[Bug c++/56961] stack overflow in gimplifier with volatile field

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56961

--- Comment #5 from Paolo Carlini <paolo.carlini at oracle dot com> ---
I think this is another manifestation of the issue discussed in cp-gimplify.c:

        /* Remove any copies of empty classes.  We check that the RHS
           has a simple form so that TARGET_EXPRs and non-empty
           CONSTRUCTORs get reduced properly, and we leave the return
           slot optimization alone because it isn't a copy (FIXME so it
           shouldn't be represented as one).

           Also drop volatile variables on the RHS to avoid infinite
           recursion from gimplify_expr trying to load the value.  */

note that it happens only when struct foo is empty...