Increased semantic actions causing parsing problems

Question

I worked with the Boost mini compiler example. Here is the root of the source code: http://www.boost.org/doc/libs/1_59_0/libs/spirit/example/qi/compiler_tutorial/mini_c/

The fragment that interests me is in statement_def.hpp

The problem I am facing is that if you attach semantic actions, such as

statement_ =
                variable_declaration[print_this_declaration]
            |   assignment
            |   compound_statement
            |   if_statement
            |   while_statement
            |   return_statement
            ;

And then run the compiler mini_cin an example program, for example:

int foo(n) {
    if (n == 3) { }
    return a;
}

int main() {
    return foo(10);
}

It launches the "Duplicate Function Error" found in the file "compile.cpp" (found using the link above). Here is a snippet for quick reference:

    if (functions.find(x.function_name.name) != functions.end())
    {
        error_handler(x.function_name.id, "Duplicate function: " + x.function_name.name);
        return false;
    }

In life, I can’t understand why.

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Answer 1

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• - , statement_, ast::statement:

  qi::rule<Iterator, ast::statement(), skipper<Iterator> > statement_;
  

• ast::statement , :

  typedef boost::variant<
          variable_declaration
      , assignment
      , boost::recursive_wrapper<if_statement>
      , boost::recursive_wrapper<while_statement>
      , boost::recursive_wrapper<return_statement>
      , boost::recursive_wrapper<statement_list>
      >
  statement;
  

• , variable_declaration!

  struct variable_declaration {
      identifier lhs;
      boost::optional<expression> rhs;
  };
  

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operator%= operator=, :

    statement_ %=
            variable_declaration [print_this_declaration]
        |   assignment
        |   compound_statement
        |   if_statement
        |   while_statement
        |   return_statement
        ;

.