task! with a static template method gives "null this"

[Lee Braiden]

Hi all,

I'm defining a template class with a static method, and adding a call to 
that to a taskpool.  However, when I run it, I get a "null this" error 
from parallelism.d.

Here's the minimised code:

class Population(GeneType)
{
        alias Population!(GeneType) ThisType;

        static void breedIndividual(ThisType oldPop, ThisType newPop)
        {
                auto mom = oldPop.selectParent();
                auto pop = oldPop.selectParent();

                auto kid = mom.crossbreedFrom(pop);

                // chance of mutation
                if (uniform(0, MUTATION_CHANCE) == 0)
                {
                    auto oldFitness = kid.fitness();
                    kid.dna.mutate();
                    auto newFitness = kid.fitness();
                }

                newPop.lifeforms_ ~= kid;
        }

        ThisType evolve(TaskPool p)
        {
                ...

                auto t = task!breedIndividual(this, newPop)

                ...
        }
}


The actual error message is:

core.exception.AssertError@/usr/include/d2/4.6/std/parallelism.d(2723): 
null this


There is no "this" usage that I can see, in the breedIndividual() 
(static) method... EXCEPT maybe for the fact that ThisType depends on the 
template class expansion.  But that's all expanded at compile-time, and 
doesn't matter, right?

So I'm not sure how to solve this.  My first thought was to move 
breedIndividual out of the class, but it does depend on ThisType, as 
defined in the class template.


Am I right that this is what's causing the "null this" error?  If so, 
what can I do to fix it?



Thanks,


-- 
Lee