https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66160
zhykzhykzhyk at gmail dot com changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |zhykzhykzhyk at gmail dot com --- Comment #1 from zhykzhykzhyk at gmail dot com --- Simplified: $ cat bug.cc template <typename T> class A { typedef decltype((T())[0]) t; }; $ g++ --std=c++14 bug.cc bug.cc:3:25: error: lambda-expression in unevaluated context typedef decltype((T())[0]) t; ^ Tested in g++ 5.1.0. Clang does the same thing.