I made a mistake in my program which exposed curious behaviour of valac. I get null 'this' pointer in a constructor. Please consider the following code snippet:

public class Foo
{
    int i;

    public Foo.from(int i)
    {
        this.i = i;
    }
}

public class Bar
{
    Foo         f;

    public Bar()
    {
        assert( this != null );
        f.from(1);                 // This line causes the trouble.
                                   // It should have been f = new Foo.from(1);
    }
}

int main(string[] argv)
{
    var b = new Bar();
    return 0;
}

If I run the compiled program I get this output:

**
ERROR:/net/tieto/home/vkirsan/sandbit/test.vala.c:305:bar_construct: assertion failed: (this != null)
Abort

The produced C code for the constructor of Bar looks like this:

Bar* bar_construct (GType object_type) {
	Bar* self = NULL;
	Foo* _tmp0_ = NULL;
	_vala_assert (self != NULL, "this != null");
	_tmp0_ = self->priv->f;
	self = (Bar*) foo_construct_from (object_type, 1);
	return self;
}

So 1) _vala_assert() is made before 'self' has been allocated 2) 'self' is set not to a Bar object but casted from a new Foo object.