port: advance VC6 typeobject frontier and preserve regression coverage

scripts/vc6-obmalloc-pymalloc-free-c89.test.py

@@ -0,0 +1,55 @@
+#!/usr/bin/env python3
+"""Guard pymalloc_free's C89 locals and complete operation order."""
+
+import re
+import sys
+from pathlib import Path
+
+source = Path(sys.argv[1]).read_text()
+match = re.search(
+    r"\npymalloc_free\(void \*ctx, void \*p\)\s*\{(.*?)\n\}",
+    source, re.S,
+)
+assert match, "pymalloc_free definition not found"
+body = re.sub(r"/\*.*?\*/", "", match.group(1), flags=re.S)
+declarations = """
+    poolp pool;
+    block *lastfree;
+"""
+assert body.split()[:len(declarations.split())] == declarations.split(), (
+    "pymalloc_free must declare pool and lastfree without initializers at function entry"
+)
+
+# Evaluate POOL_ADDR only after the Valgrind early return, and read freeblock
+# only after the address-range check and refcount assertion. Preserve all
+# free-list writes, refcount updates, branches, helper calls, and returns.
+expected = declarations + """
+    assert(p != NULL);
+#ifdef WITH_VALGRIND
+    if (UNLIKELY(running_on_valgrind > 0)) {
+        return 0;
+    }
+#endif
+    pool = POOL_ADDR(p);
+    if (UNLIKELY(!address_in_range(p, pool))) {
+        return 0;
+    }
+    assert(pool->ref.count > 0);
+    lastfree = pool->freeblock;
+    *(block **)p = lastfree;
+    pool->freeblock = (block *)p;
+    pool->ref.count--;
+    if (UNLIKELY(lastfree == NULL)) {
+        insert_to_usedpool(pool);
+        return 1;
+    }
+    if (LIKELY(pool->ref.count != 0)) {
+        return 1;
+    }
+    insert_to_freepool(pool);
+    return 1;
+"""
+assert body.split() == expected.split(), (
+    "preserve pymalloc_free initialization, evaluation, and control-flow order"
+)
+print("obmalloc pymalloc_free entry declarations and original operation order: PASS")