[Bug middle-end/71907] [6/7 regression] missing buffer overflow warnings with -flto

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71907

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
We can stream a fake abstract origin, refering to $self.  That fixes the issue
but I'm not sure of all the side-effects.

Testing that.