Re: OSX doesn't accept identical source/target for strcpy() anymore

If copying takes place between objects that overlap, the behavior is undefined.

Both gcc and glibc have been moving steadily in the direction of
aggressively exploiting "undefined behavior" cases for optimization
purposes.  I don't know if there is yet a platform where strncpy with
src == dest behaves oddly, but we'd be foolish to imagine that it's
not going to happen eventually.  If anything, Apple is probably doing
us a service by making it obvious where we're failing to adhere to spec.

However ... I still can't replicate this here, and as you say, there's
about zero chance of keeping our code clean of this problem unless we
can set up a buildfarm member that will catch it.

                        regards, tom lane