Re: (C++) mangling vector types

[Jason Merrill <jason at redhat dot com>]

On 11/12/2009 05:19 PM, Mark Mitchell wrote:
> So, I still tend to think that the best thing is to put the vector stuff
> into v4, and switch that on when we update libstdc++.  I think your
> suggest is coherent and well-reasoned, but it seems like a lot of
> complexity to deal with a template corner case.

It isn't such a corner case, unfortunately; any code that tries to 
overload on multiple vector sizes (i.e. MMX and SSE vectors) will break. 
 See bug 12909 and its duplicates.  This is becoming more of a problem 
with the advent of the Intel AVX extension.

> I guess another option is -fabi-version=implement-c++-for-petes-sake
> which means "use the ABI that implements as much of the language as
> possible".  That would be your version 2.1, but arguably more logically
> coherent in that it would be expected to move in the future if/when we
> find another feature we can't implement due to current mangling issues.

That seems useful, but I would also want a way to specify a particular 
revision.

Jason