GCC 5.1.1 Status Report (2015-06-22)

[Jason Merrill]

I'm interested in your thoughts on fixing c++/65945 in 5.2.

It's trivial to fix the alignment of nullptr_t, but I was concerned 
about ABI impact.  On further research it seems that it won't cause any 
trouble with argument alignment, since that doesn't seem to rely on 
TYPE_ALIGN at all; I think the only ABI breakage would come from 
unaligned nullptr_t fields in classes, which I expect to be very rare. 
The testcases that were breaking on SPARC and ARM without this fix have 
to do with local stack slots, which are not part of an interface.

So I think we can change this without breaking a significant amount of 
code, and better to break it now than after we've settled into the new 
library ABI.  We should certainly mention it prominently in the release 
notes if we do, and I've added a -Wabi warning for the field alignment 
change.

Does this make sense to you?

Jason