Hello,
I get errors related to lambdas not being default-constructible or copy-assignable
when using a lambda as a predicate with certain adaptors (e.g. filtered) and
certain algorithms (e.g. min_element).
The following code illustrates the problem:
#include
#include
int main()
{
int a[] = {1, 2, 3};
auto is_odd = [](int i){ return i % 2 == 1; };
boost::min_element(a | boost::adaptors::filtered(is_odd));
}
The errors are shown below.
Is there a workaround for this?
Thanks,
Nate.
Errors:
In file included from algorithm:63:0,
from /usr/lib/boost/boost/iterator/iterator_concepts.hpp:29,
from /usr/lib/boost/boost/range/concepts.hpp:20,
from /usr/lib/boost/boost/range/algorithm/min_element.hpp:15,
from test.cpp:1:
stl_algo.h: In function 'boost::filter_iterator, int *>
min_element(
boost::filter_iterator, int *>
, boost::filter_iterator, int *>
)':
/usr/lib/boost/boost/range/algorithm/min_element.hpp:44:63:
instantiated from 'boost::range_iterator<const T>::ame boost
::range_iterator<const T>::type = boost::filter_iterator<
main()::, int *
> boost::range::min_element(
const boost::range_detail::filtered_range<
main()::, int [3]
> &
)'
test.cpp:8:61: instantiated from here
stl_algo.h:6109:4: error: use of deleted function 'boost::filter_iterator<
main()::, int *
> & boost::filter_iterator, int *>::operator=(
const boost::filter_iterator, int *> &
)'
In file included from /usr/lib/boost/boost/range/adaptor/filtered.hpp
:16:0,
from test.cpp:2:
/usr/lib/boost/boost/iterator/filter_iterator.hpp:44:9: error: 'boost
::filter_iterator, int *> & boost::filter_iterator<
main()::, int *
>::operator=(
const boost::filter_iterator, int *> &
)' is implicitly deleted because the default definition would be ill-
formed:
/usr/lib/boost/boost/iterator/filter_iterator.hpp:44:9: error: use of
deleted function 'main():: & main()::::operator=(
const main():: &
)'
test.cpp:7:20: error: a lambda closure type has a deleted copy assignment
operator
In file included from /usr/lib/boost/boost/range/adaptor/filtered.hpp
:16:0,
from test.cpp:2:
/usr/lib/boost/boost/iterator/filter_iterator.hpp: In constructor
'boost::filter_iterator, int *>::filter_iterator()':
/usr/lib/boost/boost/concept_check.hpp:133:10: instantiated from
'boost::DefaultConstructible<
boost::filter_iterator, int *>
>::~DefaultConstructible()'
/usr/lib/boost/boost/concept/usage.hpp:22:29: instantiated from
'boost::concepts::usage_requirements<
boost::DefaultConstructible<
boost::filter_iterator, int *>
>
>::~usage_requirements()'
/usr/lib/boost/boost/concept/detail/general.hpp:38:28: instantiated
from 'static void boost::concepts::requirement<
boost::concepts::failed ************ boost::concepts
::usage_requirements<
boost::DefaultConstructible<
boost::filter_iterator, int *>
>
>::************
>::failed()'
/usr/lib/boost/boost/concept_check.hpp:132:1: instantiated from
'boost::DefaultConstructible<
boost::filter_iterator, int *>
>'
/usr/lib/boost/boost/range/concepts.hpp:169:16: instantiated from
'boost::range_detail::ForwardIteratorConcept<
boost::filter_iterator, int *>
>'
/usr/lib/boost/boost/concept/detail/has_constraints.hpp:42:5: [
skipping 5 instantiation contexts ]
/usr/lib/boost/boost/concept/detail/has_constraints.hpp:42:5:
instantiated from 'const bool boost::concepts::not_satisfied<
boost::ForwardRangeConcept<
const boost::range_detail::filtered_range<
main()::, int [3]
>
>
>::value'
/usr/lib/boost/boost/concept/detail/has_constraints.hpp:45:31:
instantiated from 'boost::concepts::not_satisfied<
boost::ForwardRangeConcept<
const boost::range_detail::filtered_range<
main()::, int [3]
>
>
>'
/usr/lib/boost/boost/mpl/if.hpp:67:11: instantiated from 'boost::mpl
::if_<
boost::concepts::not_satisfied<
boost::ForwardRangeConcept<
const boost::range_detail::filtered_range<
main()::, int [3]
>
>
>, boost::concepts::constraint<
boost::ForwardRangeConcept<
const boost::range_detail::filtered_range<
main()::, int [3]
>
>
>, boost::concepts::requirement<
boost::concepts::failed ************ boost::ForwardRangeConcept<
const boost::range_detail::filtered_range<
main()::, int [3]
>
>::************
>
>'
/usr/lib/boost/boost/concept/detail/general.hpp:50:8: instantiated
from 'boost::concepts::requirement_<
void (*)(
boost::ForwardRangeConcept<
const boost::range_detail::filtered_range<
main()::, int [3]
>
>
)
>'
/usr/lib/boost/boost/range/algorithm/min_element.hpp:43:1:
instantiated from 'boost::range_iterator<const T>::ame boost
::range_iterator<const T>::type = boost::filter_iterator<
main()::, int *
> boost::range::min_element(
const boost::range_detail::filtered_range<
main()::, int [3]
> &
)'
test.cpp:8:61: instantiated from here
/usr/lib/boost/boost/iterator/filter_iterator.hpp:54:25: error: use of
deleted function 'main()::::<lambda>()'
test.cpp:7:20: error: a lambda closure type has a deleted default constructor
