> > I've committed the part of the patch which disallows a NULL data pointer
> > with PyMemoryView_FromBuffer in r88550 and r88551.
> 
> Is it possible to create such buffer in Python (other than by
> exploiting a bug or writing a rogue extension module)?  If not, this
> should be a SystemError or even just an assert() rather than
> ValueError.

I'm against asserts for such use, since they get disabled in non-debug
mode (which is the mode 99.99% of users run in).

As for SystemError, it means "Internal error in the Python interpreter",
which isn't the case here (most likely it's an error in an extension
module instead, possibly a third-party one).