Implement support for closed TypedDicts (PEP 728) by alicederyn · Pull Request #21382 · python/mypy

alicederyn · 2026-04-30T14:19:36Z

Implement support for the closed keyword on TypedDicts (part of PEP 728).

Additionally, fix some preexisting issues that I came across while updating the logic.

alicederyn · 2026-05-01T17:45:31Z

I'm not sure how exactly you'd prefer to have this change raised, so I've initially opened one big PR containing multiple small commits. Please LMK how you'd like it split up if that's the preference!

ilevkivskyi · 2026-05-02T00:04:44Z

First of all thanks for working on this!

I'm not sure how exactly you'd prefer to have this change raised, so I've initially opened one big PR containing multiple small commits. Please LMK how you'd like it split up if that's the preference!

This may depend on who exactly will review this PR :-) Although this is a big PR, after quick look it seems quite non-controversial, so the review will be mostly double-checking all edge cases are handled correctly/consistently. So IMO this doesn't need splitting into parts.

@JukkaL @hauntsaninja will any of you have time to look at this? (I am not sure if I will have time/energy to do a proper review, as I still have a backlog of NumPy-related stuff.)

PEP 728 allows multiple special forms to be applied to a key when a TypedDict is created using functional syntax, but the logic was only checking and stripping a single instance. This prevents overriding the overall total status on a ReadOnly field.

Fix a bug where a non-required key was considered consistent with a required key if the latter was marked as read-only.

Fix a bug where the meet of a mutable and readonly key was incorrectly set as readonly. This bug was caused by mistakenly unioning the readonly key sets, which happened to work for the tested case where readonly keys never appeared in the other type.

The TypedDict meet is returning Never whenever inputs have mismatched keys (value types or requiredness). However: * when a key is readonly, the meet value type can be a subtype of it * when a key is readonly and not required, the meet key can be required * when both keys are readonly and not required, the meet value type can be uninhabited (absent)

A typo was causing the readonly state of keys on the LHS of a TypedDict join to be ignored.

Improve TypedDict joins where keys mismatch by returning a readonly key with the joined type instead of discarding it.

Prior to implementing support for subclass refinement, expand the test suite with all the cases that need to be tested.

Allow readonly keys to be refined in subclasses, in line with PEP 705. For cases where refinement is not permitted by spec, provide a more detailed error message. As placeholders may now affect validation without ending up in the final TypedDictType, an `analysis_incomplete` field has been added, triggering reanalysis in subsequent rounds. This closes python#7435

The fallback path in TypeAnalyser::visit_typeddict_type is copying the required keys from the original type, but not the readonly keys. This is resulting in incorrect subtyping analysis for type variables with TypedDict bounds with readonly keys.

`NotRequired[Never]` can be used to indicate that a single key in a TypedDict will not be present.

Begin implementing PEP 728 support by adding an is_closed field to TypedDictType. This is filled out from the closed keyword, and displayed in reveal_type, but not otherwise supported yet.

Continue implementing PEP 728 support with updates to the subtyping logic. Drop the previous use of 'names_are_wider_than', which will be difficult to extend to cover `extra_items`, and instead use zipall to check for key addition/removal alongside the other key-based checks.

Propagate closed from subclasses. Verify that a subclass of a closed TypedDict does not add keys, nor override the closed status.

Close the join of two closed TypedDicts, and treat a missing key in a closed TypedDict as a `NotRequired[Never]` rather than the `ReadOnly[NotRequired[object]]` of an open TypedDict.

The meet of a closed TypedDict and another TypedDict must be closed. The implicit type of a missing key in a closed TypedDict is `ReadOnly[NotRequired[Never]]`.

Narrowing a union already treats final TypedDicts as closed; use the same logic if the closed keyword is used.

If a TypeVar with a TypedDict upper bound is encountered while narrowing, narrow based on the upper bound.

Propagate closed when analysing a TypedDictType with a fallback. This ensures subtype checks work correctly for a TypeVar with a closed TypedDict upper bound.

Unpacking a TypedDict with an undeclared key to a TypedDict with that key declared as not required is acceptable if the former is closed. Unpacking an open TypedDict into a closed TypedDict is never safe.

Close the kwargs TypedDict returned by ParamSpec where possible. Use an empty, closed TypedDict instead of a `dict[str, Never]` for functions that do not accept kwargs.

ilevkivskyi

Sorry for delay. Not a full review, but there is one thing I accidentally noticed that may require a substantial update to the PR.

ilevkivskyi · 2026-05-16T23:19:44Z

    require_bool_literal_argument,
 )
 from mypy.state import state
+from mypy.subtypes import is_equivalent, is_subtype


Using is_subtype() (and in general any type-checking operations) is not safe during semantic analysis. I can give more details if you want, but it is a very hard rule. The earliest stage where type checking is acceptable is semanal_typeargs (one of semantic analysis post-processing passes), but even there it should be done only if absolutely necessary.

All I'm using this for is to flag an error if the selected field type is incompatible with any base definition, so I can easily move it to whichever stage of the analysis you recommend.

I think it should probably be somewhere in checker.py in visit_class_def().

I couldn't see a way to nicely get the typeddict base classes in checker.py, and I'm not super confident in my workaround. Please let me know what you think, especially if there's a better solution I missed.

ilevkivskyi

Looks great, thanks! I have some more comments (mostly questions). Could you please also add docs for this change? (Especially mention that there are no @final TypedDicts and people should use closed instead, with few examples.)

ilevkivskyi · 2026-05-18T18:06:49Z

-                        key in possible_iterable_type.items or not possible_iterable_type.is_final
-                    ):
+                        key in bound.items
+                        and not isinstance(get_proper_type(bound.items[key]), UninhabitedType)


This check for UninhabitedType looks suspicious, why do you need it?

If an item is explicitly declared uninhabited, we can exclude it from if_types, exactly as if it were absent on a closed/final type.

See also the testOperatorContainsNarrowsTypedDicts_*_never tests

ilevkivskyi · 2026-05-18T18:21:19Z

+                join_type = join_types(s_item_type, t_item_type)
+                is_readonly = True
+            else:
+                join_type = s_item_type


This is a bit arbitrary in presence of Any. Is this needed to match some existing logic? If not, and one of the types is Any, then using Any as a join will make it more symmetric. To reduce the number of special-casing you can simply always use join_type = join_types(s_item_type, t_item_type) and only decide writeability depending on equivalence.

ilevkivskyi · 2026-05-18T18:26:12Z

+            meet_type = t_item_type
+        elif l_mutable and r_mutable:
+            if is_equivalent(s_item_type, t_item_type) and r_required == l_required:
+                meet_type = s_item_type


Similar to the join, it is better to always defer to meet_types() when possible. This way the behavior w.r.t. Any will be consistent (which unfortunately means consistently broken for meet, but that is a separate story).

ilevkivskyi · 2026-05-18T18:27:57Z

+                    and isinstance(get_proper_type(meet_type), UninhabitedType)
+                ):
+                    # Simplify emitted type by omitting redundant ReadOnly[Never] keys
+                    # from closed TypedDicts


Why only from closed? Are there cases where having a Never key is useful?

Why only from closed?

The equivalent in open TypedDicts would be ReadOnly[NotRequired[object]], which we could do, but seemed unlikely to come up organically. The Never case was coming up as a result of constructing synthetic Never fields for missing keys in closed inputs.

Are there cases where having a Never key is useful?

I don't believe so in a synthetic meet type -- I think it will just complicate the output.

BTW this logic changed slightly with #21382 (comment) -- it's actually mutable Never keys that are redundant.

ilevkivskyi · 2026-05-18T18:41:37Z

+class Point1(TypedDict, total=False):
+    x: int
+class Point2(Point1):
+    x: int # E: Field "x" is not required and not readonly in base class "Point1"


This error message is confusing. Can you either rephrase it and/or add a note hinting a user towards a possible solution?

ilevkivskyi · 2026-05-18T18:48:56Z

-reveal_type(x["one"])   # N: Revealed type is "builtins.int"
-reveal_type(x["other"]) # N: Revealed type is "builtins.str"
-x["one"] = 1  # ok
-x["other"] = "a"  # E: ReadOnly TypedDict key "other" TypedDict is mutated


Not important now, but if possible please do not re-order test cases, as this makes reviewing harder.

ilevkivskyi · 2026-05-18T18:51:17Z

+b.py:4: error: TypedDict "A" has no key "b"
+==
+b.py:9: error: TypedDict "B" has no key "a"
+==


Can you add a similar test case going from no error to error (i.e. opposite to what you have here)? We have a special logic w.r.t. re-checking targets with errors.

alicederyn · 2026-05-19T10:29:25Z

I just realised in the course of making these fixes that I made a fundamental misread of PEP 728. It says:

When closed=True is set, no extra items are allowed. This is equivalent to extra_items=Never, because there can’t be a value type that is assignable to Never.

I've implemented it in some places as extra_items=ReadOnly[Never], i.e. continuing to disallow key deletion, whereas the PEP is implicitly requiring permitting it. I'll get started on fixing this!

JelleZijlstra · 2026-05-19T13:53:09Z

My thinking was that you can't delete keys that don't exist, so ReadOnly-ness doesn't make a difference here.

Given this program:

from typing_extensions import TypedDict

class TD(TypedDict, closed=True):
    a: int
    
def f(x: TD, key: str):
    del x["b"]
    del x[key]

Among type checkers that support PEP 728:

zuban allows deleting the literal key "b" but not the arbitrary key str
pyright allows deleting the str but not "b"
pyrefly and pycroscope disallow deleting either

The last behavior makes the most sense to me.

alicederyn · 2026-05-19T15:38:29Z

My thinking was that you can't delete keys that don't exist, so ReadOnly-ness doesn't make a difference here.

I think I agree, but I fear that results in a weird hybrid of how readonly vs mutable normally works. For example, pop with a default should be allowed in both cases, even though it looks like a mutate operation. I'm just going to go with the literal text of the PEP where it's explicitly called out in the code for now.

Selecting one of the two join types arbitrarily when they are equivalent does not work when the other one is an `Any` (which is always equivalent to any other type). Instead, recursively join_types in the typeddict join logic in all cases except a missing key in an open type (where we cannot obtain the instance of `object` that would make it clean to do so). This also makes the logic more readable.

Selecting one of the two meet types arbitrarily when they are equivalent does not work when the other one is an `Any` (which is always equivalent to any other type). Instead, recursively meet_types in the typeddict meet logic in all cases except a missing key in an open type (where we cannot obtain the instance of `object` that would make it clean to do so). This also makes the logic more readable.

Compute requiredness and mutability in zipall, and substitute Never for None for closed TypedDicts. This avoids duplicating this logic at the three callsites.

According to PEP 728: > `closed=True`...is equivalent to `extra_items=Never` This should not in practice matter, due to the `Never` type: update operations cannot provide a valid value to insert, and the item must be absent at runtime to conform to the type, so delete operations will have no effect. However, this was not explicitly called out in the PEP, and there may be edge cases that need discussion (e.g. is it legal to pop with default if the item is readonly?). Correct the code to follow the convention exactly.

A closed subtype can validly add a key, provided it is uninhabited, as this is just explicitly stating the previously implicit constraint.

Refer to deletion in error messages for incompatibility mutable not-required fields in base classes, as this is simpler, and ultimately the reason why there is an incompatibility

Calling is_subtype during semantic analysis is not legal; verifying type compatibility of a TypedDict subtype field definition with its supertypes needs to be done in TypeChecker. To avoid duplicating all the logic for determining sources, add a non-persisted field_constraints field to TypedDictType.

github-actions · 2026-05-20T15:04:14Z

Diff from mypy_primer, showing the effect of this PR on open source code:

steam.py (https://github.com/Gobot1234/steam.py)
- steam/types/trade.py:69: error: Overwriting TypedDict field "instanceid" while merging  [misc]
- steam/types/trade.py:69: error: Overwriting TypedDict field "classid" while merging  [misc]
- steam/types/trade.py:112: error: Overwriting TypedDict field "assetid" while merging  [misc]
- steam/types/trade.py:112: error: Overwriting TypedDict field "amount" while merging  [misc]
- steam/types/trade.py:112: error: Overwriting TypedDict field "appid" while merging  [misc]
- steam/types/trade.py:112: error: Overwriting TypedDict field "contextid" while merging  [misc]
- steam/types/trade.py:112: error: Overwriting TypedDict field "instanceid" while merging  [misc]
- steam/types/trade.py:112: error: Overwriting TypedDict field "classid" while merging  [misc]
- steam/types/trade.py:112: error: Overwriting TypedDict field "missing" while merging  [misc]

hydra-zen (https://github.com/mit-ll-responsible-ai/hydra-zen)
- src/hydra_zen/typing/_implementations.py:606: error: Overwriting TypedDict field "module" while extending  [misc]

altair (https://github.com/vega/altair)
+ altair/vegalite/v6/schema/_config.py:6593: error: Unused "type: ignore" comment  [unused-ignore]
+ altair/vegalite/v6/schema/_config.py:6618: error: Unused "type: ignore" comment  [unused-ignore]
+ altair/vegalite/v6/api.py:699: error: Unused "type: ignore" comment  [unused-ignore]
+ altair/vegalite/v6/api.py:725: error: Unused "type: ignore" comment  [unused-ignore]
+ altair/vegalite/v6/api.py:774: error: Unused "type: ignore" comment  [unused-ignore]

discord.py (https://github.com/Rapptz/discord.py)
- discord/types/emoji.py:42: error: Overwriting TypedDict field "animated" while extending  [misc]
+ discord/types/scheduled_event.py:84: error: Field "user_count" is required in base class "_WithUserCount" but can be deleted in base class "StageInstanceScheduledEvent"  [misc]
+ discord/types/scheduled_event.py:87: error: Field "user_count" is required in base class "_WithUserCount" but can be deleted in base class "VoiceScheduledEvent"  [misc]
+ discord/types/scheduled_event.py:90: error: Field "user_count" is required in base class "_WithUserCount" but can be deleted in base class "ExternalScheduledEvent"  [misc]
+ discord/types/interactions.py:214: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/interactions.py:220: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/interactions.py:226: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/interactions.py:232: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/interactions.py:234: error: Field "id" can be deleted in base class "ComponentBase"  [misc]
+ discord/types/interactions.py:239: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/interactions.py:241: error: Field "id" can be deleted in base class "ComponentBase"  [misc]
+ discord/types/interactions.py:246: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/interactions.py:248: error: Field "id" can be deleted in base class "ComponentBase"  [misc]
+ discord/types/interactions.py:268: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/interactions.py:273: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/components.py:54: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/components.py:59: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/components.py:87: error: Definition of field "type" incompatible with base class "SelectComponent"  [misc]
+ discord/types/components.py:92: error: Definition of field "type" incompatible with base class "SelectComponent"  [misc]
+ discord/types/components.py:97: error: Definition of field "type" incompatible with base class "SelectComponent"  [misc]
+ discord/types/components.py:102: error: Definition of field "type" incompatible with base class "SelectComponent"  [misc]
+ discord/types/components.py:107: error: Definition of field "type" incompatible with base class "SelectComponent"  [misc]
+ discord/types/components.py:113: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/components.py:125: error: Definition of field "type" incompatible with base class "SelectComponent"  [misc]
+ discord/types/components.py:133: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/components.py:139: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/components.py:156: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/components.py:169: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/components.py:174: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/components.py:182: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/components.py:188: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/components.py:195: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/components.py:202: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/components.py:210: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/components.py:220: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
+ discord/types/components.py:232: error: Definition of field "type" incompatible with base class "ComponentBase"  [misc]
- discord/types/scheduled_event.py:84: error: Overwriting TypedDict field "user_count" while merging  [misc]
- discord/types/scheduled_event.py:87: error: Overwriting TypedDict field "user_count" while merging  [misc]
- discord/types/scheduled_event.py:90: error: Overwriting TypedDict field "user_count" while merging  [misc]
- discord/types/interactions.py:214: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/interactions.py:220: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/interactions.py:226: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/interactions.py:232: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/interactions.py:234: error: Overwriting TypedDict field "id" while extending  [misc]
- discord/types/interactions.py:239: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/interactions.py:241: error: Overwriting TypedDict field "id" while extending  [misc]
- discord/types/interactions.py:246: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/interactions.py:248: error: Overwriting TypedDict field "id" while extending  [misc]
- discord/types/interactions.py:268: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/interactions.py:273: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/guild.py:142: error: Overwriting TypedDict field "stickers" while extending  [misc]
- discord/types/components.py:54: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:59: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:87: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:92: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:97: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:102: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:107: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:113: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:125: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:133: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:139: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:156: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:169: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:174: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:182: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:188: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:195: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:202: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:210: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:220: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/components.py:232: error: Overwriting TypedDict field "type" while extending  [misc]
- discord/types/gateway.py:180: error: Overwriting TypedDict field "newly_created" while extending  [misc]
- discord/channel.py:144: error: Overwriting TypedDict field "bitrate" while extending  [misc]
- discord/channel.py:145: error: Overwriting TypedDict field "user_limit" while extending  [misc]
- discord/channel.py:146: error: Overwriting TypedDict field "rtc_region" while extending  [misc]
- discord/channel.py:147: error: Overwriting TypedDict field "video_quality_mode" while extending  [misc]
- discord/channel.py:148: error: Overwriting TypedDict field "overwrites" while extending  [misc]
- discord/channel.py:151: error: Overwriting TypedDict field "topic" while extending  [misc]
- discord/channel.py:152: error: Overwriting TypedDict field "slowmode_delay" while extending  [misc]
- discord/channel.py:153: error: Overwriting TypedDict field "nsfw" while extending  [misc]
- discord/channel.py:154: error: Overwriting TypedDict field "overwrites" while extending  [misc]
- discord/channel.py:155: error: Overwriting TypedDict field "default_auto_archive_duration" while extending  [misc]
- discord/channel.py:156: error: Overwriting TypedDict field "default_thread_slowmode_delay" while extending  [misc]
+ discord/ext/commands/hybrid.py:61: error: Definition of field "description" incompatible with base class "_HybridCommandKwargs"  [misc]
+ discord/ext/commands/hybrid.py:69: error: Definition of field "description" incompatible with base class "_HybridCommandDecoratorKwargs"  [misc]
+ discord/ext/commands/hybrid.py:73: error: Definition of field "description" incompatible with base class "_HybridGroupKwargs"  [misc]
- discord/ext/commands/hybrid.py:61: error: Overwriting TypedDict field "description" while extending  [misc]
- discord/ext/commands/hybrid.py:64: error: Overwriting TypedDict field "with_app_command" while extending  [misc]
- discord/ext/commands/hybrid.py:65: error: Overwriting TypedDict field "guild_ids" while extending  [misc]
- discord/ext/commands/hybrid.py:66: error: Overwriting TypedDict field "guild_only" while extending  [misc]
- discord/ext/commands/hybrid.py:67: error: Overwriting TypedDict field "default_permissions" while extending  [misc]
- discord/ext/commands/hybrid.py:68: error: Overwriting TypedDict field "nsfw" while extending  [misc]
- discord/ext/commands/hybrid.py:69: error: Overwriting TypedDict field "description" while extending  [misc]
- discord/ext/commands/hybrid.py:73: error: Overwriting TypedDict field "description" while extending  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "max_messages" while merging  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "proxy" while merging  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "proxy_auth" while merging  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "shard_id" while merging  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "shard_count" while merging  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "application_id" while merging  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "member_cache_flags" while merging  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "chunk_guilds_at_startup" while merging  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "status" while merging  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "activity" while merging  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "allowed_mentions" while merging  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "heartbeat_timeout" while merging  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "guild_ready_timeout" while merging  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "assume_unsync_clock" while merging  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "enable_debug_events" while merging  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "enable_raw_presences" while merging  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "http_trace" while merging  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "max_ratelimit_timeout" while merging  [misc]
- discord/ext/commands/bot.py:96: error: Overwriting TypedDict field "connector" while merging  [misc]

pydantic (https://github.com/pydantic/pydantic)
- pydantic/fields.py:99: error: Unexpected keyword argument "closed" for "__init_subclass__" of "TypedDict"  [call-arg]

alicederyn · 2026-05-20T15:21:28Z

I accidentally force-pushed a complete rebase 🤦‍♀️ sorry, I think I managed to revert

alicederyn force-pushed the closed.keyword branch from bd9fee9 to 34df265 Compare April 30, 2026 14:31

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alicederyn force-pushed the closed.keyword branch from 34df265 to 26bf6d1 Compare May 1, 2026 13:40

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alicederyn force-pushed the closed.keyword branch from 26bf6d1 to 1cacf06 Compare May 1, 2026 15:17

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alicederyn force-pushed the closed.keyword branch from 1cacf06 to 595bac4 Compare May 1, 2026 17:10

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alicederyn marked this pull request as ready for review May 1, 2026 17:45

ilevkivskyi mentioned this pull request May 1, 2026

final TypedDict #7981

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alicederyn added 18 commits May 3, 2026 11:18

Subtypes fix: required keys must remain required

c06fef7

Fix a bug where a non-required key was considered consistent with a required key if the latter was marked as read-only.

Join fix: readonly keys must remain readonly

f79ba70

A typo was causing the readonly state of keys on the LHS of a TypedDict join to be ignored.

Improve TypedDict join

2ed7992

Improve TypedDict joins where keys mismatch by returning a readonly key with the joined type instead of discarding it.

Expand TypedDict subclassing tests

ab1a151

Prior to implementing support for subclass refinement, expand the test suite with all the cases that need to be tested.

Narrow on explicitly uninhabited keys

e7372e4

`NotRequired[Never]` can be used to indicate that a single key in a TypedDict will not be present.

Support parsing TypedDict closed keyword

c7115c1

Begin implementing PEP 728 support by adding an is_closed field to TypedDictType. This is filled out from the closed keyword, and displayed in reveal_type, but not otherwise supported yet.

Implement closed support in subclassing

90cb21f

Propagate closed from subclasses. Verify that a subclass of a closed TypedDict does not add keys, nor override the closed status.

Implement closed support in join logic

4106525

Close the join of two closed TypedDicts, and treat a missing key in a closed TypedDict as a `NotRequired[Never]` rather than the `ReadOnly[NotRequired[object]]` of an open TypedDict.

Implement closed support in meet logic

6cc0d63

The meet of a closed TypedDict and another TypedDict must be closed. The implicit type of a missing key in a closed TypedDict is `ReadOnly[NotRequired[Never]]`.

Implement closed support in narrowing

5bfcc43

Narrowing a union already treats final TypedDicts as closed; use the same logic if the closed keyword is used.

Implement TypeVar support in narrowing

d7449df

If a TypeVar with a TypedDict upper bound is encountered while narrowing, narrow based on the upper bound.

Implement closed support in astdiff

2621704

alicederyn added 6 commits May 3, 2026 11:18

Implement closed support in stubgen

34a13de

Implement closed support in serialization

87ede99

Implement closed support in TypeAnalyser

bbdd827

Propagate closed when analysing a TypedDictType with a fallback. This ensures subtype checks work correctly for a TypeVar with a closed TypedDict upper bound.

Implement closed support in unpacking

c1ff8b3

Unpacking a TypedDict with an undeclared key to a TypedDict with that key declared as not required is acceptable if the former is closed. Unpacking an open TypedDict into a closed TypedDict is never safe.

Implement closed support in expandtype

ca5a13f

Close the kwargs TypedDict returned by ParamSpec where possible. Use an empty, closed TypedDict instead of a `dict[str, Never]` for functions that do not accept kwargs.

Implement closed support in get method

4d3a7b0

alicederyn force-pushed the closed.keyword branch from 595bac4 to 4d3a7b0 Compare May 3, 2026 10:48

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Yuriyzabegaev mentioned this pull request May 5, 2026

Proposal: Annotate model and solver params with TypedDict pmgbergen/porepy#1667

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ilevkivskyi reviewed May 16, 2026

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ilevkivskyi reviewed May 18, 2026

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JelleZijlstra mentioned this pull request May 19, 2026

Zuban allows deleting TypedDict keys that don't exist (PEP 728) zubanls/zuban#439

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Merge branch 'master' into closed.keyword

877e000

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alicederyn force-pushed the closed.keyword branch from 271f3e8 to 6734010 Compare May 20, 2026 14:35

alicederyn added 8 commits May 20, 2026 15:45

Refactor common logic into zipall

05d3a4b

Compute requiredness and mutability in zipall, and substitute Never for None for closed TypedDicts. This avoids duplicating this logic at the three callsites.

Allow adding Never items to closed subtypes

bd05e88

A closed subtype can validly add a key, provided it is uninhabited, as this is just explicitly stating the previously implicit constraint.

Reword not-required compatibility error messages

d102505

Refer to deletion in error messages for incompatibility mutable not-required fields in base classes, as this is simpler, and ultimately the reason why there is an incompatibility

Test case from no error to error

9279a01

alicederyn force-pushed the closed.keyword branch from 6734010 to 2d1333c Compare May 20, 2026 14:46

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