Add PyBytes_AS_STRING, seen in ormsgpack

Author: timfel

newsfragments/1.added.md

@@ -1 +1,2 @@
 Added `_PyLong_Sign`
+Add `PyBytes_AS_STRING`

pyo3-ffi/src/cpython/bytesobject.rs

@@ -1,6 +1,6 @@
 use crate::object::*;
 use crate::Py_ssize_t;
-#[cfg(not(any(PyPy, GraalPy, Py_LIMITED_API)))]
+#[cfg(not(any(PyPy, Py_LIMITED_API)))]
 use std::os::raw::c_char;
 use std::os::raw::c_int;
 
@@ -23,3 +23,11 @@ extern "C" {
     #[cfg_attr(PyPy, link_name = "_PyPyBytes_Resize")]
     pub fn _PyBytes_Resize(bytes: *mut *mut PyObject, newsize: Py_ssize_t) -> c_int;
 }
+
+#[inline]
+pub unsafe fn PyBytes_AS_STRING(op: *mut PyObject) -> *const c_char {
+    #[cfg(not(any(PyPy, GraalPy, Py_LIMITED_API)))]
+    return &(*op.cast::<PyBytesObject>()).ob_sval as *const c_char;
+    #[cfg(any(PyPy, GraalPy, Py_LIMITED_API))]
+    return crate::PyBytes_AsString(op);
+}