[lex][boost 1.44] 2 oddities

I couldn't find anything about these on either Spirit list, but
apologies if I just missed it.

Oddity #1:  There is a specialization of
assign_to_attribute_from_iterators<> for bool, in
home/qi/detail/construct.hpp:

    template <typename Iterator>
    struct assign_to_attribute_from_iterators<bool, Iterator>
    {
        static void
        call(Iterator const& first, Iterator const& last, char& attr)
        { ... }
    };

Notice that attr is a char&, not a bool&.  Is this a cut-and-paste
error, or is it intentional?  It has forced me to provide my own
specialization to get lex to automatically create a token_def<bool>:

    template <>
    struct assign_to_attribute_from_iterators<bool, my_iterator_type, void>
    {
        static void call(const GG::text_iterator& first, const
my_iterator_type& last, bool& attr)
            { ... }
    };

Notice that I was forced to supply an iterator type so that my
specialization is a better fit.  This means that I can't currently
define a lexer template that takes an Iterator parameter that "just
works" -- when my users change their choice of iterator, they have to
add a new full specialization of assign_to_attribute_from_iterators<>.

I've verified that this code is still in place on the release branch,
so presumably it will go out in 1.45.


Oddity #2:  It seems that I have to define
assign_to_attribute_from_iterators<> for new types, even if I define a
semantic action that does the assignment.  This further means that any
semantic action [_val = ...] is useless, because the conversion will
happen later and overwrite the token's value anyway, right?


Thanks,
Zach Laine

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