Re: [Boost-users] [phoenix] [clang] error assigning function object

Subject: Re: [Boost-users] [phoenix] [clang] error assigning function object
From: Nathan Ridge (zeratul976_at_[hidden])
Date: 2016-01-12 17:27:42

> Every Phoenix actor has three `operator=` functions. One is a normal
> copy assignment, and the other two are for generating lazy assignment
> functions (one takes a mutable actor, and the other an immutable one).
> Gcc is selecting the copy assignment in this instance, and Clang is
> selecting the lazy assignment function. I believe Gcc is correct in
> this circumstance, because the copy-assignment function is not
> templated and therefore should take precedence according to the
> overload resolution rules. So I _think_ this is a bug in Clang. 

Thanks for the explanation!

> This
> came up in boost log over a year ago; Joel and I thought it was a bug
> in Clang at the time. We should've provided them with a minimal example
> to see their answer (maybe Joel did?) - I will reduce this further and
> provide it to them unless you feel the need to.

Please go ahead - thanks! If you end up filing a clang bug, could you share
the bug number here?

By the way, to explain _why_ I'm trying to assign the actor: I'm not trying
to assign it explicitly, but I'm capturing it by value in a lambda, and this 
seems to require the assignment operator:

#include <string>
#include <boost/phoenix/core/argument.hpp>
#include <boost/phoenix/function.hpp>

struct S {
    void operator()(std::string, int) const;
};

boost::phoenix::function<S> lazy;

void foo() {
    auto func1 = lazy(std::string(), boost::phoenix::placeholders::_1);
    [func1]{}();
}

Thanks,
Nate