Include conflict between boost/type_traits and boost/histogram #462

[ralfulrich]

The following minimal program

#include <boost/type_traits.hpp>
#include <boost/histogram.hpp>    // reversion include order --> compiles !

int main() {
  return 0;
}

fails to compile with

In file included from ./boost/histogram/indexed.hpp:12:0,
                 from ./boost/histogram/algorithm/empty.hpp:11,
                 from ./boost/histogram/algorithm.hpp:15,
                 from ./boost/histogram.hpp:27,
                 from /corsika/test/test.cc:4:
./boost/histogram/axis/traits.hpp:411:41: error: return type specified for deduction guide
 constexpr unsigned rank(const Axis& axis) {
                                         ^
./boost/histogram/axis/traits.hpp:411:11: error: decl-specifier in declaration of deduction guide
 constexpr unsigned rank(const Axis& axis) {
           ^~~~~~~~
./boost/histogram/axis/traits.hpp:411:1: error: decl-specifier in declaration of deduction guide
 constexpr unsigned rank(const Axis& axis) {
 ^~~~~~~~~
./boost/histogram/axis/traits.hpp:411:41: error: 'signed' or 'unsigned' invalid for '__dguide_rank'
 constexpr unsigned rank(const Axis& axis) {
                                         ^
./boost/histogram/axis/traits.hpp:411:20: error: deduction guide for 'boost::rank<T>' must have trailing return type
 constexpr unsigned rank(const Axis& axis) {
                    ^~~~
In file included from ./boost/type_traits.hpp:145:0,
                 from /corsika/test/test.cc:2:
./boost/type_traits/rank.hpp:82:27: note: 'template<class T> struct boost::rank' declared here
 template <class T> struct rank : public integral_constant<std::size_t, (::boost::detail::rank_imp<T, 0>::value)>{};
                           ^~~~
In file included from ./boost/histogram/indexed.hpp:12:0,
                 from ./boost/histogram/algorithm/empty.hpp:11,
                 from ./boost/histogram/algorithm.hpp:15,
                 from ./boost/histogram.hpp:27,
                 from /corsika/test/test.cc:4:
./boost/histogram/axis/traits.hpp:411:20: error: deduction guide 'constexpr boost::histogram::axis::traits::rank(const Axis&)-> rank' must not have a function body
 constexpr unsigned rank(const Axis& axis) {
                    ^~~~
./boost/histogram/axis/traits.hpp:421:47: error: return type specified for deduction guide
 unsigned rank(const axis::variant<Ts...>& axis) {
                                               ^
./boost/histogram/axis/traits.hpp:421:1: error: decl-specifier in declaration of deduction guide
 unsigned rank(const axis::variant<Ts...>& axis) {
 ^~~~~~~~
./boost/histogram/axis/traits.hpp:421:47: error: 'signed' or 'unsigned' invalid for '__dguide_rank'
 unsigned rank(const axis::variant<Ts...>& axis) {
                                               ^
./boost/histogram/axis/traits.hpp:421:10: error: deduction guide for 'boost::rank<T>' must have trailing return type
 unsigned rank(const axis::variant<Ts...>& axis) {
          ^~~~
In file included from ./boost/type_traits.hpp:145:0,
                 from /corsika/test/test.cc:2:
./boost/type_traits/rank.hpp:82:27: note: 'template<class T> struct boost::rank' declared here
 template <class T> struct rank : public integral_constant<std::size_t, (::boost::detail::rank_imp<T, 0>::value)>{};
                           ^~~~
In file included from ./boost/histogram/indexed.hpp:12:0,
                 from ./boost/histogram/algorithm/empty.hpp:11,
                 from ./boost/histogram/algorithm.hpp:15,
                 from ./boost/histogram.hpp:27,
                 from /corsika/test/test.cc:4:
./boost/histogram/axis/traits.hpp:421:10: error: deduction guide 'boost::histogram::axis::traits::rank(const boost::histogram::axis::variant<Ts ...>&)-> rank' must not have a function body
 unsigned rank(const axis::variant<Ts...>& axis) {
          ^~~~
In file included from ./boost/histogram/histogram.hpp:14:0,
                 from ./boost/histogram/algorithm/project.hpp:15,
                 from ./boost/histogram/algorithm.hpp:16,
                 from ./boost/histogram.hpp:27,
                 from /corsika/test/test.cc:4:
./boost/histogram/detail/fill.hpp: In function 'typename S::iterator boost::histogram::detail::fill(std::true_type, ArgTraits, std::size_t, S&, A&, const Args&)':
./boost/histogram/detail/fill.hpp:319:26: error: 'rank' is not a member of 'boost::histogram::axis::traits'
            axis::traits::rank(axis_get<0>(axes)) == ArgTraits::nargs::value)
                          ^~~~
./boost/histogram/detail/fill.hpp:319:26: note: suggested alternatives:
In file included from /usr/include/c++/7/bits/move.h:54:0,
                 from /usr/include/c++/7/bits/stl_pair.h:59,
                 from /usr/include/c++/7/utility:70,
                 from ./boost/type_traits/detail/has_binary_operator.hpp:41,
                 from ./boost/type_traits/has_bit_and.hpp:43,
                 from ./boost/type_traits.hpp:36,
                 from /corsika/test/test.cc:2:
/usr/include/c++/7/type_traits:1468:12: note:   'std::rank'
     struct rank
            ^~~~
In file included from ./boost/type_traits.hpp:145:0,
                 from /corsika/test/test.cc:2:
./boost/type_traits/rank.hpp:82:27: note:   'boost::rank'
 template <class T> struct rank : public integral_constant<std::size_t, (::boost::detail::rank_imp<T, 0>::value)>{};
                           ^~~~

on an ubuntu 18.04 docker container with gcc7.5.0 and boost-headers 1.74

To reproduce, e.g. sudo docker run -v $PWD:/corsika -it corsika/devel:u-18.04 /bin/bash and then compile the above mini program, while putting the boost headers right there.

[mreininghaus]

The error occurs with -std=c++17, however not with -std=c++14 (both g++ (GCC) 9.2.0).

[HDembinski]

Thank you for reporting this bug. There is a name clash, somewhere rank is used without being properly qualified by a namespace.

Link to reproduce:
https://godbolt.org/z/oK4866

Only gcc seems to be affected and only versions starting with 7.1

[HDembinski]

It looks like a bug in gcc. A workaround is to replace line 82 in boost/type_traits/rank.hpp with

template <class T> using rank = integral_constant<std::size_t, (::boost::detail::rank_imp<T, 0>::value)>;

[HDembinski]

Minimal example to reproduce the problem without including boost at all:

https://godbolt.org/z/hrcYao

msvc is OK, clang is OK, gcc fails

[HDembinski]

Simple workarounds for the gcc bug were found by Thomas Ferrand and John Maddock. Those will be applied tomorrow. Next release 1.75 will have the fix for this.

[HDembinski]

gcc bug report: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97663

[HDembinski]

fixed in develop