Unable to create a message with map<string, map<string, list<double>>>

[GiulioRomualdi]

Describe the bug
I tried to create a message with map<string, list<map<string, list<double>>>> entry, but the code fails in creating the thrift.
To Reproduce
Steps to reproduce the behavior: I created a commit that can be used to check the problem: GiulioRomualdi@0a59ebc

To reproduce, compile yarp with tests and run

ctest -R idl::thrift::demo::run --output-on-failure

Expected behavior
It should be able to generate the message

Screenshots

This is the error I got

/home/gromualdi-iit.local/robot-code/robotology-superbuild/build/src/YARP/tests/yarpidl_thrift/demo/yarp_idl_to_dir/src/MapOfLists.cpp: In member function 'bool MapOfLists::read_mapOfVectors(yarp::os::idl::WireReader&)':
/home/gromualdi-iit.local/robot-code/robotology-superbuild/build/src/YARP/tests/yarpidl_thrift/demo/yarp_idl_to_dir/src/MapOfLists.cpp:538:53: error: no match for 'operator[]' (operand types are '__gnu_cxx::__alloc_traits<std::allocator<double>, double>::value_type' {aka 'double'} and 'std::string' {aka 'std::__cxx11::basic_string<char>'})
  538 |                 std::vector<double>& _val = _val[_i][_key];
      |                                                     ^
/home/gromualdi-iit.local/robot-code/robotology-superbuild/build/src/YARP/tests/yarpidl_thrift/demo/yarp_idl_to_dir/src/MapOfLists.cpp: In member function 'bool MapOfLists::nested_read_mapOfVectors(yarp::os::idl::WireReader&)':
/home/gromualdi-iit.local/robot-code/robotology-superbuild/build/src/YARP/tests/yarpidl_thrift/demo/yarp_idl_to_dir/src/MapOfLists.cpp:688:53: error: no match for 'operator[]' (operand types are '__gnu_cxx::__alloc_traits<std::allocator<double>, double>::value_type' {aka 'double'} and 'std::string' {aka 'std::__cxx11::basic_string<char>'})
  688 |                 std::vector<double>& _val = _val[_i][_key];
      |                                                     ^
gmake[2]: *** [CMakeFiles/demo_yarp_idl_to_dir.dir/build.make:219: CMakeFiles/demo_yarp_idl_to_dir.dir/yarp_idl_to_dir/src/MapOfLists.cpp.o] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:90: CMakeFiles/demo_yarp_idl_to_dir.dir/all] Error 2
gmake: *** [Makefile:101: all] Error 2

Configuration (please complete the following information):

• OS: Ubuntu 24.04
• yarp version: YARP version 3.10.1
• compiler: gcc version 13.3.0 (conda-forge gcc 13.3.0-2)

Additional context
Add any other context about the problem here.

[GiulioRomualdi]

cc @traversaro @LoreMoretti

[randaz81]

The bug is probably located in file t_yarp_generator.cc.
If the variable debug_generator_ is set to true, the generator will add comments to generated files .cpp files, showing which line of the compiler is responsible for the generation of that specific piece of output code. With these hints, it should be easier to spot the bug.
Can you help with this?