Re: [PATCH] fix #69277 - [6 Regression] ICE mangling a flexible array member

[Jeff Law <law at redhat dot com>]

On 01/14/2016 05:02 PM, Martin Sebor wrote:
> On 01/14/2016 03:51 PM, Jakub Jelinek wrote:
> > On Thu, Jan 14, 2016 at 03:46:26PM -0700, Martin Sebor wrote:
> > > c++/69277 reports an ICE when mangling a template specialization
> > > involving flexible array member.  Debugging the problem revealed
> > > that GCC (prior to the ICE), due to treating flexible array
> > > members the same as zero-length arrays, produced the wrong mangling
> > > for the former.
> > >
> > > The attached patch fixes the ICE and also corrects the mangling
> > > (which now also matches Clang's).
> >
> > But then, shouldn't the decision whether to mangle it the old way or
> > the new
> > way depend on -fabi-version= ?
>
> Perhaps it should, I don't know.  Jason didn't mention anything
> when we briefly discussed the mangling change on IRC.  I can
> certainly modify the patch if it's necessary or a good idea.
> Let me know.
Jason would have the final call here, but I suspect we'll need to do 
something.

While it is a bugfix, we have traditionally queued them up to avoid 
regular ABI breakages.  It's also the case that we've traditionally 
added a warning for this kind of thing (controlled by Wabi) and also 
noted something in the manual (I think there's a section dedicated to 
this kind of thing).

jeff