Handler error code type (enum) doesn't match the return type of handlers (int)

[manowicz]

Handlers like readstat_set_variable_handler return an integer error code, but the three available error codes are defined as an enum:

enum {
    READSTAT_HANDLER_OK,
    READSTAT_HANDLER_ABORT,
    READSTAT_HANDLER_SKIP_VARIABLE
};

As a result when registering a handler as a lambda function, I need a cast to avoid compilation errors:

readstat_set_variable_handler(parser, [](int, readstat_variable_t*, const char*, void*) {
           return static_cast<int>(READSTAT_HANDLER_OK);
});	

While it would make sense to be able to write:

readstat_set_variable_handler(parser, [](int, readstat_variable_t*, const char*, void*) {
           return READSTAT_HANDLER_OK;
});