https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79657
--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
$ xg++-46 -c u.cc -std=c++0x
u.cc:1:35: error: expected primary-expression before ‘)’ token
u.cc:1:35: error: ‘__underlying_type’ was not declared in this scope
u.cc:1:38: error: expected ‘}’ before ‘{’ token
u.cc:1:38: error: expected unqualified-id before ‘{’ token
u.cc:1:41: error: expected declaration before ‘}’ token
and since g++4.7 we ICE.
