Indexed iterator does not work on array storage

[henryiii]

The following code fails on Wandbox with Boost 1.71 (and similar behavior has been seen in develop):

#include <iostream>
#include <cstdlib>
#include <boost/histogram.hpp>

int main()
{
    std::cout << "Hello, Wandbox!" << std::endl;
    
    namespace bh = boost::histogram;
    
    auto h = bh::make_histogram_with(std::array<double, 7>(), bh::axis::integer<>(0,5));
    h(2); h(3); h(3);
    
    for(auto&& ind : bh::indexed(h) )
        std::cout << *ind << " ";
}

The failure:

In file included from /opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram/algorithm/project.hpp:16,
                 from /opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram.hpp:31,
                 from prog.cc:4:
/opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram/indexed.hpp: In instantiation of 'class boost::histogram::indexed_range<boost::histogram::histogram<std::tuple<boost::histogram::axis::integer<int, boost::use_default, boost::use_default> >, boost::histogram::storage_adaptor<std::array<double, 7> > > >':
/opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram/indexed.hpp:343:63:   required from 'auto boost::histogram::indexed(Histogram&&, boost::histogram::coverage) [with Histogram = boost::histogram::histogram<std::tuple<boost::histogram::axis::integer<int, boost::use_default, boost::use_default> >, boost::histogram::storage_adaptor<std::array<double, 7> > >&]'
prog.cc:15:35:   required from here
/opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram/indexed.hpp:47:9: error: 'boost::histogram::indexed_range<boost::histogram::histogram<std::tuple<boost::histogram::axis::integer<int, boost::use_default, boost::use_default> >, boost::histogram::storage_adaptor<std::array<double, 7> > > >::value_iterator' {aka 'double*'} is not a class, struct, or union type
   47 |   using value_reference = typename value_iterator::reference;
      |         ^~~~~~~~~~~~~~~
/opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram/indexed.hpp:48:9: error: 'boost::histogram::indexed_range<boost::histogram::histogram<std::tuple<boost::histogram::axis::integer<int, boost::use_default, boost::use_default> >, boost::histogram::storage_adaptor<std::array<double, 7> > > >::value_iterator' {aka 'double*'} is not a class, struct, or union type
   48 |   using value_type = typename value_iterator::value_type;
      |         ^~~~~~~~~~
prog.cc: In function 'int main()':
prog.cc:16:21: error: no match for 'operator*' (operand type is 'boost::histogram::indexed_range<boost::histogram::histogram<std::tuple<boost::histogram::axis::integer<int, boost::use_default, boost::use_default> >, boost::histogram::storage_adaptor<std::array<double, 7> > > >::accessor')
   16 |        std::cout << *ind << " ";
      |                     ^~~~
In file included from /opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram/algorithm/project.hpp:15,
                 from /opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram.hpp:31,
                 from prog.cc:4:
/opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram/histogram.hpp:393:6: note: candidate: 'template<class A1, class S1, class A2, class S2> auto boost::histogram::operator*(const boost::histogram::histogram<A1, S1>&, const boost::histogram::histogram<A2, S2>&)'
  393 | auto operator*(const histogram<A1, S1>& a, const histogram<A2, S2>& b) {
      |      ^~~~~~~~
/opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram/histogram.hpp:393:6: note:   template argument deduction/substitution failed:
prog.cc:16:22: note:   'boost::histogram::indexed_range<boost::histogram::histogram<std::tuple<boost::histogram::axis::integer<int, boost::use_default, boost::use_default> >, boost::histogram::storage_adaptor<std::array<double, 7> > > >::accessor' is not derived from 'const boost::histogram::histogram<A1, S1>'
   16 |        std::cout << *ind << " ";
      |                      ^~~
In file included from /opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram/algorithm/project.hpp:15,
                 from /opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram.hpp:31,
                 from prog.cc:4:
/opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram/histogram.hpp:423:6: note: candidate: 'template<class A, class S> auto boost::histogram::operator*(const boost::histogram::histogram<A1, S1>&, double)'
  423 | auto operator*(const histogram<A, S>& h, double x) {
      |      ^~~~~~~~
/opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram/histogram.hpp:423:6: note:   template argument deduction/substitution failed:
prog.cc:16:22: note:   'boost::histogram::indexed_range<boost::histogram::histogram<std::tuple<boost::histogram::axis::integer<int, boost::use_default, boost::use_default> >, boost::histogram::storage_adaptor<std::array<double, 7> > > >::accessor' is not derived from 'const boost::histogram::histogram<A1, S1>'
   16 |        std::cout << *ind << " ";
      |                      ^~~
In file included from /opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram/algorithm/project.hpp:15,
                 from /opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram.hpp:31,
                 from prog.cc:4:
/opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram/histogram.hpp:433:6: note: candidate: 'template<class A, class S> auto boost::histogram::operator*(double, const boost::histogram::histogram<A1, S1>&)'
  433 | auto operator*(double x, const histogram<A, S>& h) {
      |      ^~~~~~~~
/opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram/histogram.hpp:433:6: note:   template argument deduction/substitution failed:
prog.cc:16:22: note:   candidate expects 2 arguments, 1 provided
   16 |        std::cout << *ind << " ";
      |                      ^~~
In file included from /opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram/axis.hpp:12,
                 from /opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram.hpp:34,
                 from prog.cc:4:
/opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram/axis/regular.hpp:41:3: note: candidate: 'template<class T> T boost::histogram::detail::operator*(T&&, const boost::histogram::detail::one_unit&)'
   41 | T operator*(T&& t, const one_unit&) {
      |   ^~~~~~~~
/opt/wandbox/boost-1.71.0/gcc-head/include/boost/histogram/axis/regular.hpp:41:3: note:   template argument deduction/substitution failed:
prog.cc:16:22: note:   candidate expects 2 arguments, 1 provided
   16 |        std::cout << *ind << " ";
      |                      ^~~
1

[HDembinski]

Thank you for reporting this, will be fixed.

[HDembinski]

fixed in develop