d053c106f731f5 Mon Sep 17 00:00:00 2001
From: Max Muoto <maxmuoto@gmail.com>
Date: Thu, 8 May 2025 21:15:55 -0500
Subject: [PATCH 13/17] Add future import

---
 stdlib/@tests/test_cases/check_json.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/stdlib/@tests/test_cases/check_json.py b/stdlib/@tests/test_cases/check_json.py
index e870bd14f2c0..febee56c0d96 100644
--- a/stdlib/@tests/test_cases/check_json.py
+++ b/stdlib/@tests/test_cases/check_json.py
@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import json
 from decimal import Decimal
 

From b16b4f66f489a05e485783425ccddc1adf3459c5 Mon Sep 17 00:00:00 2001
From: Max Muoto <maxmuoto@gmail.com>
Date: Thu, 8 May 2025 21:33:23 -0500
Subject: [PATCH 14/17] Support typed dictionaries

---
 stdlib/@tests/test_cases/check_json.py | 9 +++++++++
 stdlib/json/__init__.pyi               | 4 +++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/stdlib/@tests/test_cases/check_json.py b/stdlib/@tests/test_cases/check_json.py
index febee56c0d96..9ef267b9847f 100644
--- a/stdlib/@tests/test_cases/check_json.py
+++ b/stdlib/@tests/test_cases/check_json.py
@@ -2,6 +2,7 @@
 
 import json
 from decimal import Decimal
+from typing import TypedDict
 
 
 class _File:
@@ -77,3 +78,11 @@ def custom_encoder(obj: Decimal) -> Decimal:
 
 json.dumps(Decimal(1), default=custom_encoder)  #  type: ignore
 json.dump(Decimal(1), fp, default=custom_encoder)  #  type: ignore
+
+
+class MyTypedDict(TypedDict):
+    a: str
+    b: str
+
+
+json.dumps(MyTypedDict(a="hello", b="world"))
diff --git a/stdlib/json/__init__.pyi b/stdlib/json/__init__.pyi
index 9b58c12a6a7d..07a858cea1cf 100644
--- a/stdlib/json/__init__.pyi
+++ b/stdlib/json/__init__.pyi
@@ -10,7 +10,9 @@ __all__ = ["dump", "dumps", "load", "loads", "JSONDecoder", "JSONDecodeError", "
 
 _T = TypeVar("_T")
 
-_JSON: TypeAlias = Mapping[str, _JSON] | Sequence[_JSON] | str | float | bool | None
+# Mapping[str, object] is used to maintain compatibility with typed dictionaries
+# despite it being very loose it's preferrable to using Any.
+_JSON: TypeAlias = Mapping[str, object] | Sequence[_JSON] | str | float | bool | None
 
 @overload
 def dumps(

From ae677f10741ec36584245b6bdb0e844097b8074a Mon Sep 17 00:00:00 2001
From: Max Muoto <maxmuoto@gmail.com>
Date: Thu, 8 May 2025 22:12:38 -0500
Subject: [PATCH 15/17] Support subclasses...

---
 stdlib/@tests/test_cases/check_json.py | 12 ++++++-
 stdlib/json/__init__.pyi               | 45 +++++++++++++++++++++++---
 2 files changed, 51 insertions(+), 6 deletions(-)

diff --git a/stdlib/@tests/test_cases/check_json.py b/stdlib/@tests/test_cases/check_json.py
index 9ef267b9847f..3dae6735de6b 100644
--- a/stdlib/@tests/test_cases/check_json.py
+++ b/stdlib/@tests/test_cases/check_json.py
@@ -2,7 +2,7 @@
 
 import json
 from decimal import Decimal
-from typing import TypedDict
+from typing import Any, TypedDict
 
 
 class _File:
@@ -86,3 +86,13 @@ class MyTypedDict(TypedDict):
 
 
 json.dumps(MyTypedDict(a="hello", b="world"))
+
+
+# We should allow anything for subclasses of json.JSONEncoder.
+# Type-checking custom encoders is not practical without generics.
+class MyJSONEncoder(json.JSONEncoder):
+    def default(self, obj: Any) -> Any: ...
+
+
+json.dumps(Decimal(1), cls=MyJSONEncoder)
+json.dump(Decimal(1), fp, cls=MyJSONEncoder)
diff --git a/stdlib/json/__init__.pyi b/stdlib/json/__init__.pyi
index 07a858cea1cf..45b89da8260e 100644
--- a/stdlib/json/__init__.pyi
+++ b/stdlib/json/__init__.pyi
@@ -22,7 +22,7 @@ def dumps(
     ensure_ascii: bool = True,
     check_circular: bool = True,
     allow_nan: bool = True,
-    cls: type[JSONEncoder] | None = None,
+    cls: None = None,
     indent: None | int | str = None,
     separators: tuple[str, str] | None = None,
     default: None = None,
@@ -31,19 +31,36 @@ def dumps(
 ) -> str: ...
 @overload
 def dumps(
-    obj: _T,
+    obj: _JSON | _T,
     *,
     skipkeys: bool = False,
     ensure_ascii: bool = True,
     check_circular: bool = True,
     allow_nan: bool = True,
-    cls: type[JSONEncoder] | None = None,
+    cls: None = None,
     indent: None | int | str = None,
     separators: tuple[str, str] | None = None,
     default: Callable[[_T], _JSON],
     sort_keys: bool = False,
     **kwds: Any,
 ) -> str: ...
+
+# Type-checking subclasses without generics isn't practical.
+@overload
+def dumps(
+    obj: object,
+    *,
+    skipkeys: bool = False,
+    ensure_ascii: bool = True,
+    check_circular: bool = True,
+    allow_nan: bool = True,
+    cls: type[JSONEncoder],
+    indent: None | int | str = None,
+    separators: tuple[str, str] | None = None,
+    default: Callable[[Any], Any] | None = None,
+    sort_keys: bool = False,
+    **kwds: Any,
+) -> str: ...
 @overload
 def dump(
     obj: _JSON,
@@ -53,7 +70,7 @@ def dump(
     ensure_ascii: bool = True,
     check_circular: bool = True,
     allow_nan: bool = True,
-    cls: type[JSONEncoder] | None = None,
+    cls: None = None,
     indent: None | int | str = None,
     separators: tuple[str, str] | None = None,
     default: None = None,
@@ -62,7 +79,7 @@ def dump(
 ) -> None: ...
 @overload
 def dump(
-    obj: _T,
+    obj: _JSON | _T,
     fp: SupportsWrite[str],
     *,
     skipkeys: bool = False,
@@ -76,6 +93,24 @@ def dump(
     sort_keys: bool = False,
     **kwds: Any,
 ) -> None: ...
+
+# Type-checking subclasses without generics isn't practical.
+@overload
+def dump(
+    obj: object,
+    fp: SupportsWrite[str],
+    *,
+    skipkeys: bool = False,
+    ensure_ascii: bool = True,
+    check_circular: bool = True,
+    allow_nan: bool = True,
+    cls: type[JSONEncoder],
+    indent: None | int | str = None,
+    separators: tuple[str, str] | None = None,
+    default: Callable[[Any], Any] | None = None,
+    sort_keys: bool = False,
+    **kwds: Any,
+) -> None: ...
 def loads(
     s: str | bytes | bytearray,
     *,

From 5fab9e85ceb608c6caab02da97ecfb74cf9ed5e4 Mon Sep 17 00:00:00 2001
From: Max Muoto <maxmuoto@gmail.com>
Date: Thu, 8 May 2025 22:16:53 -0500
Subject: [PATCH 16/17] Tweak

---
 stdlib/@tests/test_cases/check_json.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/stdlib/@tests/test_cases/check_json.py b/stdlib/@tests/test_cases/check_json.py
index 3dae6735de6b..c5f959304f25 100644
--- a/stdlib/@tests/test_cases/check_json.py
+++ b/stdlib/@tests/test_cases/check_json.py
@@ -90,8 +90,7 @@ class MyTypedDict(TypedDict):
 
 # We should allow anything for subclasses of json.JSONEncoder.
 # Type-checking custom encoders is not practical without generics.
-class MyJSONEncoder(json.JSONEncoder):
-    def default(self, obj: Any) -> Any: ...
+class MyJSONEncoder(json.JSONEncoder): ...
 
 
 json.dumps(Decimal(1), cls=MyJSONEncoder)

From ab39c3fed6349928c2f68b791c901e2e3a33835a Mon Sep 17 00:00:00 2001
From: Max Muoto <maxmuoto@gmail.com>
Date: Thu, 8 May 2025 22:25:22 -0500
Subject: [PATCH 17/17] Remove Any

---
 stdlib/@tests/test_cases/check_json.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/stdlib/@tests/test_cases/check_json.py b/stdlib/@tests/test_cases/check_json.py
index c5f959304f25..15fc78a8ca48 100644
--- a/stdlib/@tests/test_cases/check_json.py
+++ b/stdlib/@tests/test_cases/check_json.py
@@ -2,7 +2,7 @@
 
 import json
 from decimal import Decimal
-from typing import Any, TypedDict
+from typing import TypedDict
 
 
 class _File: