🏷️ ufunc annotations for signbit (#372)

* 🏷️ stub `signbit`

* ✅ add `signbit` test

Author: guan404ming

src/numpy-stubs/_core/umath.pyi

@@ -446,6 +446,39 @@ class _Call11Isnat(Protocol):
         **kwds: Unpack[_Kwargs2],
     ) -> NDArray[np.bool]: ...
 
+@type_check_only
+class _Call11Signbit(Protocol):
+    @overload  # (scalar) -> bool
+    def __call__(
+        self,
+        x: _FloatLike_co,
+        /,
+        out: None = None,
+        *,
+        dtype: _DTypeLikeBool | None = None,
+        **kwds: Unpack[_Kwargs2],
+    ) -> np.bool: ...
+    @overload  # (array-like, out: T) -> T
+    def __call__(
+        self,
+        x: _ArrayLikeFloat_co,
+        /,
+        out: _Out1[_ArrayT],
+        *,
+        dtype: _DTypeLikeBool | None = None,
+        **kwds: Unpack[_Kwargs2],
+    ) -> _ArrayT: ...
+    @overload  # (array) -> Array[bool]
+    def __call__(
+        self,
+        x: NDArray[np.floating] | _NestedSequence[np.floating],
+        /,
+        out: _Out1[NDArray[np.floating]] | None = None,
+        *,
+        dtype: _DTypeLikeBool | None = None,
+        **kwds: Unpack[_Kwargs2],
+    ) -> NDArray[np.bool]: ...
+
 @type_check_only
 class _Call11Logical(Protocol):
     @overload
@@ -1384,7 +1417,9 @@ _ufunc_2_2 = TypeAliasType(
 isnat: Final[_ufunc_1_1[_Call11Isnat]] = ...
 
 # {[f]} -> ?
-signbit: Final[_ufunc_1_1] = ...
+signbit: Final[_ufunc_1_1[_Call11Signbit]] = ...
+
+# {?[uifc]Mm} -> ?
 isfinite: Final[_ufunc_1_1[_Call11Bool]] = ...
 isinf: Final[_ufunc_1_1[_Call11Bool]] = ...
 

test/static/accept/ufuncs.pyi

@@ -96,3 +96,7 @@ assert_type(np.spacing(f8), np.float64)
 assert_type(np.spacing(AR_f8), npt.NDArray[np.float64])
 assert_type(np.spacing(AR_f4), npt.NDArray[np.floating])
 assert_type(np.spacing(AR_f8, out=AR_f8), npt.NDArray[np.float64])
+
+assert_type(np.signbit(f8), np.bool_)
+assert_type(np.signbit(AR_f8), npt.NDArray[np.bool_])
+assert_type(np.signbit(AR_f8, out=AR_bool), npt.NDArray[np.bool_])

test/static/reject/ufuncs.pyi

@@ -63,3 +63,6 @@ np.logical_xor(dt64, dt64, dtype=np.datetime64)  # type: ignore[arg-type]  # pyr
 
 np.spacing(dt64)  # type: ignore[call-overload]  # pyright: ignore[reportCallIssue,reportArgumentType]
 np.spacing(AR_f8, dtype=np.datetime64)  # type: ignore[arg-type]  # pyright: ignore[reportArgumentType, reportCallIssue]
+
+np.signbit(dt64)  # type: ignore[call-overload]  # pyright: ignore[reportCallIssue,reportArgumentType]
+np.signbit(AR_f8, dtype=np.datetime64)  # type: ignore[arg-type]  # pyright: ignore[reportArgumentType, reportCallIssue]