[Bug c++/80460] Incorrect fallthrough warning after [[noreturn]] function inside always-true conditional

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80460

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2017-04-19
           Assignee|unassigned at gcc dot gnu.org      |mpolacek at gcc dot 
gnu.org
     Ever confirmed|0                           |1

--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
I think it shouldn't affect those at all.

Another idea is to return fake FALLTHROUGH () if the else branch is dead.  Let
me see.

extern void die (void) __attribute__((noreturn));
extern void nop (void);

void
f (int i)
{
  switch (i)
    {
    case 0:
      if (1)
        die ();
      else
        nop ();
    case 1:;
      i++;
    }

  switch (i)
    {
    case 0:
      if (0)
        die ();
      else
        nop ();
    case 1:;
      i++;
    }

  switch (i)
    {
    case 0:
      if (1)
        nop ();
      else
        die ();
    case 1:;
      i++;
    }

  switch (i)
    {
    case 0:
      if (0)
        nop ();
      else
        die ();
    case 1:;
      i++;
    }
}