Remove the PyArray_* allocation functions again, but give users a hint where to find the underlying PyO3 functions.

This reverts commit 712626b.

Author: adamreichold

Cargo.toml

@@ -21,9 +21,6 @@ num-traits = "0.2"
 ndarray = ">= 0.13, < 0.16"
 pyo3 = { version = "0.16", default-features = false }
 
-[build-dependencies]
-pyo3-build-config = "0.16"
-
 [dev-dependencies]
 pyo3 = { version = "0.16", features = ["auto-initialize"] }
 

build.rs

@@ -1,9 +1,14 @@
 //! Low-Level binding for [Array API](https://numpy.org/doc/stable/reference/c-api/array.html)
-use libc::FILE;
+//!
+//! Note that NumPy's low-level allocation functions `PyArray_{malloc,realloc,free}` are not part of this module.
+//! The reason is that they would be re-exports of the `PyMem_Raw{Malloc,Realloc,Free}` functions from PyO3,
+//! but those are not unconditionally exported, i.e. they are not available when using the limited Python C-API.
+
 use std::cell::Cell;
 use std::os::raw::*;
 use std::ptr::null;
 
+use libc::FILE;
 use pyo3::ffi::{self, PyObject, PyTypeObject};
 
 use crate::npyffi::*;
@@ -394,13 +399,6 @@ pub unsafe fn PyArray_CheckExact(py: Python, op: *mut PyObject) -> c_int {
     (ffi::Py_TYPE(op) == PY_ARRAY_API.get_type_object(py, NpyTypes::PyArray_Type)) as _
 }
 
-// these are under `#if NPY_USE_PYMEM == 1` which seems to be always defined as 1
-#[cfg(not(Py_LIMITED_API))]
-pub use pyo3::ffi::{
-    PyMem_RawFree as PyArray_free, PyMem_RawMalloc as PyArray_malloc,
-    PyMem_RawRealloc as PyArray_realloc,
-};
-
 #[cfg(test)]
 mod tests {
     use super::PY_ARRAY_API;