clang-tests/gcc-4_2-testsuite/src/g++.old-deja/g++.mike/misc6.C

// { dg-do assemble  }
// GROUPS uncaught
// Cfront bug A.4 (See Language System Release Notes for the
// SPARCompiler C++ version 3.0)

struct assign {
  assign& operator = (const assign&);
};
union U {
  assign a;	// { dg-error "" } member of union cannot have op= 9.4// ERROR - .*
};