port: advance VC6 compatibility frontier

2026-10-02 17:38:23 +00:00
parent df99608491
commit 01a7105be9
16 changed files with 20324 additions and 5 deletions
@@ -0,0 +1,62 @@
+#!/usr/bin/env python3
+"""Check C89 locals and mutation/cleanup order in method_vectorcall."""
+import sys
+from pathlib import Path
+
+if len(sys.argv) != 2:
+    raise SystemExit("usage: vc6-classobject-c89.test.py classobject.c")
+source = Path(sys.argv[1]).read_text()
+signature = "method_vectorcall(PyObject *method, PyObject *const *args,"
+start = source.index(signature)
+body_start = source.index("\n{\n", start) + 2
+body_end = source.index("\n}\n", body_start)
+body = source[body_start:body_end]
+first_statement = body.index("assert(Py_IS_TYPE(method, &PyMethod_Type));")
+for declaration in ("PyThreadState *tstate;", "PyObject *self;", "PyObject *func;", "Py_ssize_t nargs;", "PyObject *result;"):
+    if body.count(declaration) != 1 or body.index(declaration) > first_statement:
+        raise SystemExit("method_vectorcall locals must be declared before the assertion")
+if any(text in body for text in ("PyThreadState *tstate =", "PyObject *self =", "PyObject *func =", "Py_ssize_t nargs =")):
+    raise SystemExit("method_vectorcall declarations must be separate from assignments")
+branch_start = body.index("if (nargsf & PY_VECTORCALL_ARGUMENTS_OFFSET) {")
+branch_end = body.index("\n    else {", branch_start)
+branch = body[branch_start:branch_end]
+if "PyObject **newargs;\n        PyObject *tmp;" not in branch:
+    raise SystemExit("offset branch locals must be declared at block entry")
+if not (branch.index("newargs = (PyObject**)args - 1;") < branch.index("nargs += 1;") < branch.index("tmp = newargs[0];") < branch.index("newargs[0] = self;") < branch.index("result = _PyObject_VectorcallTstate") < branch.index("newargs[0] = tmp;")):
+    raise SystemExit("offset argument mutation and restoration order changed")
+else_start = body.index("\n    else {", branch_start)
+else_body = body[else_start:]
+first_exec = else_body.index("nkwargs =")
+for declaration in ("Py_ssize_t nkwargs;", "Py_ssize_t totalargs;", "PyObject *newargs_stack[_PY_FASTCALL_SMALL_STACK];", "PyObject **newargs;"):
+    if else_body.count(declaration) != 1 or else_body.index(declaration) > first_exec:
+        raise SystemExit("non-offset branch locals must be declared before initialization")
+if not (else_body.index("nkwargs =") < else_body.index("totalargs =") < else_body.index("if (totalargs == 0)") < else_body.index("if (totalargs <=") < else_body.index("newargs = newargs_stack;") < else_body.index("newargs[0] = self;") < else_body.index("result = _PyObject_VectorcallTstate") < else_body.index("if (newargs != newargs_stack)")):
+    raise SystemExit("non-offset allocation/call/free order changed")
+
+signature = "PyMethod_New(PyObject *func, PyObject *self)"
+start = source.index(signature)
+body_start = source.index("\n{\n", start) + 2
+body_end = source.index("\n}\n", body_start)
+body = source[body_start:body_end]
+first_statement = body.index("if (self == NULL)")
+if body.count("PyMethodObject *im;") != 1 or body.index("PyMethodObject *im;") > first_statement:
+    raise SystemExit("PyMethod_New object local must be declared before validation")
+if "PyMethodObject *im =" in body:
+    raise SystemExit("PyMethod_New allocation must remain at its original execution point")
+order = (
+    "if (self == NULL)",
+    "im = PyObject_GC_New(PyMethodObject, &PyMethod_Type);",
+    "if (im == NULL)",
+    "im->im_weakreflist = NULL;",
+    "Py_INCREF(func);",
+    "im->im_func = func;",
+    "Py_INCREF(self);",
+    "im->im_self = self;",
+    "im->vectorcall = method_vectorcall;",
+    "_PyObject_GC_TRACK(im);",
+    "return (PyObject *)im;",
+)
+positions = [body.index(item) for item in order]
+if positions != sorted(positions):
+    raise SystemExit("PyMethod_New allocation/reference/GC order changed")
+print("classobject C89 declarations and method initialization order: PASS")