🎨 massively simplify ctypeslib.as_ctypes

Author: jorenham

src/numpy-stubs/ctypeslib.pyi

@@ -2,7 +2,7 @@ import _ctypes as _ct
 import ctypes as ct
 from _typeshed import StrOrBytesPath
 from collections.abc import Iterable, Sequence
-from typing import Any, ClassVar, Generic, Literal as L, TypeAlias, overload
+from typing import Any, ClassVar, Generic, Literal as L, Protocol, TypeAlias, overload, type_check_only
 from typing_extensions import TypeVar
 
 import _numtype as _nt
@@ -35,6 +35,16 @@ _FlagsKind: TypeAlias = L[
 
 ###
 
+_CT = TypeVar("_CT", bound=ct._CData)
+_CT_co = TypeVar("_CT_co", bound=ct._CData, covariant=True)
+
+@type_check_only
+class _HasCType(Protocol[_CT_co]):
+    @property
+    def __ctype__(self, /) -> _CT_co: ...
+
+###
+
 c_intp = ct.c_ssize_t
 
 class _ndptr(ct.c_void_p, Generic[_DTypeT0_co, _ShapeT0_co]):
@@ -106,59 +116,10 @@ def as_array(obj: _ArrayLike[_ScalarT], shape: _ShapeLike | None = ...) -> _nt.A
 @overload
 def as_array(obj: object, shape: _ShapeLike | None = ...) -> _nt.Array[Any]: ...
 
-# NOTE: The overlapping overloads ignores are a temporary workaround for the non-unique
-# intp/long/longlong issues, and otherwise mypy false positives.
-# NOTE: `as_ctypes` doesn't support `void` values at the moment
-@overload  # bool
-def as_ctypes(obj: np.bool) -> ct.c_bool: ...
-@overload
-def as_ctypes(obj: _nt.Array[np.bool]) -> ct.Array[ct.c_bool]: ...
-@overload  # int8 / byte
-def as_ctypes(obj: np.int8) -> ct.c_int8: ...
-@overload
-def as_ctypes(obj: _nt.Array[np.int8]) -> ct.Array[ct.c_int8]: ...
-@overload  # int16 / short
-def as_ctypes(obj: np.int16) -> ct.c_int16: ...
-@overload
-def as_ctypes(obj: _nt.Array[np.int16]) -> ct.Array[ct.c_int16]: ...
-@overload  # int32 / int[c]
-def as_ctypes(obj: np.int32) -> ct.c_int32: ...
-@overload
-def as_ctypes(obj: _nt.Array[np.int32]) -> ct.Array[ct.c_int32]: ...
-@overload  # int64 / longlong (which might be an alias for for `long`)
-def as_ctypes(obj: np.int64) -> ct.c_int64: ...
-@overload
-def as_ctypes(obj: _nt.Array[np.int64]) -> ct.Array[ct.c_int64]: ...
-@overload  # uint8 / ubyte
-def as_ctypes(obj: np.uint8) -> ct.c_uint8: ...
-@overload
-def as_ctypes(obj: _nt.Array[np.uint8]) -> ct.Array[ct.c_uint8]: ...
-@overload  # uint16 / ushort
-def as_ctypes(obj: np.uint16) -> ct.c_uint16: ...
-@overload
-def as_ctypes(obj: _nt.Array[np.uint16]) -> ct.Array[ct.c_uint16]: ...
-@overload  # uint32 / uint
-def as_ctypes(obj: np.uint32) -> ct.c_uint32: ...
-@overload
-def as_ctypes(obj: _nt.Array[np.uint32]) -> ct.Array[ct.c_uint32]: ...
-@overload  # uint64 / ulonglong
-def as_ctypes(obj: np.uint64) -> ct.c_uint64: ...
-@overload
-def as_ctypes(obj: _nt.Array[np.uint64]) -> ct.Array[ct.c_uint64]: ...
-@overload  # float32 / single / float
-def as_ctypes(obj: np.float32) -> ct.c_float: ...
-@overload
-def as_ctypes(obj: _nt.Array[np.float32]) -> ct.Array[ct.c_float]: ...
-@overload  # float64 / double
-def as_ctypes(obj: np.float64) -> ct.c_double: ...
-@overload
-def as_ctypes(obj: _nt.Array[np.float64]) -> ct.Array[ct.c_double]: ...
-@overload  # float96 / float128 / longdouble
-def as_ctypes(obj: np.longdouble) -> ct.c_longdouble: ...
-@overload
-def as_ctypes(obj: _nt.Array[np.longdouble]) -> ct.Array[ct.c_longdouble]: ...
+#
+def as_ctypes(obj: _HasCType[_CT]) -> _CT: ...
 
-# TODO(jorenham): https://github.com/numpy/numtype/issues/522
+#
 @overload
 def as_ctypes_type(dtype: _nt.ToDTypeBool) -> type[ct.c_bool]: ...
 @overload