Use libcpp.optional provided by Cython.

python/pyarrow/lib.pxd

@@ -21,44 +21,11 @@ from cpython cimport PyObject
 from libcpp cimport nullptr, bool as c_bool
 from libcpp.cast cimport dynamic_cast
 from libcpp.memory cimport dynamic_pointer_cast
+from libcpp.optional cimport optional
 from pyarrow.includes.common cimport *
 from pyarrow.includes.libarrow cimport *
 from pyarrow.includes.libarrow_python cimport *
 
-# Will be available in Cython 3, not backported
-# ref: https://github.com/cython/cython/issues/3293#issuecomment-1223058101
-cdef extern from "<optional>" namespace "std" nogil:
-    cdef cppclass nullopt_t:
-        nullopt_t()
-
-    cdef nullopt_t nullopt
-
-    cdef cppclass optional[T]:
-        ctypedef T value_type
-        optional()
-        optional(nullopt_t)
-        optional(optional&) except +
-        optional(T&) except +
-        c_bool has_value()
-        T& value()
-        T& value_or[U](U& default_value)
-        void swap(optional&)
-        void reset()
-        T& emplace(...)
-        T& operator*()
-        # T* operator->() # Not Supported
-        optional& operator=(optional&)
-        optional& operator=[U](U&)
-        c_bool operator bool()
-        c_bool operator!()
-        c_bool operator==[U](optional&, U&)
-        c_bool operator!=[U](optional&, U&)
-        c_bool operator<[U](optional&, U&)
-        c_bool operator>[U](optional&, U&)
-        c_bool operator<=[U](optional&, U&)
-        c_bool operator>=[U](optional&, U&)
-
-    optional[T] make_optional[T](...) except +
 
 cdef extern from "Python.h":
     int PySlice_Check(object)