When trying to create a closure that uses the variable used as the iterator in a foreach block, Vala fails to capture said variable, leading to lots of confusion.

For example:

foreach(SomeType a in my_list)
{
    Gtk.Button button = new Gtk.Button();
    button.clicked.connect(() -> {
        // a is null
    });
}

Expected results:

a is captured, just like 'button', and variables from higher up in the scope.

Actual results:

a is null, and a quick readthrough of the generated C shows that it's never assigned to anything (within the "Block1Data" struct).

Caveats:

I've tried this both on the current Git tree and 0.7.7. It's broken on both.

Workaround:

I'm currently just creating another variable referring to the same thing:

foreach(SomeType a in my_list)
{
    Gtk.Button button = new Gtk.Button();
    var real_a = a;
    button.clicked.connect(() -> {
        // a is null
        // real_a is what it should be!!
    });
}

This works, but it is certainly not attractive.