fix: replace PyList_GET_ITEM()

resolves#1434 Instead use [`PyList_GetItemRef()`] for python >= 3.13. Internally, this function is conditionally defined for python < 3.13. [`PyList_GetItemRef()`] is part of the Stable ABI but also propagate errors. Whereas the previous [`PyList_GET_ITEM()`] did not do any error checking and was not part of the Stable ABI. [`PyList_GetItemRef()`]: https://docs.python.org/3/c-api/list.html#c.PyList_GetItemRef [`PyList_GET_ITEM()`]: https://docs.python.org/3/c-api/list.html#c.PyList_GET_ITEM

Author: 2bndy5

src/repository.c

@@ -46,6 +46,17 @@
 #include<git2/odb_backend.h>
 #include<git2/sys/repository.h>
 
+// TODO: remove this function when Python 3.13 becomes the minimum supported version
+#ifPY_MAJOR_VERSION==3&&PY_MINOR_VERSION<13
+staticinlinePyObject*
+PyList_GetItemRef(PyObject*op, Py_ssize_tindex)
+{
+PyObject*item=PyList_GetItem(op, index);
+Py_XINCREF(item);
+returnitem;
+}
+#endif
+
 externPyObject*GitError;
 
 externPyTypeObjectIndexType;
@@ -599,8 +610,11 @@ merge_base_xxx(Repository *self, PyObject *args, git_merge_base_xxx_t git_merge_
  }
 
 for (; i<commit_oid_count; i++){
-py_commit_oid=PyList_GET_ITEM(py_commit_oids, i);
+py_commit_oid=PyList_GetItemRef(py_commit_oids, i);
+if (py_commit_oid==NULL)
+ goto out;
 err=py_oid_to_git_oid_expand(self->repo, py_commit_oid, &commit_oids[i]);
+Py_DECREF(py_commit_oid);
 if (err<0)
  goto out;
  }
@@ -1052,8 +1066,11 @@ Repository_create_commit(Repository *self, PyObject *args)
  goto out;
  }
 for (; i<parent_count; i++){
-py_parent=PyList_GET_ITEM(py_parents, i);
+py_parent=PyList_GetItemRef(py_parents, i);
+if (py_parent==NULL)
+ goto out;
 len=py_oid_to_git_oid(py_parent, &oid);
+Py_DECREF(py_parent);
 if (len==0)
  goto out;
 err=git_commit_lookup_prefix(&parents[i], self->repo, &oid, len);
@@ -1135,8 +1152,11 @@ Repository_create_commit_string(Repository *self, PyObject *args)
  goto out;
  }
 for (; i<parent_count; i++){
-py_parent=PyList_GET_ITEM(py_parents, i);
+py_parent=PyList_GetItemRef(py_parents, i);
+if (py_parent==NULL)
+ goto out;
 len=py_oid_to_git_oid(py_parent, &oid);
+Py_DECREF(py_parent);
 if (len==0)
  goto out;
 err=git_commit_lookup_prefix(&parents[i], self->repo, &oid, len);