[Bug c++/50711] [C++0x] substitution failure reports error with result_of

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50711

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-10-13 
08:19:28 UTC ---
(In reply to comment #4)
> result_of cannot be used for SFINAE, it requires that its arguments be a valid
> expression

Should read: it requires that its arguments can form a valid expression