Deprecated --force-union-syntax flag

[cdce8p]

This PR deprecates the --force-union-syntax flag and makes it a no-op. It also removes the temporary --overwrite-union-syntax flag which was added to be able to update the mypy test output.

[cdce8p]

The primer output is expected since mypy does still support type checking with --python-version 3.9. I do think though that it makes sense to move to a unified output now, even if it's technically a bit early. By now, almost everyone using type hints should have seen the PEP 604 syntax and know what it means.

[github-actions]

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

PyWinCtl (https://github.com/Kalmat/PyWinCtl)
- src/pywinctl/_pywinctl_linux.py:805: error: Returning Any from function declared to return "Optional[int]"  [no-any-return]
+ src/pywinctl/_pywinctl_linux.py:805: error: Returning Any from function declared to return "int | None"  [no-any-return]

manticore (https://github.com/trailofbits/manticore)
- tests/wasm/json2mc.py:103: error: Invalid index type "Optional[int]" for "list[Module]"; expected type "SupportsIndex"  [index]
+ tests/wasm/json2mc.py:103: error: Invalid index type "int | None" for "list[Module]"; expected type "SupportsIndex"  [index]
- tests/wasm/json2mc.py:159: error: Invalid index type "Optional[int]" for "list[Module]"; expected type "SupportsIndex"  [index]
+ tests/wasm/json2mc.py:159: error: Invalid index type "int | None" for "list[Module]"; expected type "SupportsIndex"  [index]
- tests/wasm/json2mc.py:161: error: Invalid index type "Optional[int]" for "list[Module]"; expected type "SupportsIndex"  [index]
+ tests/wasm/json2mc.py:161: error: Invalid index type "int | None" for "list[Module]"; expected type "SupportsIndex"  [index]
- manticore/platforms/linux.py:1767: error: Unsupported operand type for unary - ("Optional[int]")  [operator]
+ manticore/platforms/linux.py:1767: error: Unsupported operand type for unary - ("int | None")  [operator]
- manticore/platforms/linux.py:1780: error: Unsupported operand type for unary - ("Optional[int]")  [operator]
+ manticore/platforms/linux.py:1780: error: Unsupported operand type for unary - ("int | None")  [operator]
- manticore/platforms/linux.py:1810: error: Unsupported operand type for unary - ("Optional[int]")  [operator]
+ manticore/platforms/linux.py:1810: error: Unsupported operand type for unary - ("int | None")  [operator]
- manticore/platforms/linux.py:2340: error: Unsupported operand type for unary - ("Optional[int]")  [operator]
+ manticore/platforms/linux.py:2340: error: Unsupported operand type for unary - ("int | None")  [operator]
- manticore/platforms/linux.py:3512: error: Unsupported operand type for unary - ("Optional[int]")  [operator]
+ manticore/platforms/linux.py:3512: error: Unsupported operand type for unary - ("int | None")  [operator]
- manticore/platforms/linux.py:3525: error: Unsupported operand type for unary - ("Optional[int]")  [operator]
+ manticore/platforms/linux.py:3525: error: Unsupported operand type for unary - ("int | None")  [operator]
- manticore/platforms/linux.py:3560: error: Unsupported operand type for unary - ("Optional[int]")  [operator]
+ manticore/platforms/linux.py:3560: error: Unsupported operand type for unary - ("int | None")  [operator]
- manticore/platforms/linux.py:3578: error: Unsupported operand type for unary - ("Optional[int]")  [operator]
+ manticore/platforms/linux.py:3578: error: Unsupported operand type for unary - ("int | None")  [operator]
- manticore/platforms/linux.py:3590: error: Unsupported operand type for unary - ("Optional[int]")  [operator]
+ manticore/platforms/linux.py:3590: error: Unsupported operand type for unary - ("int | None")  [operator]
- manticore/platforms/linux.py:3668: error: Unsupported operand type for unary - ("Optional[int]")  [operator]
+ manticore/platforms/linux.py:3668: error: Unsupported operand type for unary - ("int | None")  [operator]
- manticore/platforms/linux.py:3681: error: Unsupported operand type for unary - ("Optional[int]")  [operator]
+ manticore/platforms/linux.py:3681: error: Unsupported operand type for unary - ("int | None")  [operator]
- manticore/native/manticore.py:296: error: Incompatible types in assignment (expression has type "Callable[[Any, Any], Any]", variable has type "Union[Callable[[Any, Any, Any], Any], Callable[[Any, Any, Any, Any], Any]]")  [assignment]
+ manticore/native/manticore.py:296: error: Incompatible types in assignment (expression has type "Callable[[Any, Any], Any]", variable has type "Callable[[Any, Any, Any], Any] | Callable[[Any, Any, Any, Any], Any]")  [assignment]

dragonchain (https://github.com/dragonchain/dragonchain)
- dragonchain/lib/database/redis.py:399:36: error: Argument 2 to "zadd" of "SortedSetCommands" has incompatible type "dict[str, int]"; expected "Mapping[Union[str, bytes], Union[bytes, float, int, str]]"  [arg-type]
+ dragonchain/lib/database/redis.py:399:36: error: Argument 2 to "zadd" of "SortedSetCommands" has incompatible type "dict[str, int]"; expected "Mapping[str | bytes, bytes | float | int | str]"  [arg-type]
- dragonchain/lib/database/redis_utest.py:102:9: error: "Callable[[Union[str, bytes], Union[bytes, float, int, str], Union[float, timedelta, None], Union[float, timedelta, None], bool, bool, bool, bool, Optional[Any], Optional[Any]], Optional[bool]]" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:106:9: error: "Callable[[Union[str, bytes], Union[bytes, float, int, str], Union[float, timedelta, None], Union[float, timedelta, None], bool, bool, bool, bool, Optional[Any], Optional[Any]], Optional[bool]]" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:102:9: error: "Callable[[str | bytes, bytes | float | int | str, float | timedelta | None, float | timedelta | None, bool, bool, bool, bool, Any | None, Any | None], bool | None]" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:106:9: error: "Callable[[str | bytes, bytes | float | int | str, float | timedelta | None, float | timedelta | None, bool, bool, bool, bool, Any | None, Any | None], bool | None]" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:110:9: error: "Callable[[Union[str, bytes]], Optional[Any]]" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:110:9: error: "Callable[[str | bytes], Any | None]" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:114:9: error: "def delete(self, *names: Union[str, bytes]) -> int" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:114:9: error: "def delete(self, *names: str | bytes) -> int" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:122:9: error: "def flushall(self, asynchronous: bool = ..., **kwargs: Union[Any, Any]) -> bool" has no attribute "assert_called_once"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:122:9: error: "def flushall(self, asynchronous: bool = ..., **kwargs: Any | Any) -> bool" has no attribute "assert_called_once"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:126:9: error: "def hdel(self, name: Union[str, bytes], *keys: Union[str, bytes]) -> int" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:126:9: error: "def hdel(self, name: str | bytes, *keys: str | bytes) -> int" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:130:9: error: "def lpush(self, name: Union[bytes, float, int, str], *values: Union[bytes, float, int, str]) -> int" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:130:9: error: "def lpush(self, name: bytes | float | int | str, *values: bytes | float | int | str) -> int" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:134:9: error: "def rpush(self, name: Union[bytes, float, int, str], *values: Union[bytes, float, int, str]) -> int" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:134:9: error: "def rpush(self, name: bytes | float | int | str, *values: bytes | float | int | str) -> int" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:138:9: error: "def delete(self, *names: Union[str, bytes]) -> int" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:138:9: error: "def delete(self, *names: str | bytes) -> int" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:150:9: error: "Callable[[Any, Any, Optional[int]], Any]" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:150:9: error: "Callable[[Any, Any, int | None], Any]" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:154:9: error: "Callable[[Union[str, bytes]], Optional[Any]]" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:158:9: error: "Callable[[Union[str, bytes], int], Optional[Any]]" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:162:9: error: "Callable[[Union[str, bytes], Union[bytes, float, int, str], Union[float, timedelta, None], Union[float, timedelta, None], bool, bool, bool, bool, Optional[Any], Optional[Any]], Optional[bool]]" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:166:9: error: "Callable[[Union[str, bytes], int, int], bool]" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:170:9: error: "Callable[[Union[str, bytes], Union[str, bytes]], Optional[Any]]" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:174:9: error: "def sadd(self, name: Union[str, bytes], *values: Union[bytes, float, int, str]) -> int" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:178:9: error: "Callable[[Union[str, bytes], Union[bytes, float, int, str]], bool]" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:182:9: error: "Callable[[Union[str, bytes]], set[Any]]" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:154:9: error: "Callable[[str | bytes], Any | None]" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:186:9: error: "def srem(self, name: Union[str, bytes], *values: Union[bytes, float, int, str]) -> int" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:190:9: error: "Callable[[Union[str, bytes], int, int], list[Any]]" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:158:9: error: "Callable[[str | bytes, int], Any | None]" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:162:9: error: "Callable[[str | bytes, bytes | float | int | str, float | timedelta | None, float | timedelta | None, bool, bool, bool, bool, Any | None, Any | None], bool | None]" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:166:9: error: "Callable[[str | bytes, int, int], bool]" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:170:9: error: "Callable[[str | bytes, str | bytes], Any | None]" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:174:9: error: "def sadd(self, name: str | bytes, *values: bytes | float | int | str) -> int" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:178:9: error: "Callable[[str | bytes, bytes | float | int | str], bool]" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:182:9: error: "Callable[[str | bytes], set[Any]]" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:186:9: error: "def srem(self, name: str | bytes, *values: bytes | float | int | str) -> int" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:190:9: error: "Callable[[str | bytes, int, int], list[Any]]" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:198:9: error: "Callable[[Union[str, bytes]], int]" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:198:9: error: "Callable[[str | bytes], int]" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:206:9: error: "Callable[[Any, Optional[int]], Any]" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:206:9: error: "Callable[[Any, int | None], Any]" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:210:9: error: "Callable[[Union[str, bytes]], dict[Any, Any]]" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:210:9: error: "Callable[[str | bytes], dict[Any, Any]]" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:214:9: error: "Callable[[Union[str, bytes], Union[str, bytes]], bool]" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:214:9: error: "Callable[[str | bytes, str | bytes], bool]" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/database/redis_utest.py:218:9: error: "Callable[[Union[str, bytes], Mapping[Union[str, bytes], Union[bytes, float, int, str]], bool, bool, bool, bool, Optional[Any], Optional[Any]], int]" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/database/redis_utest.py:218:9: error: "Callable[[str | bytes, Mapping[str | bytes, bytes | float | int | str], bool, bool, bool, bool, Any | None, Any | None], int]" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/lib/interfaces/storage_utest.py:83:9: error: "Callable[[str, Union[str, bytes], Optional[int], str], bool]" has no attribute "assert_called_once_with"  [attr-defined]
+ dragonchain/lib/interfaces/storage_utest.py:83:9: error: "Callable[[str, str | bytes, int | None, str], bool]" has no attribute "assert_called_once_with"  [attr-defined]
- dragonchain/broadcast_processor/broadcast_functions.py:95:32: error: Item "None" of "Optional[Match[str]]" has no attribute "group"  [union-attr]
+ dragonchain/broadcast_processor/broadcast_functions.py:95:32: error: Item "None" of "Match[str] | None" has no attribute "group"  [union-attr]
- dragonchain/lib/authorization.py:315:19: error: Item "None" of "Optional[Match[str]]" has no attribute "group"  [union-attr]
+ dragonchain/lib/authorization.py:315:19: error: Item "None" of "Match[str] | None" has no attribute "group"  [union-attr]
- dragonchain/lib/authorization.py:317:25: error: Item "None" of "Optional[Match[str]]" has no attribute "group"  [union-attr]
+ dragonchain/lib/authorization.py:317:25: error: Item "None" of "Match[str] | None" has no attribute "group"  [union-attr]
- dragonchain/lib/authorization.py:340:31: error: Item "None" of "Optional[Match[str]]" has no attribute "group"  [union-attr]
+ dragonchain/lib/authorization.py:340:31: error: Item "None" of "Match[str] | None" has no attribute "group"  [union-attr]
- dragonchain/webserver/lib/api_keys_utest.py:48:87: error: Argument "permissions_document" to "create_api_key_v1" has incompatible type "dict[str, str]"; expected "Optional[permissions_doc]"  [arg-type]
+ dragonchain/webserver/lib/api_keys_utest.py:48:87: error: Argument "permissions_document" to "create_api_key_v1" has incompatible type "dict[str, str]"; expected "permissions_doc | None"  [arg-type]
- dragonchain/webserver/lib/api_keys_utest.py:91:59: error: Argument 3 to "update_api_key_v1" has incompatible type "dict[str, str]"; expected "Optional[permissions_doc]"  [arg-type]
+ dragonchain/webserver/lib/api_keys_utest.py:91:59: error: Argument 3 to "update_api_key_v1" has incompatible type "dict[str, str]"; expected "permissions_doc | None"  [arg-type]
- dragonchain/webserver/lib/verifications.py:85:12: error: Incompatible return value type (got "Optional[Any]", expected "str")  [return-value]
+ dragonchain/webserver/lib/verifications.py:85:12: error: Incompatible return value type (got "Any | None", expected "str")  [return-value]
- dragonchain/job_processor/contract_job_utest.py:269:13: error: "Callable[[Union[str, ContractState], str], None]" has no attribute "assert_called_once"  [attr-defined]
+ dragonchain/job_processor/contract_job_utest.py:269:13: error: "Callable[[str | ContractState, str], None]" has no attribute "assert_called_once"  [attr-defined]

[hauntsaninja]

I think we should just delete the flag, rather than make it not work

[cdce8p]

I think we should just delete the flag, rather than make it not work

Ideally yes. Tbh I'm not even sure it's actually used somewhere aside from maybe some mypy plugin tests. Nevertheless it was documented publicly and as such would be breaking setups if we were to remove it at once. Better to make it a noop now and remove it later. That's also how I did it for the related --force-uppercase-builtins flag in #19176.

I think we should add the full removal and cleanup for both of these to the v2 list.

[hauntsaninja]

If a user went to the trouble of specifying it, they want that behaviour. In which case this is the change that breaks their setup.

If you want to break this more gently, you should have it raise the warning and not change the behaviour yet.