Re: Possible regression in boost 1.61

> Oh, right, my bad. What we really need to know is the definition of start_rule. It should be something like the linker error you are having.

I think I have nailed it.
I had to change from 
    using start_type = x3::rule<start_class, ast::Start>;
to 
    using start_type = x3::rule<start_class, ast::Count>;
as the start rule contains a single count rule after the result of the preceeding character parser is omitted.
The attribute type of the count rule seems to propagate to the start rule.

I have not yet tried to fix my original problem.

It seems this is not a regression, but a breaking change. 
I have no problem requiring boost 1.61+ for the project to build.

Thanks, Peter

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