Experiment: revert datetime-date inheritance

[m-aciek]

I'll most probably open a Python forum discussion about it. I'm mostly interested in the mypy primer test.

Some context: glyph/DateType#16

[github-actions]

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

prefect (https://github.com/PrefectHQ/prefect)
+ src/prefect/_internal/schemas/validators.py:376: error: No overload variant of "__call__" of "_rrulestr" matches argument types "str", "datetime", "bool"  [call-overload]
+ src/prefect/_internal/schemas/validators.py:376: note: Possible overload variants:
+ src/prefect/_internal/schemas/validators.py:376: note:     def __call__(self, s: str, *, forceset: Literal[True], dtstart: date | None = ..., cache: bool | None = ..., unfold: bool = ..., compatible: bool = ..., ignoretz: bool = ..., tzids: Callable[[str], tzinfo] | Mapping[str, tzinfo] | None = ..., tzinfos: Mapping[str, tzinfo | int | str | None] | Callable[[str, int], tzinfo | int | str | None] | None = ...) -> rruleset
+ src/prefect/_internal/schemas/validators.py:376: note:     def __call__(self, s: str, *, compatible: Literal[True], dtstart: date | None = ..., cache: bool | None = ..., unfold: bool = ..., forceset: bool = ..., ignoretz: bool = ..., tzids: Callable[[str], tzinfo] | Mapping[str, tzinfo] | None = ..., tzinfos: Mapping[str, tzinfo | int | str | None] | Callable[[str, int], tzinfo | int | str | None] | None = ...) -> rruleset
+ src/prefect/_internal/schemas/validators.py:376: note:     def __call__(self, s: str, *, dtstart: date | None = ..., cache: bool | None = ..., unfold: bool = ..., forceset: bool = ..., compatible: bool = ..., ignoretz: bool = ..., tzids: Callable[[str], tzinfo] | Mapping[str, tzinfo] | None = ..., tzinfos: Mapping[str, tzinfo | int | str | None] | Callable[[str, int], tzinfo | int | str | None] | None = ...) -> rrule | rruleset

zulip (https://github.com/zulip/zulip)
+ zerver/lib/rate_limiter.py:451: error: Argument 1 to "timeuntil" has incompatible type "datetime"; expected "date"  [arg-type]
+ corporate/lib/stripe.py:2757: error: Unrecognized format specification "%B"  [str-format]
+ corporate/lib/stripe.py:2774: error: Unrecognized format specification "%B"  [str-format]
+ corporate/views/support.py:312: error: Argument 1 to "timesince" has incompatible type "datetime"; expected "date"  [arg-type]

core (https://github.com/home-assistant/core)
+ homeassistant/components/habitica/util.py:86: error: Argument "dtstart" to "rrule" has incompatible type "datetime"; expected "date | None"  [arg-type]
+ homeassistant/components/here_travel_time/coordinator.py:392: error: Argument 1 to "combine" of "datetime" has incompatible type "datetime"; expected "date"  [arg-type]
+ homeassistant/components/input_datetime/__init__.py:396: error: Argument 1 to "combine" of "datetime" has incompatible type "datetime"; expected "date"  [arg-type]
+ homeassistant/helpers/template/extensions/datetime.py:263: error: Argument 1 to "combine" of "datetime" has incompatible type "datetime"; expected "date"  [arg-type]
+ homeassistant/components/google_travel_time/helpers.py:61: error: Argument 1 to "combine" of "datetime" has incompatible type "datetime"; expected "date"  [arg-type]
+ homeassistant/components/radarr/coordinator.py:179: error: Unsupported operand types for >= ("datetime" and "date")  [operator]
+ homeassistant/components/radarr/coordinator.py:179: note: Left operand is of type "date | datetime"
+ homeassistant/components/radarr/coordinator.py:195: error: Unsupported operand types for >= ("datetime" and "date")  [operator]
+ homeassistant/components/radarr/coordinator.py:195: note: Left operand is of type "date | datetime"
+ homeassistant/components/evohome/storage.py:100: error: Argument 1 to "fromisoformat" of "datetime" has incompatible type "object"; expected "str"  [arg-type]
+ homeassistant/components/electric_kiwi/sensor.py:99: error: Argument 1 to "combine" of "datetime" has incompatible type "datetime"; expected "date"  [arg-type]
+ homeassistant/components/electric_kiwi/sensor.py:105: error: Argument 1 to "combine" of "datetime" has incompatible type "datetime"; expected "date"  [arg-type]
- homeassistant/components/evohome/storage.py:100: error: Argument 1 to "fromisoformat" of "date" has incompatible type "object"; expected "str"  [arg-type]
+ homeassistant/components/lamarzocco/calendar.py:101: error: Unsupported operand types for < ("date" and "datetime")  [operator]
+ homeassistant/components/lamarzocco/calendar.py:101: note: Left operand is of type "date | datetime"
+ homeassistant/components/lamarzocco/calendar.py:103: error: Unsupported operand types for > ("date" and "datetime")  [operator]
+ homeassistant/components/lamarzocco/calendar.py:103: note: Left operand is of type "date | datetime"
+ homeassistant/components/habitica/calendar.py:251: error: Unsupported operand types for < ("datetime" and "date")  [operator]
+ homeassistant/components/habitica/calendar.py:251: note: Left operand is of type "date | datetime"
+ homeassistant/components/habitica/calendar.py:372: error: Argument 2 to "start" of "HabiticaDailyRemindersCalendarEntity" has incompatible type "datetime"; expected "date"  [arg-type]
+ homeassistant/components/sonarr/calendar.py:68: error: Unsupported operand types for > ("date" and "datetime")  [operator]
+ homeassistant/components/sonarr/calendar.py:68: note: Left operand is of type "date | datetime"
+ homeassistant/components/workday/binary_sensor.py:77: error: Argument 1 to "date_is_workday" of "BaseWorkdayEntity" has incompatible type "datetime"; expected "date"  [arg-type]
+ homeassistant/components/workday/calendar.py:95: error: Unsupported operand types for >= ("datetime" and "date")  [operator]
+ homeassistant/components/workday/calendar.py:95: note: Left operand is of type "date | datetime"
+ homeassistant/components/workday/calendar.py:105: error: Unsupported operand types for <= ("date" and "datetime")  [operator]
+ homeassistant/components/workday/calendar.py:105: note: Right operand is of type "date | datetime"
+ homeassistant/components/workday/calendar.py:105: error: Unsupported operand types for <= ("datetime" and "date")  [operator]
+ homeassistant/components/workday/calendar.py:105: note: Left operand is of type "date | datetime"

django-stubs (https://github.com/typeddjango/django-stubs)
+ django-stubs/db/models/fields/__init__.pyi:592: error: Incompatible types in assignment (expression has type "str | datetime | date | Combinable", base class "DateField" defined the type as "str | date | Combinable")  [assignment]
+ django-stubs/db/models/fields/__init__.pyi:593: error: Incompatible types in assignment (expression has type "datetime", base class "DateField" defined the type as "date")  [assignment]
+ django-stubs/db/models/fields/__init__.pyi:594: error: Incompatible types in assignment (expression has type "str | datetime", base class "DateField" defined the type as "str | date")  [assignment]

pandas-stubs (https://github.com/pandas-dev/pandas-stubs)
+ pandas-stubs/_libs/tslibs/offsets.pyi:52: error: Unused "type: ignore" comment  [unused-ignore]
+ pandas-stubs/_libs/tslibs/offsets.pyi:64: error: Unused "type: ignore" comment  [unused-ignore]
+ pandas-stubs/_libs/tslibs/offsets.pyi:77: error: Unused "type: ignore" comment  [unused-ignore]
+ tests/test_timefuncs.py:110: error: Expression is of type "Timedelta", not "timedelta"  [assert-type]
+ tests/test_timefuncs.py:111: error: Expression is of type "Timedelta", not "timedelta"  [assert-type]
+ tests/test_timefuncs.py:1575: error: Argument 1 to "to_datetime" has incompatible type "list[datetime]"; expected "Sequence[float | date] | list[str] | tuple[float | str | date, ...] | ndarray[tuple[Any, ...], dtype[datetime64[Any]]] | ndarray[tuple[Any, ...], dtype[str_]] | ndarray[tuple[Any, ...], dtype[integer[Any]]] | ndarray[tuple[Any, ...], dtype[floating[Any]]] | Index[Any] | ExtensionArray"  [arg-type]
+ tests/test_timefuncs.py:1611: error: Argument 1 to "to_datetime" has incompatible type "tuple[datetime, datetime, datetime]"; expected "Sequence[float | date] | list[str] | tuple[float | str | date, ...] | ndarray[tuple[Any, ...], dtype[datetime64[Any]]] | ndarray[tuple[Any, ...], dtype[str_]] | ndarray[tuple[Any, ...], dtype[integer[Any]]] | ndarray[tuple[Any, ...], dtype[floating[Any]]] | Index[Any] | ExtensionArray"  [arg-type]

pandas (https://github.com/pandas-dev/pandas)
+ pandas/_libs/tslibs/timestamps.pyi:164: error: Unused "type: ignore" comment  [unused-ignore]
+ pandas/_libs/tslibs/timestamps.pyi:165: error: Unused "type: ignore" comment  [unused-ignore]
+ pandas/_libs/tslibs/timestamps.pyi:166: error: Unused "type: ignore" comment  [unused-ignore]
+ pandas/_libs/tslibs/timestamps.pyi:167: error: Unused "type: ignore" comment  [unused-ignore]
+ pandas/io/stata.py:366: error: No overload variant of "to_datetime" matches argument type "datetime"  [call-overload]
+ pandas/io/stata.py:366: note: Possible overload variants:
+ pandas/io/stata.py:366: note:     def to_datetime(arg: float | str | date | datetime64[Any], errors: Literal['raise', 'coerce'] = ..., dayfirst: bool = ..., yearfirst: bool = ..., utc: bool = ..., format: str | None = ..., exact: bool = ..., unit: str | None = ..., origin: Any = ..., cache: bool = ...) -> Timestamp
+ pandas/io/stata.py:366: note:     def to_datetime(arg: Series | FulldatetimeDict | DataFrame, errors: Literal['raise', 'coerce'] = ..., dayfirst: bool = ..., yearfirst: bool = ..., utc: bool = ..., format: str | None = ..., exact: bool = ..., unit: str | None = ..., origin: Any = ..., cache: bool = ...) -> Series
+ pandas/io/stata.py:366: note:     def to_datetime(arg: list[Any] | tuple[Any, ...] | Index | ExtensionArray | ndarray[tuple[Any, ...], dtype[Any]], errors: Literal['raise', 'coerce'] = ..., dayfirst: bool = ..., yearfirst: bool = ..., utc: bool = ..., format: str | None = ..., exact: bool = ..., unit: str | None = ..., origin: Any = ..., cache: bool = ...) -> DatetimeIndex
+ pandas/core/tools/datetimes.py:834: error: Overloaded function implementation cannot produce return type of signature 1  [misc]

ibis (https://github.com/ibis-project/ibis)
- ibis/expr/datatypes/core.py:1125: error: Overloaded function signatures 7 and 8 overlap with incompatible return types  [overload-overlap]

sphinx (https://github.com/sphinx-doc/sphinx)
+ sphinx/util/i18n.py: note: In function "babel_format_date":
+ sphinx/util/i18n.py:240:26: error: Argument 1 to "__call__" of "DateFormatter" has incompatible type "datetime"; expected "date | None"  [arg-type]
+ sphinx/util/i18n.py:240:26: error: Argument 1 to "__call__" of "DatetimeFormatter" has incompatible type "datetime"; expected "date | time | float | None"  [arg-type]
+ sphinx/util/i18n.py:249:26: error: Argument 1 to "__call__" of "DateFormatter" has incompatible type "datetime"; expected "date | None"  [arg-type]
+ sphinx/util/i18n.py:249:26: error: Argument 1 to "__call__" of "DatetimeFormatter" has incompatible type "datetime"; expected "date | time | float | None"  [arg-type]

werkzeug (https://github.com/pallets/werkzeug)
+ src/werkzeug/http.py:1186: error: Argument 1 to "formatdate" has incompatible type "datetime | int | float | None"; expected "float | None"  [arg-type]