[Python-Dev] warning in initpyexpat

[Jeremy Hylton]

gcc -Wall is complaining about possible use of errors_module without
initialization in the initpyexpat function.  Here's the offending code:

    sys_modules = PySys_GetObject("modules");
    {
        PyObject *errmod_name = PyString_FromString("pyexpat.errors");

        if (errmod_name != NULL) {
            errors_module = PyDict_GetItem(d, errmod_name);
            if (errors_module == NULL) {
                errors_module = PyModule_New("pyexpat.errors");
                if (errors_module != NULL) {
                    PyDict_SetItemString(d, "errors", errors_module);
                    PyDict_SetItem(sys_modules, errmod_name, errors_module);
                }
            }
            Py_DECREF(errmod_name);
            if (errors_module == NULL)
                /* Don't code dump later! */
                return;
        }
    }
    errors_dict = PyModule_GetDict(errors_module);

It is indeed the case that errors_module can be used without
initialization.  If PyString_FromString("pyexpat.errors") fails, you
ignore the error and will immediately call PyModule_GetDict with an
uninitialized variable.

You ought to check for the error condition and bail cleanly, rather
than ignoring it and failing somewhere else.

I also wonder why the code that does this check is in its own set of
curly braces; thus, the post to python-dev to discuss the style issue.
Why did you do this?  Is it approved Python style?  It looks cluttered
to me.

Jeremy