utilities.tex:any_cast<string&>(y);                       // error; cannot
g<int>(0);        // error, substituting parameter type instantiates \tcode{A<int>}
S<char> s1;                     // error: no matching constructor
template<> enum A<char>::E : char { echar };        // ill-formed, \tcode{A<char>::E} was instantiated
struct Inner2;                // ill-formed, no diagnostic required
// ill-formed, no diagnostic required: the two expressions are functionally equivalent but not equivalent
void A<Y>::B<double>::mf2() { }       // ill-formed; \tcode{B<double>} is specialized but
template<class T> void f(T::R);         // ill-formed (no diagnostic required), attempt to declare
p->x.j = 99;                            // undefined: modifies a const subobject
int m = g(false);   // undefined behavior due to access of \tcode{x.n} outside its lifetime
C().C::~C();      // undefined behavior: temporary of type \tcode{C} destroyed twice
pb->f();          // undefined behavior, lifetime of \tcode{*pb} has ended

  // ill-formed, no diagnostic required: <explanation>
  // error: <explanation>
  // undefined behavior: <explanation>