port: advance VC6 typeobject frontier and preserve regression coverage

scripts/vc6-sliceobject-py-slice-new-c89.test.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+"""Regression for PySlice_New declarations accepted by VC6 C89."""
+import re
+import subprocess
+import sys
+import tempfile
+from pathlib import Path
+
+source = Path(sys.argv[1] if len(sys.argv) > 1 else "cpython/Objects/sliceobject.c")
+text = source.read_text()
+match = re.search(r"PySlice_New\(PyObject \*start, PyObject \*stop, PyObject \*step\)\s*\{(.*?)\n\}", text, re.S)
+assert match, "PySlice_New definition not found"
+body = match.group(1)
+assert re.search(r"^\s*PyInterpreterState \*interp;\s*$", body, re.M), "interp must be declared at function entry"
+assert re.search(r"^\s*PySliceObject \*obj;\s*$", body, re.M), "obj must be declared at function entry"
+assert "PyInterpreterState *interp = _PyInterpreterState_GET();" not in body, "interp initialization must remain a separate assignment"
+assert re.search(r"interp\s*=\s*_PyInterpreterState_GET\(\);", body), "preserve interpreter lookup"
+print("PySlice_New C89 declaration placement and lookup: PASS")