Merge pull request #21111 from BvB93/__array_finalize__

TYP, MAINT: Relax the `obj` type in `__array_finalize__`

6 files changed, 18 insertions, 4 deletions

diff --git a/numpy/__init__.pyi b/numpy/__init__.pyi
index 6ecb3d2da..297c482e5 100644
--- a/numpy/__init__.pyi
+++ b/numpy/__init__.pyi
@@ -1526,7 +1526,9 @@ class ndarray(_ArrayOrScalarCommon, Generic[_ShapeType, _DType_co]):
         kwargs: Mapping[str, Any],
     ) -> Any: ...
 
-    @property
+    # NOTE: In practice any object is accepted by `obj`, but as `__array_finalize__`
+    # is a pseudo-abstract method the type has been narrowed down in order to
+    # grant subclasses a bit more flexiblity
     def __array_finalize__(self, obj: None | NDArray[Any], /) -> None: ...
 
     def __array_wrap__(
@@ -3699,7 +3701,7 @@ class memmap(ndarray[_ShapeType, _DType_co]):
         shape: None | int | tuple[int, ...] = ...,
         order: _OrderKACF = ...,
     ) -> memmap[Any, dtype[Any]]: ...
-    def __array_finalize__(self, obj: memmap[Any, Any]) -> None: ...
+    def __array_finalize__(self, obj: object) -> None: ...
     def __array_wrap__(
         self,
         array: memmap[_ShapeType, _DType_co],
@@ -3811,7 +3813,7 @@ class matrix(ndarray[_ShapeType, _DType_co]):
         dtype: DTypeLike = ...,
         copy: bool = ...,
     ) -> matrix[Any, Any]: ...
-    def __array_finalize__(self, obj: NDArray[Any]) -> None: ...
+    def __array_finalize__(self, obj: object) -> None: ...
 
     @overload
     def __getitem__(self, key: (
@@ -3972,7 +3974,7 @@ class chararray(ndarray[_ShapeType, _CharDType]):
         order: _OrderKACF = ...,
     ) -> chararray[Any, dtype[str_]]: ...
 
-    def __array_finalize__(self, obj: NDArray[str_ | bytes_]) -> None: ...
+    def __array_finalize__(self, obj: object) -> None: ...
     def __mul__(self, other: _ArrayLikeInt_co) -> chararray[Any, _CharDType]: ...
     def __rmul__(self, other: _ArrayLikeInt_co) -> chararray[Any, _CharDType]: ...
     def __mod__(self, i: Any) -> chararray[Any, _CharDType]: ...
diff --git a/numpy/typing/tests/data/fail/ndarray_misc.pyi b/numpy/typing/tests/data/fail/ndarray_misc.pyi
index 8320a44f3..77bd9a44e 100644
--- a/numpy/typing/tests/data/fail/ndarray_misc.pyi
+++ b/numpy/typing/tests/data/fail/ndarray_misc.pyi
@@ -39,3 +39,5 @@ AR_b.__index__()  # E: Invalid self argument
 AR_f8[1.5]  # E: No overload variant
 AR_f8["field_a"]  # E: No overload variant
 AR_f8[["field_a", "field_b"]]  # E: Invalid index type
+
+AR_f8.__array_finalize__(object())  # E: incompatible type
diff --git a/numpy/typing/tests/data/reveal/chararray.pyi b/numpy/typing/tests/data/reveal/chararray.pyi
index 3da2e1599..61906c860 100644
--- a/numpy/typing/tests/data/reveal/chararray.pyi
+++ b/numpy/typing/tests/data/reveal/chararray.pyi
@@ -127,3 +127,6 @@ reveal_type(AR_S.istitle())  # E: ndarray[Any, dtype[bool_]]
 
 reveal_type(AR_U.isupper())  # E: ndarray[Any, dtype[bool_]]
 reveal_type(AR_S.isupper())  # E: ndarray[Any, dtype[bool_]]
+
+reveal_type(AR_U.__array_finalize__(object()))  # E: None
+reveal_type(AR_S.__array_finalize__(object()))  # E: None
diff --git a/numpy/typing/tests/data/reveal/memmap.pyi b/numpy/typing/tests/data/reveal/memmap.pyi
index 86de8eb08..af7307499 100644
--- a/numpy/typing/tests/data/reveal/memmap.pyi
+++ b/numpy/typing/tests/data/reveal/memmap.pyi
@@ -14,3 +14,5 @@ reveal_type(np.memmap("file.txt", offset=5))  # E: memmap[Any, dtype[{uint8}]]
 reveal_type(np.memmap(b"file.txt", dtype=np.float64, shape=(10, 3)))  # E: memmap[Any, dtype[{float64}]]
 with open("file.txt", "rb") as f:
     reveal_type(np.memmap(f, dtype=float, order="K"))  # E: memmap[Any, dtype[Any]]
+
+reveal_type(memmap_obj.__array_finalize__(object()))  # E: None
diff --git a/numpy/typing/tests/data/reveal/ndarray_misc.pyi b/numpy/typing/tests/data/reveal/ndarray_misc.pyi
index f91d6351b..c9a42b3e8 100644
--- a/numpy/typing/tests/data/reveal/ndarray_misc.pyi
+++ b/numpy/typing/tests/data/reveal/ndarray_misc.pyi
@@ -212,3 +212,7 @@ reveal_type(AR_f8.dump("test_file"))  # E: None
 reveal_type(AR_f8.dump(b"test_file"))  # E: None
 with open("test_file", "wb") as f:
     reveal_type(AR_f8.dump(f))  # E: None
+
+reveal_type(AR_f8.__array_finalize__(None))  # E: None
+reveal_type(AR_f8.__array_finalize__(B))  # E: None
+reveal_type(AR_f8.__array_finalize__(AR_f8))  # E: None
diff --git a/numpy/typing/tests/data/reveal/rec.pyi b/numpy/typing/tests/data/reveal/rec.pyi
index b2eaca899..8ea4a6ee8 100644
--- a/numpy/typing/tests/data/reveal/rec.pyi
+++ b/numpy/typing/tests/data/reveal/rec.pyi
@@ -33,6 +33,7 @@ reveal_type(REC_AR_V.field(0, AR_i8))  # E: None
 reveal_type(REC_AR_V.field("field_a", AR_i8))  # E: None
 reveal_type(REC_AR_V["field_a"])  # E: Any
 reveal_type(REC_AR_V.field_a)  # E: Any
+reveal_type(REC_AR_V.__array_finalize__(object()))  # E: None
 
 reveal_type(np.recarray(  # recarray[Any, dtype[record]]
     shape=(10, 5),