[Bug c++/44277] [C++0x] Add warning to facilitate nullptr conversion.

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44277

--- Comment #2 from Jason Merrill <jason at gcc dot gnu.org> 2011-10-17 18:53:07 UTC ---
That seems reasonable, though I wouldn't have it enabled by default or -Wall. 
Could start with replacing convert_and_check with a cp_convert_and_check that
also performs this check.