[core.atomic] atomicStore not work with struct that has template parameter list and function pointer (-preview=all)

[thewilsonator]

Transfered from https://issues.dlang.org/show_bug.cgi?id=24736 from dlang/phobos#9876

Description

import core.atomic; // Compile with -preview=all

enum VARS_AFTER_FP = true;

synchronized shared class A
{
	static void proc() {}

	void fn(ARGS...)(ARGS args)
	{
		static struct S
		{
			static if (VARS_AFTER_FP)
			{
				void function() fp;
				ARGS vars;
			}
			else
			{
				ARGS vars;
				void function() fp;
			}
		}
		S s;
		s.fp.atomicStore(&proc);
		static foreach (i, e; args)
		{
			s.vars[i].atomicStore(e.atomicLoad());
		}
	}
}

void main()
{
	auto a = new A;
	a.fn(1); // OK
	a.fn(2, "str"); // Runtime error when VARS_AFTER_FP is false.
	a.fn("str", 3); // Runtime error when VARS_AFTER_FP is true.
}