[Bug c++/94701] New: coroutines: Wrong code for structured bindings.

["iains at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94701

            Bug ID: 94701
           Summary: coroutines: Wrong code for structured bindings.
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: iains at gcc dot gnu.org
  Target Milestone: ---

Created attachment 48330
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48330&action=edit
patch under test

As reported by Michał Dominiak, the following code gets an incorrect answer -
this is because we fail to check for DECL_VALUE_EXPR in the handling for local
vars.

struct promise;

struct future
{
  using promise_type = promise;
};

struct promise
{
  template<typename... Args>
  promise (Args&... args) {}

  coro::suspend_never initial_suspend() { return {}; }
  coro::suspend_never final_suspend() { return {}; }

  future get_return_object() { return {}; }

  void return_value(int) {}
  void unhandled_exception() {}
};

#include <cassert>

struct pair
{
  int i;
};

pair 
something ()
{
  return { 1 };
}

future 
my_coro ()
{   
  auto ret = something ();
  assert(ret.i == 1);

  auto [ i ] = something ();
  assert(i == 1);

  co_return 1;
}

int main ()
{
  my_coro ();
}