[Bug c++/124785] [module] ICE Regression in trees_out::decl_value

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124785

--- Comment #3 from Nathaniel Shead <nshead at gcc dot gnu.org> ---
Reduced:

  // a.cpp
  export module M:A;
  extern "C++" {
    template <typename T>
    struct Iterator {
      constexpr friend auto operator<=>(const Iterator&, const Iterator&) =
default;
    };
  }

  // b.cpp
  export module M:B;
  extern "C++" {
    template <typename T>
    struct Iterator {
      constexpr friend auto operator<=>(const Iterator&, const Iterator&) =
default;
    };
  }

  // c.cpp
  export module M;
  export import :A;
  export import :B;

$ g++ -fmodules -S [abc].cpp
c.cpp:1:8: internal compiler error: in decl_value, at cp/module.cc:8410
    1 | export module M;
      |        ^~~~~~
...