#!/usr/bin/env python3
"""Check only update_arg's first declaration frontier, before later blockers."""

import re
import subprocess
import sys
import tempfile
from pathlib import Path

source = Path(sys.argv[1]).read_text()
match = re.search(
    r"static int\nmutablemapping_update_arg\(PyObject \*self, PyObject \*arg\)\n\{"
    r".*?(?=    if \(func != NULL\) \{)", source, re.S,
)
assert match, "mutablemapping_update_arg prefix not found"
# Compile the untouched prefix only: iterator/key declarations farther down
# are independent frontier defects. The synthetic tail observes lookup output.
harness = r'''
#include <assert.h>
#include <stddef.h>
typedef struct { int unused; } PyObject;
static PyObject self_obj, arg_obj, items_obj, func_obj;
static int scenario, stage, keys;
#define _Py_ID(name) name
static int PyDict_CheckExact(PyObject *arg) {
    assert(stage == 0 && arg == &arg_obj);
    stage = 1;
    return scenario < 3;
}
static PyObject *PyDict_Items(PyObject *arg) {
    assert(stage == 1 && arg == &arg_obj);
    stage = 2;
    return scenario == 0 ? NULL : &items_obj;
}
static int mutablemapping_add_pairs(PyObject *self, PyObject *items) {
    assert(stage == 2 && self == &self_obj && items == &items_obj);
    stage = 3;
    return scenario == 1 ? -1 : 0;
}
static void Py_DECREF(PyObject *obj) {
    assert(stage == 3 && obj == &items_obj);
    stage = 4;
}
static int _PyObject_LookupAttr(PyObject *arg, int *id, PyObject **func) {
    assert(stage == 1 && arg == &arg_obj && id == &keys);
    stage = 5;
    *func = scenario == 5 ? &func_obj : NULL;
    return scenario == 3 ? -1 : scenario == 5;
}
'''
harness += match.group(0)
harness += r'''
    assert(stage == 5 && res == 0);
    assert(func == (scenario == 5 ? &func_obj : NULL));
    stage = 6;
    return 0;
}
int main(void) {
    int result;
    for (scenario = 0; scenario < 6; ++scenario) {
        stage = 0;
        result = mutablemapping_update_arg(&self_obj, &arg_obj);
        assert(result == ((scenario < 2 || scenario == 3) ? -1 : 0));
        assert(stage == (scenario == 0 ? 2 : scenario < 3 ? 4 :
                         scenario == 3 ? 5 : 6));
    }
    return 0;
}
'''
with tempfile.TemporaryDirectory(prefix="vc6-odict-update-arg-func-") as directory:
    path = Path(directory)
    (path / "test.c").write_text(harness)
    result = subprocess.run([
        "cc", "-std=c89", "-pedantic-errors", "-Wall", "-Wextra", "-Werror",
        str(path / "test.c"), "-o", str(path / "test"),
    ])
    if result.returncode:
        sys.exit(result.returncode)
    subprocess.run([str(path / "test")], check=True)
print("mutablemapping_update_arg prefix C89 compile and dict/lookup ordering: PASS (6 cases)")