frontend cpp limitations

[DavidKorczynski]

Adding some code snippets that fail with the tree-sitter frontend

[DavidKorczynski]

From: https://github.com/zeux/pugixml/blob/9d7fcbf7410e20720b093f9bb3d81dfe6500d30d/src/pugixml.cpp#L7746-L7751

PUGI_IMPL_FN xml_parse_result xml_document::load_buffer(const void* contents, size_t size, unsigned int options, xml_encoding encoding)
{
    reset();

    return impl::load_buffer_impl(static_cast<impl::xml_document_struct*>(_root), _root, const_cast<void*>(contents), size, options, encoding, false, false, &_buffer);
}

The tree looks like:

translation_unit [0, 0] - [6, 0]
  function_definition [0, 0] - [5, 1]
    type: type_identifier [0, 0] - [0, 12]
    declarator: function_declarator [0, 13] - [0, 135]
      declarator: qualified_identifier [0, 13] - [0, 55]
        scope: namespace_identifier [0, 13] - [0, 29]
        MISSING "::" [0, 29] - [0, 29]
        name: qualified_identifier [0, 30] - [0, 55]
          scope: namespace_identifier [0, 30] - [0, 42]
          name: identifier [0, 44] - [0, 55]
      parameters: parameter_list [0, 55] - [0, 135]
        parameter_declaration [0, 56] - [0, 76]
          type_qualifier [0, 56] - [0, 61]
...

The problem is that function_definition.type == PUGI_IMPL_FN and it analyses xml_parse_result as the initial scope. This is also why we have an error MISSING "::" which is because tree-sitter want's the function to be: PUGI_IMPL_FN xml_parse_result::xml_document::load_buffer

[DavidKorczynski]

When macros are used in the code, we need to include everything

void f1() {
  #ifdef M1
    f1();
  #endif

  #ifdef M2
    f2();
  #endif
}

In this case, the executable depends on the way it's compiled, so we will include both f1 and f2 in the calltree.