mypy fixup

Author: jbrockmendel

pandas/core/arrays/datetimelike.py

@@ -2140,9 +2140,9 @@ def unit(self) -> TimeUnit:
         >>> idx.as_unit("s").unit
         's'
         """
-        # error: Argument 1 to "dtype_to_unit" has incompatible type
-        # "ExtensionDtype"; expected "Union[DatetimeTZDtype, dtype[Any]]"
-        return dtype_to_unit(self.dtype)  # type: ignore[arg-type]
+        # error: Incompatible return value type (got "str", expected
+        # "Literal['s', 'ms', 'us', 'ns']")  [return-value]
+        return dtype_to_unit(self.dtype)  # type: ignore[return-value]
 
     def as_unit(self, unit: TimeUnit, round_ok: bool = True) -> Self:
         """

pandas/core/arrays/datetimes.py

@@ -395,7 +395,10 @@ def _from_sequence_not_strict(
         result = cls._simple_new(subarr, freq=inferred_freq, dtype=data_dtype)
         if unit is not None and unit != result.unit:
             # If unit was specified in user-passed dtype, cast to it here
-            result = result.as_unit(unit)
+            # error: Argument 1 to "as_unit" of "TimelikeOps" has
+            # incompatible type "str"; expected "Literal['s', 'ms', 'us', 'ns']"
+            # [arg-type]
+            result = result.as_unit(unit)  # type: ignore[arg-type]
 
         validate_kwds = {"ambiguous": ambiguous}
         result._maybe_pin_freq(freq, validate_kwds)

pandas/core/arrays/period.py

@@ -962,7 +962,9 @@ def astype(self, dtype, copy: bool = True):
             # GH#45038 match PeriodIndex behavior.
             tz = getattr(dtype, "tz", None)
             unit = dtl.dtype_to_unit(dtype)
-            return self.to_timestamp().tz_localize(tz).as_unit(unit)
+            # error: Argument 1 to "as_unit" of "TimelikeOps" has incompatible
+            # type "str"; expected "Literal['s', 'ms', 'us', 'ns']"  [arg-type]
+            return self.to_timestamp().tz_localize(tz).as_unit(unit)  # type: ignore[arg-type]
 
         return super().astype(dtype, copy=copy)