boost::program_options appends vector options with similar names

Question

I'm using program_options to parse commandLine and configuration options and I found what seems to be a bug. The problem appears when using vector options with similar names. If I have an unspecified parameter "myParam" and another specified parameter "myParam2", the library appends the values of myParam to myParam2.

For example, when I call my program like this:

./model -myParam2={7,8,9}  -myParam={5,6}

I get:

myParam not declared   <-- This is OK
myParam2 size: 5       <-- I would expect this to be size:3

I reduced my code to the following example showing the problem:

// Declare a group of options that will be allowed both on command line and in config file
po::options_description options("Simulator Configuration (and Command Line) options");
options.add_options()
            //("myParam", po::value<std::vector<int>>(), "test")  --> If I uncomment this line, it works as expected
            ("myParam2", po::value<std::vector<int>>(), "test");

// parse the cmdline options
auto parsed_cmdLine_options = po::command_line_parser(ac,av).options(options)
                            .style(po::command_line_style::unix_style | po::command_line_style::allow_long_disguise) // to enable options to start with a '-' instead of '--'
                            .allow_unregistered()    // to allow generic parameters (which can be read by models)
                            .run();
po::store(parsed_cmdLine_options, simulatorParams);
notify(simulatorParams);

// print parsed options
std::vector<int> tmp1, tmp2;
if(simulatorParams.count("myParam")){
    tmp1 = simulatorParams["myParam"].as<std::vector<int>>();
    std::cout << "myParam size: " << tmp1.size() << "\n";

    if(tmp1.size()!= 2){
        throw "Wrong Size";
    }
}else
{
    std::cout << "myParam not declared \n";
}

if(simulatorParams.count("myParam2")){
    tmp2 = simulatorParams["myParam2"].as<std::vector<int>>();
    std::cout << "myParam2 size: " << tmp2.size() << "\n";

    if(tmp2.size()!= 3){
        throw "Wrong Size";
    }
}

If I uncomment the line which registers "myParam" it all works as expected:

options.add_options()
            ("myParam", po::value<std::vector<int>>(), "test")
            ("myParam2", po::value<std::vector<int>>(), "test");

It prints:

myParam size: 2
myParam2 size: 3

I really need to use unregistered options as I re process them later in the execution.

It seem to be a very simple bug, so maybe I'm using the library somehow wrong.

Does anyone saw this problem before or any ideas how to workaround it?

Thank you very much!

EDIT: I'm using boost 1.48. I tried several other syntaxes for the parameters and it behaves the same way:

• with double "--": ./model --myParam2={7,8,9} --myParam={5,6}
• with single values per declaration: ./model --myParam2=7 --myParam2=8 --myParam2=9 --myParam=5 --myParam=6
• combining the previous.

Answer 1

It's a feature. See command line style options:

• allow_guessing

Allow abbreviated spellings for long options, if they unambiguously identify long option. No long option name should be prefix of other long option name if guessing is in effect.