[boost] [function] Placement new warnings from gcc 6

Subject: [boost] [function] Placement new warnings from gcc 6
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2016-04-01 04:11:47

Hi,

In my tests on gcc 6 I'm seeing these warnings which stem from 
Boost.Function:

../boost/function/function_template.hpp:572:11: warning: placement new 
constructing an object of type 
'boost::spirit::qi::detail::parser_binder<boost::spirit::qi::sequence<boost::fusion::cons<boost::spirit::qi::any_uint_parser<unsigned 
int, 10u, 1u, -1>, 
boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, 
true, false>, 
boost::fusion::cons<boost::spirit::qi::any_uint_parser<unsigned int, 
10u, 1u, -1>, 
boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, 
true, false>, 
boost::fusion::cons<boost::spirit::qi::any_uint_parser<unsigned int, 
10u, 1u, -1>, 
boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, 
true, false>, 
boost::fusion::cons<boost::spirit::qi::any_uint_parser<unsigned int, 
10u, 1u, -1>, boost::fusion::nil_> > > > > > > >, mpl_::bool_<false> >' 
and size '8' in a region of type 'char' and size '1' [-Wplacement-new=]
../boost/function/function_base.hpp:308:13: warning: placement new 
constructing an object of type 
'boost::detail::function::functor_manager_common<boost::spirit::qi::detail::parser_binder<boost::spirit::qi::sequence<boost::fusion::cons<boost::spirit::qi::any_uint_parser<unsigned 
int, 10u, 1u, -1>, 
boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, 
true, false>, 
boost::fusion::cons<boost::spirit::qi::any_uint_parser<unsigned int, 
10u, 1u, -1>, 
boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, 
true, false>, 
boost::fusion::cons<boost::spirit::qi::any_uint_parser<unsigned int, 
10u, 1u, -1>, 
boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, 
true, false>, 
boost::fusion::cons<boost::spirit::qi::any_uint_parser<unsigned int, 
10u, 1u, -1>, boost::fusion::nil_> > > > > > > >, mpl_::bool_<false> > 
 >::functor_type {aka 
boost::spirit::qi::detail::parser_binder<boost::spirit::qi::sequence<boost::fusion::cons<boost::spirit::qi::any_uint_parser<unsigned 
int, 10u, 1u, -1>, 
boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, 
true, false>, 
boost::fusion::cons<boost::spirit::qi::any_uint_parser<unsigned int, 
10u, 1u, -1>, 
boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, 
true, false>, 
boost::fusion::cons<boost::spirit::qi::any_uint_parser<unsigned int, 
10u, 1u, -1>, 
boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::standard, 
true, false>, 
boost::fusion::cons<boost::spirit::qi::any_uint_parser<unsigned int, 
10u, 1u, -1>, boost::fusion::nil_> > > > > > > >, mpl_::bool_<false> >}' 
and size '8' in a region of type 'char' and size '1' [-Wplacement-new=]

I'm not familiar with boost::function internals, but the warning looks 
serious enough to do something about it. I.e. if it's actually benign, 
it would be nice to silence it to avoid causing panic.