https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63723
--- Comment #8 from Tavian Barnes <tavianator at gmail dot com> --- Actually it is a regression: according to http://gcc.godbolt.org/, GCC 4.6.4 compiled it correctly with -std=c++0x and typedef decltype(helper<From, To>(0)) type; instead of using type = decltype(helper<From, To>(0)); while still allowing int x{1.0};