[Bug c++/92831] New: extend_ref_init_temps_1 punts on COND_EXPRs

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92831

            Bug ID: 92831
           Summary: extend_ref_init_temps_1 punts on COND_EXPRs
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
  Target Milestone: ---

http://eel.is/c++draft/class.temporary#6.7
says that even ?: second and third operands need to be handled, but short
testcase modified from the standard one:
template<typename T> using id = T;

int i = 1;
int&& a = id<int[3]>{1, 2, 3}[i];           // temporary array has same
lifetime as a
const int& b = static_cast<const int&>(0);  // temporary int has same lifetime
as b
int&& c = cond ? id<int[3]>{1, 2, 3}[i] : static_cast<int&&>(0);
                                            // exactly one of the two
temporaries is lifetime-extended
like:
template<typename T> using id = T;
struct S { S () { s++; } ~S () { s--; } S (int) { s++; } static int s; };
int S::s = 0;

void
bar (bool cond)
{
  if (S::s != (cond ? 7 : 5))
    __builtin_abort ();
}

void
foo (bool cond)
{
  int i = 1;
  // temporary array has same lifetime as a
  S&& a = id<S[3]>{1, 2, 3}[i];
  // temporary S has same lifetime as b
  const S& b = static_cast<const S&>(0);
  // exactly one of the two temporaries is lifetime-extended
  S&& c = cond ? id<S[3]>{1, 2, 3}[i] : static_cast<S&&>(0);
  bar (cond);
}

int
main ()
{
  foo (true);
  foo (false);
}

fails with g++ and succeeds with clang++.