[Bug ipa/63745] [4.9/5 Regression] mythtv build failure due to aggressive speculative devirtualization

[hubicka at ucw dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63745

--- Comment #4 from Jan Hubicka <hubicka at ucw dot cz> ---
> struct VideoBuffers
> {
>   void StartDisplayingFrame ();
> };
> struct B
> {
>   VideoBuffers vbuffers;
>   virtual void
>   StartDisplay ()
>   {
>     vbuffers.StartDisplayingFrame ();
>   }
So we devirtualize to StartDisplay but that leads to linker failure because
StartDisplayingFrame is not linked with the object file.

I think this is similar to some earlier testcases we run across in libreoffice
and we managed to declare it invalid - if you provide inline function body you
need to link the unit with symbols it uses.

Honza