IDL4-CPP 1.1b1 RTF Avatar
  1. OMG Issue

IDL4CPP11 — Problem with struct mapping with forward declared types usage with C++23

Open Closed All
  • Key: IDL4CPP11-35
  • Status: open   Implementation work Blocked
  • Source: Remedy IT ( Johnny Willemsen)
  • Summary:

    When using the IDL

    struct AA;
typedef sequence<AA> AASeq;

struct BB
{
  AASeq aa_;
};
typedef sequence<BB> BBSeq;

struct AA
{
  BBSeq bb_;
};

    And compile this to C++ code according to the mapping, with C++23 clang this doesn't compile, the mapped C++ code as far as I can determine should be:

    #include <vector>

struct AA;

using AASeq = std::vector<::AA>;

struct BB
{
  ::AASeq aa_{};
};// BB

using BBSeq = std::vector<::BB>;

struct AA
{
  ::BBSeq bb_{};
};// AA

    But with clang20 with C++23 enabled this gives

    In file included from <source>:1:
In file included from /opt/compiler-explorer/gcc-14.2.0/lib/gcc/x86_64-linux-gnu/14.2.0/../../../../include/c++/14.2.0/vector:66:
/opt/compiler-explorer/gcc-14.2.0/lib/gcc/x86_64-linux-gnu/14.2.0/../../../../include/c++/14.2.0/bits/stl_vector.h:369:35: error: arithmetic on a pointer to an incomplete type 'AA'
  369 |                       _M_impl._M_end_of_storage - _M_impl._M_start);
      |                       ~~~~~~~~~~~~~~~~~~~~~~~~~ ^
/opt/compiler-explorer/gcc-14.2.0/lib/gcc/x86_64-linux-gnu/14.2.0/../../../../include/c++/14.2.0/bits/stl_vector.h:531:7: note: in instantiation of member function 'std::_Vector_base<AA, std::allocator<AA>>::~_Vector_base' requested here
  531 |       vector() = default;
      |       ^
<source>:9:14: note: in defaulted default constructor for 'std::vector<AA>' first required here
    9 |   ::AASeq aa_{};
      |              ^
<source>:3:8: note: forward declaration of 'AA'
    3 | struct AA;
      |        ^
1 error generated.
Compiler returned: 1
  • Reported: IDL4-CPP 1.0 — Thu, 14 Aug 2025 12:05 GMT
  • Updated: Mon, 18 Aug 2025 19:29 GMT