[Bug c++/69970] Surprising warning with -Wnonnull-compare - 'this' compared to NULL

[larsbj at gullik dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69970

--- Comment #3 from Lars Gullik Bjønnes <larsbj at gullik dot net> ---
The warning might be right, but is very unhelpful.
Also with gcc 5 I get no warning (and seeming working code).
Note that this is reduced (and thus a bit strange) from a much
larger code base.