View Compilation Error

0_0_30423868_2519.cpp: In function 'constexpr bool same(double, double)':
0_0_30423868_2519.cpp:8:60: error: call to non-constexpr function 'double fabs(double)'
 constexpr bool same(double x, double y) { return fabs(x - y) < eps; }
                                                            ^