View Compilation Error

0_0_36411020_25311.cpp:348:19: error: 'arr' function uses 'auto' type specifier without trailing return type
 auto arr(int n = 0)
                   ^
0_0_36411020_25311.cpp:348:19: note: deduced return type only available with -std=c++1y or -std=gnu++1y
0_0_36411020_25311.cpp:354:29: error: 'arr' function uses 'auto' type specifier without trailing return type
 auto arr(int n, Args... args)
                             ^
0_0_36411020_25311.cpp:354:29: note: deduced return type only available with -std=c++1y or -std=gnu++1y