[Bug c++/120499] import std: indirect use of an exported class using a vector yields undefined symbol

[nshead at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120499

Nathaniel Shead <nshead at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |nshead at gcc dot gnu.org
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2025-06-01
             Blocks|                            |103524
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Nathaniel Shead <nshead at gcc dot gnu.org> ---
Confirmed.  Minimal reproduction (without 'std'):

  // a.cpp
  export module A;
  struct allocator {
    ~allocator() {}
  };
  export template <typename _Tp>
  struct vector {
    struct _Vector_impl : public allocator {};
    _Vector_impl _M_impl;
    vector() = default;
  };
  template <typename T>
  struct regex_token_iterator {
    vector<int> _M_subs;
  };
  using cregex_token_iterator = regex_token_iterator<const char*>;


  // b.cpp
  export module B;
  import A;
  class Coll {
    vector<int> vals;
  };
  export Coll createColl() {
    return Coll{};
  }


  // c.cpp
  import B;
  int main() {
    createColl();
  }


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103524
[Bug 103524] [meta-bug] modules issue