[Bug c++/122774] The compiler ICEs when compiling a file that mixes a module import with a traditional header include.

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122774

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2025-11-28

--- Comment #7 from Nathaniel Shead <nshead at gcc dot gnu.org> ---
Reduced:

  // a.cpp
  export module M;
  export extern "C" int scanf(const char *...);

  // b.cpp
  import M;
  extern "C" int scanf(const char *...);
  int scanf(const char *...);
  using ::scanf;

The issue specifically occurs when matching hidden builtins (so changing
'scanf' to 'foo' silences the ICE).  From a quick look we're adding the same
declaration multiple times to a binding, which we should not do.