RTTI support in devel/llvm40 (and maybe other llvm ports)

[Alexey Dokuchaev]

On Sun, Nov 12, 2017 at 07:41:04PM +0700, Alexey Dokuchaev wrote:
> On Sun, Nov 12, 2017 at 08:03:19AM +0000, Brooks Davis wrote:
> > On Fri, Nov 10, 2017 at 02:07:48PM +0700, Alexey Dokuchaev wrote:
> > > I've just found out that our `devel/llvm40' port comes without
> > > -DLLVM_ENABLE_RTTI=ON on the CMAKE_ARGS.  This is a regression
> > > from e.g. 3.4 times when it was enabled by default.
> > > 
> > > The problem is that RTTI support is required by some consumers,
> > > e.g. `graphics/openshadinglanguage' and `graphics/appleseed'
> > > (cf. https://github.com/appleseedhq/appleseed/issues/1625),
> > > but I cannot enable RTTI in those ports unless I enable it in
> > > LLVM port(s) first.
> > 
> > It's been a few years since we disabled it so I don't remember the
> > details of the decision.  I'll look into it, but am not in a position
> > to test for breakage to other ports.
> 
> Well it's probably OK to expect users or maintainers of those ports
> would speak up if enabling RTTI breaks their software. :-)
> 
> > IIRC there were once ports that failed to build both with and
> > without so it may be that we need to wait for flavors to make this
> > change.
> 
> Hmm, that's weird: I'd expect it is easier to *not* use RTTI when
> one does not need it than try to find the way around when it is not
> available (which might not be possible).  I also don't see why we
> should wait for FLAVORS: if needed, we can always make it optional
> (cf. existing EXTRAS LIT LLD LLDB options) but enabled by default.

Did you have a chance to make up your mind on this?  (If you worry
that enabling RTTI might break some ports we can always ask portmgr@
for an exp-run).

./danfe