[Bug middle-end/67785] New: irrevocable-3.c: transaction_callable does nothing on external declaration

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67785

            Bug ID: 67785
           Summary: irrevocable-3.c: transaction_callable does nothing on
                    external declaration
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jason at gcc dot gnu.org
                CC: aldyh at gcc dot gnu.org, rth at gcc dot gnu.org,
                    torvald at gcc dot gnu.org
  Target Milestone: ---

In gcc.dg/tm/irrevocable-3.c:

extern void bar(void) __attribute__((transaction_callable));

void
foo()
{
        __transaction_relaxed {
                bar();
        }
}

The transaction_callable attribute seems to have no effect; the transaction
goes irrevocable and calls the non-transaction entry point for bar whether or
not it is present.

Shouldn't the transaction call the TM clone if _ITM_beginTransaction says to
run instrumented code?  If not, what is the point of the attribute?