[Bug c++/71904] comparing this to NULL should give a warning by default (this == NULL)

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71904

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
For an inline function like your example there's no warning unless the function
is used. If it's used, or not inline, it always warns.