port: advance VC6 typeobject frontier and preserve regression coverage

scripts/vc6-tupleobject-freelist-push-index-c89.test.py

@@ -0,0 +1,32 @@
+#!/usr/bin/env python3
+"""Check only maybe_freelist_push's index declaration and evaluation order."""
+import re
+import sys
+from pathlib import Path
+
+source = Path(sys.argv[1] if len(sys.argv) > 1 else "cpython/Objects/tupleobject.c")
+match = re.search(
+    r"static inline int\nmaybe_freelist_push\(PyTupleObject \*op\)\n\{(.*?)\n\}",
+    source.read_text(),
+    re.S,
+)
+assert match, "maybe_freelist_push definition missing"
+body = match.group(1)
+assert re.match(
+    r"\s*#if PyTuple_NFREELISTS > 0\s*"
+    r"PyInterpreterState \*interp = _PyInterpreterState_GET\(\);\s*"
+    r"Py_ssize_t index;\s*#ifdef Py_DEBUG",
+    body,
+), "maybe_freelist_push: index must be declared before the debug assertion and empty-tuple check"
+assert len(re.findall(r"\bPy_ssize_t\s+index\b", body)) == 1, (
+    "maybe_freelist_push: exactly one index declaration required"
+)
+assert re.search(
+    r"if \(Py_SIZE\(op\) == 0\)\s*\{\s*return 0;\s*\}\s*"
+    r"index = Py_SIZE\(op\) - 1;\s*if \(index < PyTuple_NFREELISTS",
+    body,
+), "maybe_freelist_push: assign index at its original evaluation point after the empty-tuple return"
+assert len(re.findall(r"\bindex\s*=", body)) == 1, (
+    "maybe_freelist_push: exactly one index assignment required"
+)
+print("maybe_freelist_push index C89 declaration and evaluation order: PASS")