Re: (C++) mangling vector types

[Jason Merrill <jason at redhat dot com>]

On 11/12/2009 04:32 PM, Mark Mitchell wrote:
> I understand the argument, but it sounds overly complicated.  Or else
> not complicated enough.  If we no longer think that a linear progression
> of ABI versions is sufficient, then we should have switches for picking
> your point in the multi-dimensional space, rather than just a numerical
> version.

I think that a linear progression is sufficient, but I want an 
additional point between 2 and 3 since 2 is the current default and 3 
already has meaning.  Thus the 2.1 suggestion.

> That sounds theoretically right to me, but awfully complicated
> in practice.
>
> Do we have another libstdc++ ABI change coming?  I'd suggest doing this
> as -fabi-version=4, and making that the default at that point.

We do; once C++0x is finalized we will need to switch to non-refcounted 
strings and support constant time list.size().  But I believe the plan 
is to manage that transition with namespace versioning so that old and 
new code can continue to coexist as long as they aren't actually trying 
to share affected data structures.

Jason