RFR: 8209758: 2 classes with same name G1PrintCollectionSetClosure cause crash when logging is enabled

[Thomas Schatzl]

Hi,

On Tue, 2018-08-21 at 12:06 -0400, Kim Barrett wrote:
> > On Aug 21, 2018, at 4:27 AM, Thomas Schatzl <thomas.schatzl at oracle.
> > com> wrote:
> > 
> > Hi,
> > 
> > On Mon, 2018-08-20 at 15:25 -0700, Leonid Mesnik wrote:
> > > Hi
> > > 
[...]
> > > I think it would be enough just to rename one of classes to avoid
> > > confusion.
> > 
> > Although I think this is a clang compiler bug, let's rename it…
> 
> This is an ODR violation, which is UB and no diagnostic required.
> I think there’s a gcc compiler/linker option to check for such, but
> we’re not turning it on.  Use of anonymous namespaces to limit the
> scope of such “local” classes would also avoid such problems, but
> there are apparently other problems with those.

I tried to enable -Wodr for some test builds but it did not warn in
this case - apparently it needs lto enabled too which we apparently do
not either.

Thanks,
  Thome