https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63715
Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution|--- |INVALID --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- > gccbug.cc:15:43: error: reinterpret_cast from integer to pointer > But the result of the expression is well-defined in compile time... > Moreover, gcc-4.8.3 compiles this code just fine. Yes it might be well-defined outside of a constexpr but it is not allowed inside a constexpr as mentioned by the C++ standard. Basically 4.8.x did not implement all constraints on constexpr and 4.9 does.