id,summary,reporter,owner,description,type,status,milestone,component,version,severity,resolution,keywords,cc
5146,Assertion fails in visitation_impl.hpp with nested variants,Florian Goujeon <flo.goujeon@…>,Antony Polukhin,"Let test_variant be following typedef:
{{{
typedef
	variant
	<
		int,
		ptr_to_test_variant
	>
	test_variant
;
}}}

ptr_to_test_variant is a simple class which contains a test_variant object allocated on the heap (to break the circular dependency, see attachment).

Here is the test case:
{{{
int main()
{
	test_variant tv1 = 88;
	test_variant ptr_to_tv1 = ptr_to_test_variant(tv1);
	test_variant ptr_to_ptr_to_tv1 = ptr_to_test_variant(ptr_to_tv1);

	const ptr_to_test_variant& direct_ptr_to_ptr_to_tv1 = get<ptr_to_test_variant>(ptr_to_ptr_to_tv1);
	ptr_to_ptr_to_tv1 = direct_ptr_to_ptr_to_tv1.pointed_test_variant();
}
}}}

Here is the output:
{{{
/usr/include/boost/variant/detail/visitation_impl.hpp:207: typename Visitor::result_type boost::detail::variant::visitation_impl(int, int, Visitor&, VPCV, mpl_::true_, NBF, W*, S*) [with W = mpl_::int_<20>, S = boost::detail::variant::visitation_impl_step<boost::mpl::l_iter<boost::mpl::l_end>, boost::mpl::l_iter<boost::mpl::l_end> >, Visitor = boost::variant<int, ptr_to_test_variant>::convert_copy_into, VPCV = void*, NBF = boost::variant<int, ptr_to_test_variant>::has_fallback_type_, typename Visitor::result_type = int, mpl_::true_ = mpl_::bool_<true>]: Assertion `false' failed.
}}}

I'm experiencing the exact same issue with my own implementation of stack-based variant (using variadic templates) as well. I'd like to know how to fix this…",Bugs,closed,To Be Determined,variant,Boost 1.45.0,Problem,invalid,variant assert assertion nested,