port: advance VC6 typeobject frontier and preserve regression coverage

scripts/vc6-setobject-make-new-set-c89.test.py

@@ -0,0 +1,27 @@
+#!/usr/bin/env python3
+"""Check make_new_set's C89 declaration and assertion/allocation order."""
+import re
+import sys
+from pathlib import Path
+
+source = Path(sys.argv[1]).read_text()
+match = re.search(
+    r"static PyObject \*\nmake_new_set\(PyTypeObject \*type, PyObject \*iterable\)"
+    r"\n\{(.*?)\n\}",
+    source,
+    re.S,
+)
+assert match, "make_new_set not found"
+body = match.group(1)
+assert re.match(r"\s*PySetObject \*so;", body), (
+    "so must be declared without initializer before the assertion"
+)
+assert re.match(
+    r"\s*PySetObject \*so;\s*assert\(PyType_Check\(type\)\);"
+    r"\s*so = \(PySetObject \*\)type->tp_alloc\(type, 0\);"
+    r"\s*if \(so == NULL\)\s*return NULL;",
+    body,
+), "type assertion, allocation, and allocation failure check must retain their order"
+assert body.count("PySetObject *so;") == 1, "so must be declared exactly once"
+assert body.count("type->tp_alloc(") == 1, "allocation must occur exactly once"
+print("make_new_set C89 declaration and assertion/allocation order: PASS")