X3: position_tagged is not filled for container AST types

[Xeverous]

Hello, it's me again.

repro: https://wandbox.org/permlink/BwnJubJ7NTQl2UAW

To be more precise: position tag members in AST types that both inherit from x3::position_tagged and are containers do not get filled. position_cache.get_positions.size() is smaller than expected.

[Xeverous]

Reduced:

#include <boost/spirit/home/x3.hpp>
#include <boost/spirit/home/x3/support/ast/position_tagged.hpp>
#include <vector>
#include <string_view>
#include <iostream>

namespace x3 = boost::spirit::x3;

namespace ast
{

struct arguments : std::vector<int>, x3::position_tagged
{};

}

x3::rule<class arguments_class, ast::arguments> arguments;
auto const arguments_def = x3::int_ % ',';
BOOST_SPIRIT_DEFINE(arguments)

using iterator_type = std::string_view::const_iterator;
using range_type = boost::iterator_range<iterator_type>;
using position_cache_type = x3::position_cache<std::vector<iterator_type>>;

int main()
{
    const std::string_view input = "1, 2, 3";
          iterator_type it   {input.begin()};
    const iterator_type begin{input.begin()};
    const iterator_type end  {input.end()};
    position_cache_type position_cache(begin, end);

    const auto parser = x3::with<struct position_cache_tag>(std::ref(position_cache))[arguments];

    ast::arguments ast;
    const bool result = x3::phrase_parse(
        it,
        end,
        parser,
        x3::space,
        ast);

    if (!result)
        std::cout << "parsing failed\n";

    std::cout << position_cache.get_positions().size() << "\n";
}

Expected output: 1

Actual output: 0

[djowel]

OK, I assumed that the code was correct. After looking, it all boils down to incorrect usage. For documentation and an example of the correct usage see:

https://www.boost.org/doc/libs/1_69_0/libs/spirit/doc/x3/html/spirit_x3/tutorials/annotation.html

I'll remove my comments above. They are irrelevant.

Here's the correct code:

#include <boost/spirit/home/x3.hpp>
#include <boost/spirit/home/x3/support/ast/position_tagged.hpp>
#include <vector>
#include <string_view>
#include <iostream>

namespace x3 = boost::spirit::x3;

namespace ast
{

   struct arguments : std::vector<int>, x3::position_tagged
   {};

}

struct position_cache_tag;

struct annotate_position
{
   template <typename T, typename Iterator, typename Context>
   inline void on_success(Iterator const& first, Iterator const& last
                          , T& ast, Context const& context)
   {
      auto& position_cache = x3::get<position_cache_tag>(context).get();
      position_cache.annotate(ast, first, last);
   }
};

struct arguments_class : annotate_position {};

x3::rule<arguments_class, ast::arguments> arguments;
auto const arguments_def = x3::int_ % ',';
BOOST_SPIRIT_DEFINE(arguments)

using iterator_type = std::string_view::const_iterator;
using range_type = boost::iterator_range<iterator_type>;
using position_cache_type = x3::position_cache<std::vector<iterator_type>>;

int main()
{
   const std::string_view input = "1, 2, 3";
   iterator_type it   {input.begin()};
   const iterator_type begin{input.begin()};
   const iterator_type end  {input.end()};
   position_cache_type position_cache(begin, end);

   const auto parser = x3::with<position_cache_tag>(std::ref(position_cache))[arguments];

   ast::arguments ast;
   const bool result = x3::phrase_parse(
                                        it,
                                        end,
                                        parser,
                                        x3::space,
                                        ast);

   if (!result)
      std::cout << "parsing failed\n";

   std::cout << position_cache.get_positions().size() << "\n";
}

[Xeverous]

Ok, I have checked it, the bug was indeed in my code. Some grammar objects had duplicated code which made them bypass the need for a sub-grammar where that subgrammar did not have any associated rule ID.