https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101355
--- Comment #2 from Dan Klishch <daklishch at gmail dot com> ---
GCC incorrectly gimplifies the program. The code that is causing the warning is
in the coroutine's actor function:
try
{
D.9829 = &frame_ptr->__p;
.UBSAN_NULL (D.9829, 4B, 0);
coro::promise_type::return_void (D.9829);
goto final.suspend;
}
finally
{
.UBSAN_NULL (D.9828, 4B, 0); // here
a::~a (D.9828);
}
Obviously, an assignment to D.9828 is missing. However, a little bit earlier a
similar destruction of `struct a' is handled correctly:
try
{
b::~b (&D.9562);
}
catch
{
D.9828 = &frame_ptr->__obj.2.3;
.UBSAN_NULL (D.9828, 4B, 0);
a::~a (D.9828);
}
I guess one of this destructor calls is a copy of another and this might be the
root of the problem. After ubsan instrumentation the call to the destructor
looks like this:
a::~a (.UBSAN_NULL (SAVE_EXPR <&frame_ptr->__obj.2.3>, 4B, 0);,
SAVE_EXPR <&frame_ptr->__obj.2.3>;);
I believe the same SAVE_EXPR is copied to the second invocation of the
destructor but the enclosed expression evaluation is placed only before the
first use of SAVE_EXPR and the control flow does not reach it before a call to
the actual (second) destructor.
I guess this can be fixed by instrumenting the calls to the destructors using
temporary variable and not SAVE_EXPR, like this:
void *ptr = &frame_ptr->__obj.2.3;
.UBSAN_NULL (ptr, 4B, 0);
a::~a (ptr);
But I don't have a solid understanding of GCC internals, so I'm not sure if it
is right.
