[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 #4 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-10-13 08:18:07 UTC ---
See http://lwg.github.com/issues/lwg-defects.html#1225 and also 1270

result_of cannot be used for SFINAE, it requires that its arguments be a valid
expression