#!/usr/bin/env python3
"""Check debug-only before pointer is C89-declared in bytes formatting."""
import sys
from pathlib import Path

if len(sys.argv) != 2:
    raise SystemExit("usage: vc6-bytes-format-c89.test.py bytesobject.c")
source = Path(sys.argv[1]).read_text()
signature = "_PyBytes_FormatEx(const char *format, Py_ssize_t format_len,"
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]
branch_marker = "else {\n            /* Got a format specifier */"
branch_start = body.index(branch_marker)
branch_end = body.index("\n            fmt++;", branch_start)
branch = body[branch_start:branch_end]
expected_decl = "#ifndef NDEBUG\n            char *before;\n#endif"
if expected_decl not in branch:
    raise SystemExit("debug before pointer must be declared in the format-specifier block's declaration group")
fmt_statement = body.index("\n            fmt++;", branch_start)
if branch_start + branch.index(expected_decl) > fmt_statement:
    raise SystemExit("debug before declaration occurs after executable statements")
if source.count("char *before;") != 1 or "char *before = res;" in source:
    raise SystemExit("debug before pointer must have one declaration and a separate assignment")
prepare = body.index("_PyBytesWriter_Prepare(&writer, res, alloc - 2)")
assignment = body.index("before = res;")
assertion = body.index("assert((res - before) == alloc);")
if not (prepare < assignment < body.index("/* Write the sign if needed */") < assertion):
    raise SystemExit("bytes format pointer capture / output / size assertion order changed")
print("bytes format debug pointer C89 declaration and capture order: PASS")